1
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Ji T, Su S, Wu S, Hori Y, Shigeta Y, Huang Y, Zheng W, Xu W, Zhang X, Kiyanagi R, Munakata K, Ohhara T, Nakanishi T, Sato O. Development of an Fe II Complex Exhibiting Intermolecular Proton Shifting Coupled Spin Transition. Angew Chem Int Ed Engl 2024; 63:e202404843. [PMID: 38622084 DOI: 10.1002/anie.202404843] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2024] [Revised: 04/13/2024] [Accepted: 04/15/2024] [Indexed: 04/17/2024]
Abstract
In this study, we investigated reversible intermolecular proton shifting (IPS) coupled with spin transition (ST) in a novel FeII complex. The host FeII complex and the guest carboxylic acid anion were connected by intermolecular hydrogen bonds (IHBs). We extended the intramolecular proton transfer coupled ST phenomenon to the intermolecular system. The dynamic phenomenon was confirmed by variable-temperature single-crystal X-ray diffraction, neutron crystallography, and infrared spectroscopy. The mechanism of IPS was further validated using density functional theory calculations. The discovery of IPS-coupled ST in crystalline molecular materials provides good insights into fundamental processes and promotes the design of novel multifunctional materials with tunable properties for various applications, such as optoelectronics, information storage, and molecular devices.
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Affiliation(s)
- Tianchi Ji
- Institute for Materials Chemistry and Engineering & IRCCS, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, 819-0395, Japan
| | - Shengqun Su
- Institute for Materials Chemistry and Engineering & IRCCS, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, 819-0395, Japan
| | - Shuqi Wu
- Institute for Materials Chemistry and Engineering & IRCCS, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, 819-0395, Japan
| | - Yuta Hori
- Center for Computational Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8577, Japan
| | - Yasuteru Shigeta
- Center for Computational Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8577, Japan
| | - Yubo Huang
- Institute for Materials Chemistry and Engineering & IRCCS, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, 819-0395, Japan
| | - Wenwei Zheng
- Institute for Materials Chemistry and Engineering & IRCCS, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, 819-0395, Japan
| | - Wenhuang Xu
- Institute for Materials Chemistry and Engineering & IRCCS, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, 819-0395, Japan
| | - Xiaopeng Zhang
- Institute for Materials Chemistry and Engineering & IRCCS, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, 819-0395, Japan
| | - Ryoji Kiyanagi
- J-PARC Center, Japan Atomic Energy Agency, 2-4 Shirakata, Tokai, Ibaraki, 319-1195, Japan
| | - Koji Munakata
- Neutron Science and Technology Center, Comprehensive Research Organization for Science and Society, 162-1 Shirakata, Tokai, Ibaraki, 319-1106, Japan
| | - Takashi Ohhara
- J-PARC Center, Japan Atomic Energy Agency, 2-4 Shirakata, Tokai, Ibaraki, 319-1195, Japan
| | - Takumi Nakanishi
- Institute for Materials Research, Tohoku University, 211 Katahira, Aoba Ward, Sendai, Miyagi, 980-8577, Japan
| | - Osamu Sato
- Institute for Materials Chemistry and Engineering & IRCCS, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, 819-0395, Japan
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2
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Zakrzewski J, Liberka M, Wang J, Chorazy S, Ohkoshi SI. Optical Phenomena in Molecule-Based Magnetic Materials. Chem Rev 2024; 124:5930-6050. [PMID: 38687182 PMCID: PMC11082909 DOI: 10.1021/acs.chemrev.3c00840] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/02/2024]
Abstract
Since the last century, we have witnessed the development of molecular magnetism which deals with magnetic materials based on molecular species, i.e., organic radicals and metal complexes. Among them, the broadest attention was devoted to molecule-based ferro-/ferrimagnets, spin transition materials, including those exploring electron transfer, molecular nanomagnets, such as single-molecule magnets (SMMs), molecular qubits, and stimuli-responsive magnetic materials. Their physical properties open the application horizons in sensors, data storage, spintronics, and quantum computation. It was found that various optical phenomena, such as thermochromism, photoswitching of magnetic and optical characteristics, luminescence, nonlinear optical and chiroptical effects, as well as optical responsivity to external stimuli, can be implemented into molecule-based magnetic materials. Moreover, the fruitful interactions of these optical effects with magnetism in molecule-based materials can provide new physical cross-effects and multifunctionality, enriching the applications in optical, electronic, and magnetic devices. This Review aims to show the scope of optical phenomena generated in molecule-based magnetic materials, including the recent advances in such areas as high-temperature photomagnetism, optical thermometry utilizing SMMs, optical addressability of molecular qubits, magneto-chiral dichroism, and opto-magneto-electric multifunctionality. These findings are discussed in the context of the types of optical phenomena accessible for various classes of molecule-based magnetic materials.
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Affiliation(s)
- Jakub
J. Zakrzewski
- Faculty
of Chemistry, Jagiellonian University, Gronostajowa 2, 30-387 Krakow, Poland
- Doctoral
School of Exact and Natural Sciences, Jagiellonian
University, Lojasiewicza
11, 30-348 Krakow, Poland
| | - Michal Liberka
- Faculty
of Chemistry, Jagiellonian University, Gronostajowa 2, 30-387 Krakow, Poland
- Doctoral
School of Exact and Natural Sciences, Jagiellonian
University, Lojasiewicza
11, 30-348 Krakow, Poland
| | - Junhao Wang
- Department
of Materials Science, Faculty of Pure and Applied Science, University of Tsukuba, 1-1-1 Tonnodai, Tsukuba, Ibaraki 305-8573, Japan
| | - Szymon Chorazy
- Faculty
of Chemistry, Jagiellonian University, Gronostajowa 2, 30-387 Krakow, Poland
| | - Shin-ichi Ohkoshi
- Department
of Chemistry, School of Science, The University
of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
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3
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Luo YH, Jin XT, Zhang SX, Xue C, Liu M. Dynamic Aggregation Triggering Reversible Spin-State Switching. ACS APPLIED MATERIALS & INTERFACES 2023; 15:48365-48374. [PMID: 37793189 DOI: 10.1021/acsami.3c10181] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/06/2023]
Abstract
The manipulation of spin-state switching (SSS) under ambient conditions is of significant importance for the construction of molecular switches. Herein, we demonstrate that reversible SSS can be mediated by the aggregation state of a near-infrared (NIR)-sensitive ferrous complex. The ferrous complex was J-aggregated in a DMF suspension and with a low-spin (LS) state; however, with the addition of water, it changed to H-aggregation and reached a high-spin (HS) state, owing to the enhanced intramolecular charge transfer and metal-to-ligand charge transfer. Interestingly, the following NIR irradiation can restore the J-aggregation and LS states owing to the enhanced ligand-to-ligand charge transfer. More interestingly, the ferrous complex can be further incorporated into a hygroscopic sponge that was capable of capturing humidity effectively for all weather conditions, which displayed reversible SSS via alternating atmospheric humidity capture and NIR irradiation under ambient conditions in the sponge state. This study thus opens up a new avenue for the development of novel smart molecular switches at the device level.
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Affiliation(s)
- Yang-Hui Luo
- School of Chemistry and Chemical Engineering, Southeast University, Nanjing 211189, P. R. China
| | - Xue-Ting Jin
- School of Chemistry and Chemical Engineering, Southeast University, Nanjing 211189, P. R. China
| | - Shu-Xin Zhang
- School of Chemistry and Chemical Engineering, Southeast University, Nanjing 211189, P. R. China
| | - Cheng Xue
- School of Chemistry and Chemical Engineering, Southeast University, Nanjing 211189, P. R. China
| | - Min Liu
- School of Chemistry and Chemical Engineering, Southeast University, Nanjing 211189, P. R. China
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4
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Nakanishi T, Hori Y, Shigeta Y, Sato H, Kiyanagi R, Munakata K, Ohhara T, Okazawa A, Shimada R, Sakamoto A, Sato O. Development of an Iron(II) Complex Exhibiting Thermal- and Photoinduced Double Proton-Transfer-Coupled Spin Transition in a Short Hydrogen Bond. J Am Chem Soc 2023; 145:19177-19181. [PMID: 37623927 DOI: 10.1021/jacs.3c06323] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/26/2023]
Abstract
Multiple proton transfer (PT) controllable by external stimuli plays a crucial role in fundamental chemistry, biological activity, and material science. However, in crystalline systems, controlling multiple PT, which results in a distinct protonation state, remains challenging. In this study, we developed a novel tridentate ligand and iron(II) complex with a short hydrogen bond (HB) that exhibits a PT-coupled spin transition (PCST). Single-crystal X-ray and neutron diffraction measurements revealed that the positions of the two protons in the complex can be controlled by temperature and photoirradiation based on the thermal- and photoinduced PCST. The obtained results suggest that designing molecules that form short HBs is a promising approach for developing multiple PT systems in crystals.
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Affiliation(s)
- Takumi Nakanishi
- Institute for Materials Chemistry and Engineering & IRCCS, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
| | - Yuta Hori
- Center for Computational Sciences, University of Tsukuba, Tsukuba 305-8577, Japan
| | - Yasuteru Shigeta
- Center for Computational Sciences, University of Tsukuba, Tsukuba 305-8577, Japan
| | - Hiroyasu Sato
- Rigaku Corporation, 3-9-12 Matsubaracho, Akishima, Tokyo 196-8666, Japan
| | - Ryoji Kiyanagi
- J-PARC center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195, Japan
| | - Koji Munakata
- J-PARC center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195, Japan
| | - Takashi Ohhara
- J-PARC center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195, Japan
| | - Atsushi Okazawa
- Department of Electrical Engineering and Bioscience, Waseda University, Okubo 3-4-1, Shinjuku-ku, Tokyo, 169-8555, Japan
| | - Rintaro Shimada
- Graduate School of Science and Engineering, Aoyama Gakuin University, 5-10-1 Fuchinobe, Chuo-ku, Sagamihara, Kanagawa 252-5258, Japan
| | - Akira Sakamoto
- Graduate School of Science and Engineering, Aoyama Gakuin University, 5-10-1 Fuchinobe, Chuo-ku, Sagamihara, Kanagawa 252-5258, Japan
| | - Osamu Sato
- Institute for Materials Chemistry and Engineering & IRCCS, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
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5
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Yang XD, Zhou JH, Cui JW, Yang J, Jia HP, Sun JK, Zhang J. Long-Lived Multiple Charge Separation by Proton-Coupled Electron Transfer. Angew Chem Int Ed Engl 2023; 62:e202215591. [PMID: 36691958 DOI: 10.1002/anie.202215591] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2022] [Revised: 01/23/2023] [Accepted: 01/23/2023] [Indexed: 01/25/2023]
Abstract
Multiple charge separation has been successfully realized by a proton-coupled electron transfer reaction in an organic cocrystal. Benefiting from the adjustable electronic energy level of the electron donor and acceptor through thermal-induced proton migration, distinct optical absorption behaviors combined with color changes to blue or green are observed in these charge-separated states. It is of interest to note that such charge-separated states exhibit a longer lifetime of over a month as a result of the excellent coplanarity and π-π interaction of the electron acceptors. Moreover, the enhanced absorption toward longer wavelengths endows the charge-separated state with near-infrared (808 nm) photothermal conversion for imaging and bacterial inhibition, whereby the conversion performance can be controlled by the degree of proton migration.
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Affiliation(s)
- Xiao-Dong Yang
- MOE Key Laboratory of Cluster Science, Beijing Key Laboratory of Photoelectronic/Electrophotonic Conversion Materials, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing, 102488, P. R. China
| | - Jun-Hao Zhou
- MOE Key Laboratory of Cluster Science, Beijing Key Laboratory of Photoelectronic/Electrophotonic Conversion Materials, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing, 102488, P. R. China
| | - Jing-Wang Cui
- MOE Key Laboratory of Cluster Science, Beijing Key Laboratory of Photoelectronic/Electrophotonic Conversion Materials, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing, 102488, P. R. China
| | - Jie Yang
- MOE Key Laboratory of Cluster Science, Beijing Key Laboratory of Photoelectronic/Electrophotonic Conversion Materials, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing, 102488, P. R. China
| | - Hong-Peng Jia
- Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, 361021, P. R. China
| | - Jian-Ke Sun
- MOE Key Laboratory of Cluster Science, Beijing Key Laboratory of Photoelectronic/Electrophotonic Conversion Materials, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing, 102488, P. R. China
| | - Jie Zhang
- MOE Key Laboratory of Cluster Science, Beijing Key Laboratory of Photoelectronic/Electrophotonic Conversion Materials, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing, 102488, P. R. China
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6
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Li J, Sun XP, Bi S, Xu M, Jia S, Tang Z, Ma P, Wang J, Tao J, Niu J. Regulating Spin-State Switching by Integrating Polyoxometalate Anion into Spin Crossover System. Inorg Chem 2022; 61:17932-17936. [DOI: 10.1021/acs.inorgchem.2c03032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Jiajia Li
- Henan Key Laboratory of Polyoxometalate Chemistry, Institute of Molecular and Crystal Engineering, School of Chemistry and Chemical Engineering, Henan University, Kaifeng 475004, China
| | - Xiao-Peng Sun
- Henan Key Laboratory of Polyoxometalate Chemistry, Institute of Molecular and Crystal Engineering, School of Chemistry and Chemical Engineering, Henan University, Kaifeng 475004, China
| | - Shiqi Bi
- Henan Key Laboratory of Polyoxometalate Chemistry, Institute of Molecular and Crystal Engineering, School of Chemistry and Chemical Engineering, Henan University, Kaifeng 475004, China
| | - Minglu Xu
- Henan Key Laboratory of Polyoxometalate Chemistry, Institute of Molecular and Crystal Engineering, School of Chemistry and Chemical Engineering, Henan University, Kaifeng 475004, China
| | - Siyu Jia
- Henan Key Laboratory of Polyoxometalate Chemistry, Institute of Molecular and Crystal Engineering, School of Chemistry and Chemical Engineering, Henan University, Kaifeng 475004, China
| | - Zheng Tang
- Key Laboratory of Cluster Science of the Ministry of Education, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing 102488, China
| | - Pengtao Ma
- Henan Key Laboratory of Polyoxometalate Chemistry, Institute of Molecular and Crystal Engineering, School of Chemistry and Chemical Engineering, Henan University, Kaifeng 475004, China
| | - Jingping Wang
- Henan Key Laboratory of Polyoxometalate Chemistry, Institute of Molecular and Crystal Engineering, School of Chemistry and Chemical Engineering, Henan University, Kaifeng 475004, China
| | - Jun Tao
- Key Laboratory of Cluster Science of the Ministry of Education, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing 102488, China
| | - Jingyang Niu
- Henan Key Laboratory of Polyoxometalate Chemistry, Institute of Molecular and Crystal Engineering, School of Chemistry and Chemical Engineering, Henan University, Kaifeng 475004, China
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7
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Dey B, Chandrasekhar V. Fe II spin crossover complexes containing N 4O 2 donor ligands. Dalton Trans 2022; 51:13995-14021. [PMID: 36040413 DOI: 10.1039/d2dt01967a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Spin crossover (SCO) is one of the most studied magnetic bistable phenomena because of its application in the field of multifunctional magnetic materials. FeII complexes in a N6 coordination environment have been the most well-studied in terms of their SCO behaviour. Other coordination environments, notably the N4O2 coordination environment, has also been quite effective in inducing SCO behaviour in the corresponding FeII complexes. This review deals with such systems. The three ligand families that are discussed are: Jager type ligands, hydrazone based ligands and tridentate ligands having salicylaldehyde derivatives. These ligands allow the assembly of both mononuclear and multinuclear complexes that exhibit cooperative spin transitions. Also, FeII complexes obtained from some of these ligands are multifunctional and exhibit a coupling of optical and magnetic properties. Most of the FeII complexes obtained from these families of ligands are charge neutral which allows easy surface deposition. Further, modulation of these ligand families allows a fine tuning of the ligand field strength which results in varying SCO behavior. In addition some of the FeII complexes derived from these ligands exhibit a light induced excited spin state trapping (LIESST) effect. All of the above aspects are reviewed in this review.
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Affiliation(s)
- Bijoy Dey
- Tata Institute of Fundamental Research Hyderabad, Gopanpally, Hyderabad - 500046, Telangana, India.
| | - Vadapalli Chandrasekhar
- Tata Institute of Fundamental Research Hyderabad, Gopanpally, Hyderabad - 500046, Telangana, India. .,Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur-208016, India
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8
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Zhao XH, Shao D, Chen JT, Gan DX, Yang J, Zhang YZ. A trinuclear {FeIII2FeII} complex involving both spin and non-spin transitions exhibits three-step and wide thermal hysteresis. Sci China Chem 2022. [DOI: 10.1007/s11426-021-1153-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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9
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Shen KY, Zhang CJ, Qu LY, Jiang SQ, Zhang Y, Tong ML, Bao X. Thermodriven, Acidity-Driven, and Photodriven Spin-State Switching in Pyridylacylhydrazoneiron(II) Complexes at or above Room Temperature. Inorg Chem 2021; 60:18225-18233. [PMID: 34784709 DOI: 10.1021/acs.inorgchem.1c02866] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The magnetic bistability of spin-crossover (SCO) materials is highly appealing for applications as molecular switches and information storage. However, switching of the spin state around room temperature remains challenging. In this work, we reported the successful manipulation of the spin states of two iron(II) complexes (1-Fe and 2-Fe) based on pyridylacylhydrazone ligands in manifold ways. Both complexes are stabilized in the low-spin (LS) state at room temperature because of the strong ligand-field strength imposed by the ligands. 2-Fe shows thermoinduced SCO above room temperature with a very large and reproducible hysteresis (>50 K), while 1-Fe remains in the LS state up to 400 K. Acidity-driven spin-state switching of the two complexes was achieved at room temperature as a result of the complex dissociation and release of iron(II) in its high-spin (HS) state. Recovery of the complex is feasible upon further alkalization treatment in the case of 1-Fe, allowing bidirectional modulation of the spin state of the metal center. Light-driven one-way switching from LS to HS is also achieved by virtue of E-to-Z isomerization at the C═N double bond, which results in dissociation of the complex because of the poor binding affinity in the Z configuration.
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Affiliation(s)
- Kai Yan Shen
- School of Chemistry and Chemical Engineering, Nanjing University of Science and Technology, Nanjing 210094, P. R. China
| | - Chen Ju Zhang
- School of Chemistry and Chemical Engineering, Nanjing University of Science and Technology, Nanjing 210094, P. R. China
| | - Lei Yu Qu
- School of Chemistry and Chemical Engineering, Nanjing University of Science and Technology, Nanjing 210094, P. R. China
| | - Shi Qing Jiang
- School of Chemistry and Chemical Engineering, Nanjing University of Science and Technology, Nanjing 210094, P. R. China
| | - Yi Zhang
- School of Chemistry and Chemical Engineering, Nanjing University of Science and Technology, Nanjing 210094, P. R. China
| | - Ming Liang Tong
- School of Chemistry, Sun Yat-Sen University, Guangzhou 510275, P. R. China
| | - Xin Bao
- School of Chemistry and Chemical Engineering, Nanjing University of Science and Technology, Nanjing 210094, P. R. China
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Kulmaczewski R, Bamiduro F, Shahid N, Cespedes O, Halcrow MA. Structural Transformations and Spin-Crossover in [FeL 2 ] 2+ Salts (L=4-{tert-Butylsulfanyl}-2,6-di{pyrazol-1-yl}pyridine): The Influence of Bulky Ligand Substituents. Chemistry 2021; 27:2082-2092. [PMID: 33073890 DOI: 10.1002/chem.202004072] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Revised: 10/16/2020] [Indexed: 11/06/2022]
Abstract
4-(tert-Butylsulfanyl)-2,6-di(pyrazol-1-yl)pyridine (L) was obtained in low yield from a one-pot reaction of 2,4,6-trifluoropyridine with 2-methylpropane-2-thiolate and sodium pyrazolate in a 1:1:2 ratio. The materials [FeL2 ][BF4 ]2 ⋅solv (1[BF4 ]2 ⋅solv) and [FeL2 ][ClO4 ]2 ⋅solv (1[ClO4 ]2 ⋅solv; solv=MeNO2 , MeCN or Me2 CO) exhibit a variety of structures and spin-state behaviors including thermal spin-crossover (SCO). Solvent loss on heating 1[BF4 ]2 ⋅x MeNO2 (x≈2.3) occurs in two steps. The intermediate phase exhibits hysteretic SCO around 250 K, involving a "reverse-SCO" step in its warming cycle at a scan rate of 5 K min-1 . The reverse-SCO is not observed in a slower 1 K min-1 measurement, however, confirming its kinetic nature. The final product [FeL2 ][BF4 ]2 ⋅0.75 MeNO2 was crystallographically characterized, and shows abrupt but incomplete SCO at 172 K which correlates with disorder of an L ligand. The asymmetric unit of 1[BF4 ]2 ⋅y Me2 CO (y≈1.6) contains five unique complex molecules, four of which undergo gradual SCO in at least two discrete steps. Low-spin 1[ClO4 ]2 ⋅0.5 Me2 CO is not isostructural with its BF4 - congener, and undergoes single-crystal-to-single-crystal solvent loss with a tripling of the crystallographic unit cell volume, while retaining the P 1 ‾ space group. Three other solvate salts undergo gradual thermal SCO. Two of these are isomorphous at room temperature, but transform to different low-temperature phases when the materials are fully low-spin.
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Affiliation(s)
- Rafal Kulmaczewski
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK
| | - Faith Bamiduro
- School of Chemical and Process Engineering, University of Leeds, Leeds, LS2 9JT, UK
| | - Namrah Shahid
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK
| | - Oscar Cespedes
- School of Physics and Astronomy, University of Leeds, E. C. Stoner Building, Leeds, LS2 9JT, UK
| | - Malcolm A Halcrow
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK
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11
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Jornet-Mollá V, Giménez-Saiz C, Cañadillas-Delgado L, Yufit DS, Howard JAK, Romero FM. Interplay between spin crossover and proton migration along short strong hydrogen bonds. Chem Sci 2020; 12:1038-1053. [PMID: 34163870 PMCID: PMC8179063 DOI: 10.1039/d0sc04918b] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2020] [Accepted: 11/16/2020] [Indexed: 12/19/2022] Open
Abstract
The iron(ii) salt [Fe(bpp)2](isonicNO)2·HisonicNO·5H2O (1) (bpp = 2,6-bis(pyrazol-3-yl)pyridine; isonicNO = isonicotinate N-oxide anion) undergoes a partial spin crossover (SCO) with symmetry breaking at T 1 = 167 K to a mixed-spin phase (50% high-spin (HS), 50% low-spin (LS)) that is metastable below T 2 = 116 K. Annealing the compound at lower temperatures results in a 100% LS phase that differs from the initial HS phase in the formation of a hydrogen bond (HB) between two water molecules (O4W and O5W) of crystallisation. Neutron crystallography experiments have also evidenced a proton displacement inside a short strong hydrogen bond (SSHB) between two isonicNO anions. Both phenomena can also be detected in the mixed-spin phase. 1 undergoes a light-induced excited-state spin trapping (LIESST) of the 100% HS phase, with breaking of the O4W⋯O5W HB and the onset of proton static disorder in the SSHB, indicating the presence of a light-induced activation energy barrier for proton motion. This excited state shows a stepped relaxation at T 1(LIESST) = 68 K and T 2(LIESST) = 76 K. Photocrystallography measurements after the first relaxation step reveal a single Fe site with an intermediate geometry, resulting from the random distribution of the HS and LS sites throughout the lattice.
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Affiliation(s)
- Verónica Jornet-Mollá
- Instituto de Ciencia Molecular, Universitat de València P. O. Box 22085 46071 València Spain
| | - Carlos Giménez-Saiz
- Instituto de Ciencia Molecular, Universitat de València P. O. Box 22085 46071 València Spain
| | | | - Dmitry S Yufit
- Department of Chemistry, Durham University Durham DH1 3LE UK
| | | | - Francisco M Romero
- Instituto de Ciencia Molecular, Universitat de València P. O. Box 22085 46071 València Spain
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