Calculations on the electronic structure and nonlinear second-order susceptibilities of fulleropyrrolidine-tetrathiafulvalene(C60PY-TTF) based on donor-bridge-acceptor dyads

The semiempirical INDO calculations were carried out to investigate the cha rge-transfer interaction and to evaluate the second-order nonlinear suscept ibilities for a series of fulleropyrrolidine-tetrathiafulvalene(C60PY-TTF) dyads, C60PY, and C60PY-(CH=CH)(n)-TTF (n = 0-6). The equilibrium geometrie s, electronic structures, and UV-vis spectra of these C60PY-TTFs D-B-A dyad s were determined by using ZINDO methods. On the basis of electronic spectr a, we calculated the beta for the dyads using the ZINDO-SOS expression, and found that these dyads have relatively large beta. The calculated values o f beta are 48.78, 62.34, 97.90, 123.24, 183.78, 189.43, 193.45, 195.82 x 10 (-30) esu for C60PY and C60PY-(CH=CH)(n)-TTF (n = 0-6), respectively, which shows the enhancing effect when TTF is introduced. The beta significantly increases as n increases from 0-3; and it tends to be saturated in the end.