Precise synthesis of π-conjugated [3]catenanes and Solomon link for photothermal responses via a dual-tuning strategy

Domain: neuroscience
Published: 2026-02-13
Editorial outcome: major_revision

Abstract
Mechanically interlocked supramolecular compounds have garnered widespread attention but it remains challenging to investigate topological adjustments in such complicated structures. Here, the authors use a bidentate pyridyl ligand featuring an extended π-conjugated plane for coordination-directed self-assembly to engineer three different kinds of sophisticated complexes, including three Linear [3] catenanes 1(OTf)12, 2(OTf)12 and 3(OTf)12, two Borromean rings 4(OTf)12 and 5(OTf)12, and one heterometallic Solomon link 6(OTf)8 by modulating the Ru···Ru distances and conjugation planes of the building units or incorporating bridging silver ions. Subtle alterations in the building units can yield a diversity of topological architectures. Differences in the photothermal conversion properties of 1(OTf)12 − 6(OTf)8 are investigated. Various photothermal conversion efficiencies (23%−81%) are obtained because of the synergistic effect of π···π stacking interactions and the free radical effect of building units. This finding enables the precise regulation of topology, thereby leading to a remarkable enhancement in photothermal conversion efficiency.

Introduction
Mechanically interlocked supramolecular compounds have garnered widespread attention, primarily because of their intriguing structures and broad application prospects across various fields1–5. In recent years, an increasing number of interlocked supramolecular compounds, covering rotaxanes6, [2-6]catenanes7–11, interlocked cages12–15, ravels16,17 or molecular knots18–20, have been constructed through coordination-driven self-assembly, metal ion templating, or hydrogen bonding interactions, etc, promoting major advances in synthetic chemistry and biological molecule simulations. However, the unique topological advantages and functional differences of the reported topologies have rarely been explored because these structures are often synthesized based on different subcomponents, which may introduce many variable factors. Therefore, a more effective approach, termed the “two-component construction strategy” has been proposed. This strategy involves using an identical subcomponent unit to construct different topological architectures by varying the composition of the second component, thus enabling a comparative investigation of their characteristic differences.

Significant advances in the synthesis of multiple sophisticated interlocking molecules based on the same ligand precursors have been made by Leigh et al.21,22, Fujita et al.23,24, Stoddart et al.25,26, and others27–29. Recently, Jin et al. utilized various rigid angular, semi-flexible conjugated, or asymmetric pyridyl ligand precursors in conjunction with rhodium-based building units to synthesize and characterize 8 knots and Borromean rings, Solomon links and trefoil knots, as well as 4 knots and double trefoil knots, demonstrating that two topological species can be obtained by changing the rhodium-based building units based on the same pyridine ligand30–32. Interestingly, Sun et al. achieved structural changes between different interlocked cages based on the positive polypyridine ion ligands33–35. Furthermore, Han et al. developed a series of metallacyclic building units that incorporate N-heterocyclic metal carbenes, π-cyclopentadienyl, and π-cycloheptatrienyl motifs, establishing an innovative strategy to form unprecedented organometallic supramolecular structures36–39. While previous work has achieved diverse topologies by varying the linker ligand. In contrast, constructing multiple complex architectures from a single ligand by fine-tuning other intriguing topological species remains rare.

To our knowledge, Linear [3]catenanes40,41, Borromean rings42–44, and Solomon links45 exhibit distinct entanglement patterns. The Linear [3]catenane consists of three interlocked rings arranged in a linear sequence. In contrast, the Borromean rings constitute a highly symmetrical structure of three rings, characterized by their collective interlocking without any pairwise interlocking. Conversely, the Solomon link is a complex entity formed from just two macrocycles, each adopting a figure-eight conformation and doubly interwoven with the other. A careful analysis of the three kinds of topologies revealed that the two-component assembly strategy, which is based on the dinuclear building unit and the connecting ligand, is expected to simultaneously achieve the construction of three types of topological compounds. As we know, the synthesis of Linear [3]catenanes and Borromean rings necessitates the use of straight, rigid connecting ligands. Therefore, on the basis of a rigid and linear ligand, controlling the size and conjugation of dinuclear building units to achieve stacking interactions between connecting ligands is expected to lead to the formation of Linear [3]catenane. Meanwhile, increasing the size and conjugation properties of the dinuclear building unit to result in stacking interactions between the ligand and the building unit might generate a Borromean ring structure. However, the preparation of a Solomon link, which consists of double interlocked rings, typically requires a flexible or angular connecting ligand. To construct a Solomon link using a rigid and linear connecting ligand, it might be necessary to employ building units with torsional characteristics. Therefore, simultaneously constructing the construction of the three types of topologies based on a rigid connecting ligand might require the selection of three different construction units (those with weak conjugation, strong conjugation and distortion characteristics).

Half-sandwich organometallic compounds exhibit specific coordination sites, coordination directions and tunable electronic, steric, and catalytic properties, making them ideal components for the construction of complicated structures with specific performance46. Typically, the p-cymene Ru unit can act as a versatile platform for the assembly of functional complexes. Therefore, the three topological structures (Linear [3]catenane, Borromean ring, and Solomon link) are expected to be realized by adjusting p-cymene Ru building units based on a rigid and linear ligand.

In this work, a unique rigid pyridyl ligand precursor, 2,5-di(pyridin-4-yl)thiazolo[5,4-d]thiazole (L1) was utilized to synthesize three kinds of different topologies47, covering three Linear [3]catenanes, two Borromean rings, and one heterometallic Solomon link. Note that the thiazolo[5,4-d]thiazole unit of L1 functions as an effective π-conjugated core and an electron-rich moiety. Moreover, the pyridine groups provide two coordination sites and an electron-deficient unit. The building units E1(OTf)2, E2(OTf)2, and E3(OTf)2, which possess slightly shorter distances and weak conjugate effects, induced stacking interactions between the central unit and the pyridine unit of different ligands L1, resulting in the generation of three Linear [3]catenanes. The building units E4(OTf)2 and E5(OTf)2 with longer sizes and greater conjugation resulted in stacking interactions between the building unit and the central unit of ligand L1, leading to the formation of two Borromean rings. Interestingly, the addition of two bridging silver ions resulted in a twisted building unit E6(OTf)2, which led to the formation of a heterometallic Solomon link. The formation of all the structures was confirmed by Single-crystal X-ray diffraction (SC-XRD) analysis, Nuclear Magnetic Resonance (NMR) spectroscopy, and Electrospray Ionization-Time of Flight Mass (ESI-TOF-MS) analysis. Subsequent photothermal conversion studies were conducted using the obtained compounds, and compound 4(OTf)12 demonstrated the most significant photothermal response, with temperatures increasing from 25°C to 64.5°C and conversion efficiencies ranging from 77% to 81%. The exceptional photothermal conversion efficiency of 4(OTf)12 was attributed to the strong π···π stacking interactions between its building blocks and central unit of ligands, as well as to the free radical effect of the half-sandwich fragment. Furthermore, the results of the EPR tests confirmed that more electrons were excited in compound 4(OTf)12 before photostimulation than after, with the signal intensity increasing by 11.66 times.

Results
Self-assembly of Linear [3]catenanes 1(OTf)12, 2(OTf)12, and 3(OTf)12
In general, building units endowed with short, conjugated planes possess minimal spatial steric hindrance and exhibit a relatively weak conjugation effects. Therefore, their capacity to establish robust π···π stacking interactions with the conjugated centre of the linker ligand precursor L1 is constrained. Additionally, the donor electron property of thiazolo[5,4-d]thiazole centre and the electron deficiency property of two pyridine units of L1 enable the formation of the stacking interactions. Thus, the selection of building units with short sizes and weak conjugation effects enables the formation of Linear [3]catenanes, in which a metallamacrocycle is interlocked with two additional metallamacrocycles. A mixture of L1 (0.12 mmol) and E1(OTf)2 (0.12 mmol) in methanol at ambient temperature was stirred for 12 h to yield a dark earthy brown solution. A single crystal of 1(OTf)12 suitable for X-ray diffraction analysis was obtained by slowly diffusing diethyl ether into a saturated solution of compound 1(OTf)12 in methanol/diisopropyl ether. 2(OTf)12 and 3(OTf)12 were obtained similarly to 1(OTf)12 by using E2(OTf)2 and E3(OTf)2 instead of E1(OTf)2, and they were isolated as dark green and brown solids in high yields (1(OTf)12: 89%, 2(OTf)12: 90%, and 3(OTf)12: 91%, Fig. 1).

The structures of compounds 1(OTf)12, 2(OTf)12 and 3(OTf)12 were confirmed by single-crystal X-ray diffraction analysis. All three complexes crystallize in the triclinic P-1 space group (Supplementary Tables 1–3). Compounds 1(OTf)12, 2(OTf)12, and 3(OTf)12 were identified as Linear [3]catenanes, which were constructed by intramolecular π···π stacking interactions and steric effects. In the structure of compound 1(OTf)12, three mutually interpenetrating, rectangular metallamacrocycles form a discrete and indivisible ensemble. Each metallamacrocycle is defined by edge lengths of 16.99 Å and 7.92 Å (Supplementary Figs. 5a, 6a, 7a). Compounds 2(OTf)12 and 3(OTf)12 were halogen-substituted derivatives of 1(OTf)12, where the hydrogen atoms on the phenyl groups of the building blocks were replaced by halogen atoms. Despite modifications to the building blocks, the Ru···Ru distance remained constant, resulting in no alteration to the structural type. Each single molecule interacts with its two adjacent counterparts, thereby establishing a structural connection that does not involve direct chemical bonding (Fig. 2a, b). The molecular structure of compound 1(OTf)12 revealed that the distances between each ring ranged from 3.49 Å to 3.60 Å. Note that multiple π···π stacking interactions constituted dodecanuclear supramolecular compound 1(OTf)12 with side dimensions of 25.52 Å and 28.25 Å (Fig. 2c, d). Similarly, the molecular structure of compound 2(OTf)12 exhibited distances ranging from 3.44 Å to 3.64 Å between rings and side distances of 24.47 Å and 27.13 Å. Structural analysis revealed that compound 3(OTf)12 features ring separations spanning from 3.35 Å to 3.68 Å, with overall molecular widths of 23.54 Å and 27.39 Å on the sides (Supplementary Figs. 2, 3, 5b, c, 6b, c, 7b, c). Furthermore, space-filling representations revealed the spatial relationship of each metal ring (Fig. 2e). These high-resolution structural representations delineate the precise geometric configurations of individual metallacycles and demonstrate their relative orientations, intermolecular distances, and packing patterns in the solid state.

To investigate the behaviour of compounds 1(OTf)12, 2(OTf)12, and 3(OTf)12 in solution, the 1H NMR, 1H-1H COSY NMR, and 1H DOSY NMR spectra of these compounds were recorded. In the 1H NMR spectrum of compound 1(OTf)12 (Supplementary Fig. 15), the signals at 8.44, 8.41, 8.38, 8.03, 7.72 and 7.39 ppm were assigned to the pyridyl protons of ligand L1. Furthermore, the resonances at 6.02 and 5.78 ppm were attributed to the benzoquinone protons of the building unit E1(OTf)2. Moreover, the protons of the p-cymene moiety displayed ten characteristic signals at 6.17, 6.05, 5.95, 5.83, 3.00, 2.90, 2.31, 2.20, 1.46, and 1.38 ppm. This multiplicity in the NMR spectrum is attributed to the uniquely entangled topology of these compounds, which creates distinct proton environments within the same chemical moiety. All the resonances were assigned using the 1H-1H COSY NMR spectrum of compound 1(OTf)12 (Supplementary Fig. 16). Interestingly, the presence of a single diffusion signal in the 1H DOSY NMR spectrum of 1(OTf)12 (D = 2.42×10−6 cm2·s−1) (Supplementary Fig. 17) confirmed the homogeneity of the solution, with the calculated hydrodynamic radii (15.5 Å) closely matching the crystallographic dimensions of the molecule (Supplementary Fig. 50). For compound 2(OTf)12 (Supplementary Fig. 18), three sets of signals at 8.46, 8.43, 8.41, 8.06, 7.81 and 7.49 ppm were observed in the 1H NMR spectrum, and have been assigned to the protons within the pyridyl groups. Additionally, the signals at 6.25, 6.14, 6.05, 5.92, 3.04, 2.95, 2.38, 2.27, 1.52 and 1.44 ppm were assigned to the p-cymene protons. Similar to compound 2(OTf)12, in the 1H NMR spectrum of compound 3(OTf)12 (Supplementary Fig. 21), the signals at 8.42, 8.41, 8.39, 7.98, 7.79 and 7.47 ppm were assigned to the pyridyl protons of ligand L1, and the signals at 6.25, 6.13, 6.05, 5.92, 3.05, 2.95, 2.41, 2.28, 1.53 and 1.45 ppm were attributed to the protons of the p-cymene moiety.

The recorded 1H-1H COSY NMR and 1H DOSY NMR spectra (D = 2.34×10−6 cm2·s−1) of 2(OTf)12 and 3(OTf)12 (D = 2.40×10−6 cm2·s−1) (Supplementary Figs. 19, 20, 22, 23) unambiguously supported their formation in solution. Moreover, the calculated hydrodynamic radii of 2(OTf)12 (16.0 Å) and 3(OTf)12 (15.7 Å) were consistent with the proposed molecular structures of the compounds (Supplementary Figs. 51, 52).

Self-assembly of Borromean rings 4(OTf)12 and 5(OTf)12
Previous results have shown that building units with relatively short Ru···Ru distances and small conjugated planes can form Linear [3]catenanes 1(OTf)12, 2(OTf)12 and 3(OTf)12 through intermolecular π···π stacking interactions between the central moiety of ligand L1 and the pyridine rings of another ligand L1. We assumed that increasing the π-conjugated area of the building unit could significantly increase the π···π stacking interactions between the building unit and the ligand L1, thereby leading to the formation of structurally more robust supramolecular architectures. Note that the ligand L1 and the building units must be sufficiently large and in the correct proportions to achieve the desired ring interactions. Therefore, a difference in length between ligand L1 and the building unit that is twice the characteristic π···π interaction distance necessitates the combination of equimolar amounts of building units E4(OTf)2 and E5(OTf)2 with 0.12 mmol of L1. Methanolic mixtures of E4(OTf)2 and E5(OTf)2 with L1 were stirred at room temperature, resulting in homogeneous solutions with varying colouration (4(OTf)12: 90% and 5(OTf)12: 87%, Fig. 3a).

Furthermore, a detailed comparison of the spatial configurations between E4(OTf)2 and E5(OTf)2, as well as E1(OTf)2, E2(OTf)2 and E3(OTf)2, revealed a discernible increase in metal-metal separation distances, which occurred concurrently with the extension of the conjugated plane. These structural modifications offered critical insights and a solid foundation for the rational design of more stable supramolecular assemblies in future studies.

The synthesis of two Borromean rings was successfully achieved through multidimensional control of the constructed building blocks, with the resulting compounds being comprehensively characterized by single-crystal X-ray diffraction analysis. The molecular structures of 4(OTf)12 and 5(OTf)12 belonged to the P2/n and Fd-3c space groups, respectively (Supplementary Tables 4, 5). Specifically, compound 4(OTf)12 was formed by three mutually dependent rings, and the absence of any of them resulted in the separation of the other two (Fig. 3b, c). In both structures, three rectangular metallamacrocycles are mechanically interlocked to form a highly symmetrical topology. The metallamacrocycle in 4(OTf)12 has dimensions of 16.99 × 8.29 Å, while that in 5(OTf)12 measures 17.06 × 8.28 Å (Supplementary Figs. 5d, 5e, 6d, 6e, 7d, 7e). Furthermore, the recorded distances between the building units and the ligand L1 in compound 4(OTf)12 ranged from 3.40 Å to 3.54 Å (Fig. 3d). The spatial arrangement of molecular building units was governed by synergistic stacking interactions and the spatial constraints of the building units, resulting in the formation of a stable topological structure (Fig. 3e). Notably, as the conjugated plane of the building units expanded, no subsequent structural alterations were observed. Furthermore, the stability between each ring was maintained through their inherent interactions. Similarly, the internal π···π stacking distances of compound 5(OTf)12 ranged from 3.52 Å to 3.56 Å. (Supplementary Fig. 4).

While the conjugated plane of the building unit increased in size for both raw E4(OTf)2 and E5(OTf)2, no significant structural alterations were observed. Moreover, the presence of intramolecular π···π stacking interactions among the internal ligands and building units drove the formation of a highly symmetrical dodecanuclear topological architecture in both compounds (Fig. 4a). The behaviour of compounds 4(OTf)12 and 5(OTf)12 in solution was studied through 1H NMR, 1H-1H COSY NMR and 1H DOSY NMR spectroscopy. In the 1H NMR spectrum of compound 4(OTf)12 (Supplementary Fig. 24), two doublets were observed at 9.17 and 8.08 ppm, which were attributed to the protons of the pyridyl groups of ligand L1. Furthermore, the resonances corresponding to the protons of the naphthyl moiety appeared at 6.67 ppm, the phenyl protons of the p-cymene group appeared at 5.90 and 5.74 ppm, and the alkyl protons of the p-cymene group appeared at 2.86, 2.34 and 1.32 ppm, respectively. Moreover, the recorded diffusion coefficient (D = 2.64×10−6 cm2·s−1) and 1H-1H COSY NMR spectrum (Supplementary Figs. 25, 26) of 4(OTf)12 were consistent with the proposed structure. The 1H NMR spectrum of compound 5(OTf)12 was very similar to that of 4(OTf)12 and exhibited signals corresponding to the protons of the pyridyl group at 9.01 and 8.55 ppm, as well as resonances at 7.67, 7.44, 6.03, 5.96, 2.55, 2.17 and 1.45 ppm belonging to the protons of building unit E5(OTf)2 (Supplementary Fig. 27). Notably, the hydrodynamic radii of all the reported Borromean rings (4(OTf)12: 14.2 Å and 5(OTf)12: 12.0 Å) were determined by using the diffusion coefficients from 1H DOSY NMR spectra (D = 3.14×10−6 cm2·s−1) (Fig. 4b, c and Supplementary Fig. 29) and were in good agreement with the SC-XRD data (Supplementary Figs. 53, 54). Additionally, the ESI-TOF-MS analysis revealed strong peaks at m/z = 3460.39 ([1(OTf)12 - 2OTf-]2+) (Fig. 4d), m/z = 1354.81 ([4(OTf)12 - 5OTf-]5+) (Fig. 4e) and m/z = 1891.30 ([5(OTf)12 - 4OTf-]4+) (Supplementary Fig. 57) for the respective compounds. NMR analysis revealed the behaviour of each compound in solution. Conversely, ESI-TOF-MS analysis confirmed that it was consistent with the dodecanuclear supramolecular structure disclosed by SC-XRD.

Next, the effects of concentration variations on the structural integrity of Borromean rings 4(OTf)12 and 5(OTf)12 were examined. Remarkably, no significant changes were detected in the 1H NMR spectra of 4(OTf)12 and 5(OTf)12 when their concentrations were increased or decreased in CD3OD (Supplementary Figs. 33–36). These outcomes indicated that compounds 4(OTf)12 and 5(OTf)12 retain high stability in solution without experiencing structural changes that are dependent on concentration.

Self-assembly of Solomon link 6(OTf)8
We have demonstrated that Linear [3]catenanes and Borromean rings can be synthesized using building units of varying sizes and π-conjugation planes while employing the same ligand precursor L1. Synthesizing a novel Solomon link structure using ligand L1 might present greater challenges for the design of the building units. The formation of Solomon links typically involves the mutual twisting of interlocked metallamacrocycles, which are stabilized by π···π stacking interactions. However, the intrinsic rigidity of the ligand precursor L1 could impede torsional adjustments between its constituent rings. This topological feature of L1 prompted us to focus our attention on the use of hinge-containing building units with controlled rotational freedom, achievable through silver ion coordination known to stabilize topological conformations and provide rotational flexibility48,49, in an attempt to obtain a molecular Solomon link through dynamic conformational modulation (Fig. 5a). The building unit E6(OTf)2 was synthesized using 2-(1H-benzimidazol-2-yl)-1H-benzimidazole (BiBzlm), which possessed multiple coordination sites, and was subsequently mixed with the ligand precursor L1 in methanol. Yellow crystals of compound 6(OTf)8, suitable for X-ray diffraction analysis, were obtained by diffusing isopropyl ether into a methanolic mixture of E6(OTf)2 and ligand L1 (0.12 mmol) at room temperature (Supplementary Table 6). Each metallamacrocycle experienced structural twisting, which was then followed by interlocking to create a heterometallic Solomon link topology (Fig. 5b–d). Each macrocyclic component has dimensions of 17.03 × 11.74 Å (Supplementary Figs. 5f, 6f, 7f). Furthermore, the measured distances between the building unit E6(OTf)2 and the ligand L1 ranged from 3.19 Å to 3.37 Å within the molecular structure of compound 6(OTf)8 (Fig. 5e). Additionally, the lateral and longitudinal dimensions of 6(OTf)8 were 22.03 Å and 12.58 Å, respectively (Fig. 5f). Moreover, multiple π···π stacking interactions cooperatively stabilized its octanuclear topological architecture.

The structure of compound 6(OTf)8 was also characterized by 1H NMR (Supplementary Fig. 30), 1H-1H COSY NMR (Supplementary Fig. 31), and 1H DOSY NMR (Supplementary Fig. 32) spectroscopy. Distinct sets of resonances appeared in the 1H NMR spectrum of 6(OTf)8 at 7.12, 7.00, 6.78, and 6.39 ppm and were assigned to the protons of the pyridine groups. The signals corresponding to the protons of E6(OTf)2 appeared at 8.44, 8.33, 8.17, 7.94, 7.85, 7.66, 7.58, and 7.43 ppm, while the resonances of the p-cymene protons were recorded at 7.72, 6.69, 6.23, 5.41, 2.26, 2.16, 1.87, 1.73, 1.29, and 1.17 ppm. Interestingly, the dimensions of 6(OTf)8, as determined by SC-XRD data (Supplementary Fig. 55), were in close agreement with the hydrodynamic radii (13.8 Å) calculated from 1H DOSY NMR spectroscopy (D = 2.72×10−6 cm2·s−1). Moreover, the observed signal at m/z = 1247.18 in the ESI-TOF-MS spectrum of E6(OTf)2 was attributed to the [6(OTf)8 - 5OTf-]5+ ion (Supplementary Fig. 58), which further supported the crystallographic data.

Photothermal conversion studies
In recent years, materials featuring outstanding photothermal properties have found remarkable applications in photothermal therapy, solar light-induced seawater desalination, photothermal actuation or dynamic camouflage, among other fields50,51. Notably, supramolecular compounds with multiple π···π stacking interactions significantly enhance photothermal conversion efficiency, reinforce topological stability, advance biological applications, and enable efficient energy transduction52,53. Subsequently, the photothermal conversion properties of ligand precursor L1, building units E1(OTf)2 - E6(OTf)2, and compounds 1(OTf)12 - 6(OTf)8 were systematically investigated (Supplementary Fig. 65). To compare equivalent stacking quantities and achieve a 2:2:2:2:2:3 molar ratio of the compounds, their absorption profiles were systematically recorded across relevant wavelengths, yielding comprehensive UV-Vis spectral data. Notably, compound 4(OTf)12 exhibited the strongest absorption intensity (Fig. 6a). We evaluated the photothermal conversion performance of these compounds under 730 nm laser irradiation (Fig. 6b). Comparative photothermal analysis revealed distinct performance variations: Borromean rings 4(OTf)12 and 5(OTf)12 exhibited superior photothermal response compared to Linear [3]catenanes 1(OTf)12, 2(OTf)12 and 3(OTf)12, while Solomon link 6(OTf)8 demonstrated minimal activity (Supplementary Figs. 66–71). Remarkably, compound 4(OTf)12 exhibited the most substantial temperature increase (ΔT=132.8°C) upon irradiation. To further substantiate the photothermal conversion results with experimental data, the photothermal performance of the compounds in solution was systematically evaluated, and the corresponding conversion efficiency was calculated on the basis of the UV-Vis absorption properties of the solutions (1(OTf)12: 0.368; 2(OTf)12: 0.396; 3(OTf)12: 0.444; 4(OTf)12: 0.652; 5(OTf)12: 0.490; 6(OTf)8: 0.235) (Fig. 6c). Interestingly, compound 4(OTf)12 showed the most sensitive photothermal response (Fig. 6d and Supplementary Figs. 72–77) and compound 4(OTf)12 showed approximately the same heating trend during ten cycles of testing (Fig. 6e, f). Moreover, compounds 1(OTf)12 - 6(OTf)8 exhibited conversion efficiencies of 35–43%, 52–54%, 54–61%, 77–81%, 65–73%, and 23–30%, respectively (Supplementary Figs. 78–83). Note that thermogravimetric analysis revealed the frameworks of compounds 1(OTf)12, 2(OTf)12, 3(OTf)12, 4(OTf)12, 5(OTf)12, and 6(OTf)8 began to collapse at 214°C, 205°C, 236°C, 191°C, 208°C, and 304°C, respectively, demonstrating their good thermal stability (Supplementary Figs. 59–64). All compounds retained outstanding photothermal performance after 10 cycles, mirroring the trend initially reported for the highest-performing sample (Supplementary Fig. 84), compared with other reported materials, our supramolecular architectures demonstrate a promising photothermal conversion efficiency (Supplementary Table 7), underscoring their significant potential.

Comparative EPR spectroscopic measurements were then conducted on the building units and their corresponding compounds. Intense EPR signals indicated the presence of unpaired electrons from the organic radicals of the building units, consistent with the ground-state charge-transfer interactions observed in photothermal conversion studies54,55. EPR spectroscopy signal changes before and after light exposure were observed for each compound. Moreover, the signal intensities of compounds 1(OTf)12 - 6(OTf)8 were increased by 4.59, 5.08, 6.58, 11.66, 6.64, and 3.67 times, respectively (Fig. 7). The results indicated that the organic radical properties of the components directly govern the photoresponsive behaviour of the compounds.

Methods
Materials
Reagents and solvents were acquired from commercial suppliers and employed as received, unless specifically stated otherwise.

Synthesis of ligand L1
A mixture of dithiooxamide (180.3 mg, 1.5 mmol) and 4-Pyridinecarboxaldehyde (0.20 mL, 2.2 mmol) in anhydrous DMF (20 mL) was refluxed at 150°C for 6 h. Upon cooling, The product was washed with deionized water. The resulting yellow solid was isolated by filtration, and obtained in 76% yield.

Synthesis of E1(OTf)2, E2(OTf)2, E3(OTf)2, E4(OTf)2, and E5(OTf)2
Adding AgOTf (123.2 mg, 0.48 mmol) and Dichloro(p-cymene)ruthenium(II) dimer (73.49 mg, 0.12 mmol) to 18 ml methanol at room temperature, the mixture was treated with light protection and stirred in dark condition for 12 h, and then the white AgCl precipitate was filtered out to obtain yellow solution. Subsequently 2,5-Dihydroxy-1,4-Benzoquinone (16.8 mg, 0.12 mmol), 2,5-Dichloro-3,6-Dihydroxy-1,4-Benzoquinone (25.1 mg, 0.12 mmol), 2,5-Dibromo-3,6-Dihydroxy-1,4-Benzoquinone (35.7 mg, 0.12 mmol), 5,8-Dihydroxy-1,4-naphthoquinone (22.8 mg, 0.12 mmol) or 6,11-Dihydroxy-5,12-Naphthacenedione (34.8 mg, 0.12 mmol), and NaOH (9.6 mg, 0.24 mmol) were added to the filtrate. Then the mixed solution was stirred at room temperature for 12 h to give different colours solution, the nonpolar solvent ether was added to the mixed solution of methanol, the product was recrystallized from a diethyl ether mixture to afford E1(OTf)2, E2(OTf)2, E3(OTf)2, E4(OTf)2, and E5(OTf)2.

Synthesis of E6(OTf)2
A mixture of AgOTf (184.8 mg, 0.72 mmol) and dichloro(p-cymene)ruthenium(II) dimer (73.49 mg, 0.12 mmol) in methanol (18 mL) was stirred under light protection at room temperature for 12 h. Subsequently, the white AgCl precipitate was removed by filtration to afford a yellow solution. This filtrate was then charged with 2-(1H-benziMidazol-2-yl)-1H-benziMidazole (28.1 mg, 0.12 mmol) and NaOH (9.6 mg, 0.24 mmol). Then the mixed solution was stirred at room temperature for 12 h to give a yellow solution, the product was precipitated by adding diethyl ether to the methanol solution, collected by filtration, and then recrystallized from diethyl ether to afford E6(OTf)2.

Synthesis of 1(OTf)12, 2(OTf)12, 3(OTf)12, 4(OTf)12, 5(OTf)12, and 6(OTf)8
Mixing the ligand L1 with compounds E1(OTf)2, E2(OTf)2, E3(OTf)2, E4(OTf)2, E5(OTf)2 or E6(OTf)2 in equal molar amount in 18 ml methanol solution for 12 h. The single crystals were grown by liquid diffusion, and the nonpolar solvent ether was added to the mixed solution of methanol. The product was recrystallized from a diethyl ether mixture to afford crystals 1(OTf)12, 2(OTf)12, 3(OTf)12, 4(OTf)12, 5(OTf)12, and 6(OTf)8. Notably, single crystals of compound 6(OTf)8 suitable for X-ray diffraction were obtained via diffusion after just one day, whereas compounds 1(OTf)12, 2(OTf)12, and 3(OTf)12 required two or three days, and compounds 4(OTf)12 and 5(OTf)12 required five to seven days.

Characterization data for 1(OTf)12 (Linear [3]catenane)
Total yield of crystals: 89%, 1H NMR (500 MHz, CD3OD, ppm, with respect to p-cymene Ru): δ = 8.44 (d, 2H J=7.5 Hz, pyridyl-Ha1), δ = 8.41 (d, 2H J=9.0 Hz, pyridyl-Ha2), δ = 8.38 (d, 2H J=7.0 Hz, pyridyl-Ha3), δ = 8.03 (d, 2H J=7.5 Hz, pyridyl-Hb1), δ = 7.72 (d, 2H J=7.5 Hz, pyridyl-Hb3), δ = 7.39 (d, 2H J=7.0 Hz, pyridyl-Hb2), δ = 6.17 (d, 2H J=7.5 Hz, phenyl-Hf1 of p-cymene), δ = 6.05 (d, 2H J=7.5 Hz, phenyl-Hf2 of p-cymene), δ = 6.02 (s, 1H, benzoquinonyl-Hc1), δ = 5.95 (d, 2H J=7.5 Hz, phenyl-He1 of p-cymene), δ = 5.83 (d, 2H J=6.5 Hz, phenyl-He2 of p-cymene), δ = 5.78 (s, 1H, benzoquinonyl-Hc2), δ = 3.00 (m, 1H J=34.5 Hz, substituted-methyl-Hg1 of p-cymene), δ = 2.90 (m, 1H J=33.5 Hz, substituted-methyl-Hg2 of p-cymene), δ = 2.31 (s, 3H, methyl-Hd1 of p-cymene), δ = 2.20 (d, 3H J=12.0 Hz, methyl-Hd2 of p-cymene), δ = 1.46 (d, 6H J=8.5 Hz, methyl-Hh1 of p-cymene), δ = 1.38 (d, 6H J=8.5 Hz, methyl-Hh2 of p-cymene); ESI-TOF-MS (m/z): [1(OTf)12 - 2OTf]2+ calcd. for C252H228O60N24S24F36Ru12, 3460.3936; found, 3460.3938; analysis (calcd., found for C252H228O60N24S24F36Ru12): C (41.93, 41.64), H (3.18, 3.23), N (4.66, 4.78).

Characterization data for 2(OTf)12 (Linear [3]catenane)
Total yield of crystals: 90%. 1H NMR (500 MHz, CD3OD, ppm, with respect to p-cymene Ru): δ = 8.46 (d, 2H J=6.5 Hz, pyridyl-Ha1), δ = 8.43 (d, 2H J=6.0 Hz, pyridyl-Ha1), δ = 8.41 (d, 2H J=6.5 Hz, pyridyl-Ha2), δ = 8.06 (d, 2H J=6.5 Hz, pyridyl-Hb1), δ = 7.81 (d, 2H J=6.5 Hz, pyridyl-Hb3), δ = 7.49 (d, 2H J=5.5 Hz, pyridyl-Hb2), δ = 6.25 (d, 2H J=6.0 Hz, phenyl-He1 of p-cymene), δ = 6.14 (d, 2H J=6.0 Hz, phenyl-He2 of p-cymene), δ = 6.05 (d, 2H J=6.0 Hz, phenyl-Hd1 of p-cymene), δ = 5.92 (d, 2H J=6.0 Hz, phenyl-Hd2 of p-cymene), δ = 3.04 (m, 1H J=27.5 Hz, substituted-methyl-Hj1 of p-cymene), δ = 2.95 (m, 1H J=26.5 Hz, substituted-methyl-Hj2 of p-cymene), δ = 2.38 (s, 3H, methyl-Hf1 of p-cymene), δ = 2.27 (s, 3H, methyl-Hf2 of p-cymene), δ = 1.52 (d, 6H J=7.0 Hz, methyl-Hc1 of p-cymene), δ = 1.44 (d, 6H J=6.5 Hz, methyl-Hc2 of p-cymene); analysis (calcd., found for C252H216O60N24S24F36Cl12Ru12): C (39.66, 39.95), H (2.85, 2.73), N (4.40, 4.26).

Characterization data for 3(OTf)12 (Linear [3]catenane)
Total yield of crystals: 91%. 1H NMR (500 MHz, CD3OD, ppm, with respect to p-cymene Ru): δ = 8.42 (d, 2H J=2.0 Hz, pyridyl-Ha1), δ = 8.41 (d, 2H J=7.0 Hz, pyridyl-Ha2), δ = 8.39 (d, 2H J=2.0 Hz, pyridyl-Ha3), δ = 7.98 (d, 2H J=4.0 Hz, pyridyl-Hb1), δ = 7.79 (d, 2H J=7.0 Hz, pyridyl-Hb3), δ = 7.47 (d, 2H J=5.0 Hz, pyridyl-Hb2), δ = 6.25 (d, 2H J=6.0 Hz, phenyl-He1 of p-cymene), δ = 6.13 (d, 2H J=6.0 Hz, phenyl-He2 of p-cymene), δ = 6.05 (d, 2H J=6.0 Hz, phenyl-Hd1 of p-cymene), δ = 5.92 (d, 2H J=6.0 Hz, phenyl-Hd2 of p-cymene), δ = 3.05 (m, 1H J=14.0 Hz, substituted-methyl-Hf2 of p-cymene), δ = 2.95 (m, 1H J=28.5 Hz, substituted-methyl-Hf1 of p-cymene), δ = 2.41 (s, 3H, methyl-Hc1 of p-cymene), δ = 2.28 (s, 3H, methyl-Hc2 of p-cymene), δ = 1.53 (d, 6H J=7.0 Hz, methyl-Hg1 of p-cymene), δ = 1.45 (d, 6H J=7.0 Hz, methyl-Hg2 of p-cymene); analysis (calcd., found for C252H216O60N24S24F36Br12Ru12): C (37.07, 37.36), H (2.67, 2.42), N (4.12, 3.96).

Characterization data for 4(OTf)12 (Borromean ring)
Total yield of crystals: 90%. 1H NMR (500 MHz, CD3OD, ppm, with respect to p-cymene Ru): δ = 9.16 (d, 2H J=5.0 Hz, pyridyl-Ha), δ = 8.08 (d, 2H J=5.0 Hz, pyridyl-Hb), δ = 6.67 (s, 2H, naphthyl-Hc), δ = 5.90 (d, 2H J=5.5 Hz, phenyl-Hf of p-cymene), δ = 5.74 (d, 2H J=5.5 Hz, phenyl-He of p-cymene), δ = 2.86 (s, 1H, substituted-methyl-Hg of p-cymene), δ = 2.24 (s, 3H, methyl-Hd of p-cymene), δ = 1.32 (s, 6H, methyl-Hh of p-cymene); ESI-TOF-MS (m/z): [4(OTf)12 - 5OTf]5+ calcd. for C276H240O60N24S12F36Ru12, 1354.8094; found, 1354.8053 analysis (calcd., found for C276H240O60N24S12F36Ru12): C (46.46, 46.13), H (3.39, 3.48), N (4.71, 4.63).

Characterization data for 5(OTf)12 (Borromean ring)
Total yield of crystals: 87%. 1H NMR (500 MHz, CD3OD, ppm, with respect to p-cymene Ru): δ = 9.01 (d, 2H J=2.0 Hz, pyridyl-Ha), δ = 8.55 (d, 2H J=6.5 Hz, tetracene-Hc), δ = 7.67 (d, 2H J=7.5 Hz, tetracene-Hd), δ = 7.44 (d, 2H J=5.5 Hz, pyridyl-Hb), δ = 6.03 (d, 2H J=5.0 Hz, phenyl-Hg of p-cymene), δ = 5.95 (d, 2H J=9.0 Hz, phenyl-Hf of p-cymene), δ = 2.55 (s, 3H, methyl-He of p-cymene), δ = 2.17 (s, 1H, substituted-methyl-Hh of p-cymene), δ = 1.47 (d, 6H J=6.5 Hz, methyl-Hi of p-cymene); ESI-TOF-MS (m/z): [5(OTf)12 - 4OTf]4+ calcd. for C324H264O60N24S24F36Ru12, 1881.0448; found, 1881.0420 analysis (calcd., found for C324H264O60N24S24F36Ru12): C (47.93, 47.73), H (3.28, 3.35), N (4.14, 4.25).

Characterization data for 6(OTf)8 (Solomon link)
Total yield of crystals: 86%. 1H NMR (500 MHz, CD3OD, ppm, with respect to p-cymene Ru): δ = 8.46 (m, 2H J=15.0 Hz, benzimidazole-Hc1), δ = 8.33 (d, 2H J=7.5 Hz, benzimidazole-Hf1), δ = 8.17 (d, 2H J=8.5 Hz, benzimidazole-Hc2), δ = 7.94 (m, 2H J=15.0 Hz, benzimidazole-Hf2), δ = 7.85 (d, 2H J=8.5 Hz, benzimidazole-Hd1), δ = 7.72 (d, 2H J=5.0 Hz, phenyl-Hi1 of p-cymene), δ = 7.68 (d, 2H J=7.0 Hz, benzimidazole-He1), δ = 7.59 (m, 2H J=15.5 Hz, benzimidazole-Hd2), δ = 7.43 (d, 2H J=6.5 Hz, benzimidazole-He2), δ = 7.13 (m, 2H J=15.0 Hz, pyridyl-Hb1), δ = 7.01 (d, 2H J=5.0 Hz, pyridyl-Hb2), δ = 6.78 (d, 2H J=7.5 Hz, pyridyl-Hb2), δ = 6.69 (d, 2H J=6.0 Hz, phenyl-Hh1 of p-cymene), δ = 6.40 (d, 2H J=5.5 Hz, pyridyl-Hb2), δ = 6.23 (d, 2H J=5.5 Hz, phenyl-Hh2 of p-cymene), δ = 5.42 (d, 2H J=3.5 Hz, phenyl-He1 of p-cymene), δ = 2.67 (s, 3H, methyl-He2 of p-cymene), δ = 2.16 (s, 6H, methyl-Hd1 of p-cymene), δ = 1.87 (s, 1H, substituted-methyl-Hk1 of p-cymene), δ = 1.73 (s, 1H, substituted-methyl-Hk2 of p-cymene), δ = 1.29 (s, 3H, methyl-Hf1 of p-cymene), δ = 1.19 (m, 6H J=14.0 Hz, methyl-Hg2 of p-cymene); ESI-TOF-MS (m/z): [6(OTf)8 - 5OTf]5+ calcd. for C256H208O24N48S16F24Ag8Ru8, 1246.9790; found, 1246.9770; analysis (calcd., found for C256H208O24N48S16F24Ag8Ru8): C (44.04, 43.86), H (3.00, 3.13), N (9.63, 9.97).

Peer review rounds
[{"round": 1, "reviewer_comments": {"reviewer_1": "I have read the manuscript written by Zhao, Li, Dang and coworkers with title “Precise Synthesis of π-Conjugated Metalla-Links ( 412 413 and 623) for Photothermal Responses via a Dual-Tuning Strategy.” The paper shows new interlocked structures synthesized using a new bidentate pyridyl ligand with an extended π-conjugated plane by means of the molecular clip strategy (pioneered by Prof. Stang) already used by some of the authors in a recent article (Ref. Angew. Chem. Int. Ed, 2024, 63, e202406552). All the reported structures of the macromolecular compounds are unambiguously determined via SC-XRD analysis, NMR spectroscopic characterization, and electrospray ionization-time of flight mass spectrometry (ESI-TOF-MS). The materials have been studied regarding their photothermal conversion properties in the solution state. The authors claim the photothermal conversion due to the synergistic effect on the π···π interactions and the free radical effect (corroborated by EPR spectroscopy) of the building units.\n\nThe work has a strong fundamental supramolecular chemistry and has used a new ligand for their assembly by also modulating the Ru···Ru distances and conjugation planes of the building units or by incorporating bridging silver metal centers in a heterometallic structure (Solomon link). Conceptually, the general strategy of using the Ru and p-cymene molecular clips with pyridine-based ligands has already been demonstrated by P. J. Stang, K.-W. Chi and coworkers (Chem.Commun. 50, 7542–7544 (2014) and the authors in other publications.). Also, the photothermal conversion approach has been used by the same authors in Angew. Chem. Int. Ed, 2024, 63, e202406552.\n\nThe X-ray structures are solved and refined with good statistics. Only the 2(OTf)12 structure has high R-factors (from Table 2 Supplementary Material: Final R indexes [all data] R1 = 0.1576, wR2 = 0.3140). This can be observed by the flat and elongated thermal parameters of all the atoms in the asymmetric unit. While this structure will not be accepted in a Acta. Cryst. journals, however, for the purpose of this work, I feel it is sufficient to see the topological features but I will be cautious with the reported distances.\n\nThe work is of interest to the readers of Nature Communications because it demonstrates the control in the formation of different mechanically interlocked structures ranging from catenanes, Borromean rings and Solomon links by changing the dimensions and the aromaticity the self-assembling clips. The supramolecular approach used by the authors to synthesize the reported structures is fundamental in this field and I feel that will help other researchers to create new self-assembling materials with potential chemical and physical properties. Thus, I will be happy to accept the submitted work after the raised points reported below have been addressed.\n\nMajor Revisions\n1. It will be good to know if the reported structures have channels or voids that could be applied to explore some host-guest chemistry. The authors should give the % of void space occupied by the disordered solvent as the Squeeze protocol has been applied to all the structures.\n2. In the main article and supplementary material, I could not find the time needed for the crystallization process. It is mentioned that antisolvent diffusion is used to obtain the crystals, but it is not specified for how many hours or days. This should be added.\n3. I am wondering about the stability of the reported structures in the solid state. Are they stable if maintained at room temperature for some hours? This should be commented on in the paper. This is important for applications such as actuators as reported by the authors (Angew. Chem. Int. Ed, 2024, 63, e202406552)\n4. One important aspect to be mentioned is if the structures can be also obtained as microcrystalline (powder) samples. This is crucial to see if the reported structures are obtained homogeneously and if they are produced faster than using slower single crystallization methods. The structural stability in the solid-state is very important to think of applications like photothermal conversion efficiencies. Can the authors mention about it?\n5. The authors should mention the Alert-A of 2(OTf)12 structure in the Check-CIF.\nIt should be mentioned why this structure 2(OTf)12, compared to the rest (that are very good), gave such alert.\nI suggest also to try (if possible) to recrystallize and solve again this Linear [3]catenane (2(OTf)12).\n6. In Line 32, the first sentence in the introduction contains only three (1-3) references on mechanically interlocked materials. To strengthen the introduction, the authors should include more relevant contributions in this area like the following recent reports: J. Am. Chem. Soc. 2020, 142, 9537–9543; J. Am. Chem. Soc. 142, 10267−10272 (2020); Angew. Chem. Int. Ed. 2025, e202516952; Commun. Chem. 2025, 8, 92; ChemistryEurope 1, e202300047 (2023).\nIn line 35, in reference 10, the authors should include relevant work on interlocked cages such as those (or some) mentioned above.\n\nMinor Revisions\nIn line 40, the sentence starting…… and finishing: “Therefore, the best method….different topological complexes” does not read well and it is difficult to understand the message the authors are trying to give. This should be revised.\nIn line 60, the authors used the word complicated. For instance “three complicated topological species…” I would use another word instead of complicated like intriguing.", "reviewer_2": "In this paper, the authors report a novel, efficient, and precise method for constructing supramolecular architectures and synthesized a series of catenanes, Borromean rings and other related structures compounds via this method. The structure of these compounds were confirmed by single-crystal diffraction and other methods. These compounds exhibit excellent photothermal conversion properties. This work is interesting and suitable for publication after minor revisions.\n1. The authors should discuss the application prospects of this photothermal conversion property. In which areas might it have potential applications?\n2. Compared with the reported photothermal conversion materials, what advantages do these supramolecular architectures in this work possess?\n3. How about the stability of these supramolecular architectures in photothermal conversion process?", "reviewer_3": "The manuscript by Zhao, Li, Dang and co-workers describes an investigation of a series of ruthenium complexes that form a variety of metallacycles through the employment of bridging and terminal ligands. Of particular importance is the generation of topologically interesting compounds with the generation of catenanes, Borromean rings and a Solomon link structure.\nWhilst the topology of the structures is interesting, there are many aspects that require attention before the manuscript would be suitable for publication. In particular, I have the following concerns:\n1. The authors provide a long introduction focussed on changing various components and examining the structural impact of these changes. This is presented as a 'formidable frontier challenge in synthetic chemistry.'\nIn my opinion this approach is really quite common i.e. tinker with the components to various extents and see if the structures change, if at all. I would strongly favour omission of most of the introduction and use the introduction to merely introduce the various components employed and discuss relevant types of macrocycle entanglement.\n2. The introduction contains numerous sentences that are difficult to understand, for example,\n'Therefore, the best method is that using the identical subcomponent units to synthesize different topological structures by changing the structure of other components, which is conducive to studying the influence of the same component on the structure and function of different topological complexes.'\n3. The photothermal studies seem somewhat out of place in this work. I am not sure I understand the reasons for performing these measurements. Are there specific applications for these molecules relating to this property? Are these materials behaving differently to discrete metallacycles or even metal complexes? Does the entanglement enhance the photothermal response? If so, what is the reason?\n4. In the EPR studies there are enhancements of signals indicating unpaired electrons. Are there unpaired electrons in the freshly prepared samples? If so, which component has the unpaired electron. What fraction of compounds have unpaired electrons? Could it be less than 1%? Does the entanglement of the metallacycles affect the EPR signal? What is the origin of the paramagnetism?\n5. In the discussion, the synthetic method is described as novel and highly precise when in fact it seems that if only minor changes are made to the structure, like changing from dihydroxybenzoquinone, to chloranilic acid and bromanilic acid a similar structure is obtained. When the oxygen donor ligand is substituted for a different type of oxygen donor, with different geometry, there is a topological change and finally when the oxygen donor ligand is changed to a Ag(I)bis(benzimidazole) type donor, it is not surprising that a very different topology is obtained. Thus when considerable changes are made to the ligands it is not at all surprising to obtain a different structure. I do not think the claims of being 'novel' and 'highly precise' are justified.\n6. Given the determination of crystal structure for these materials it was surprising to see a very limited discussion of the actual structure e.g. internal van der Waals ring dimensions and macrocycle shapes.\n7. Space groups reported in the manuscript do not always match the space groups indicated in the cifs."}, "author_response": "Reply: Many thanks for your advice and your careful work. Through single crystal X-ray diffraction analysis, the size of channels/voids in all structures are well confirmed. The calculated cavity diameters are 2.3 Å (1(OTf) ), 2.35 Å (2(OTf) ), 1.9 Å (3(OTf) ), 4.5 Å (4(OTf) ), 4.3 Å 12 12 12 12 (5(OTf) ), and 4.3 Å (6(OTf) ) (Figure S1). The larger cavities in compounds 4(OTf) - 6(OTf) 12 8 12 8 (approximately 4.3 - 4.5 Å) show potential in host-guest chemistry, as their dimensions are suitable for accommodating small guest molecules or ions. In contrast, the smaller voids in compounds 1(OTf) - 3(OTf) (1.9 - 2.35 Å) can potentially be explored for selective ion exchange or the 12 12 encapsulation of very small species like protons or lithium ions. Furthermore, we have calculated the percentage of void space occupied by the disordered solvent that were treated using the SQUEEZE routine in PLATON. The results are as follows: for compound 1(OTf) , the total 12 potential solvent-accessible volume is 1205.4 Å3, with the disordered solvent constituting 0.44%; for compound 2(OTf) , the total potential solvent-accessible volume is 4631.7 Å3, with the 12 disordered solvent constituting 1.75%; for compound 3(OTf) , the total potential solvent-accessible 12 volume is 3939.4 Å3, with the disordered solvent constituting 0.61%; for compound 4(OTf) , the 12 total potential solvent-accessible volume is 8211.4 Å3, with the disordered solvent constituting 0.39%; for compound 5(OTf) , the total potential solvent-accessible volume is 89473.3 Å3, with 12 the disordered solvent constituting 1.90%; for compound 6(OTf) , the total potential solvent- 8 accessible volume is 10956.6 Å3, with the disordered solvent constituting 0.33%.\n\nFigure S1. The cavity structure of compounds (a) 1(OTf) (2.3 Å) (b) 2(OTf) (2.35 Å) (c) 12 12 3(OTf) (1.9 Å) (d) 4(OTf) (4.5 Å) (e) 5(OTf) (4.3 Å) and (f) 6(OTf) (4.3 Å). For clarity, the 12 12 12 8 hydrogen atoms are omitted.\n\n2. In the main article and supplementary material, I could not find the time needed for the crystallization process. It is mentioned that antisolvent diffusion is used to obtain the crystals, but it is not specified for how many hours or days. This should be added.\nReply: We thank the reviewer for this valuable suggestion. The crystallization times, based on our repeated experimental observations, have now been updated in the revised manuscript methods section. Specifically: Crystals of compound 6(OTf) suitable for single-crystal X-ray diffraction 8 were typically obtained within 1 day. Compounds 1(OTf) , 2(OTf) , and 3(OTf) required 2 - 3 12 12 12 days to form under the same conditions. Compounds 4(OTf) and 5(OTf) required a longer period 12 12 of 5 - 7 days.\n\n3. I am wondering about the stability of the reported structures in the solid state. Are they stable if maintained at room temperature for some hours? This should be commented on in the paper. This is important for applications such as actuators as reported by the authors (Angew. Chem. Int. Ed, 2024, 63, e202406552)\nReply: We thank the reviewer for raising this important point regarding the solid-state stability of our compounds. To directly address the reviewer's concern regarding solid-state stability, we conducted 10 heating-cooling cycles on all solid samples to evaluate their photothermal performance. The results show negligible attenuation in conversion efficiency over these cycles (Figure S2), demonstrating excellent robustness at room temperature and above. Furthermore, we observed strong evidence of stability during routine handling. Powdered samples stored in Eppendorf tubes for up to two weeks retained their structural integrity, as confirmed by high-quality ¹H NMR spectra in CD₃OD. Thermogravimetric analysis further corroborated these findings, revealing decomposition onset temperatures of 213.5 °C, 204.8 °C, 236.2 °C, 191.3 °C, 208.2 °C, and 304.3 °C for compounds 1(OTf)₁₂, 2(OTf)₁₂, 3(OTf)₁₂, 4(OTf)₁₂, 5(OTf)₁₂, and 6(OTf)₈, respectively (Figures S3a-S3f). This confirms their outstanding thermal stability and validates long- term stability under ambient storage conditions. All additional data have been incorporated into the Supporting Information.\n\nFigure S2. Cycling photothermal property of compounds 1(OTf) - 6(OTf) under 730 nm laser 12 8 irradiation in the solid state (0.6 W/cm2).\n\nFigure S3. Thermogravimetric analysis of compounds (a) 1(OTf) , (b) 2(OTf) , (c) 3(OTf) , (d) 12 12 12 4(OTf) , (e) 5(OTf) , and (f) 6(OTf) .\n12 12 8\n\n4. One important aspect to be mentioned is if the structures can be also obtained as microcrystalline (powder) samples. This is crucial to see if the reported structures are obtained homogeneously and if they are produced faster than using slower single crystallization methods. The structural stability in the solid-state is very important to think of applications like photothermal conversion efficiencies. Can the authors mention about it?\nReply: We are grateful to the reviewer's emphasis on the critical importance of structural homogeneity and stability. To address this point, we carried out control experiments to confirm the structural identity of the microcrystalline powders with the single crystals. The powders were prepared by adding diethyl ether into the mixture after 8 hours of reaction in methanol. Initial characterization by 1H NMR spectroscopy revealed spectra identical to those of the single crystals grown via slow diffusion, thereby confirming their chemical homogeneity. Moreover, single-crystal X-ray diffraction analysis of recrystallized samples from these powders unequivocally confirmed that their unit cell parameters matched the previously tested single-crystal data in this work. Consequently, we have established that the rapidly precipitated powders and the slowly grown single crystals are structurally identical. This outcome not only verifies the homogeneous nature of the obtained structures but also highlights a more efficient and faster synthetic pathway to the same solid-state structure—a key consideration for evaluating application potential.\n\n5. The authors should mention the Alert-A of 2(OTf) structure in the Check-CIF. 12 It should be mentioned why this structure 2(OTf) , compared to the rest (that are very good), gave 12 such alert. I suggest also to try (if possible) to recrystallize and solve again this Linear [3]catenane (2(OTf) ). 12\nReply: We sincerely thank the reviewer for this valuable comment. In response, we have successfully recrystallized the sample of compound 2(OTf) and collected a new single-crystal X- 12 ray diffraction dataset. The newly refined structure no longer shows any Alert A-level issues in the CheckCIF report. The updated crystallographic data for 2(OTf) have been deposited at the 12 Cambridge Crystallographic Data Centre (CCDC No. 2503127). A revised description of the crystal parameters for compound 2(OTf) has been included in the Supporting Information and highlighted 12 for clarity.\n\n6. In Line 32, the first sentence in the introduction contains only three (1-3) references on mechanically interlocked materials. To strengthen the introduction, the authors should include more relevant contributions in this area like the following recent reports: J. Am. Chem. Soc. 2020, 142, 9537–9543; J. Am. Chem. Soc. 142, 10267−10272 (2020); Angew. Chem. Int. Ed. 2025, e202516952; Commun. Chem. 2025, 8, 92; ChemistryEurope 1, e202300047 (2023).\nIn line 35, in reference 10, the authors should include relevant work on interlocked cages such as those (or some) mentioned above.\nReply: We are grateful to the reviewer for pointing out these highly relevant references on interlocked cages, which represent significant contributions to the field. We completely agree that citing these recent contributions is crucial to providing a more comprehensive background on mechanically interlocked materials. We have incorporated all the suggested references (J. Am. Chem. Soc. 2020, 142, 9537–9543; J. Am. Chem. Soc. 142, 10267−10272 (2020); Angew. Chem. Int. Ed. 2025, e202516952; Commun. Chem. 2025, 8, 92; ChemistryEurope 1, e202300047 (2023)) into the revised manuscript. These references have been added to the introduction and to the discussion concerning interlocked cages.\n\n7. In line 40, the sentence starting…… and finishing: \"Therefore, the best method….different topological complexes\" does not read well and it is difficult to understand the message the authors are trying to give. This should be revised.\nReply: We appreciate the reviewer's feedback regarding the lack of clarity in the original sentence. As suggested, we have revised it by splitting the long sentence into two separate statements and toning down the absolute claim. We believe the revised version now more clearly conveys our methodological approach. The revised text states: \"Therefore, a more effective approach, termed the \"two-component construction strategy\" has been proposed. This strategy involves using an identical subcomponent unit to construct different topological architectures by varying the composition of the second component, thus enabling a comparative investigation of their characteristic differences.\". All revisions have been highlighted in yellow in the manuscript.\n\n8. In line 60, the authors used the word complicated. For instance “three complicated topological species…” I would use another word instead of complicated like intriguing.\nReply: We are grateful to the reviewer for this constructive comment. We agree that “intriguing” is a more appropriate and scientifically objective term than “complicated” in this context, as it better reflects the fascinating nature of the structures without undue subjective bias. The change has been made accordingly, and we have also revised similar language throughout the text to maintain consistency. The revisions are marked in yellow.\n\nReviewer 2:\nIn this paper, the authors report a novel, efficient, and precise method for constructing supramolecular architectures and synthesized a series of catenanes, Borromean rings and other related structures compounds via this method. The structure of these compounds were confirmed by single-crystal diffraction and other methods. These compounds exhibit excellent photothermal conversion properties. This work is interesting and suitable for publication after minor revisions.\n1. The authors should discuss the application prospects of this photothermal conversion property. In which areas might it have potential applications?\nReply: We sincerely thank the reviewer for highlighting this important aspect of our material's photothermal properties. As the reviewer correctly pointed out, materials with robust photothermal performance indeed possess significant potential. In the original manuscript, we briefly mentioned several application fields. Following the reviewer's valuable suggestion, we have now substantially expanded this discussion in the revised manuscript photothermal section. We now elaborate that this combination of efficient photothermal conversion and high cycling stability is particularly promising for applications requiring long-term reliability and repeated use. For solar-driven seawater desalination, the material's stability under prolonged light irradiation is essential for sustainable, continuous freshwater production. For photothermal catalysis, the ability to maintain performance over numerous reaction cycles is critical for practical industrial applications. For durable photothermal devices, the use in dynamic camouflage or actuation systems that must function reliably over extended periods is essential. We believe this revised discussion, now strengthened by connecting the photothermal property with the key attribute of cycling stability, provides a more comprehensive and convincing outlook on the potential real-world applications of our work. We thank the reviewer again for prompting this improvement.\n\n2. Compared with the reported photothermal conversion materials, what advantages do these supramolecular architectures in this work possess?\nReply: Thank you for your insightful comments. The supramolecular system presents distinct advantages over current photothermal materials, including tunability, ease of processing, excellent recyclability, broad applicability, and superior conversion efficiency. Specifically, its performance can be improved by fine-tuning the molecular building units. The rapidly precipitated powders maintain the same structural integrity (as evidenced by matching 1H NMR spectra and unit cell parameters) and photothermal performance as single crystals. The system exhibits remarkable stability, with no significant performance degradation over ten cycles, and achieves high efficiency in both solid and solution states, outperforming many reported counterparts (Table S1). We believe these attributes make them promising candidates for advanced photothermal applications across various fields. All additional data have been incorporated into the Supporting Information.\n\nTable S1. Comparison of supramolecular complexes in photothermal conversion with other literature systems.\nPhotothermal Temperature rise Sample conversion References efficiency\nCs CuSb Cl 29.7 - 59.8 ℃ 93.4% 1 4 2 12\nmatchstick-like 25.0 - 62.9 ℃ 60.3% 2 Bi Se /CdSe-Au 2 3\nDTS 35.0 - 53.0 ℃ 86.0% 3\nBAF4 25.0 - 60 ℃ 80% 4\nWMG1 22.6 - 58.6 ℃ 60% 5\nPSQ-NSs 25.0 - 96.1 ℃ 81.2% 6\nHeterogeneous 25.0 - 70.0 ℃ 27.3% 7 Metalla[2]catenanes\nRh-2 27.6 - 45.8 ℃ 58.29% 8\nBorromean 4(OTf) 25.0 - 64.5 ℃ 81.3% In work 12\n\n3. How about the stability of these supramolecular architectures in photothermal conversion process?\nReply: We sincerely thank the reviewer for raising the important question about the stability of our supramolecular architectures during the photothermal conversion process. Thermogravimetric analysis revealed that the frameworks of compounds 1(OTf) , 2(OTf) , 3(OTf) , 4(OTf) , 12 12 12 12 5(OTf) , and 6(OTf) began to collapse at 213.5 ℃, 204.8 ℃, 236.2 ℃, 191.3 ℃, 208.2 ℃, and 12 8 304.3 ℃, respectively (Figures S3a - S3f), demonstrating their good thermal stability. In our initial manuscript, we presented the cycling stability test for the most representative compound 4(OTf) 12 to demonstrate the potential stability of this class of materials. We agree with the reviewer’s suggestion that the stability of all synthesized structures need to be investigated. In direct response to the reviewer's suggestion, we have now performed detailed cycling stability tests on all compounds. The recently acquired data consistently indicate that all compounds retain outstanding photothermal performance after 10 cycles, mirroring the trend initially reported for the highest- performing sample (Figure S4). The complete set of cycling stability data for all compounds has been added to the revised manuscript. Once again, we are grateful to the reviewer for the valuable suggestion, which has undoubtedly strengthened our work.\n\nFigure S4. Cycling performance of compounds 1(OTf) - 6(OTf) upon 730 nm laser 12 8 irradiation (a) in the solid state (0.6 W/cm2) and (b) in methanol (1.5 W/cm2).\n\nReviewer 3:\nThe manuscript by Zhao, Li, Dang and co-workers describes an investigation of a series of ruthenium complexes that form a variety of metallacycles through the employment of bridging and terminal ligands. Of particular importance is the generation of topologically interesting compounds with the generation of catenanes, Borromean rings and a Solomon link structure.\nWhilst the topology of the structures is interesting, there are many aspects that require attention before the manuscript would be suitable for publication. In particular, I have the following concerns:\n1. The authors provide a long introduction focussed on changing various components and examining the structural impact of these changes. This is presented as a 'formidable frontier challenge in synthetic chemistry.' In my opinion this approach is really quite common i.e. tinker with the components to various extents and see if the structures change, if at all. I would strongly favour omission of most of the introduction and use the introduction to merely introduce the various components employed and discuss relevant types of macrocycle entanglement.\nReply: Thank you very much for your valuable feedback and for your careful review of our introduction. In crafting the original introduction, our aim was to underscore the inherent complexity and unpredictability involved in predicting final assembly structures from molecular components in the realm of supramolecular chemistry. We recognize that referring to systematic component screening as a “formidable frontier challenge” was perhaps an overstatement and may have overshadowed the primary focus of our work. We fully accept your suggestion for revision. In the revised manuscript, we make the introduction more concise and focus the discussion on the types of macrocycle entanglement that are directly pertinent to our work. We believe that the revised introduction is more concise, sharply focused, and more accurately set the stage for the background and value of our work.\n\n2. The introduction contains numerous sentences that are difficult to understand, for example,\n'Therefore, the best method is that using the identical subcomponent units to synthesize different topological structures by changing the structure of other components, which is conducive to studying the influence of the same component on the structure and function of different topological complexes.'\nReply: We thank the reviewer for pointing out the lack of clarity in the original sentence. Following the constructive feedback, we have revised the problematic sentence by breaking it into two clearer statements and moderating the absolute claim. The text now reads: \"Therefore, a more effective approach, termed the \"two-component construction strategy\" has been proposed. This strategy involves using an identical subcomponent unit to construct different topological architectures by varying the composition of the second component, thus enabling a comparative investigation of their characteristic differences.\". We believe the revised version better conveys our intended message. The revised sentences of the manuscript have been incorporated and marked with yellow highlighting.\n\n3. The photothermal studies seem somewhat out of place in this work. I am not sure I understand the reasons for performing these measurements. Are there specific applications for these molecules relating to this property? Are these materials behaving differently to discrete metallacycles or even metal complexes? Does the entanglement enhance the photothermal response? If so, what is the reason?\nReply: We are grateful to the reviewer for this insightful comment, which provides us with an excellent opportunity to elaborate on the rationale and significance of our photothermal investigations. While the synthesis and topological classification of complex supramolecular architectures have advanced remarkably, research into their emergent functional properties remains comparatively limited. We intentionally chose photothermal conversion as a central functionality to explore, given its considerable potential in applications spanning photothermal catalysis, therapy, actuation, and solar-driven water desalination. Our control experiments confirmed that the individual molecular components—namely the half-sandwich rhodium building units and the linker ligands—exhibit only marginal photothermal effects (Figure S5). This finding strongly indicates that the enhanced photothermal conversion observed in the supramolecular assemblies arises primarily from the multiple stacking interactions within the organized architecture, rather than from the intrinsic properties of any isolated component. Moreover, these extensive π···π stacking interactions create a rigid microenvironment that restricts molecular motion. This confinement favors non-radiative relaxation pathways, effectively channeling excited-state energy into vibrational modes over radiative processes. We have incorporated this explanation into the revised manuscript and included the corresponding comparative data in the Supporting Information.\n\nFigure S5. Photothermal conversion curves of Borromean ring 4(OTf) , building units 12 E1(OTf) - E6(OTf) , and ligand precursor L1.\n2 2\n\n4. In the EPR studies there are enhancements of signals indicating unpaired electrons. Are there unpaired electrons in the freshly prepared samples? If so, which component has the unpaired electron. What fraction of compounds have unpaired electrons? Could it be less than 1%? Does the entanglement of the metallacycles affect the EPR signal? What is the origin of the paramagnetism?\nReply: We thank the reviewer for these insightful questions regarding the EPR signals. Taking compound 2(OTf) as an example, we utilized EPR spectroscopy to investigate the origin of the 12 unpaired electrons. No radical signals were detected for the ligand L1 before and after light irradiation, as confirmed by control experiments, which rules it out as the source and indicates that the unpaired electrons originate from the organic radical of the building units (Figure S6a). The light-induced generation of organic radicals, where each building block contributes one pair of unpaired electrons9,10, results in a total of six pairs of unpaired electrons within the entire compound (Figure S6b). Meanwhile, the multiple π···π stacking interactions within the supramolecular structure suppress radiative transitions while promoting non-radiative decay, thereby facilitating the generation of organic radicals. As depicted in Figure S6c, the overall negative magnetization indicates that the material is predominantly diamagnetic. At low temperatures, there may be a minor contribution from paramagnetic impurities, which slightly reduces the absolute value of the total magnetization. Nonetheless, the overall magnetic behavior remains predominantly diamagnetic. Additionally, the absence of sharp inflections or plateaus in the magnetization curve suggests that there is no transition to ferrimagnetic or paramagnetic states. We have updated the discussion in the EPR section of the revised manuscript and complemented it with the pertinent references.\n\nFigure S6. (a) The EPR spectra of compound 2(OTf) , building unit E2(OTf) , and ligand 12 2 precursor L1; (b) Changes of the oxidation states of H CA; (c) Variable-temperature 2 magnetic susceptibility for compound 2(OTf) at 1000Oe.\n12\n\n5. In the discussion, the synthetic method is described as novel and highly precise when in fact it seems that if only minor changes are made to the structure, like changing from dihydroxybenzoquinone, to chloranilic acid and bromanilic acid a similar structure is obtained. When the oxygen donor ligand is substituted for a different type of oxygen donor, with different geometry, there is a topological change and finally when the oxygen donor ligand is changed to a Ag(I)bis(benzimidazole) type donor, it is not surprising that a very different topology is obtained. Thus when considerable changes are made to the ligands it is not at all surprising to obtain a different structure. I do not think the claims of being 'novel' and 'highly precise' are justified.\nReply: We sincerely thank you for your critical comment. Upon reflection, we wish to clarify the intended message. The primary novelty of our work does not lie in the synthesis of any single structure, but rather in the systematic investigation of how subtle to considerable changes in ligand structure influence the final topological outcome. In response to your comment, we have thoroughly revised the discussion in the manuscript. We have removed the terms \"novel\" and \"highly precise\" where they were ambiguous and replaced them with more accurate descriptions. We believe that these revisions have significantly improved the accuracy and impact of our manuscript.\n\n6. Given the determination of crystal structure for these materials it was surprising to see a very limited discussion of the actual structure e.g. internal van der Waals ring dimensions and macrocycle shapes.\nReply: We sincerely thank you for your insightful comment and valuable suggestion. In response to your comment, we have performed a detailed analysis of the metallamacrocycle structures using crystallographic data and Mercury software. In the structure of compound 1(OTf) , three mutually 12 interpenetrating, rectangular metallamacrocycles form a discrete and indivisible ensemble. Each metallamacrocycle is defined by edge lengths of 16.99 Å and 7.92 Å (Figure S7). Although compounds 1(OTf) , 2(OTf) , and 3(OTf) are isostructural, there is a notable difference in the 12 12 12 geometry of their metallamacrocycle building blocks. The metallamacrocycle in 1(OTf) is a 12 perfect rectangle, while those in 2(OTf) and 3(OTf) are slightly but distinctly distorted, with 12 12 dimensions of 16.95 × 7.93 Å and 16.99 × 7.90 Å, respectively (Figures S8 and S9). Compounds 4(OTf) and 5(OTf) feature discrete molecular Borromean rings. In both structures, three 12 12 rectangular metallamacrocycles are mechanically interlocked to form a highly symmetrical topology. The metallamacrocycle in 4(OTf) has dimensions of 16.99 × 8.29 Å, while that in 12 5(OTf) measures 17.06 × 8.28 Å (Figures S10 and S11). Compound 6(OTf) is composed of two 12 8 distorted and interlocked metallamacrocycles, which form a complete topological entity. Each macrocyclic component has dimensions of 17.03 × 11.74 Å (Figure S12). We have incorporated all the requested revisions into the manuscript and have added the new figures to the Supporting Information. All changes have been highlighted in yellow within the manuscript crystal description section. We believe the revised manuscript now fully meets the journal's standards for publication.\n\nFigure S7. (a) Molecular structure and (b) single metallamacrocycle component of Linear [3]catenane 1(OTf) .\n8\n\n7. Space groups reported in the manuscript do not always match the space groups indicated in the cifs.\nReply: We sincerely thank you for your careful review and for identifying the inconsistency between the space groups reported in the manuscript and those in the CIF files. This was an oversight on our part during the preparation of the manuscript, and we sincerely apologize for this error. We have thoroughly checked all the crystal structures and confirmed that the space groups in the original CIF files are correct. We have now corrected all the space group symbols in the revised manuscript to ensure they are fully consistent with the corresponding CIF files. Thank you again for bringing this critical issue to our attention."}, {"round": 2, "reviewer_comments": {"reviewer_1": "I have read with interest the revised manuscript written by Zhao, Li, Dang and coworkers with title “Precise Synthesis of π-Conjugated Metalla-Links (42, 43 and 63) for Photothermal Responses via a Dual-Tuning Strategy” The paper has been revised by the authors and the concerns raised by the referees have been addressed. I am satisfied with the revisions addressed but there is one point that needs to be controlled.\n\nThe crystallographic data for crystal 2(OTf) (the structure that has been done again) needs to be checked as the lattice parameters in the Supporting Information do not match with the revised Check-CIF. The unit cell volume in the Check-CIF = 15498.5(8) while in the Supporting Information is 15293.0 (11). Please update this structure correctly as all the lattice parameters and R-factors (obviously all the crystallographic data is different) do not match.", "reviewer_2": "The quality of this manuscript has been significantly improved. It can be accepted for publication.", "reviewer_3": "I have reviewed the revised manuscript and I am generally satisfied with the responses of the authors to the original comments of the reviewers and the changes to the manuscript.\n\nI am pleased to recommend publication however there are some minor issues that should be addressed in the preparation of a final version of the manuscript.\n\n1. In the 1H NMR spectrum of 1(OTf)2, the authors note two sets of independent resonances which are attributed to absence of 'complete molecular symmetry'. I do not understand what the authors mean by this statement. Can the authors clarify this?\nFrom my perspective, two sets of independent resonance is sensible because there are two distinct macrocycles in the assembly. The first (central macrocycle) has two other macrocycles passing through it while the other two have only macrocycle passing through each. Thus, two sets of signals should be apparent in a 1:2 ratio. The spectra for 2(OTf)2 and 3(OTf)2 should be similar but perhaps the peaks are overlapping. It would be useful if this section was clarified.\n2. The number of significant figures in % yields, decomposition temperatures (TGA) and photothermal conversion efficiencies does not appear to be justified. I would recommend no decimal places for these values.\n3. In Supplementary Table 6 all numerals in the empirical formula should be subscripted.\n4. In Figure 2a the bridging anilate ligand is represented with an aromatic ring which means that the ligand would have a 4- charge. The ligands should be represented in its quinone (2-) forms as depicted in Figure 1.\n5. Similar to the point above, in Supplementary Figures 13, 16 and 19 the bridging dianion is represented as an aromatic ligand. In fact it should be represented in its quinone form as indicated in Supplementary Figures 7, 8 and 9."}, "author_response": "Reply: Thank you for your careful review and for pointing out the significant discrepancy in the crystallographic data for crystal 2(OTf) . We sincerely apologize for this error and the confusion it 12 has caused. Upon thorough re-examination, the crystallographic data table for Compound 2(OTf) 12 in the Supporting Information has been revised to align with the latest CIF file. We sincerely appreciate the time and expertise invested in evaluating our manuscript.\n\nReviewer 2:\nWe sincerely thank you for recommending our manuscript for publication in Nature Communications. We are also grateful for the rigorous review process and the insightful comments provided.\n\nReviewer 3:\nWe are extremely delighted to read your positive feedback and are thankful that you have recommended our manuscript for publication. We sincerely appreciate your time and the insightful comments you provided throughout the review process. We will meticulously address the remaining minor issues while preparing the final version of the manuscript.\n\n1. In the 1H NMR spectrum of 1(OTf) , the authors note two sets of independent resonances which 12 are attributed to absence of 'complete molecular symmetry'. I do not understand what the authors mean by this statement. Can the authors clarify this?\nFrom my perspective, two sets of independent resonance is sensible because there are two distinct macrocycles in the assembly. The first (central macrocycle) has two other macrocycles passing through it while the other two have only macrocycle passing through each. Thus, two sets of signals should be apparent in a 1:2 ratio. The spectra for 2(OTf) and 3(OTf) should be similar but 12 12 perhaps the peaks are overlapping. It would be useful if this section was clarified.\nReply: Many thanks for your thoughtful comments and meticulous review. In the 1H NMR spectrum of 1(OTf) , two sets of independent resonances are attributed to the uniquely entangled topology, 12 which creates distinct proton environments within the same chemical moiety. This description in the main text has been revised.\n\nFurthermore, we have re-analyzed the 1H NMR spectrum of compound 1(OTf) and revised the 12 proton signal assignments accordingly (Figure S1). Additionally, new NMR measurements of compounds 2(OTf) and 3(OTf) were conducted. And the NMR analysis results of compounds 12 12 1(OTf) , 2(OTf) and 3(OTf) corroborate your opinion (Figures S2 and S3). The Figures in 12 12 12 Supporting information have been revised.\n\nFigure S1. The 1H NMR (298 K, 500 MHz, CD OD, ppm) for Linear [3]catenane 1(OTf) (15.0 3 12 mM, with respect to p-cymene Ru).\n\nFigure S2. The 1H NMR (298 K, 500 MHz, CD OD, ppm) for Linear [3]catenane 2(OTf) (25.0 3 12 mM, with respect to p-cymene Ru).\n\nFigure S3. The 1H NMR (298 K, 500 MHz, CD OD, ppm) for Linear [3]catenane 3(OTf) (20.0 3 12 mM, with respect to p-cymene Ru).\n\n2. The number of significant figures in % yields, decomposition temperatures (TGA) and photothermal conversion efficiencies does not appear to be justified. I would recommend no decimal places for these values.\nReply: We thank the reviewer for their valuable suggestion. Following this recommendation, we have revised the manuscript to report percentage yields, TGA decomposition temperatures (Supplementary Figures 57 - 62), and photothermal conversion efficiencies as whole numbers (Supplementary Figures 76 - 81), without decimal places, to better align with the precision of our measurements. All related data in the text, tables, and figures have been updated accordingly.\n\n3. In Supplementary Table 6 all numerals in the empirical formula should be subscripted.\nReply: Thank you for your careful review. We have corrected the numerals in the empirical formulas to subscripts in Supplementary Table 6.\n\n4. In Figure 2a the bridging anilate ligand is represented with an aromatic ring which means that the ligand would have a 4- charge. The ligands should be represented in its quinone (2-) forms as depicted in Figure 1.\nReply: We appreciate your insightful observation. And the bridging anilate ligands in Figure 2a have been revised to represent in their quinone (2-) forms as depicted in Figure 1.\n\n5. Similar to the point above, in Supplementary Figures 13, 16 and 19 the bridging dianion is represented as an aromatic ligand. In fact it should be represented in its quinone form as indicated in Supplementary Figures 7, 8 and 9.\nReply: Many thanks for your advice and your meticulous work. The bridging dianions have been revised to represent in their quinone form in Supporting Information section."}]

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