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Theoretical Study on Open‐Shell Singlet Character and Second Hyperpolarizabilities in Cofacial π‐Stacked Dimers Composed of Weak Open‐Shell Antiaromatic Porphyrins
Author(s) -
Fujiyoshi JunYa,
Tonami Takayoshi,
Yamane Masaki,
Okada Kenji,
Kishi Ryohei,
Muhammad Shabbir,
AlSehemi Abdullah G.,
Nozawa Ryo,
Shinokubo Hiroshi,
Nakano Masayoshi
Publication year - 2018
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.201800745
Subject(s) - antiaromaticity , diradical , stacking , porphyrin , chemistry , open shell , dimer , chemical physics , density functional theory , aromaticity , computational chemistry , molecule , monomer , singlet state , molecular physics , crystallography , photochemistry , atomic physics , physics , organic chemistry , excited state , polymer
From the analysis based on the broken‐symmetry density functional theory (DFT) calculations, we in this study propose a strategy to enhance the open‐shell characters and third‐order nonlinear optical (NLO) properties of π‐stacked dimers composed of antiaromatic molecules with weak open‐shell characters. For this purpose, we here constructed cofacial π‐stacked dimer models composed of aromatic and antiaromatic Ni II porphyrins in order to examine the π‐π stacking distance ( R ) dependence of the diradical characters ( y ) and static second hyperpolarizabilities (γ). The antiaromatic porphyrin dimers are found to have intermediate y around R ∼3.3 Å, the result of which originates in the unique intermolecular interactions between the antiaromatic monomers. Static γ along the stacking direction of such antiaromatic porphyrin dimers with intermediate diradical characters are shown to be enhanced significantly as compared to those of the isolated monomers and the aromatic porphyrin dimers.