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Davenport AM, Marshall CR, Nishiguchi T, Kadota K, Andreeva AB, Horike S, Brozek CK. Size-Dependent Spin Crossover and Bond Flexibility in Metal-Organic Framework Nanoparticles. J Am Chem Soc 2024. [PMID: 39145699 DOI: 10.1021/jacs.4c08883] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/16/2024]
Abstract
Size reduction offers a synthetic route to tunable phase change behavior. Preparing materials as nanoparticles causes drastic modulations to critical temperatures (Tc), hysteresis widths, and the "sharpness" of first-order versus second-order phase transitions. A microscopic picture of the chemistry underlying this size dependence in phenomena ranging from melting to superconductivity remains debated. As a case study with broad implications, we report that size-dependent spin crossover (SCO) in nanocrystals of the metal-organic framework (MOF) Fe(1,2,3-triazolate)2 arises from metal-linker bonds becoming more labile in smaller particles. In comparison to the bulk material, differential scanning calorimetry indicates a ∼ 30-40% reduction in Tc and ΔH in the smallest particles. Variable-temperature vibrational spectroscopy reveals a diminished long-range structural cooperativity, while X-ray diffraction evidence an over 3-fold increase in the thermal expansion coefficients. This "phonon softening" provides a molecular mechanism for designing size-dependent behavior in framework materials and for understanding phase changes in general.
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Affiliation(s)
- Audrey M Davenport
- Department of Chemistry and Biochemistry, Material Science Institute, University of Oregon, Eugene, Oregon 97403, United States
| | - Checkers R Marshall
- Department of Chemistry and Biochemistry, Material Science Institute, University of Oregon, Eugene, Oregon 97403, United States
| | - Taichi Nishiguchi
- Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto 615-8510, Japan
| | - Kentaro Kadota
- Department of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwakecho, Sakyo-ku, Kyoto 606-8502, Japan
| | - Anastasia B Andreeva
- Department of Chemistry and Biochemistry, Material Science Institute, University of Oregon, Eugene, Oregon 97403, United States
| | - Satoshi Horike
- Department of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwakecho, Sakyo-ku, Kyoto 606-8502, Japan
| | - Carl K Brozek
- Department of Chemistry and Biochemistry, Material Science Institute, University of Oregon, Eugene, Oregon 97403, United States
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Olejnik A, Kopec W, Maskowicz D, Sawczak M. Spin-Resolved Band Structure of Hoffman Clathrate [Fe(pz) 2Pt(CN) 4] as an Essential Tool to Predict Optical Spectra of Metal-Organic Frameworks. ACS APPLIED MATERIALS & INTERFACES 2023; 15:15848-15862. [PMID: 36929712 DOI: 10.1021/acsami.2c22626] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Paramount spin-crossover properties of the 3D-Hoffman metalorganic framework (MOF) [Fe(pz)2Pt(CN)4] are generally described on the basis of the ligand field theory, which provides adequate insight into theoretical and simulation analysis of spintronic complexes. However, the ligand field approximation does not take into account the 3D periodicity of the actual complex lattice and surface effects and therefore cannot predict a full-scale periodic structure without utilizing more advanced methods. Therefore, in this paper, the electronic properties of the exemplar MOF were analyzed from the band structure perspective in low-spin (LS) and high-spin (HS) states. The density-of-states spectra determined for both spin-up and spin-down electrons of Fe d6 orbitals indicate spin-orbital splitting and delocalization for HS due to spin polarization in the iron atom ligand field. Presence of the surface states in the real crystal causes a red shift of the metal-metal charge transfer (MMCT) and metal-ligand charge transfer (MLCT) peaks for both HS and LS states. The addition of residual water molecules and disorder among the pyrazine rings reveal additional influences on the positions of the pyrazine band and, therefore, on the absorption spectra of the crystal. The results show a magnification of the peak correlated with the MLCT in the HS state and a significant red shift of the LS characteristic absorption band. The presented approach involving band structure analysis delivers a more complete image of the electronic properties of the [Fe(pz)2Pt(CN)4] crystalline network and can be a landmark for insightful studies of other MOFs.
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Affiliation(s)
- Adrian Olejnik
- Faculty of Electronics, Telecommunications and Informatics, Gdansk University of Technology, 11/12 G. Narutowicza Street, 80-233 Gdansk, Poland
- Centre for Plasma and Laser Engineering, The Szewalski Institute of Fluid-Flow Machinery, Polish Academy of Sciences, Fiszera 14 Street, 80-231 Gdańsk, Poland
| | - Wioletta Kopec
- Centre for Plasma and Laser Engineering, The Szewalski Institute of Fluid-Flow Machinery, Polish Academy of Sciences, Fiszera 14 Street, 80-231 Gdańsk, Poland
| | - Dominik Maskowicz
- Centre for Plasma and Laser Engineering, The Szewalski Institute of Fluid-Flow Machinery, Polish Academy of Sciences, Fiszera 14 Street, 80-231 Gdańsk, Poland
| | - Mirosław Sawczak
- Centre for Plasma and Laser Engineering, The Szewalski Institute of Fluid-Flow Machinery, Polish Academy of Sciences, Fiszera 14 Street, 80-231 Gdańsk, Poland
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Kitase K, Akahoshi D, Kitazawa T. Guest-triggered "Soma-Iwamoto-type" penetration complex {Fe(4-methoxypyrimidine) 2[M(CN) 2] 2}·Guest (M = Ag, Au). Dalton Trans 2023; 52:2571-2579. [PMID: 36752163 DOI: 10.1039/d2dt03716e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
Many laboratories have performed extensive studies on the spin-crossover (SCO) phenomenon. Herein, we synthesized novel "Soma-Iwamoto type" complexes containing a 4-methoxypyrimidine (4-MeOPmd) ligand, i.e., {Fe(4-MeOPmd)2[Ag(CN)2]2} (1Ag), {Fe(4-MeOPmd)2[Au(CN)2]2} (1Au), and {Fe(4-MeOPmd)2[Ag(CN)2]2·0.25(4-MeOPmd)} (1Ag·0.25G). Moreover, we synthesized a 4,6-dimethoxypyrimidine (4,6-diMeOPmd) clathrate complex, i.e., {Fe(4-MeOPmd)2[Ag(CN)2]2·0.25(4,6-diMeOPmd)} (2Ag·0.25G) and {Fe(4-MeOPmd)2[Au(CN)2]2·0.25(4,6-diMeOPmd)} (2Au·0.25G). Some of these complexes, i.e., 1Ag·0.25G, 2Ag·0.25G, and 2Au·0.25G, demonstrated penetrated structures, which are very interesting given that they have rarely been reported to date. 1Au and 1Ag did not show the SCO phenomenon, 1Ag·0.25G showed a gradual multi-step SCO phenomenon, and 2Au·0.25G and 2Ag·0.25G showed an abrupt half SCO phenomenon.
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Affiliation(s)
- Kosuke Kitase
- Department of Chemistry, Toho University, Chiba 274-8510, Japan.
| | | | - Takafumi Kitazawa
- Department of Chemistry, Toho University, Chiba 274-8510, Japan. .,Research Centre for Materials with Integrated Properties, Toho University, Chiba 274-8510, Japan
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Kumar B, Paul A, Mondal DJ, Paliwal P, Konar S. Spin-State Modulation in Fe II -Based Hofmann-Type Coordination Polymers: From Molecules to Materials. CHEM REC 2022; 22:e202200135. [PMID: 35815939 DOI: 10.1002/tcr.202200135] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Revised: 06/21/2022] [Indexed: 11/05/2022]
Abstract
Spin crossover complexes that reversibly interconvert between two stable states imitate a binary state of 0 and 1, delivering a promising possibility to address the data processing concept in smart materials. Thus, a comprehensive understanding of the modulation of magnetic transition between high spin and low spin and the factors responsible for stabilizing the spin states is an essential theme in modern materials design. In this context, the present review attempts to provide a concise outline of the design strategy employed at the molecular level for fine-tuning the spin-state switching in FeII -based Hofmann-type coordination polymers and their effects on the optical and magnetic response. In addition, development towards the nanoscale architectures of HCPs, i. e., in terms of nanoparticles and thin films, are emphasized to bridge the gap between the laboratory and reality.
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Affiliation(s)
- Bhart Kumar
- Molecular Magnetism Lab, Department of Chemistry, Indian Institute of Science Education and Research, Bhopal, Bhopal Bypass Road, Bhopal, Madhya Pradesh, 462066, India
| | - Abhik Paul
- Molecular Magnetism Lab, Department of Chemistry, Indian Institute of Science Education and Research, Bhopal, Bhopal Bypass Road, Bhopal, Madhya Pradesh, 462066, India
| | - Dibya Jyoti Mondal
- Molecular Magnetism Lab, Department of Chemistry, Indian Institute of Science Education and Research, Bhopal, Bhopal Bypass Road, Bhopal, Madhya Pradesh, 462066, India
| | - Piyush Paliwal
- Molecular Magnetism Lab, Department of Chemistry, Indian Institute of Science Education and Research, Bhopal, Bhopal Bypass Road, Bhopal, Madhya Pradesh, 462066, India
| | - Sanjit Konar
- Molecular Magnetism Lab, Department of Chemistry, Indian Institute of Science Education and Research, Bhopal, Bhopal Bypass Road, Bhopal, Madhya Pradesh, 462066, India
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