Crystal Structure of Diphenylacetylene-Tetracyanobenzene 1:1 CT Complex and Spin Polarization of Triplet Exciton and of Trans-Stilbene Triplet Trap

Abstract

The crystal structure of diphenylacetylene and 1, 2, 4, 5-tetracyanobenzene 1:1 charge transfer complex has been determined at room temperature. pe crystals belong to the monoclinic system with space group C2/m, a = 9.632(4) Å, b = 12.403(6) A, c = 8.131(4) Å, β = 101.59(4)° with two translationally equivalent complexes per unit cell. EPR spectra of photoexcited mobile and trapped triplet species were recorded. The nature of the trap has been investigated and attributed to the trans-Stilbene-TCNB 1:2 CT complex. The analysis of the orientation dependence of polarized spectra of exciton and trap has shown that spin polarization is provided by ISC in which the TCNB is involved. Excitation transfer to the trap takes place by preseming alignment of the spin states.