Influence of Br substituent position at the carbazole on spin-orbit coupling element matrix

Abstract

Based on reported PDCz (1), eight isomers (2–9) were designed by changing Br substituent positions at the carbazole group to investigate the structure-property relationship by quantum chemistry calculations. The calculated results indicate that an appropriate Br substituent position at the carbazole group is essential for enhancing the spin–orbit coupling (SOC) strength. Among 2–9, The <S1|HSOC|Tn> (n = 1–5) values of 3 and 7 with Br substituent at 3, 6-position and 1, 3-position are close to those of 1. However, other compounds (2, 4–6, 8 and 9) have significant increase in SOC values between singlet and triplet excited states. Thus, simply changing the Br substituent position would result in significant SOC variation. The systematical investigation on Br substituent position at the carbazole group would provide valuable information for choosing better Br position in experimental synthesis.