Mallia, Ajith R. ; Sethy, Ramarani ; Bhat, Vinayak ; Hariharan, Mahesh (2016) Crystallization induced enhanced emission in conformational polymorphs of a rotationally flexible molecule Journal of Materials Chemistry C, 4 (14). pp. 2931-2935. ISSN 2050-7526
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Official URL: http://doi.org/10.1039/C5TC03188E
Related URL: http://dx.doi.org/10.1039/C5TC03188E
Abstract
The crystallization of weakly fluorescent 4-amino-2,2′-bipyridine (AMBPY) in solution phase under ambient conditions afforded three fluorescent conformational polymorphs. The marginal increase in the barrier to rotation observed in AMBPY as compared to unsubstituted 2,2′-bipyridine could be attributed to the “buttressing effect” offered by the amino substituent at the meta position. A smaller yet significant difference in energy (0.1–2.6 kJ mol−1) with respect to the global minima facilitates the isolation of AMBPY-I–III polymorphs. A unique nitrogen–nitrogen interaction is observed in two of the polymorphs, namely, AMBPY-I and AMBPY-III, promoted by cooperative C⋯H and N⋯H interactions. A crystallization-induced enhancement (ca. 5–10 fold) in the fluorescence quantum yield of AMBPY polymorphs is observed relative to the solution/amorphous state. Controlling the luminescence properties of molecular solids by tuning their packing arrangements via various interactions is an integral aspect in the construction of novel photo-functional materials.
Item Type: | Article |
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Source: | Copyright of this article belongs to Royal Society of Chemistry. |
ID Code: | 128187 |
Deposited On: | 18 Oct 2022 07:52 |
Last Modified: | 18 Oct 2022 07:52 |
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