Issue 14, 2016

Crystallization induced enhanced emission in conformational polymorphs of a rotationally flexible molecule

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.

Graphical abstract: Crystallization induced enhanced emission in conformational polymorphs of a rotationally flexible molecule

Supplementary files

Article information

Article type
Paper
Submitted
05 Eki 2015
Accepted
25 Kas 2015
First published
26 Kas 2015

J. Mater. Chem. C, 2016,4, 2931-2935

Author version available

Crystallization induced enhanced emission in conformational polymorphs of a rotationally flexible molecule

A. R. Mallia, R. Sethy, V. Bhat and M. Hariharan, J. Mater. Chem. C, 2016, 4, 2931 DOI: 10.1039/C5TC03188E

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements