Four dyad systems composed of a central truxene and either one or three β-substituted zinc(II) porphyrins (ZnP: TruZnP (7) and TruTriZnP (9)) or free-bases (H2P: TruP (6) and TruTriP (8)) have been prepared. The presence of β-methyl groups minimizes π-conjugation through the quasi right angle made by the porphyrin and the truxene planes, and renders these dyads relatively rigid. The position of the absorption and emission 0–0 peaks confirms the role of the truxene and porphyrin as the energy donor and acceptor, respectively. Selective excitation of the truxene results in an efficient singlet energy transfer (S1 ET) from the truxene to the porphyrin unit. The rates for S1 ET (k ET ) are extracted from the change in the fluorescence lifetime of truxene in the presence and absence of the acceptor, and are temperature independent, (TruP (6), TruTriP (8), TruZnP (7) and TruTriZnP (9) are 5.0, 1.4, 1.0 and 1.4 at 298 K and 5.9, 1.3, 2.6, and 0.86 (ns)-1 at 77 K, respectively), consistent with their relative rigidity. These k ET 's are similar to other related but more flexible systems reported by one of us (Inorg. Chem.2011, 50, 11493–11505). The k ET 's time scale was assumed, based on modeling, to be related with hindered rotations about the truxene-porphyrin C–C bonds due to steric hexyl–hexyl interactions. This work confirms this earlier conclusion was correct.
我们制备了由一个中心三烯和一个或三个 β 取代的锌(II)卟啉(ZnP:TruZnP (7) 和 TruTriZnP (9))或游离碱(H2P:TruP (6) 和 TruTriP (8))。β-甲基基团的存在通过卟啉平面和三甲苯平面所成的准直角将π-共轭作用减至最小,并使这些二元化合物相对坚硬。吸收和发射 0-0 峰的位置证实了三并烯和卟啉分别作为能量供体和受体的作用。楚克森的选择性激发导致高效的单线能量转移(S1 ET)从楚克森转移到卟啉单元。S1 ET 的速率(k ET )是从受体存在和不存在时三红烯荧光寿命的变化中提取出来的,与温度无关(TruP (6)、TruTriP (8)、TruZnP (7) 和 TruTriZnP (9) 在 298 K 时分别为 5.0、1.4、1.0 和 1.4,在 77 K 时分别为 5.9、1.3、2.6 和 0.86 (ns)-1),这与它们的相对刚性是一致的。这些 k ET 与我们其中一人报告的其他相关但更灵活的系统相似(Inorg.)在建模的基础上,假定 k ET 的时间尺度与由于己基-己基的立体相互作用导致的三叉蒽-卟啉 C-C 键旋转受阻有关。这项研究证实了之前的结论是正确的。