Spectrophotometric Study of Bridging N-Donor Ligand-Induced Supramolecular Assembly of Conjugated Zn-Trisporphyrin with a Triphenylamine Core

초록

This article studies the supramolecular assembly behavior of a Zn-trisporphyrin conjugate containing a triphenylamine core (1) with bridging N-donor ligands using the UV-vis spectrophotometric titration method at micromolar concentrations. Our results show that pyridine, a non-bridging ligand, formed a 3:1 open complex with 1. The corresponding binding constant was estimated to be (2.7 +/- 0.15) x 10(14) M-3. In contrast, bridging ligands, 4,4-bipyridine (BIPY) and 1,3-di(4-pyridyl)propane (DPYP), formed stable 3:2 double-decker complexes with 1 in solution, which collapsed to yield a 3:1 open complex when excess BIPY or DPYP was added. The binding constants for forming BIPY and DPYP double-decker complexes were estimated to be (9.26 +/- 0.07) x 10(27) M-4 and (3.62 +/- 0.16) x 10(27) M-4, respectively. The UV-vis titration profiles supported the conclusion that the degradation of the 3:2 double-decker 1 center dot BIPY complex is less favorable compared to that of 1 center dot DPYP. Consequently, the formation of the 3:1 1 center dot DPYP open complex proceeded more readily than that of 1 center dot BIPY.

키워드