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Synthesis of hydroxyoligophenylenes containing electron‐donating, electron‐accepting groups, or π‐deficient aromatic ring and their solvatochromic behavior
Author(s) -
Yamaguchi Isao,
Yamaji Ryosuke
Publication year - 2017
Publication title -
journal of physical organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.325
H-Index - 66
eISSN - 1099-1395
pISSN - 0894-3230
DOI - 10.1002/poc.3671
Subject(s) - solvatochromism , chemistry , bathochromic shift , deprotonation , pyridine , medicinal chemistry , ring (chemistry) , photochemistry , solvent , organic chemistry , fluorescence , ion , physics , quantum mechanics
We have reported oligo( p‐ phenylene)s (OPPs) with an OH group located at one end, namely, OPP( n )‐OHs (where n is the number of benzene rings). The OPPs exhibited significant solvatochromism; the deprotonation of the OH groups of OPP( n )‐OHs , when treated with NaH, caused a bathochromic shift of absorption maxima (λ max ) that increased with the donor numbers (DNs) of the solvents. We assumed that the solvatochromism exhibited by OPP( n )‐ONa was attributed to an intramolecular charge shift from the sodium phenoxy group(s) to the adjacent rings. In this study, to investigate the assumption, hydroxyoligophenylenes ( R‐OPP( n )‐OH ) with an electron‐donating dimethylamino group ( n = 3, R = NMe 2 ), an electron‐accepting nitro group ( n = 3, R = NO 2 ), and a π‐deficient pyridine ring ( n = 2, R = Py) were synthesized by the Suzuki coupling reaction. The deprotonation of the OH group of by treatment with NaH caused a bathochromic shift (Δλ) of λ max of R‐OPP( m )‐ONa . The Δ λ of the deprotonated species increased with the DNs of the solvents. The emission peak positions of R‐OPP( m )‐ONa depended on the DNs of the solvents; therefore, the emission color could be tuned by changing the solvent. R‐OPP( m )‐OH received an electrochemical oxidation of the OH group and OPP unit. The data related to the remarkable solvatochromic behavior of R‐OPP( n )‐ONa will be useful information for the development of new luminescent materials.