Supramolecular Chromotropism of the Crystalline Phases of 4,5,6,7-Tetrafluorobenzo-2,1,3-telluradiazole
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- 作者：Anthony F. Cozzolino ; Pamela S. Whitfield ; Ignacio Vargas-Baca
- 刊名：Journal of the American Chemical Society
- 出版年：2010
- 出版时间：December 8, 2010
- 年：2010
- 卷：132
- 期：48
- 页码：17265-17270
- 全文大小：259K
- 年卷期：v.132,no.48(December 8, 2010)
- ISSN：1520-5126
文摘
The remarkable effect that secondary bonding interactions can have on the macroscopic properties of a material is illustrated by two polymorphs of the title compound. The phase which is most stable under ambient pressure and temperature consists of puckered supramolecular ribbon polymers assembled by Te--N secondary bonding interactions and displays a characteristic red-orange color. A second yellow phase consists of ribbons with alternating short and long intermolecular Te--N secondary bonding distances and is metastable; at 127 °C the material undergoes an exothermic irreversible transition to the red polymorph. A third phase consists of pyridine-solvated supramolecular dimers; it is also yellow and transforms into the red phase after the crystals effloresce. Computational DFT studies indicate that the observed changes in optical properties are related to intermolecular mixing of π orbitals enabled by the supramolecular interactions and the symmetry of the supramolecular synthon.