Crystal Structure of Biphenyl-1,2,4,5-Tetracyanobenzene 1:1 CT Complex and EPR Investigation of Photoexcited Triplet Excitons
- 1 January 1983
- journal article
- research article
- Published by Taylor & Francis in Molecular Crystals and Liquid Crystals
- Vol. 91 (1-2) , 25-38
- https://doi.org/10.1080/00268948308083071
Abstract
The crystal structure of biphenyl and 1,2,4,5-tetracyanobenzene 1:1 charge transfer complex has been determined at room temperature. The crystals belong to the triclinic system with space group CI, a = 9.592(6) Å, b = 12.359(9) Å, c = 7.335(5) Å, α = 94.17(6)°, β = 96.50(8)° and γ = 89.07(7)° with two complexes per unit cell. The increase of the zero-field splitting tensor of photoexcited triplet excitons with increasing temperature has been discussed in terms of two early proposed models. In the former approach a thermal equilibrium between two triplet states was assumed. In the second the variation of the fine structure tensor elements was attributed to changes of the charge transfer character of the triplet state as a consequence of the temperature dependent molecular packing in the crystal. Experimental evidences are in favor of this latter model.Keywords
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