bluuebunny/crossref_metadata_2025_split huggingface dataset:
(Invited) Metal-Metal Bond and Metal-Cage Interaction in Endohedral Actinidofullerenes
Authors: Rodriguez-Fortea Antonio , Roselló Yannick , Abella Laura , Poblet Josep M. 
Published: August 2024

Since the isolation and characterization of the first metallofullerene containing an actinide, Th@C82,1 many other mono-actinidofullerenes as non-IPR U@C80, Th@C80; IPR U@C76, U@C2n (2n=82-86), Th@C2n (2n=82-86); di-actinidofullerenes U2@C80, Th2@C80; and mixed actinido-lanthanidofullerenes ThDy@C2n (2n = 72, 76-80) and ThY@C2n (2n = 72, 78) have been characterized.2 In mono-actinidofullerenes, the actinide usually shows oxidation state +4, which involves important metal-cage interactions with significant covalent contributions, in contrast to lanthanofullerenes where the lanthanide shows oxidation state +3. In di-actinidofullerenes and mixed actinido-lanthanidofullerenes, the cage plays the role of a nanocontainer that makes possible the formation of the metal-metal bond. We here discuss on the nature of those actinide-actinide and actinide-lanthanide bonds, as well as on the particular actinide-cage interaction in these systems.
References

Wang, Y.; Morales-Martínez, R.; Zhang, X.; Yang, W.; Wang, Y.; Rodriguez-Fortea, A.; Poblet, J. M.; Feng, L.; Wang, S.; Chen, N.J. Am.
Chem. Soc.
2017, 139, 5110-5116.

a) Cai, W.; Abella, L.; Zhuang, J.; Zhang, X.; Feng, L.; Wang, Y.; Morales-Martínez, R.; Esper, R.; Boero, M.; Metta-Magaña, A.; Rodriguez-Fortea, A.; Poblet, J. M.; Echegoyen, L.; Chen, N. J. Am. Chem. Soc.
2018, 140, 18039-18050; b) Yao, Y.-R.; Roselló, Y.; Ma, L.; Puente Santiago, A. R.; Metta-Magaña, A.; Chen, N.; Rodriguez-Fortea, A.; Poblet, J. M.; Echegoyen, L. J. Am. Chem. Soc.
2021, 143, 15309-15318; c) Zhang, X.; Wang, Y.; Morales-Martínez, R.; Zhong, J.; de Graaf, C.; Rodriguez-Fortea, A.; Poblet, J. M.; Echegoyen, L.; Feng, L.; Chen, N. J. Am. Chem. Soc.
2018, 140, 3907-3915; d) Zhuang, J.; Morales-Martínez,R.; Zhang, J.; Wang, Y.; Yao, Y.-R.; Rodríguez-Fortea, A.; Wang, S.; Echegoyen, L.; de Graaf, C.; Poblet, J. M.; Chen, N. Nat.
Commun.
2021, 12, 2372; e) Yan, Y.; Abella, L.; Sun, R.; Fang, Y.; Roselló, Y.; Shen, Y.; Jin, M.; Rodríguez-Fortea, A.; de Graaf, C.; Meng, Q.; Yao, Y.-R.; Echegoyen, L.; Wang, B.-W.; Gao, S.; Poblet, J. M.; Chen, N. Nat.
Commun.
2023, 14, 6637.
(Invited) 1. Chalcogen-Substituted PC61/71BX Derivatives in Perovskite Solar Cells
Authors: Delgado Juan L 
Published: August 2024

Taking into account the outstanding electronic and physical properties of fullerenes, novel functionalized fullerenes are synthesized, with adapted structures aimed at improving the efficiency and stability of inverted PSC architectures.
By means of [2+1] cycloadditions, chalcogen-substituted fullerene C60 and C70 derivatives were successfully synthesized using tosylhydrazone derivatives containing thiophene, selenophene, and furan. These derivatives were based on the chemical structures of PC71BM and PC61BM, resulting in the preparation of PC71BX: T70, S70, and F70, and PC61BX: T60, S60 and F60. The chemical structure of the synthesized mono-adducts PC61/71BM was confirmed through 1H and 13C NMR spectroscopy, MALDI-TOF mass spectroscopy, UV-Vis spectroscopy, and cyclic voltammetry.
Inverted PSCs were fabricated employing the synthesized chalcogen-substituted PC61/71BM as dopant-free ETLs. In the current presentation we will comment on the data obtained in this photovoltaic study and the explanation for the different behaviour of these PC61BX and PC71BX materials.

Figure 1
(Invited) Magnetism of Tb3N@C80 Endofullerenes
Authors: Greber Thomas , Yu Lebin , Jin Huaimin , Stalder Urs , Therampilly Sam , Bigler Laurent , Braun Hans-Benjamin , Yang Shangfeng 
Published: August 2024

Tb3N@C80 was one of the first trimetallic endofullerenes to be studied in view of its magnetization where the microscopic picture of 3 Tb magnetic moments non-collinearly aligned by the ligand field of the central nitrogen ion was proposed [1]. The triangular geometry results in a net molecular magnetization of two Tb3+ ions or 18 μB. Today, this is confirmed with 23 possible pseudospin arrangements of the 3 Tb magnetic moments, resulting in a frustrated magnetic ground state with fluctuating pseudospins [2]. This picture does not include coherent tunneling of the magnetization, which is predicted within an 8-dimensional Hamiltonian and can be tested with low temperature magnetization measurements. Experimentally, we find a low temperature hysteresis that identifies Tb3N@C80 as a single molecule magnet. More surprisingly, we observe room temperature ferromagnetism in cubic single crystallites of the molecules using SQUID magnetometry. Since the magnetic interaction between adjacent carbon cages is expected to be dipolar it is neglected in the explanation of magnetic order above 3 K [3] and it is challenging to explain this finding with endofullerene magnetism. We present a series of analytical chamistry results of samples with and without room temperature ferromagnetism.
[1] M. Wolf et al. Angew. Chem. Int. Ed. 44, 3306 (2005).
[2] R. Westerström et al. Phys. Rev. B, 89, 060406(R) (2014).
[3] A. Kostanyan et al. Phys. Rev. B, 101, 134429 (2020).
(Invited) On the Optical Response of Layered Materials Exfoliated in Liquid Phase: Evidence of Functional Groups and Size-Dependent Features
Authors: Olaya Daniel , Rico Julian , Cardenas-Chirivi Gabriel , Navarrete Cristina , Hernandez Yenny 
Published: August 2024

Liquid phase exfoliation of layered materials has proven successful for a range of applications [1]. However, the range of organic solvents needed, and the broad distribution of thicknesses [2] can be aided by applying intercalation steps such as electrochemical or solvothermal expansion which leads to thinner crystals in the dispersion [2, 3]. In this talk I will present the effect of electrochemical exfoliation on the basal functionalization of graphene and a proposal for a more accurate determination of the optical extinction coefficient based on oxidation levels for standardization [4]. I will also present a few examples of MoS2 and WS2 exfoliated via ultrasonication which display non-linear optical effects in fluorescence spectroscopy [5] and the effect of crystal-size selection on the piezoresistive and photoconduction response of MoS2 and WS2 exfoliated via lithium intercalation.
[1] Yenny Hernandez, et al, Nature Nanotechnology, 3, 563–568 (2008)
[2] Jonathan N. Coleman et al. Science 331, 568-571 (2011)
[3] Zhongfen Ding, et al, J. Mater. Chem., 2009, 19, 2588-2592 (2009)
[4] Khaled Parvez, et al, ACS Nano 2013, 7, 4, 3598–3606 (2013)
[5] J Rico, et al, J. Phys.: Condens. Matter 34 105701 (2022)
[6] Gabriel Cardenas-Chirivi, et al, Optical Materials, 133,112890 (2022)
(Invited) Designer 2D Materials and Machine-Learning Assisted Characterization
Authors: Huang Shengxi 
Published: August 2024

2D materials offer enormous opportunities to build designer structures with widely tunable properties. The precise atomic engineering and quick characterization approach are critical to advance the application of designer 2D materials. This talk will introduce new optical features of designer 2D materials [1-4] with a focus on atomic substitution in monolayer WS2 [1]. The engineering of 2D materials presents unique opportunities for optoelectronic device and quantum information platform. When designing optoelectronic devices of 2D materials, spectroscopic permittivity of 2D material is a key parameter. While ellipsometry has been used to measure permittivity, it requires simple device structure, non-trivial parameter fitting, and special setup. This talk will also present a new machine-learning assisted approach to measure permittivity of 2D materials embedded in complex device structures without model fitting, which can facilitate a quick, accurate, and in-situ characterization of 2D and other thin film materials [5].

References

[1] Q. Qian, et al. “Photoluminescence Induced by Substitutional Nitrogen in Single-Layer Tungsten Disulfide,” ACS Nano, 16 (5), 7428-7437 (2022).
[2] K. Zhang, et al. “Enhancement of van der Waals Interlayer Coupling Through Polar Janus MoSSe,” Journal of the American Chemical Society, 142 (41), 17499-17507 (2020).
[3] K. Zhang, et al. “Spectroscopic signatures of interlayer coupling in Janus MoSSe/MoS2 heterostructures,” ACS Nano, 15 (9), 14394-14403 (2021).
[4] Q. Qian, et al. “Chirality-Dependent Second Harmonic Generation of MoS2 Nanoscroll with Enhanced Efficiency,” ACS Nano, 14 (10), 13333–13342 (2020).
[5] Z. Wang, et al. “Measuring complex refractive index through deep-learning-enabled optical reflectometry,” 2D Materials, 10, 025025 (2023).
Covalent Patterning of Graphene: from Sophistication to Simplicity
Authors: Perez Emilio M 
Published: August 2024

Patterning of graphene (functionalizing some areas while leaving others intact) is challenging, as all the C atoms in the basal plane are identical, but it is also desirable for a variety of applications, like opening a bandgap in the electronic structure of graphene. Several methods have been reported to pattern graphene, but most of them are very technologically intensive. For example, some groups have explored electron beam lithography,[1] or laser writing.[2]

Here, we will present the two approaches that we have studied. First, we describe a method to functionalize graphene covalently under ultra-high vacuum conditions and characterized with scanning tunnelling microscopy.[3] We achieve exquisite (>97%) atomic selectivity and yield (92%). The periodic landscape is provided by a single monolayer of graphene grown on Ru(0001) that presents a moiré pattern due to the mismatch between the carbon and ruthenium hexagonal lattices. The moiré contains periodically arranged areas where the graphene–ruthenium interaction is enhanced and shows higher chemical reactivity. Furthermore, we will show how this type of functionalized graphene acts as a catalyst for an unusual and reversible C-C bond forming reaction.[4] Secondly, we will describe easy and scalable protocol for the covalent patterning of graphene based on using microemulsions as templates.[5] This method is technologically trivial and can achieve resolution in the µm range.
[1] M. C. Rodríguez González, A. Leonhardt, H. Stadler, S. Eyley, W. Thielemans, S. De Gendt, K. S. Mali, S. De Feyter, ACS Nano
2021, 15, 10618-10627.
[2] K. F. Edelthalhammer, D. Dasler, L. Jurkiewicz, T. Nagel, S. Al-Fogra, F. Hauke, A. Hirsch, Angew. Chem., Int. Ed.
2020, 59, 23329-23334; T. Wei, S. Al-Fogra, F. Hauke, A. Hirsch, J. Am. Chem. Soc.
2020, 142, 21926-21931.
[3] J. J. Navarro, S. Leret, F. Calleja, D. Stradi, A. Black, R. Bernardo-Gavito, M. Garnica, D. Granados, A. L. Vazquez de Parga, E. M. Perez, R. Miranda, Nano Lett.
2016, 16, 355-361; J. J. Navarro, F. Calleja, R. Miranda, E. M. Pérez, A. L. V. d. Parga, Chem. Commun.
2017, 53, 10418--10421.
[4] J. J. Navarro, M. Pisarra, B. Nieto-Ortega, J. Villalva, C. G. Ayani, C. Díaz, F. Calleja, R. Miranda, F. Martín, E. M. Pérez, A. L. Vázquez de Parga, Science Advances
2018, 4, eaau9366.
[5] A. Naranjo, N. Martín Sabanés, M. Vázquez Sulleiro, E. M. Pérez, Chemical Communications
2022, 58, 7813-7816.
(Invited) Low Temperature Atomic Layer Deposition Processes for Large-Area Synthesis of 2D Transition Metal Dichalcogenides
Authors: Bol Ageeth Anke 
Published: August 2024

2D materials have been the focus of intense research in the last decade due to their unique physical properties. This presentation will highlight our recent progress on the large-area synthesis of two-dimensional transition metal chalcogenides for nanoelectronics using advanced atomic layer deposition cycle schemes. First, how we can use advanced cycle schemes to deposit wafer-scale polycrystalline MoS2 thin films at very low temperatures down to 100 °C. We have identified the critical role of hydrogen during the plasma step in controlling the composition and properties of molybdenum sulfide films. By increasing the H2/H2S ratio or adding an extra hydrogen plasma step to our ALD process, we are able to deposit pure polycrystalline MoS2 films at temperatures as low as 100 °C. To the best of our knowledge, this represents the lowest temperature for crystalline MoS2 films prepared by any chemical gas-phase method.[1]
The most dominant methods for preparing MoS2 via ALD is to alternately expose a substrate to a metalorganic precursor and a hydrogen sulfide (H2S) or a plasma containing H2S. H2S is a corrosive, toxic, and flammable gas that is heavier than air, which makes it hazardous and expensive to store, install, and transport. Alternative sulfur precursors in the solid or liquid phase would be beneficial in terms of cost and safety and would require the installation of no additional hardware for most ALD reactors. In the second half of this contribution, the widely researched ALD process using bis(tert-butylimido)bis(dimethylamino)molybdenum(IV) ((tBuN)2(NMe2)2Mo) and H2S plasma is compared to a novel ALD process using (tBuN)2(NMe2)2Mo, hydrogen plasma, and di-tert-butyl disulfide (TBDS), which is an inexpensive, liquid-phase sulfur precursor.
[1] M. Mattinen et al., Chem. Mater. (2022), 34, 5104
(Invited) Delayed Fluorescence from Inverted Singlet and Triplet Excited States
Authors: Aizawa Naoya 
Published: August 2024

Hund’s multiplicity rule states that for a given electronic configuration, a higher spin state has a lower energy. Rephrasing this rule for molecular excited states predicts a positive energy gap between singlet and triplet excited states (∆E
ST). Although there is general agreement that ∆E
ST must be positive, the potential for negative ∆E
ST in phenalene analogues, such as cycl[3.3.3]azine and heptazine has been discussed during the last two decades.1–4 In this presentation, we report a fluorescent heptazine analogue HzTFEX2 that disobeys Hund’s rule, possessing negative ∆E
ST of –11 meV (Fig. 1).5 The energy inversion of the singlet and triplet excited states results in delayed fluorescence with short time constants of 0.2 μs, which anomalously decrease with decreasing temperature due to the emissive singlet character of the lowest-energy excited state. Organic light-emitting diodes using this molecule exhibit a fast transient electroluminescence decay with a maximum external quantum efficiency of 17%, demonstrating potential implications for optoelectronic devices.
(1) W. Leupin, J. Wirz, J. Am. Chem. Soc. 102, 6068–6075 (1980).
(2) W. Leupin, D. Magde, G. Persy, J. Wirz, J. Am. Chem. Soc. 108, 17–22 (1986).
(3) J. Ehrmaier, E. J. Rabe, S. R. Pristash, K. L. Corp, C. W. Schlenker, A. L. Sobolewski, W. Domcke, J. Phys. Chem. A
123, 8099–8108 (2019).
(4) P. de Silva, J. Phys. Chem. Lett. 10, 5674–5679 (2019).
(5) N. Aizawa, Y.-J. Pu, Y. Harabuchi, A. Nihonyanagi, R. Ibuka, H. Inuzuka, B. Dhara, Y. Koyama, K. Nakayama, S. Maeda, F. Araoka, D. Miyajima, Nature
609, 502 (2022).

Figure 1
(Invited) Dynamic Relaxation of Charge Carrier Mobilities in Organic Photovoltaics
Authors: Saeki Akinori 
Published: August 2024

A non-fullerene small molecular acceptor (NFA) is a prominent molecule that shows moderate electron mobility and a narrow bandgap complementary to middle-bandgap p-type conjugated polymers, which leads to great improvement in the performance of organic photovoltaic (OPV) cells. However, little is known about the relaxation of charge carriers, which is key to efficient charge transport. Herein, we report simultaneous time-of-flight (TOF) and time-resolved microwave conductivity (TRMC) measurements[1] employing benzodithiophene-based polymer (PBDB-T):soluble C70-fullerere (PCBM) and PBDB-T:NFA (ITIC or Y6) blends, as benchmark systems[2, 3]. In addition to the conventional TOF mobilities, relaxation of the hole and electron mobility was evaluated by TRMC under an external electric field. Although PBDB-T:ITIC exhibited much faster relaxation than PBDB-T:PCBM, the relaxation in PBDB-T:Y6 was considerably moderate. This is consistent with the energetic disorder estimated from the photoabsorption onset. Interestingly, the slower relaxation of the electrons compared to the holes in PBDB-T:Y6 is in line with the preferred normal device structure. Our work deepens the understanding of the energetics of polymer:NFA blends and offers a basis for achieving efficient NFA properties.
Reference
[1] Y. Shimata, A. Saeki, J. Phys. Chem. C 121 (2017) 18351.
[2] F. Hamada, A. Saeki, ChemSusChem 14 (2021) 3528.
[3] S. Li, F. Hamada, R. Nishikubo, A. Saeki, Sustainable Energy Fuels 6 (2022) 756.
(Invited) Comprehensive Analysis of Exciton Diffusion with Time-Resolved Fluorescence Spectroscopy, Anisotropy and Imaging
Authors: Sotome Hikaru 
Published: August 2024

Excitons produced in materials play a crucial role in photo-energy conversion such as photovoltaics and electroluminescence devices. The temporal and spatial diffusion of excitons is a key factor for dominating the fundamental performance of optoelectronic materials. In this context, analysis of the exciton diffusion dynamics is an important issue for obtaining the rational design of the materials. Excitons diffusing in materials can be characterized by several parameters such as the energy level, orientation of the transition dipole moment and spatial distribution, and the detection of these properties is required for the comprehensive analysis. In the present study, we show time-resolved fluorescence methods for detecting the above relevant properties of excitons.
First, time-resolved fluorescence spectroscopy is a basic technique for analyzing the exciton diffusion dynamics. Fluorescence intensity is detected as functions of observation wavelength and time, and the spectral intensity and shift of fluorescence bands provide information on the population of excitons and their energy level. For example, dynamic Stokes shift indicates downhill energy migration and excitons are trapped by the defective site in molecular aggregates. Second, fluorescence anisotropy can be a good indicator for tracking the exciton diffusion in amorphous materials. Fluorescence anisotropy is sensitive to orientation change in transition dipole moments (TDMs) between absorption and fluorescence. In systems where the relative orientation of adjacent molecules is different from each other, such as amorphous solids, the exciton diffusion is accompanied with the change in TDM. Thus, appropriate modeling of molecular alignment enables quantitative estimation of the exciton diffusion coefficient and diffusion length from the anisotropy signal. Finally, time-resolved imaging is a combination of time-resolved spectroscopy and super-resolution microscopy, and an emergent technique for visualizing real-space propagation of excitons in materials. The diffraction-limited excitation beam produces excitons in several hundreds of nanometers and the subsequent exciton diffusion is evaluated by the spatial width of the fluorescence spot. The temporal broadening of the fluorescence spot directly reflects the exciton distribution and we can intuitively obtain the diffusion coefficient and length. Unlike the conventional methods for bulk materials, the advantage of the time-resolved imaging is the applicability to materials with nano- and meso-scale heterogeneous structure and it enables site-selective evaluation of the exciton transport capability. In the conference site, we will also show the application of the above methods to supramolecular polymers and thermally activated delayed fluorescence materials.

Figure 1
(Invited) Phase Engineering for Enhanced Stability of Perovskite Nanowire Optoelectronics
Authors: Ho Johnny C 
Published: August 2024

The crystallization of halide perovskites (HPs) into one-dimensional structures has generated considerable research interest for their promising prospects in studying electron transport characteristics and multifunctional nanoscale devices. Various strategies have been developed to achieve in-plane growth of one-dimensional (1D) structures, including epitaxy, capillary-bridge-manipulated graphoepitaxy, and van der Waals epitaxy. Typically, the VLS growth mode, which involves the initial seeding of metallic catalytic nanoparticles to facilitate the process, has realized the out-of-plane and bottom-up synthesis route, opening up a new pathway for the one-dimensional perovskite electronics and optoelectronics.
Among many recent advances, Zinc (Zn) has become a significant suppressor of vacancy formation in halide perovskites, establishing its pivotal role in defect engineering for these materials. Herein, we report the Zn-catalyzed vapor-liquid-solid (VLS) route to render black-phase CsPbI3 nanowires operationally stable at room temperature. Based on ﬁrst-principle calculations, the doped Zn2+ can not only lead to the partial crystal lattice distortion but also reduce the formation energy value from the black phase to the yellow phase, improving the stability of the desired black phase. A series of contrast tests further confirm the stabilization effect of the Zn-doped strategy. Besides, the polarization-sensitive characteristics of black phase CsPbI3 nanowires were revealed. Our work highlights the importance of phase stabilization engineering for CsPbI3 nanowires and their potential applications in anisotropic optoelectronics.
Cooperativity in Molecular Recognition of Porphyrin Clefts
Authors: Haino Takeharu , Hisano Naoyuki 
Published: August 2024

The electron-rich cleft cavities of porphyrin-based molecular tweezers encapsulate various electron-deficient guest molecules via π-π stacking and donor-acceptor interactions. In this presentation, we will describe negative cooperativity in the molecular recognition of a trisporphyrin host molecule possessing two cleft cavities. A 1:2 host-guest complexation of the trisporphyrin host with various electron-deficient guest molecules showed strong negative cooperativity. The quantitative discussion of the negative cooperativity was provided by a detailed analysis using isothermal titration calorimetry.
1) Hisano, N.; Kodama, T.; Haino, T., Chem. Eur. J. 2023, 29, e202300107
2) Hisano, N.; Haino, T., J. Org. Chem. 2022, 87, 4001-4009.

Figure 1
Engineering Thin Films of Silicon Phthalocyanines for Organic Thin Film Transistors
Authors: Lessard Benoit 
Published: August 2024

Metal phthalocyanines (MPc) show great promise as semiconductors due to their exceptional optoelectronic properties, high thermal and photochemical stability, and ability to be easily synthesized and functionalized for specific applications. The metal/metalloid ion in the center of the MPc ring can significantly influence the electronic, optical, and magnetic properties of the compound, as well as its solubility and stability. The majority of MPc, such as copper phthalocyanine (CuPc) are used as hole-transport materials (p-type) in organic electronics. Silicon phthalocyanines (R2-SiPc) are emerging semiconductors which predominantly moves electrons and have led to high performance n-type organic thin-film transistors (OTFTs). Their low synthetic complexity paired with their versatile axial group facilitates the finetuning of their chemical properties, solution properties and processing characteristics without significantly affecting their frontier orbital levels or their absorption properties. The crystal engineering and film forming characteristics of R2-SiPc semiconductors can be tuned through appropriate axial group functionalization, therefore facilitating their integration into both OTFTs and OPVs by solution processing or vapor deposition.
Our group has developed families of R2-SiPc and integrated them into OTFTs with an emphasis on thin film processing and engineering of the interfaces for improved device performance. We have established structure property relationships of the final device performance as a function of 1) R2-SiPc axial groups and peripheral groups, 2) surface chemistry and composition and 3) thin film deposition conditions. I will also be discussing our recent work using advanced film characterization such as polarized Raman microscopy and synchrotron based scanning transmission x-ray microscopy to evaluate the resulting films and optimize the OTFT performance.

Figure 1