Substituent-Control Exciton in J-Aggregates of Protonated Water-Insoluble Porphyrins

Abstract

A series of protonated porphyrin J-aggregates of various water-insoluble tetraphenylporphyrin derivatives was prepared by aggregation at the liquid-liquid or gas-liquid interface. Using atomic force microscopy, we observed microcrystalline porphyrin J-aggregates. The J-aggregates have two strong exciton bands corresponding to the B (Soret)- and Q-bands of the protonated porphyrin. Interestingly, the excitation energy of the lower exciton (denoted by S1) markedly depends on the meso-substituents, whereas that of the higher exciton (denoted by S2) does not depend on them. These results indicate that the nature of the exciton coupling of the S1 transition dipole moment can be systematically changed by the substituents.

Interfacial Adsorption State of Protonated Lipophilic Porphyrins in a Liquid-Liquid System by Using Reflection Spectrometry

“…This explanation is supported by the fact that the aggregate formation was not observed even in the case of tetrakis-(3,5-dimethoxy-phenyl)-porphine. 15 Further, the enhanced hydrophobicity by halogen or methyl substitution may shift the equilibrations toward the left-hand side in Fig. 3.…”

“…Similar J-aggregate formations are also found for the other TPP derivatives having a substituent at the p-position of the meso-phenyl group, such as tetra-pnitrophenylporphyrin, tetra-p-methoxyphenylporphyrin, and so on. 15 …”

Challenges and breakthroughs in recent research on self-assembly

“…Prodi reported wavelength-dependent electron and energy transfer in assemblies of ruthenium porphyrin and perylene bisimide [394]. Okada and Segawa reported sustituent-controlled excitation in J-aggregated self-assembly of porphyrins [395]. Supramolecular chiral memory was demonstrated in porphyrin assemblies as reported by Purrello and coworkers [396].…”

Electrochemically Switchable Molecular-Tweezers

“…It was difficult to determine two K values for two step complexation upon applied voltage. Examination of CPK molecular models assuming an affinity of two zinc porphyrin radical cations 28 suggests that 1 may allow guest 2 to approach from the external side of the porphyrin.…”