Visible-light-triggered exclusive bistable E/Z photoswitching based on sterically frustrated dicyanostilbene derivatives

Domain: neuroscience
Published: 2026-02-12
Editorial outcome: major_revision

Abstract
Developing photoswitches with precise control over reaction pathways, visible-light responsiveness, and robust thermal stability remains a significant challenge in photoresponsive materials. Here we report a class of sterically frustrated dicyanostilbene-based molecular photoswitches that achieve exclusive, efficient, and robust visible-light-triggered E/Z photoisomerization in both solution and aggregated states. They function as bistable switches with thermal half-lives reaching up to 1817 years. Furthermore, their pronounced polarity and solubility differences between isomers, together with photofluorochromic behavior, enable facile separation, real-time switching monitoring, and photonic encryption demonstrations. Single-crystals and theoretical calculation elucidates the dual steric control mechanism: in solution, molecular distortion of the Z-isomer suppresses intramolecular photocyclization while stabilizing the Z-conformation to enable ultralong thermal half-lives; in the aggregated state, isolated and loosely packed molecules inhibit intermolecular photocycloaddition and concurrently provide the free volume required for isomerization. This work advances the design of bistable dicyanostilbene photoswitches, offering a versatile platform for green chemistry and smart materials.

Introduction
Light has emerged as a promising green energy in chemistry, materials science, and energy technologies due to its outstanding spatio-temporal resolution, non-invasive characteristics, and precise tunability1–3. Nature provides excellent examples of highly efficient and specific light-driven biological processes. A representative case is the role of rhodopsin in visual signal transduction, where retinal molecules undergo photoinduced Z/E isomerization through a single, dynamically adjustable reaction pathway to trigger signals4. Inspired by such biological precision, chemists have devoted considerable efforts to developing artificial photo-responsive systems that can mimic nature’s exquisite control5–10. However, synthetic photochemical systems frequently exhibit multiple competing reaction pathways, including E/Z isomerization11, photocyclization12, and photocycloaddition13–16, resulting in low reaction selectivity and compromised product purity. This complexity not only substantially increases the difficulty of product isolation and purification, which contradicts the principles of green chemistry, but also adversely affects the controllability and reproducibility of material properties. The situation becomes even more challenging in aggregated or solid states, where intermolecular interactions further amplify the unpredictability of reaction pathways17. Therefore, achieving precise control over photoreaction pathways through rational molecular design and developing molecular switches with unimodal photoresponsiveness have become crucial yet highly challenging objectives in this field.

A diverse array of prominent photoswitches featuring well-defined single reaction pathways, including azo(hetero)arenes18–24, hydrazones25–28, hemi(thio)indigos29–32, diarylethenes5,33,34, spiropyrans35, and donor–acceptor Stenhouse adducts (DASAs)36,37, have been developed for applications in drug delivery, energy storage, and biological regulation. Among these, the (di)cyanodiarylethene motif38–46, a derivative of stilbene47–52, has recently emerged as a robust and promising platform for modulating (bio)material properties, owing to its intriguing and distinct photochemical and photophysical behavior in both solution and solid states. Despite this potential, the photoswitching performance of (di)cyanodiarylethene-based systems remains relatively underexplored compared to other established photoswitch families8,53–55. For instance, the Katz group developed a bis(dithienyl) dicyanoethene photoswitch that leverages the β-position inertness of thiophene rings to achieve efficient visible-light-driven isomerization8. Our group has also investigated strategies to tune their photoreaction pathways, rates, and efficiencies across various states56,57.

Nevertheless, several critical limitations continue to hinder their deployment in photoswitching applications. Firstly, similar to its parent stilbene, the (di)cyanodiarylethene motif also exhibits complex and competitive photochemical pathways (Fig. 1). In addition to isomerization, it readily undergoes side reactions such as photocyclization, photodimerization, and radical-mediated processes58–63 (Supplementary Table 1). This photochemical instability likely explains its limited use as a general-purpose photoswitch to date. Secondly, low thermal barriers often result in fast back-isomerization to thermodynamically stable states at room temperature8,64,65. As state switching is thus only effectively driven by light (i.e., long thermal half-life) becomes critical for applications requiring precise photomodulation and durable state stability. Third, many derivatives still require UV light for isomerization, which can induce material degradation, cellular apoptosis, and limited tissue penetration12,66,67. Finally, minimal physicochemical differentiation (e.g., polarity) between isomers complicates their separation and greatly compromise the capability of photoswitching12,58,68. Therefore, the design of modified (di)cyano-diarylethene-based photoswitches capable of overcoming some, if not all, of these limitations represents a compelling and sought-after goal.

As part of our effort to address the drawbacks associated with (di)cyanodiarylethene compounds, we present here on three easy to-make, sterically hindered dicyanostilbene-based photoswitches (PTZ, DPA, CBZ) with improved photoresponsive properties: (1) Reaction pathway control: The steric hindrance effectively suppresses both solution-phase photocyclization and aggregate-state photocycloaddition side reactions, ensuring exclusive E/Z isomerization across various states with considerable photostability and conversion yields (∼80% E⇄Z isomerization for DPA in aggregate, >92% Z→E for Z-CBZ); (2) Long thermal half-lives: these systems display the slowest thermal back isomerization half-lives (t1/2 can reach as long as 1817 years) among all reported (di)cyanodiarylethene-based systems; (3) Visible-light responsiveness: The strong push-pull (D-π-A) effect red-shifts absorption to the visible region which thus facilitates visible-light activation (515 nm for E→Z, 403 nm for Z→E); (4) Distinct physicochemical properties: The big polarity and solubility differences between E/Z-isomers enable straightforward separation. Moreover, the pronounced photofluorochromic behavior69,70 permits naked-eye monitoring of the isomerization process. This sterically frustrated dicyanostilbene platform represents a valuable addition to the toolbox of visible-light-activated bistable photoswitches and can open the door to many new opportunities.

Results
Synthesis and photoswitching of E→Z isomerization
Starting from 2-(4-bromophenyl)acetonitrile, we synthesized 2,3-bis(4-bromophenyl)fumaronitrile (E-Br) as the key intermediate (Supplementary Figs. 1–4). Subsequently, through coupling reactions, we successfully introduced similar bulky substituents (DPA, PTZ, and CBZ) with increased rigidity at both terminals of E-Br, yielding the target compounds E-DPA, E-PTZ, and E-CBZ (Supplementary Figs. 7–18). The absorption maxima (λmax) of the E-isomers in CHCl3 are 492 nm for E-DPA (ε=24105 M−1·cm−1), 449 nm for E-PTZ (ε=22531 M−1·cm−1), and 450 nm for E-CBZ (ε=12985 M−1·cm−1). A ca. 40 nm red-shift in the λmax of E-DPA compared to E-PTZ and E-CBZ may be attributed to the stronger electron donating ability of diphenylamine group (DPA), which leads to the extension of the π-system through resonance between the dicyanoethene and DPA groups and thus a narrower HOMO−LUMO gap (Supplementary Figs. 102–104).

After irradiating the samples with light of different wavelengths ranging from 365 to 530 nm (including white light), we selected the stimuli wavelength with the highest conversion ratio (515 nm for E→Z, Supplementary Figs. 31 and 32).

To validate the steric hindrance strategy for controlling the photoreaction pathway, we systematically investigated their photochemical behavior in solution. UV-vis absorption spectra of E-DPA upon 515 nm green light irradiation revealed an obvious decrease in absorbance at 492 nm accompanied by a slight blue shift, while a new absorption band emerged at ∼420 nm and gradually intensified until reaching the photostationary state (PSS), clearly indicating the formation of new species (Supplementary Fig. 33a). Time-resolved PL spectroscopy revealed a decrease in emission intensity upon prolonged irradiation (Supplementary Fig. 48a). Notably, the maximum absorption wavelength showed minimal variation. Compounds E-PTZ and E-CBZ show similar trends in UV-vis absorption and PL spectra upon 515 nm light irradiation (Supplementary Fig. 33b, c and Fig. 48b, c).

We further conducted 1H NMR to monitor the isomerization of E-isomer. Taken E-DPA as an example, the characteristic peaks of the E-isomer (Ha: 7.68–7.62 ppm; Hb: 7.31–7.33 ppm) gradually decreased in intensity with prolonged irradiation, while new peaks corresponding to the Z-isomer (Hα: 7.28–7.30 ppm; Hβ: 7.23–7.24 ppm) consistently intensified, providing direct evidence for E→Z photoisomerization (Supplementary Fig. 34). The reaction kinetics profile demonstrated progressive increase in conversion rate until equilibrium was achieved in 25 min (Supplementary Fig. 35). The E→Z conversion efficiency was determined to be ∼70% with ΦE→Z=9.13% (Supplementary Fig. 38, Table 2). E-PTZ and E-CBZ exhibited analogous NMR behavior (Supplementary Figs. 36, 37). The PSSs for E→Z conversion are lower for compounds E-PTZ (PSS515 = 50%; ΦE→Z=2.33%, Supplementary Fig. 39, Table 2, and E-CBZ (PSS515 = 65%; ΦE→Z=3.29%, Supplementary Fig. 40, Table 2), which may due to the less separated absorption bands of their two isomers (Fig. 3b, c). 1H NMR analysis detected no characteristic signals (such as left-shifted proton signals for aromatic region) of photocyclized products (Fig. 2d), which can be typically observed in dicyanostilbene derivatives12. This exclusively E/Z isomerization validates the general applicability of the steric hindrance strategy for controlling photoreaction pathways.

Thin-layer chromatography (TLC) analysis further revealed that 515 nm irradiation of the E-isomers produced only two distinct spots, demonstrating significant polarity differences between each E/Z isomer pair. Specifically, the E-isomers exhibited substantially lower polarity (Rf = 0.6–0.7) than their Z-counterparts (Rf = 0.2–0.3) as shown on TLC plates (petroleum ether: dichloromethane, v/v, 1:2 as eluent) (Fig. 2a). Theoretical calculations indicated remarkable differences in molecular dipole moments between the isomers. The dipole moment of Z-DPA was approximately 12 times greater than that of E-DPA, while Z-PTZ and Z-CBZ showed 3.8-fold and 10-fold increases in dipole moments compared to their respective E-isomers (Table 1). This substantial disparity in dipole moments correlates well with the observed polarity differences on TLC plates, suggesting it as the primary origin of their distinct polarity differences. Finally, we can separate the mixed photoproducts by column chromatography and obtain Z-isomers (Z-PTZ, Z-DPA, and Z-CBZ, Supplementary Figs. 19–30) very easy.

To further demonstrate the crucial role of steric hindrance in controlling photoreaction pathways, we investigated the photobehavior of the small-hindered precursor E-Br as control. TLC analysis revealed multiple photoproducts with complex fluorescence characteristics that proved difficult to separate (Supplementary Fig. 6a). 1H NMR studies showed that short-term irradiation primarily yielded the Z-isomer, but prolonged exposure led to cyclized product c-Br (as evidenced by 1H NMR and mass spectra, Supplementary Figs. 5, 6), demonstrating the non-selective nature of the photoreaction pathway in contrast to the well-controlled behavior observed with sterically hindered derivatives.

Z→E isomerization
Prior to investigating Z→E isomerization, we examined the photophysical properties of the three Z-isomer by UV spectra (Fig. 3a-c and Table 1). The λmax (475 and 405 nm; ε=18210 M−1·cm−1) of Z-DPA is shifted hypsochromically by 17 and 87 nm as compared to E-DPA. In both Z-PTZ and Z-CBZ, the absorption band is shifted hypsochromically by 25 nm to λmax = 425 nm (ε=12140 and 10568 M−1·cm−1 for Z-PTZ and Z-CBZ, respectively). Notably, Z-DPA displayed two distinct absorption peaks at 405 and 475 nm (Fig. 3a), consistent with theoretical predictions of two major electronic transitions (HOMO→LUMO and HOMO-1→LUMO) (Supplementary Fig. 102 and Supplementary Table 5). Similar calculations based on CBZ and PTZ only showed one major electronic transition (HOMO→LUMO for E-PTZ, HOMO-1→LUMO for Z-PTZ, HOMO→LUMO for E-CBZ, HOMO→LUMO for Z-CBZ), consistent with their single main absorption peak (Supplementary Figs. 103, 104 and Supplementary Tables 6, 7). The E-isomer showed higher absorbance, correlating with its deeper solution color (Supplementary Fig. 49). This difference originates from their distinct molecular geometries: the E-isomer adopts a planar configuration and allows optimal π-electron delocalization, while the Z-isomer forms a V-shaped structure with distorted conjugation. The separation in the absorption bands caused by these shifts allowed us to photochemically address the backward Z→E isomerization processes.

The emission properties of three pairs isomers were studied in solution using fluorescence spectroscopy (Fig. 3d–e and Supplementary Fig. 48). The compounds show emissions with varying intensities in CHCl3 at wavelengths (λF) ranging from 596 to 675 nm. Compunds E/Z-DPA bearing more donating group exhibit emission at longer wavelengths in general. It should be noted that although these dicyanostilbene derivatives are aggregation-induced emission active71,72, we can still observe emission in solution with quantum yields (ФF) ranging from 0.2 to 40.6%. Notably, all the E-isomers exhibit much higher brightness (higher ФF) than its Z-counterpart. For example, compound E-CBZ (ФF=40.6%) is the most emissive in solution among all the compounds and is 3.1-fold that of Z-CBZ (ФF=12.8%). The weaker emission of E-isomers likely results from the lower conjugation compared to Z-isomers. The nanosecond-scale lifetimes (0.2–3.7 ns, Supplementary Fig. 47) revealed their fluorescence origin.

Given the shorter absorption wavelengths of Z-isomers, 403 nm blue light was selected as the excitation for Z→E isomerization (Supplementary Figs. 31 and 32). These results indicate that the strong push−pull between the electron-withdrawing cyano groups and electron-donating bulky substituents induces significant absorption redshift into the visible region, facilitating visible-light-driven E⇄Z isomerization. 1H NMR spectra revealed gradual decrease in the peak intensity of Z-isomers concomitant with the emergence and growth of the E-isomers’ peak (Supplementary Figs. 41–43). Notably, only signals corresponding to E-isomers were detected without any byproduct formation, demonstrating the reversibility of this photoswitching system. A sample of pure Z-PTZ yields a PSS consisting of 86% E-PTZ (ΦZ→E=31.56%, Supplementary Fig. 45). For Z-DPA, a PSS403 of 80% is obtained (ΦZ→E=5.90%, Supplementary Fig. 44). Interestingly, E-CBZ and Z-CBZ exhibit remarkable differences in solubility: E-CBZ had poor solubility in common organic solvents, such as dichloromethane, chloroform, THF, et al., while Z-isomer can be well disolved. Upon irradiating the concentrated Z-CBZ solution, pure E-CBZ progressively precipitates out of the chloroform solution. This distinctive solubility differences enables simultaneous E-isomer generation and rapid separation (PSS403 >92%; ΦZ→E=41.15%, Supplementary Fig. 46). During the isomerization from Z-isomers to E-isomers, pronounced fluorescence enhancement was observed (Fig. 3d–f and Supplementary Fig. 48 for reverse E→Z isomerization), demonstrating typical “turn-on” signals and enabling visual monitoring of the isomerization process. Notably, although fluorescence enriches the functionality of the photoswitch and allows visual tracking of isomerization, this benefit comes at the cost of certain reduced photoisomerization quantum yields (Φisom = 2.33–41.15%) due to competition between the two pathways in the excited state. All compounds can be photoswitched multiple times between their E and Z forms with minimal photo-fatigue (Fig. 3a–c and Supplementary Fig. 51).

Thermal-stability of E/Z isomers
Thermodynamically, Z-isomers typically exhibit lower stability compared to their E-counterparts and are prone to back isomerization under elevated temperatures. This is also confirmed by DFT calculations (B3LYP/6-31G*) which shows that the E-isomer is 0.36-1.03 kcal/mol more stable than the Z one (Table 2 and Fig. 4c). However, during the synthetic process in our system (conducted at 110 °C under dark conditions), while E-isomer was the major product, trace amounts of Z-isomers were consistently detected. Firstly, we use 1H NMR spectra to study the stability of Z-isomers, which showed no change after heating at 60 °C for 5 h in CDCl3 (Supplementary Fig. 52). Even under rigorous conditions (toluene-d8, 105 °C, 12 h, dark), minimal conversion to the E-isomer was observed, with Z-isomer signals remaining dominant (82% for Z-DPA, 94% for Z-PTZ, 92% for Z-CBZ, Fig. 4b and Supplementary Fig. 54), demonstrating their exceptional thermal stability.

Next, we studied the thermal isomerization processes. Pure Z isomerizes to E with a slow first-order rate was studied as a function of temperature, and the data were extrapolated to room temperature (RT) using the Arrhenius and Eyring equations to yield thermal half-lives (t1/2) and activation parameters, respectively (Table 2, Supplementary Table 4, Supplementary Figs. 96–101). All the compounds exhibit very long thermal half-lives at RT, ranging from 14.2 to 1817 years. It is worth noting that literature reports on the thermal stability of Z-configured (di)cyanodiarylethenes remain relatively scarce. For instance, Zhu and Katz reported half-lives of 40 s for a cyanostilbene and 2–12 min for a dicyanodithienylethene, respectively8,64. In another study, the Z-isomer of a related system showed no significant change after 96 h in DMSO at room temperature in the dark68.

The half-lives for Z-CBZ are somewhat shorter than in Z-DPA and Z-PTZ. Kinetic analysis reveals that the acceleration in thermal isomerization rate (from 1.21×10⁻¹¹ to 1.55×10⁻⁹ s⁻¹) is governed by both enthalpy and entropy. The large negative ΔS‡ value (−33.95 cal·mol⁻¹·K⁻¹) observed for Z-CBZ suggests a more ordered transition state with reduced conformational freedom, likely due to the rigid carbazole moiety. As the flexibility of the steric group increases in Z-PTZ and Z-DPA, the ΔS‡ values rise to −4.98 and 24.61 cal·mol⁻¹·K⁻¹, respectively, may indicating increased disorder in the transition state. Simultaneously, the ΔH‡ value increases from 19.32 kcal·mol⁻¹ for Z-CBZ to 39.65 kcal·mol⁻¹ for Z-DPA, implying a more stabilized ground state in Z-DPA. We hypothesize that this stabilization may arise from intramolecular interactions between the two twisted phenyl rings adjacent to the dicyanoethene motif. This assumption is validated by noncovalent interaction (NCI) analysis (Supplementary Fig. 53) and the following crystal analysis (Fig. 6g–i). The combined effects of ΔH‡ and ΔS‡ ultimately lead to a decrease in half-life from 1817 years for Z-DPA to 14.2 years for Z-CBZ.

We also investigated the thermodynamic stability of the isomers in the solid state. Thermogravimetric analysis (TGA) revealed their decomposition temperatures in the range of 290–397 °C (Supplementary Fig. 66), confirming their thermal stability. Differential scanning calorimetry curves showed high melting points at 205–330 °C (Supplementary Figs. 67–70). Heating experiments on the three Z-isomer powders demonstrated that they remained stable below their melting temperatures. However, after melting and subsequent cooling, changes in color and fluorescence were observed (Supplementary Fig. 71). 1H NMR and PXRD analysis confirmed near-quantitative conversion of the Z-isomers to the E-configuration (Supplementary Figs. 72 and 73). The experiments indicate that the Z-isomer exhibits kinetic stability (keeping stable below melting points) in the solid state, but converts to the thermodynamically more stable E-isomer upon heating and melting, demonstrating that the Z-isomer possesses higher energy.

Aggregated state reversible E/Z isomerization
Previous studies have demonstrated the feasibility of the steric hindrance strategy in controlling photoinduced isomerization in solution. To expand the applicability of this strategy, we aim to extend it to the aggregated state. Unlike the dispersed molecules in solution, the intermolecular distances in the aggregated state are significantly reduced, bringing the reactive double bonds into closer proximity. This pre-organization of reaction sites may facilitate [2+2] photocycloaddition in the solid state. Meanwhile, the tight molecular packing also introduces multiple weak intramolecular interactions that restrict the conformational freedom required for isomerization, potentially reducing its efficiency.

The Z-isomers were dissolved in the good solubility solvent CHCl3, followed by dropwise addition into a large volume of poor solubility solvent (n-hexane) to prepare aggregated solutions with fH = 99%. Upon irradiation with 403 nm blue light for 2 h, all three solutions exhibited slight color darkening (Supplementary Fig. 56). Similar to the behavior in solution, the fluorescence of Z-DPA, Z-PTZ, and Z-CBZ in aggregated state was enhanced upon light exposure (Supplementary Fig. 55d–f). This trend is opposite to the fluorescence quenching observed for the E→Z isomerization (Supplementary Fig. 55a–c). Z-CBZ solution displayed the formation of orange-red precipitates (Fig. 5b). As supported by previous findings, this phenomenon can be attributed to the precipitation of the generated E-CBZ isomer due to its poor solubility. Further characterization by 1H NMR spectra of all three Z-isomers revealed only the presence of mixed E/Z isomers in the post-irradiated aggregated solutions, with no detectable signals corresponding to cyclobutane dimers (characteristic peak at ~5 ppm, Fig. 5c and Supplementary Figs. 57–65). This demonstrates that Z-isomers undergo exclusive photoisomerization in the aggregated state. Similarly, 515 nm irradiation experiments performed on fH = 99% E-isomers yielded only E/Z isomers signals in the NMR spectra, confirming that E-isomers also undergo solely isomerization reactions in the aggregated state.

Based on the 1H NMR spectra before irradiation and at the PSS, the photoisomerization yields in the aggregated state were determined. The E→Z conversion efficiencies for the three E‑isomers ranged between 66% and 80%, while the Z→E process for the three Z‑isomers ranged from 73% to 81%. These values are generally comparable to and in some cases even higher than those measured in solution (for E-DPA and E-PTZ), indicating that the photoisomerization is not suppressed by molecular aggregation. Taken together, we propose that the steric hindrance introduced by the bulky substituents not only effectively prevents the close molecular packing required for dimerization, but also creates sufficient free space for the intramolecular isomerization to proceed. As a result, the photoisomerization in the aggregated state remains clean and efficient.

Mechanism study
To elucidate the molecular mechanism underlying the exclusive photoisomerization and long thermal half-lives, we successfully cultivated five single crystals using slow evaporation and vapor diffusion methods (Fig. 6a). Crystalline-state emission spectra covered the 589–750 nm range (orange to red emission, Supplementary Fig. 74). Due to the poor solubility of E-CBZ in common solvents, we were unable to obtain crystals suitable for X-ray diffraction analysis. Most of the compounds exhibit considerable quantum efficiency, including the red-emitting Z-DPA, which achieves a high quantum yield of 24.0% at 702 nm (Table 1).

At the molecular level, intramolecular photocyclization requires the two phenyl rings adjacent of the double bond to adopt an early parallel conformation with close proximity. However, single-crystal structure analysis revealed that both E- and Z-configurations exhibit highly distorted molecular conformations, resulting from the combined steric effects of the dicyanostilbene core and bulky substituents. Since E-isomers must first isomerize to Z-configuration to undergo photocyclization, we focused our structural analysis on the Z-isomers. The structural data demonstrate that the introduced bulky groups measure approximately 8 Å × 3 Å (Fig. 6b–c). Crucially, with both bulky moieties positioned on the same side of the double bond, steric repulsion induces exceptionally large dihedral angles between the phenyl rings. Specifically, the three Z-isomers exhibit dihedral angles of 57.1°, 63.0°, and 44.1°, respectively (Fig. 6d–f and Supplementary Fig. 87). This pronounced molecular distortion significantly reduces π-orbital overlap, thereby suppressing the photocyclization pathway.

The twisted conformation of Z-isomers gives rise to unique intramolecular interactions, particularly the formation of a typical intramolecular C–H···π interaction between the two phenyl rings adjacent to the dicyanoethene motif (Fig. 6g–i). Hirshfeld surface analysis of the crystal further confirms the presence of such intramolecular interactions (Supplementary Fig. 88). Although crystal structures may differ from solution behavior, this observation is consistent with solution-phase NCI analysis (Supplementary Fig. 53). We therefore propose that similar intramolecular interactions also exist in solution to stabilize the Z-isomers, contributing to their high activation barrier (ΔG‡) for thermal Z→E isomerization. Moreover, this is also consistent with the small free energy differences (ΔG) between the E- and Z-isomers, which range from 0.36 to 1.03 kcal·mol⁻¹ (Table 2).

According to Schmidt’s criteria, the [2+2] photocycloaddition between molecules requires parallel alignment of double bonds with an intermolecular distance of less than 4.2 Å (Supplementary Fig. 76)73. Through systematic crystal packing analysis, we investigated molecular arrangements from both in-layer and intercolumnar dimensions. For E-configuration compounds (E-DPA and E-PTZ), in-layer analysis revealed parallel molecular packing with double bond distance of 9.10 Å and 13.05 Å, respectively (Fig. 7a–c). This significant separation results from steric isolation by bulky substituents. In the intercolumnar dimension, E-PTZ molecules adopt a staggered arrangement (10.12 Å spacing, Fig. 7c), while E-DPA exhibits antiparallel alignment (4.88 Å spacing, Fig. 7b). All these distances exceed Schmidt’s 4.2 Å threshold, precluding photodimerization of E-isomers in the aggregated state.

Z-isomers similarly demonstrate pronounced intermolecular isolation. Z-DPA crystals show parallel packing with 13.50 Å double bond separation due to diphenylamine group separation. Z-PTZ and Z-CBZ adopt head-to-tail packing to alleviate steric crowding, yet maintain a minimum double bond distance of 7.59 Å (Fig. 7d–f). Vertical arrangements of Z-PTZ and Z-DPA display antiparallel orientation with 9.33 Å and 9.88 Å separations. Notably, although Z-CBZ maintains consistent double bond orientation, the bulky carbazole group adopts an 8.53 Å intermolecular distance. These structural features fundamentally explain the complete suppression of intermolecular photocycloaddition in the aggregated state.

Crystallographic analysis reveals that the spatial isolation effect of bulky substituents significantly diminishes strong π-π interactions between molecules, with crystal stability instead being maintained through multiple weak intermolecular forces (Supplementary Figs. 77–86). In the E-PTZ crystal structure, in-plane molecular alignment is primarily driven by C-H···π interactions (bond lengths: 3.003 Å and 2.660 Å), while the intercolumnar packing is stabilized by a network of weak interactions including C-H···π (2.928 Å), C-H···N (3.502 Å), and C-H···S (3.610 Å). Similar patterns of weak intermolecular forces are observed in both interlayer and intralayer dimensions across all four additional crystal structures studied. Notably, while these intermolecular interactions promote molecular proximity, their collective strength remains relatively weak. More importantly, the spatial isolation created by bulky groups provides sufficient freedom for conformational changes and further E/Z photoisomerization in the aggregated state.

Structural analysis reveal that the exclusive photoisomerization behavior with long thermal half-lives arises from the dual steric effects: intramolecular conformational restriction and intermolecular spatial isolation. In solution, the steric bulk induces large torsional and dihedral angles, which disrupt the π‑orbital overlap required for photocyclization while simultaneously stabilizing the Z‑isomer to achieve ultralong thermal half-lives. In aggregated states, these steric groups prevent close molecular packing, thereby inhibiting [2+2] photocycloaddition while supplying the free volume necessary for isomerization.

Encryption application
Given the distinct fluorescence intensity changes of the three E/Z compounds in solution, they demonstrate potential for applications such as constructing encrypting dynamic information. As illustrated in Fig. 8a, a dynamic information encryption system based on fluorescence intensity changes was designed, using the difference in fluorescence intensity before and after light irradiation at around λ=650 nm as the output signal. When using E-DPA and Z-CBZ solutions as inputs, we define IC and ID as the difference in fluorescence intensity before and after light irradiation for CBZ and DPA. Taking CBZ as an example: when the fluorescence intensity increases significantly after irradiation (IC >0), the output signal is defined as “o”; when it decreases significantly (IC <0), the output is “h”; and when there is almost no change (IC ≈0), the output is “c”. The same logic is applied to the DPA solution, with different letters assigned according to its fluorescence behavior.

As shown in Fig. 8b, different sequences of 515 nm and 403 nm blue light irradiation on E-CBZ and Z-DPA solutions produced distinct output signals, thereby encoding information. For instance, when the solutions are first irradiated with 403 nm blue light, which promotes Z-to-E isomerization, the fluorescence intensity of DPA increases significantly (output “e”), while that of CBZ remains largely unchanged (output “c”). Subsequent 515 nm irradiation, which drives E-to-Z conversion, leads to a pronounced decrease in the fluorescence of CBZ (output “h”) and minimal change in DPA (output “m”), ultimately spelling the word “chem”. Altering the light sequence results in a different message, such as “hope”.

As demonstrated in Fig. 8c, the pronounced fluorescence changes between different isomeric forms allow reversible switching under varied light conditions. Furthermore, leveraging the thermal Z-to-E conversion behavior of the compounds at elevated temperatures, we fabricated composite films by blending the compounds with polyamide-imide (PAI). As shown in Fig. 8d, after heating at 250 °C, the films exhibit noticeable changes in both color and fluorescence. In particular, the Z-CBZ-doped film shows a fluorescence shift from orange-yellow to green after heating. This transformation of invisible thermal information into visible optical signals highlight the potential of these films in high-temperature warning applications. As suggested in Supplementary Fig. S89, such films could be used to enhance safety in laboratory settings, for instance, by providing visual alerts on hot-plates. Additionally, the thermally activated fluorescence response could be applied in dynamic anti-counterfeiting labels or in monitoring overheated components in aerospace engines and nuclear reactors, indicating broad practical potential.

Methods
General methods
All reagents were commercially available and used as supplied without further purification. Solvents were either employed as purchased or dried according to procedures described in the literature. NMR spectra were recorded on a Bruker Advance DMX 400 MHz spectrophotometer with deuterated solvent as the lock and residual solvent or tetramethylsilane (TMS) as the internal reference. Chemical shifts were reported relative to residual solvent signals. High-resolution mass spectra were obtained on a Finnigan MAT TSQ 7000 Mass Spectrometer operated at MALDI-TOF mode or a Bruker Daltonics Apex IV spectrometer at at ESI mode. Absorption and photoluminescence spectra were recorded on a UV-Vis Spectrophotometer U-3900 spectrophotometer and a spectrofluorometer FS5, respectively. The lifetimes of fluorescence were acquired with a NanoLED laser with the excitation peak at 365 nm or a Horiba Fluoro max plus spectrometer equipped with a xenon arc lamp (Xe900). Lifetime data was analyzed with Data Station v6.6 (Horiba Scientific). Absolute fluorescence quantum yields were measured on a Hamamatsu Quantaurus QY spectrometer or a Fluormax-4p spectrometer. Fluorescent microscopy images were acquired at an excitation wavelength of 365 nm using a Nikon Ni-U Fluorescence Microscope. Thermogravimetric analysis (TGA) was carried out on a Shimadzu-50 thermoanalyser under flowing N2 with a heating rate of 10 °C/min. Differential scanning calorimetry (DSC) were performed with a DSC Q2000 analyzer under nitrogen atmosphere with a heating rate of 10 °C/min. The crystal data were collected on a Stoe Stadivari instrument. Density functional theory (DFT) calculations were performed using the Gaussian 09 software package on the basis of the crystal structures at the B3LYP/6-31G* level. The Gibbs free energies of the solvated compounds were computed using the PWPB95 double-hybrid functional in conjunction with the def2-TZVP basis set. Solvent effects (chloroform) were incorporated via the SMD continuum model. Thermodynamic corrections, derived from frequency calculations performed at the BLYP/def2-SVP level of theory, were subsequently added to these single-point energies. Hirshfeld surface calculations were performed with Crystal Explorer software version 17.5 on crystal structures imported from CIF files.

Preparation of the single crystals of E/Z-DPA, E/Z-PTZ and Z-CBZ
E-DPA: The single crystals of E-DPA was grown by slow solvent evaporation. E-DPA (2.00 mg) was fully dissolved in 2.00 ml of acetonitrile solution to obtain a clear solution, which was then placed in a small crystallization vial. The small crystallization vial was put into a large glass bottle containing 3.00 ml of isopropyl ether, and the bottle was sealed. After slow volatilization for 4 days in a dark environment at room temperature, red rod-shaped crystals were precipitated.
Z-DPA: The single crystals of Z-DPA was grown by slow vapor diffusion. Z-DPA (2.00 mg) was fully dissolved in 2.00 ml of acetonitrile to obtain a clear solution, which was then placed in a small crystallization vial. The small crystallization vial was put into a large glass bottle containing 3.00 ml of isopropyl ether, and the bottle was sealed. After slow volatilization for 5 days in a dark environment at room temperature, red rod-shaped crystals were precipitated.
E-PTZ: The single crystals of E-PTZ was grown by slow solvent evaporation. E-PTZ (2.00 mg) was placed into a crystallization vial, fully dissolved with 1 ml of dichloromethane, followed by the dropwise addition of 2 ml of n-hexane. After thorough mixing, the vial was sealed, and slow volatilization was allowed to proceed for 5 days, yielding deep yellow block-shaped crystals.
Z-PTZ: The single crystals of Z-PTZ was grown by slow solvent evaporation. Z-PTZ (2.00 mg) was placed into a crystallization vial, fully dissolved with 1 ml of dichloromethane, followed by the dropwise addition of 2 ml of n-hexane. After thorough mixing, the vial was sealed, and slow volatilization was allowed to proceed for 7 days, yielding red rod-shaped crystals.
Z-CBZ: The single crystals of Z-CBZ was grown by slow vapor diffusion. Z-CBZ (2.00 mg) was fully dissolved in 1.50 ml of CHCl3 to obtain a clear solution, which was then placed in a small crystallization vial. The small crystallization vial was placed into a large glass bottle containing 3.00 ml of n-hexane, and the bottle was sealed. After slow volatilization for 3 to 5 days in a dark environment at room temperature, orange flake-like crystals were precipitated.

Preparation of the thin films
Z-CBZ@PAI: Weigh 500 mg of Polyamide-imide (PAI), add 5 mL of N,N-dimethylformamide (DMF), and heat with stirring at 80 °C until fully dissolved. Under light-protected conditions, add 3 mg of Z-CBZ and stir until completely dissolved. Using a rubber-tipped dropper, transfer the solution onto a clean glass substrate and place it in an oven at 100 °C for 90 min. Finally, allow it to cool to room temperature before removal.
Z-DPA@PAI: Weigh 500 mg of PAI, add 5 mL of DMF, and heat with stirring at 80 °C until fully dissolved. Under light-protected conditions, add 3 mg of Z-DPA and stir until completely dissolved. Using a rubber-tipped dropper, transfer the solution onto a clean glass substrate and place it in an oven at 100 °C for 90 min. Finally, allow it to cool to room temperature before removal.
PAI: Weigh 500 mg of PAI into a flask, add 5 mL of DMF, and heat with stirring at 80 °C until fully dissolved. Using a rubber-tipped dropper, transfer the solution onto a clean glass substrate and place it in an oven at 100 °C for 90 min. Finally, allow it to cool to room temperature before removal.

Peer review rounds
[{"round": 1, "reviewer_comments": {"reviewer_1": "In this work Wei et al. describe a novel class of three sterically crowded dicyanostilbene-based molecular photoswitches that\nexhibit exclusive E/Z isomerization upon visible light irradiation in both directions, combined with thermal stability of each\nisomer, aggregation-induced emission and fluorescence switching. The steric hindrance brought by symmetrical bulky\ngroups prevents both photocyclization and photoaddition, usually encountered with stilbene derivatives.\nThe works presented are consequent with a large panel of results obtained with various techniques and the systems are\ninteresting candidates for stimuli-responsive materials with potential applications in information encryption. I believe that it\ncertainly has the potential to be publishable in a high-impact journal such as Nature Communications.\nHowever, the photoswitching between E and Z isomers is effectively exclusive but I have some reservations about the\nirradiation time needed to reach PSS. Several hours correspond to a very long duration, that can represent a brake for\napplications. In solution state the PSS E-->Z is around 50/56% after 8 hours of irradiation and the reverse is between 70 and\n80 % after one hour of irradiation. In aggregated state, authors reported 16 hours for E-->Z and 2 hours for the reverse\nreaction. Authors could consider other previously reported photochromic systems from literature to rationalize their results.\nThey could also look for optimizing the irradiation conditions to gain a faster and higher conversion.\nAll along the manuscript (main text and supplementary file), several critical concerns, mainly about the experimental data,\nmust be addressed before the manuscript can be considered for publication.\nThe experimental conditions must be given more accurately for each reported experiment (duration of irradiation,\nconcentrations of solution, solvent, followed method). A detailed presentation of irradiation system must be done. As the\nirradiation time is very long (several hours), it is not judicious to speak about “Time-resolved NMR).\nThe native NMR spectra must be provided without any modification (in manuscript and in supplementary file). For example,\nin Fig 4b, spectra with different colors for peaks and baseline indicated that they were modified. More particularly, for PTZ,\nthe multiplets in the spectrum after heating seem to have larger coupling constants. It is the same with Fig 5e, peak intensity\nof solvent is not the same before and during irradiation and the doublet at 6.9 ppm is larger.\nThe Larmor frequency of 13C NMR is 100 MHz\nThe coupling constants should be measured and indicated and 1H NMR spectra must be enlarged to clearly view key\nchemical shifts to facilitate independent verification.\n1H NMR for the six compounds (E and Z) evidences one type of signal (one compound) while in the 13C spectrum, a lot of\nsignals are observed. Is it the same sample which was studied ?\nE-Br : it is surprising that 1H NMR evidences only one singlet signal instead of two doublets. In the 13C data list, chemical\nshifts of CDCl3 are indicated instead of data for E-Br\nFig S5 : After 1 min of UV light irradiation, authors indicated the formation of Z-Br and c-Br while the two new doublets seem\nto belong to the same species. Did they try to identify the photoproducts?\nSynthesis of E-DPA, E-PTZ, E-CBZ: the amount is given in mM (millimolar) instead of mol. Pd(OAc)2 is indicated in\nsynthetic route while Pd(PPh3)4 is noted in text. For E-CBZ, the NMR data reported are those of E-DPA\nE-CBZ synthesis : dissolution is performed in THF, while DCM is indicated two lines below.\nSynthesis of Z-DPA, Z-PTZ, Z-CBZ: please check all 1H and 13C NMR data which are not always in accordance with\nspectra.\nPhotophysical properties : data in table1 do not agree with data in figure 3 (Lambda max (E-DPA; Z-DPA; Z-PTZ) lambda\nem (E-DPA; E-PTZ; Z-PTZ) are different).\nLine 184 : CBZ and Z-CBZ shared identical emission maxima at 645 nm (values different in table 1).\nLines 188-192 : Quantum yields and lifetimes are reported without any discussion or bibliographic reference. What is the\nsignificance of the number of decimals for quantum yield?\nLine 203 : “… conventional energy barrier threshold (21 kcal/mol)…” bibliographic reference to add\nFig 4a : Details about the calculations of minimized energy path should be done in SI\nFig 4b : spectra of DPA and PTZ are inverted\nFig 4c : How did the authors determine the decomposition temperature for E-PTZ and E-CBZ (Curves are distorded) ?\nAbout the thermal stability of Z-isomers, authors indicated that dissolution was done in CDCl3 and heated at 65°C for 5\nhours : How is it possible with a boiling temperature of 61°C for chloroform. Same question with experiment in toluene at\n110°C for 12 hours (boiling point = 110°C).\nNMR spectra of Z-CBZ in Fig S41 : it is very difficult to distinguish signals (only toluene peaks are observed)\nFig S43 : DSC curve of E-PTZ : there is no peak for E-PTZ\nFig S44 : DSC curve of Z-CBZ : temperature seems to be 310 not 330 as written line 226\nValues given for decomposition and melting temperatures could be discussed.\nAuthors reported changes in color and fluorescence (lines 226-228) after melting and subsequent cooling. Photographs\npowder (Fig S45) show it clearly but NMR spectra reported in Fig 4 indicate that only E-isomer is present. How explain that\nresult? Did the authors use other techniques to check it?\nFig 5a,b,c : what is the wavelength of excitation for PL spectra?\nLines 265-271 (Fatigue resistance = photostability): How long were the solutions irradiated? I don’t understand the meaning\nof curves in Fig 5d and S50 (please correct bule and rad with blue and red in caption), absorbance decreases from 1.11 to\n1.07 for example for CBZ, is it significant? Authors should report the entire UV-vis spectra with visualization of isosbestic\npoint\nLines 286-287 : Aggregation experiment : authors should explain what they call good and poor solvents. Also, as\ncompounds were dissolved and irradiated in CHCl3 and Hexane, how NMR samples (fig 6c) were obtained?\nLines 289-290 : “The fluorescence intensities of Z-DPA and Z-PTZ solutions remained largely unchanged” whereas lines\n239-240, “Particularly notable was the pronounced fluorescence enhancement of Z-DPA and Z-CBZ,” : authors could\ncomment this different behavior\nBased on the concerns outlined above, I recommend a Major Revision before the manuscript can be considered for\npublication.", "reviewer_2": "In the manuscript, the authors introduced bulky and electron-donating groups into both ends of the dicyanostilbene skeleton,\ninvestigated their photophysical properties as photoswitches, and demonstrated that the dicyanostilbene derivatives\nexclusively underwent E–Z photoisomerization in the solution and aggregated states without photocyclization and\nphotocycloaddition. Particularly, the exclusive E–Z photoisomerization was well demonstrated by the crystallographic\nanalysis. However, the work does not appear to present sufficient novelty to merit publication in Nature Communications.\nThe dicyanostilbene derivatives do not offer any unique properties as photoswitches or any properties superior to those of\nexisting photoswitches. The yields of 50–60% and 70–80% for the E-to-Z and Z-to-E photoisomerization, respectively, are\nconsidered very low, and the dicyanostilbene derivatives were gradually degraded upon several photoswitching cycles.\nRecently, several new photoswitches that offer visible light responses and high thermal stability comparable to those of the\ndicyanostilbene derivatives have been developed, such as (sterically hindered) stiff stilbenes, azoheteroarenes,\nhydrazones, and hemi(thio)indigos, in addition to diarylethenes. Because fluorescence competes with photoisomerization\nand lowers the quantum yield, it cannot be regarded as an advantageous property for a photoswitch. Additionally, the work\nappears to be limited to modifying the substituents of the already known dicyanostilbene photoswitch. Therefore, I cannot\nrecommend acceptance of the manuscript for publication in Nature Communications. The followings are my questions and\ncomments.\n1. I regarded the manuscript to concern the development of new photoswitches based on the title and introduction. However,\nany original papers on the development of new photoswitches are not cited in the manuscript. Papers on applications of\nphotoswitches are exclusively cited.\n2. The properties of the dicyanostilbene derivatives developed in this study should be compared to those of the parent\nstilbene and dicyanostilbene photoswitches.\n3. The authors mentioned that the Z-to-E photoisomerization is nearly quantitative. However, the 70–80% yield cannot be\nconsidered nearly quantitative.\n4. I could not understand why the authors used white light although one of the main advantages of photoswitches is their\nwavelength selectivity.\n5. In the section of “thermal stability of E/Z isomers”, the conventional energy barrier threshold (21 kcal/mol) was referenced.\nIt is unclear which molecule this value corresponds to. Additionally, the calculated values should be compared to those of\nother thermally bistable photoswitches.\n6. The Z isomers underwent thermal back isomerization at 110 °C. Therefore, the activation energies of the thermal\nisomerization (ΔG‡), half-lives of the Z isomers at room temperature, and free energy differences between the E and Z\nisomers (ΔG) can be determined experimentally.\n7. Quantum yields of the fluorescence and photoisomerization in solution should be measured and discussed, because they\nare important for this study but compete with each other.\n8. The emission spectra of the white light and 400 nm blue light are highly important for photoisomerization and should be\nprovided in the Supplementary Information.\n9. I am interested in the photoisomerization yields in the aggregated state.", "reviewer_3": "This manuscript presents a novel family of sterically frustrated dicyanostilbene-based molecular photoswitches capable of\ncontrol of photoisomerization pathways. This systematic work advances the field by offering a compelling demonstration that\nstrategic balancing of steric and electronic effects can circumvent long-standing performance trade-offs. The ability to\ncombine exclusive visible-light-driven E/Z isomerization, remarkable thermal stability, and\nmultimodal outputs within a single molecular system provides a versatile tool that will be of\ngreat interest to researchers in photoresponsive and luminescent materials. The manuscript is well-written with solid discussions, therefore, I would like to recommend its publication in\nNature Communications after minor revisions. Some specific comments are detailed below.\n1. The Z-isomers solid powder converts to the E-isomer during the heating-cooling cycle. It is recommended to perform\nPXRD to further verify these transition processes.\n2. The authors have provided DSC data for the relevant compounds in the SI. However, we note a minor upward peak in the\nDSC curve of compound Z-PTZ (Supplementary Fig. 43b). A clarification regarding the origin of this feature should be\nprovided.\n3. To better highlight the advantage of fluorescence turn-on, it is recommended that the authors include a comparison picture\nof the solution under daylight before and after irradiation.\n4. Regarding the photo-conversion ratios, it would be beneficial to include a more detailed calculation process in the SI. For\nexample, using one representative compound and showing the analysis based on the NMR data would greatly enhance\nclarity."}, "author_response": "Point-by-point response to the reviewers’ comments (NCOMMS-25-71915):\nReviewer 1\nComment 1: In this work Wei et al. describe a novel class of three sterically crowded\ndicyanostilbene-based molecular photoswitches that exhibit exclusive E/Z isomerization upon\nvisible light irradiation in both directions, combined with thermal stability of each\nisomer, aggregation-induced emission and fluorescence switching. The steric hindrance brought by\nsymmetrical bulky groups prevents both photocyclization and photoaddition, usually\nencountered with stilbene derivatives.\nThe works presented are consequent with a large panel of results obtained with various\ntechniques and the systems are interesting candidates for stimuli-responsive materials with\npotential applications in information encryption. I believe that it certainly has the potential to\nbe publishable in a high-impact journal such as Nature Communications. However, the\nphotoswitching between E and Z isomers is effectively exclusive but I have some reservations\nabout the irradiation time needed to reach PSS. Several hours correspond to a very long\nduration, that can represent a brake for applications. In solution state the PSS E-->Z is around\n50/56 % after 8 hours of irradiation and the reverse is between 70 and 80 % after one hour of\nirradiation. In aggregated state, authors reported 16 hours for E-->Z and 2 hours for the\nreverse reaction. Authors could consider other previously reported photochromic systems from\nliterature to rationalize their results. They could also look for optimizing the irradiation\nconditions to gain a faster and higher conversion.\nAll along the manuscript (main text and supplementary file), several critical concerns,\nmainly about the experimental data, must be addressed before the manuscript can be\nconsidered for publication.\nThe experimental conditions must be given more accurately for each reported experiment\n(duration of irradiation, concentrations of solution, solvent, followed method). A detailed\npresentation of irradiation system must be done. As the irradiation time is very long (several\nhours), it is not judicious to speak about “Time-resolved NMR). The native NMR spectra must\nbe provided without any modification (in manuscript and in supplementary file). For example,\nin Fig 4b, spectra with different colors for peaks and baseline indicated that they were modified.\nMore particularly, for PTZ, the multiplets in the spectrum after heating seem to have larger\ncoupling constants. It is the same with Fig 5e, peak intensity of solvent is not the same before\nand during irradiation and the doublet at 6.9 ppm is larger.\nResponse: Thanks for your valuable comments which really improved our manuscript. By\nreferring to the experimental conditions of other photochromic systems in the references, we\ntracked the changes of absorbance with the irradiation of different light sources ranging from\n365 to 530 nm (including white light, Supplementary Figure 31). Finally, we selected the\nstimuli wavelength with the highest conversion ratio (Supplementary Fig. 32). The conversion\nfrom the E-isomers to the Z configuration is achieved by a 515 nm light (with 515 nm\nirradiation of 23 mW/cm2), Z-isomers to the E configuration is achieved by a 403 nm light\n(with 403 nm irradiation of 32 mW/cm2).\nAfter optimizing the irradiation conditions, all the systems have indeed gained a faster and\nhigher conversion in both solution and the aggregate state as shown in Table 2 (partially shown).\nThe 1H NMR results show that the PSS E→Z is around 50-70 % after 20 minutes of irradiation\nand the reverse is between 80 and 92 % after 60 minutes of irradiation (Fig. 2c and\nSupplementary Figs. 34-46). This duration time is greatly shorter than our previous ones.\nNotably, this time is for 1H NMR spectra and the concentration is usually within 5  10-3\nmo/L. For UV-vis and PL spectra with 7.0 × 10-5 mo/L, the time to reach PSS is within 5\nminutes (Fig. 3d-e, Supplementary Figs. 48, 55).\nThe experimental conditions (duration of irradiation, concentrations of solution, solvent,\nfollowed method) have accurately been provided for all the 1H NMR, UV-vis, PL spectra and\nTables. A detailed presentation of irradiation system has been done (Supplementary Figs. 31\nand 32). The description of “Time-resolved NMR” has been deleted. The native for all NMR\nspectra have been provided without any modification in manuscript and supplementary file.\nSome specific comments have also been resolved. For example, the original modified Fig. 4b\nhas been replaced with native NMR (see Supplementary Fig. 52 in the revised version). The\nlarger coupling constants for Z- PTZ after heating has been resolved with new replaced 1H\nNMR spectra. Peak intensity of solvent (Fig. 5e of original version) now is the same before\nand during irradiation (Supplementary Fig. 41 in revised version). The doublet at 6.9 ppm is\nalso correct now.\n[... truncated for brevity ...]"}, {"round": 2, "reviewer_comments": {"reviewer_1": "The authors answered to each of my critical concerns, leading to a highly improved manuscript.\nI recommend the acceptance of manuscript for publication", "reviewer_2": "The authors have fully addressed my questions and comments. The manuscript has been revised so thoroughly that the\noriginality and novelty of the work are now clearly conveyed. I therefore recommend acceptance of the manuscript for\npublication in Nature Communications. However, I suggest that the authors carefully proofread the manuscript once more,\nsince a few typographical and formatting errors remain, as listed below.\n1. In the footnote of Table 2, the description “f Values at 298 K in CHCl3” should be corrected.\n2. In Table 2 and Figure 4c, the thermodynamic and kinetic parameters G, H, and S should be italicized.\n3. In the sections of Thermal stability of E/Z isomers and Mechanism study, the phrase “intermolecular interactions” should\nbe corrected to “intramolecular interactions” in some instances.\n4. In the Mechanism study section, “Supplementary Fig. 54” should be corrected to “Supplementary Fig. 53.”", "reviewer_3": "All the issues have addressed, and it can be accepted in current form."}, "author_response": "Responses to reviewers’ comments for the manuscript titled\n“Visible-light-triggered exclusive bistable E/Z photoswitching based on\nsterically frustrated dicyanostilbene derivatives” (NCOMMS-25-71915A)\nReviewer #1 (Remarks to the Author):\nThe authors answered to each of my critical concerns, leading to a highly improved manuscript. I\nrecommend the acceptance of manuscript for publication.\nResponses: We sincerely thank the reviewer’s recognition and support of publication of our\nwork.\nReviewer #2 (Remarks to the Author):\nThe authors have fully addressed my questions and comments. The manuscript has been revised\nso thoroughly that the originality and novelty of the work are now clearly conveyed. I therefore\nrecommend acceptance of the manuscript for publication in Nature Communications. However, I\nsuggest that the authors carefully proofread the manuscript once more, since a few typographical\nand formatting errors remain, as listed below.\nResponses: We sincerely thank the reviewer for the comments and supporting publication of our\nwork. We have checked the whole manuscript very carefully to avoid any typographical and\nformatting errors.\nComment 1: In the footnote of Table 2, the description “f Values at 298 K in CHCl ” should be\n3\ncorrected.\nComment 2: In Table 2 and Figure 4c, the thermodynamic and kinetic parameters G, H, and S\nshould be italicized.\nComment 3: In the sections of Thermal stability of E/Z isomers and Mechanism study, the phrase\n“intermolecular interactions” should be corrected to “intramolecular interactions” in some\ninstances.\nComment 4: In the Mechanism study section, “Supplementary Fig. 54” should be corrected to\n“Supplementary Fig. 53.”\nResponses: Thanks for your detailed and valuable comments. We have corrected “f Values at\n3 8\ninto “intramolecular interactions”, corrected “Supplementary Fig. 54” into “Supplementary Fig.\n53”. The thermodynamic and kinetic parameters G, H, and S has been italicized.\nReviewer #3 (Remarks to the Author):\nAll the issues have addressed, and it can be accepted in current form.\nResponses: We sincerely thank the reviewer for the comments and supporting publication of our\nwork."}]

Decision letter