制备了Bodipy(BDP)-perylenebisimide(PBI)供体-受体二组/三组,以研究自旋轨道电荷转移系统间交叉(SOCT-ISC)。对于BDP-PBI-3,其中BDP连接在PBI的酰亚胺位置,观察到比海湾取代的衍生物BDP-PBI-1(ΦΔ=30%)更高的单态氧量子产率(ΦΔ=85%)。飞秒瞬态吸收光谱表明BDP-PBI-3中的Frster共振能量转移(FRET;40.4ps)和电荷分离(CS;1.55ns)缓慢,而对于BDP-PBI-1,CS需要2.8ps。对于三联体BDP-PBI-2,观察到超快FRET(149fs)和CS(4.7ps)过程,随后的电荷重组(CR)占用5.8ns,并且填充长寿命3PBI*(179.8μs)状态。BDP-PBI-3的纳秒瞬态吸收光谱表明,CR给出上三重激发态(3BDP*),通过缓慢的分子内三重态能量转移(14.5μs),3PBI*状态最终被填充,表明SOCT-ISC中涉及上三元组状态。时间分辨电子顺磁共振波谱显示,自由基对ISC(RPISC)和SOCT-ISC都对ISC有贡献。(e,e,e,e,e,e)观察到通过RPISC机制形成的三重态,由于S-T+1/T0状态混合。
Bodipy (BDP)-perylenebisimide (PBI) donor-acceptor dyads/triad were prepared to study the spin-orbit charge-transfer intersystem crossing (SOCT-ISC). For BDP-PBI-3, in which BDP was attached at the imide position of PBI, higher singlet oxygen quantum yield (ΦΔ =85 %) was observed than the bay-substituted derivative BDP-PBI-1 (ΦΔ =30 %). Femtosecond transient absorption spectra indicate slow Förster resonance energy transfer (FRET; 40.4 ps) and charge separation (CS; 1.55 ns) in BDP-PBI-3, while for BDP-PBI-1, CS takes 2.8 ps. For triad BDP-PBI-2, ultrafast FRET (149 fs) and CS (4.7 ps) process were observed, the subsequent charge recombination (CR) takes 5.8 ns and long-lived 3 PBI* (179.8 μs) state is populated. Nanosecond transient absorption spectra of BDP-PBI-3 show that the CR gives upper triplet excited state (3 BDP*) and subsequently, via a slow intramolecular triplet energy transfer (14.5 μs), the 3 PBI* state is finally populated, indicating that upper triplet state is involved in SOCT-ISC. Time-resolved electron paramagnetic resonance spectroscopy revealed that both radical pair ISC (RP ISC) and SOCT-ISC contribute to the ISC. A rare electron spin polarization of (e, e, e, e, e, e) was observed for the triplet state formed via the RP ISC mechanism, due to the S-T+1 /T0 states mixing.