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Arshia Sulaiman, Yi-Zhan Jiang, Mohammad Khurram Javed, Shu-Qi Wu, Zhao-Yang Li, Xian-He Bu, Tuning of spin-crossover behavior in two cyano-bridged mixed-valence (Fe2FeII)-Fe-III trinuctear complexes based on a Tp(R) tigand, INORGANIC CHEMISTRY FRONTIERS, 10.1039/d1qi01086g, 9, 2, 241-248, 2022.01, Spin-crossover (SCO) complexes have been extensively studied in the past few decades owing to their bistable nature which find application in a myriad of areas. In order to enhance and optimize the SCO behavior, considerable attention is being paid towards the synthesis of discrete multinuclear spin-crossover complex systems. Here, two mixed-valence (Fe2FeII)-Fe-III trinuclear complexes of the formula {[Fe-II(TPMA)][Fe-III(Tp(R))(CN)(3)](2)}center dot MeOH center dot 2H(2)O (1) and {[Fe-II(TPMA)][Fe-III(Tp(R))(CN)(3)](2)}center dot H2O (2) [where TPMA = tris(2-pyridylmethyl)amine, Tp = tris(pyrazol-1-yl)borate, R = 3,5-dimethyl for 1 and H for 2] were synthesized and characterized. Magnetic measurements confirmed that complex 1 undergoes SCO at a high temperature (T-1/2 = 410 K for the fresh sample and T-1/2 = 406 K for the dried sample), while complex 2 displays near room temperature SCO (T-1/2 = 283 K for the fresh sample and T-1/2(up arrow) = 283 K and T-1/2(down arrow) = 257 K for the dried sample). To the best of our knowledge, complex 1 has the highest transition temperature reported among trinuclear SCO complexes so far, which is a remarkable feature of multinuclear materials. Slight structural modifications tend to upend the SCO behavior which paves the way for fine tuning SCO.. |
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Yun Li, Shu-Qi Wu, Jin-Peng Xue, Xiao-Lei Wang, Osamu Sato, Zi-Shuo Yao, Jun Tao, A Molecular Crystal Shows Multiple Correlated Magnetic and Ferroelectric Switchings, CCS Chemistry, 10.31635/ccschem.020.202000489, 3, 9, 2464-2472, 2021.09. |
| 3. |
Pritam Sadhukhan, Shu-Qi Wu, Jeremy Ian Long, Takumi Nakanishi, Shinji Kanegawa, Kaige Gao, Kaoru Yamamoto, Hajime Okajima, Akira Sakamoto, Michael L Baker, Thomas Kroll, Dimosthenis Sokaras, Atsushi Okazawa, Norimichi Kojima, Yoshihito Shiota, Kazunari Yoshizawa, Osamu Sato, Manipulating electron redistribution to achieve electronic pyroelectricity in molecular [FeCo] crystals., Nature communications, 10.1038/s41467-021-25041-4, 12, 1, 4836-4836, 2021.08, Pyroelectricity plays a crucial role in modern sensors and energy conversion devices. However, obtaining materials with large and nearly constant pyroelectric coefficients over a wide temperature range for practical uses remains a formidable challenge. Attempting to discover a solution to this obstacle, we combined molecular design of labile electronic structure with the crystal engineering of the molecular orientation in lattice. This combination results in electronic pyroelectricity of purely molecular origin. Here, we report a polar crystal of an [FeCo] dinuclear complex exhibiting a peculiar pyroelectric behavior (a substantial sharp pyroelectric current peak and an unusual continuous pyroelectric current at higher temperatures) which is caused by a combination of Fe spin crossover (SCO) and electron transfer between the high-spin Fe ion and redox-active ligand, namely valence tautomerism (VT). As a result, temperature dependence of the pyroelectric behavior reported here is opposite from conventional ferroelectrics and originates from a transition between three distinct electronic structures. The obtained pyroelectric coefficient is comparable to that of polyvinylidene difluoride at room temperature.. |
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Hui-Miao Li, Gui-Ming Zhong, Shu-Qi Wu, Osamu Sato, Xiao-Yan Zheng, Zi-Shuo Yao, Jun Tao, Adjusting Rotational Behavior of Molecular Rotors by a Rational Tuning of Molecular Structure, INORGANIC CHEMISTRY, 10.1021/acs.inorgchem.1c00558, 60, 11, 8042-8048, 2021.06, Many crystalline molecular rotors have been developed in the past decades. However, manipulating the rotational gesture that intrinsically controls the physical performance of materials remains a challenge. Herein, we report a series of crystalline rotors whose rotational gestures can be modulated by modifying the structures of molecular stators. In these dynamic crystals, the ox(2-) (ox(2-) = oxalate anion) behave as molecular rotators performing axial-free rotation in cavities composed of five complex cations, [M-II(en)(3)](2+) (en = ethylenediamine). The structure of [M-II(en)(3)](2+) that serves as a molecular stator can be tuned by varying the metal center with different ionic radii, consequently altering the chemical environment around the molecular rotator. Owing to the quasi-transverse isotropy of ox(2-) and multiple hydrogen-bond interactions around it, the molecular rotator exhibits unusual motional malleability, i.e., it can rotate either longitudinally in the compound of Zn-II, or with a tilt angle of 42 degrees in the compound of Fe-II, or even laterally in the compound of Cd-II. The atypical dynamic behavior demonstrated here provides a new chance for the development of exquisite crystalline molecular rotors with advanced tunable functionalities.. |
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Sheng-Qun Su, Shu-Qi Wu, Masato Hagihala, Ping Miao, Zhijian Tan, Shuki Torii, Takashi Kamiyama, Tongtong Xiao, Zhenxing Wang, Zhongwen Ouyang, Yuji Miyazaki, Motohiro Nakano, Takumi Nakanishi, Jun-Qiu Li, Shinji Kanegawa, Osamu Sato,, Water-oriented magnetic anisotropy transition, Nat. Commun., https://doi.org/10.1038/s41467-021-23057-4, 2021.05. |
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Shu-Qi Wu, Meijiao Liu, Kaige Gao, Shinji Kanegawa, Yusuke Horie, Genki Aoyama, Hajime Okajima, Akira Sakamoto, Michael L. Baker, Myron S. Huzan, Peter Bencok, Tsukasa Abe, Yoshihito Shiota, Kazunari Yoshizawa, Wenhuang Xu, Hui-Zhong Kou, Osamu Sato, Macroscopic Polarization Change via Electron Transfer in a Valence Tautomeric Cobalt Complex, Nature Communications, https://doi.org/10.1038/s41467-020-15988-1, 2020.04, Polarization change induced by directional electron transfer attracts wide attention for its fast switching rate and potential light control. Here, electronic pyroelectricity was investigated in the crystal of a mononuclear complex, [Co(phendiox)(rac-cth)](ClO4)·0.5EtOH (1·0.5EtOH, H2phendiox = 9, 10-dihydroxyphenanthrene, rac-cth = racemic 5, 5, 7, 12, 12, 14-hexamethyl-1, 4, 8, 11-tetraazacyclotetradecane), which undergoes a two-step valence tautomerism (VT). Correspondingly, pyroelectric current exhibited double peaks in the same temperature domain with the polarization change consistent with the change in dipole moments during the VT process. The time-resolved IR spectroscopy showed that the photo-induced metastable state can be generated within 150 ps at 190 K. Such state can be trapped for tens of minutes at 7 K, revealing that photo-induced polarization change could be realized in this system. These results directly demonstrate that the change in the molecular dipole moments induced by intramolecular electron transfer can introduce a macroscopic polarization change in VT compounds.. |
