| Summary: | This article studies the supramolecular assembly behavior of a Zn-trisporphyrin conjugate containing a triphenylamine core (<b>1</b>) with bridging <i>N</i>-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 <b>1</b>. The corresponding binding constant was estimated to be (2.7 ± 0.15) × 10<sup>14</sup> M<sup>−3</sup>. In contrast, bridging ligands, 4,4-bipyridine (BIPY) and 1,3-di(4-pyridyl)propane (DPYP), formed stable 3:2 double-decker complexes with <b>1</b> 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) × 10<sup>27</sup> M<sup>−4</sup> and (3.62 ± 0.16) × 10<sup>27</sup> M<sup>−4</sup>, respectively. The UV-vis titration profiles supported the conclusion that the degradation of the 3:2 double-decker <b>1</b>∙BIPY complex is less favorable compared to that of <b>1</b>∙DPYP. Consequently, the formation of the 3:1 <b>1</b>∙DPYP open complex proceeded more readily than that of <b>1</b>∙BIPY.
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