Charge‐Transfer‐Adaptable Double‐Strand Formation of a Porphyrin‐BODIPY‐Porphyrin Triad

Abstract

A quadrupolar porphyrin-BODIPY-porphyrin array (1) displayed a moderate negative solvatochromism. The elastic 3,4,5-tri((S)dihydrocitronellyloxy)phenyl groups of 1 facilitated the solubility of such a polarized chromophore array in a nonpolar solvent, and 1 was assembled into a double-strand as elucidated by extensive NMR spectroscopic experiments in [D 8 ]toluene and electronic absorption spectra in cyclohexane. Thermodynamic analyses revealed a small entropy change upon double-strand formation, indicating that cyclohexane did not preferably solvate the porphyrin rings and BODIPY segment presumably because of their polarized nature. At the same time, the significant enthalpy change likely explained the intermolecular attractive force, such as the BF 2 •••Zn cation-dipole interaction. The solvent polarity effect on the electronic spectra together with thermodynamic analyses suggested that the charge-transfer (CT) character was decreased by the double-strand formation in a nonpolar solvent. It was rationalized that insufficient solvent polarity stabilized the CT character of 1 only in part, and the residual polarization character might be stabilized by supramolecular assembly. The charge transfer character of 1 was stabilized by double-strand formation which partially decreased the CT character enough to be stabilized by solvation with cyclohexane.

Enhancing Planar Inverted Perovskite Solar Cells with Innovative Dumbbell‐Shaped HTMs: A Study of Hexabenzocoronene and Pyrene‐BODIPY‐Triarylamine Derivatives

“…These bands could be associated with charge transfer processes via cumulene conjugation. [ 54 ] TM‐04 presents a distinct band at 601 nm and all the higher energy bands, which would correspond to the pyrene moiety, they are red‐shifted but with their typical three‐band staircase shape at 349, 369, and 390 nm. In films, TM‐02 follows a similar behavior as TM‐01, and the three bands related to the HBC merge and become two bands at 366 and 433 nm.…”