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Phenylene‐Bridged Core‐Modified Planar Aromatic Octaphyrin: Aromaticity, Photophysical and Anion Receptor Properties
Author(s) -
Karthik Ganesan,
Cha WonYoung,
Ghosh Arindam,
Kim Taeyeon,
Srinivasan A.,
Kim Dongho,
Chandrashekar Tavarekere K.
Publication year - 2016
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.201600177
Subject(s) - phenylene , planarity testing , chemistry , intramolecular force , aromaticity , protonation , hydrogen bond , photochemistry , crystallography , porphyrin , spectroscopy , ultrafast laser spectroscopy , ion , stereochemistry , molecule , organic chemistry , quantum mechanics , polymer , physics
The synthesis of a planar expanded meso porphyrin with an intramolecular para‐ phenylene‐bridged core is reported. The planarity of the octaphyrin macrocycle was confirmed by single‐crystal X‐ray structural analysis, in which the bridged para‐ phenylene unit deviated by 27° from the mean macrocyclic plane. Spectroscopic analyses and theoretical calculations suggested that the macrocycle was Hückel aromatic and followed a major [34 π] single‐conjugation pathway, which indicated that the bridging para‐ phenylene unit was not involved in the macrocyclic conjugation. Analysis of the photophysical properties of this system by steady‐state absorption/fluorescence spectroscopy and transient absorption spectroscopy revealed moderate enhancement in the parameters of the octaphyrin as compared to its non‐bridged octaphyrin congeners, which was attributed to the planarity and rigidity of the macrocycle as imposed by the bridging para‐ phenylene unit. Preliminary anion‐binding studies revealed that the protonated macrocycle bound selectively with chloride ions through N−H⋅⋅⋅Cl hydrogen‐bonding interactions.