Unusually large D values of zero-field splitting parameters were observed for 1,6-diphenylhexatriyne (D=0.396 cm-1) and 1,8-diphenyloctatetrayne (D=0.533 cm-1) by using time-resolved EPR (TREPR) spectroscopy. The lowest excited triplet (T1) states of these diphenylpolyynes were assigned to 3B1u(3πxπ *x) in character from the degree of the polarization of phosphorescence. It has been concluded that the present diphenylpolyynes have a linear planar structure in the T1 states, although the TREPR and phosphorescence spectra indicate interactions between the T1(3πxπ*x) and Tn(3πxπ*y) states through spin-orbit and vibronic interactions.
ASJC Scopus subject areas
- Physics and Astronomy(all)
- Physical and Theoretical Chemistry