Premium
Synthesis and Aggregation Behavior of meso ‐Sulfinylporphyrins: Evaluation of S‐Chirality Effects on the Self‐Organization to S–Oxo‐Tethered Cofacial Porphyrin Dimers
Author(s) -
Matano Yoshihiro,
Shinokura Tomonori,
Matsumoto Kazuaki,
Imahori Hiroshi,
Nakano Haruyuki
Publication year - 2007
Publication title -
chemistry – an asian journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.18
H-Index - 106
eISSN - 1861-471X
pISSN - 1861-4728
DOI - 10.1002/asia.200700191
Subject(s) - chemistry , porphyrin , chirality (physics) , photochemistry , delocalized electron , zinc , cyclic voltammetry , monomer , chromophore , crystallography , organic chemistry , electrochemistry , chiral symmetry breaking , physics , nambu–jona lasinio model , quark , polymer , electrode , quantum mechanics
The synthesis and aggregation behavior of meso ‐sulfinylporphyrins are described. The copper‐catalyzed C–S cross‐coupling reaction of a meso ‐iodoporphyrin with benzenethiol and n ‐octanethiol has proved to be an efficient method for the synthesis of meso ‐sulfanylporphyrins, which are oxygenated by m ‐chloroperbenzoic acid to produce the corresponding meso ‐sulfinylporphyrins. Optically active zinc meso ‐sulfinylporphyrins were successfully isolated by means of optical resolution of the racemates on a chiral HPLC column. Zinc sulfinylporphyrins readily undergo self‐organization through S–oxo–zinc coordination to form cofacial porphyrin dimers in solution, in which the hetero‐ and homodimers are present as a diastereomeric mixture. The aggregation modes of the S–oxo‐tethered porphyrin dimers were fully characterized by 1 H NMR, IR, and UV/Vis spectroscopy as well as DFT calculations on their model compounds, thus revealing that the self‐aggregation behavior depends on the combination of S chirality. The absolute configurations at the sulfur center can be determined by the exciton‐coupled CD method. The observed self‐association constant for the S–oxo‐tethered dimerization of ( S )‐phenylsulfinylporphyrin in toluene is larger than that in dichloromethane, which reflects the difference in dipole moments between the homodimer and the monomer. In cyclic and differential pulse voltammetry, the first oxidation process of the cofacial dimers is split into two reversible steps, which indicates that the initially produced π radical cations are delocalized efficiently between the two porphyrin rings. The present findings demonstrate the potential utility of meso ‐sulfinyl groups as promising ligands for investigating the effects of peripheral chirality on the structures and optical and electrochemical properties of metal‐assisted porphyrin self‐assemblies.