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Sussardi AN, Turner GF, Richardson JG, Spackman MA, Turley AT, McGonigal PR, Jones AC, Moggach SA. Tandem High-Pressure Crystallography-Optical Spectroscopy Unpacks Noncovalent Interactions of Piezochromic Fluorescent Molecular Rotors. J Am Chem Soc 2023; 145:19780-19789. [PMID: 37649399 DOI: 10.1021/jacs.3c05444] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/01/2023]
Abstract
To develop luminescent molecular materials with predictable and stimuli-responsive emission, it is necessary to correlate changes in their geometries, packing structures, and noncovalent interactions with the associated changes in their optical properties. Here, we demonstrate that high-pressure single-crystal X-ray diffraction can be combined with high-pressure UV-visible absorption and fluorescence emission spectroscopies to elucidate how subtle changes in structure influence optical outputs. A piezochromic aggregation-induced emitter, sym-heptaphenylcycloheptatriene (Ph7C7H), displays bathochromic shifts in its absorption and emission spectra at high pressure. Parallel X-ray measurements identify the pressure-induced changes in specific phenyl-phenyl interactions responsible for the piezochromism. Pairs of phenyl rings from neighboring molecules approach the geometry of a stable benzene dimer, while conformational changes alter intramolecular phenyl-phenyl interactions correlated with a relaxed excited state. This tandem crystallographic and spectroscopic analysis provides insights into how subtle structural changes relate to the photophysical properties of Ph7C7H and could be applied to a library of similar compounds to provide general structure-property relationships in fluorescent organic molecules with rotor-like geometries.
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Affiliation(s)
- Alif N Sussardi
- School of Chemistry, The University of Edinburgh, Edinburgh EH9 3FL, U.K
| | - Gemma F Turner
- School of Molecular Sciences, The University of Western Australia, Crawley, Perth 6009, Australia
| | | | - Mark A Spackman
- School of Molecular Sciences, The University of Western Australia, Crawley, Perth 6009, Australia
| | - Andrew T Turley
- Department of Chemistry, Durham University, Durham DH1 3LE, U.K
| | - Paul R McGonigal
- Department of Chemistry, Durham University, Durham DH1 3LE, U.K
- School of Chemistry, The University of York, York YO10 5DD, U.K
| | - Anita C Jones
- School of Chemistry, The University of Edinburgh, Edinburgh EH9 3FL, U.K
| | - Stephen A Moggach
- School of Molecular Sciences, The University of Western Australia, Crawley, Perth 6009, Australia
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Broadhurst ET, Wilson CJG, Zissimou GA, Nudelman F, Constantinides CP, Koutentis PA, Parsons S. A first-order phase transition in Blatter's radical at high pressure. ACTA CRYSTALLOGRAPHICA SECTION B, STRUCTURAL SCIENCE, CRYSTAL ENGINEERING AND MATERIALS 2022; 78:107-116. [PMID: 35411850 DOI: 10.1107/s2052520622000191] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2021] [Accepted: 01/06/2022] [Indexed: 06/14/2023]
Abstract
The crystal structure of Blatter's radical (1,3-diphenyl-1,4-dihydrobenzo[e][1,2,4]triazin-4-yl) has been investigated between ambient pressure and 6.07 GPa. The sample remains in a compressed form of the ambient-pressure phase up to 5.34 GPa, the largest direction of strain being parallel to the direction of π-stacking interactions. The bulk modulus is 7.4 (6) GPa, with a pressure derivative equal to 9.33 (11). As pressure increases, the phenyl groups attached to the N1 and C3 positions of the triazinyl moieties of neighbouring pairs of molecules approach each other, causing the former to begin to rotate between 3.42 to 5.34 GPa. The onset of this phenyl rotation may be interpreted as a second-order phase transition which introduces a new mode for accommodating pressure. It is premonitory to a first-order isosymmetric phase transition which occurs on increasing pressure from 5.34 to 5.54 GPa. Although the phase transition is driven by volume minimization, rather than relief of unfavourable contacts, it is accompanied by a sharp jump in the orientation of the rotation angle of the phenyl group. DFT calculations suggest that the adoption of a more planar conformation by the triazinyl moiety at the phase transition can be attributed to relief of intramolecular H...H contacts at the transition. Although no dimerization of the radicals occurs, the π-stacking interactions are compressed by 0.341 (3) Å between ambient pressure and 6.07 GPa.
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Affiliation(s)
- Edward T Broadhurst
- EaStCHEM School of Chemistry and Centre for Science at Extreme Conditions, The University of Edinburgh, King's Buildings, West Mains Road, Edinburgh, EH9 3FJ, United Kingdom
| | - Cameron J G Wilson
- EaStCHEM School of Chemistry and Centre for Science at Extreme Conditions, The University of Edinburgh, King's Buildings, West Mains Road, Edinburgh, EH9 3FJ, United Kingdom
| | - Georgia A Zissimou
- Department of Chemistry, University of Cyprus, PO Box 20537, 1678 Nicosia, Cyprus
| | - Fabio Nudelman
- EaStCHEM School of Chemistry and Centre for Science at Extreme Conditions, The University of Edinburgh, King's Buildings, West Mains Road, Edinburgh, EH9 3FJ, United Kingdom
| | - Christos P Constantinides
- Department of Natural Sciences, University of Michigan-Dearborn, 4901 Evergreen Road, Dearborn, Michigan, 48128-1491, USA
| | | | - Simon Parsons
- EaStCHEM School of Chemistry and Centre for Science at Extreme Conditions, The University of Edinburgh, King's Buildings, West Mains Road, Edinburgh, EH9 3FJ, United Kingdom
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Romanenko GV, Letyagin GA, Ovcharenko VI. Effect of pressure on the structure of multispin complexes. RUSSIAN CHEMICAL REVIEWS 2022. [DOI: 10.1070/rcr5028] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Polarized Neutron Diffraction: An Excellent Tool to Evidence the Magnetic Anisotropy—Structural Relationships in Molecules. MAGNETOCHEMISTRY 2021. [DOI: 10.3390/magnetochemistry7120158] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
This publication reviews recent advances in polarized neutron diffraction (PND) studies of magnetic anisotropy in coordination compounds comprising d or f elements and having different nuclearities. All these studies illustrate the extent to which PND can provide precise and direct information on the relationship between molecular structure and the shape and axes of magnetic anisotropy of the individual metal sites. It makes this experimental technique (PND) an excellent tool to help in the design of molecular-based magnets and especially single-molecule magnets for which strong uniaxial magnetic anisotropy is required.
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