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Solvatochromic Study of Highly Fluorescent Alkylated Isocyanonaphthalenes, Their π‐Stacking, Hydrogen‐Bonding Complexation, and Quenching with Pyridine
Author(s) -
Nagy Miklós,
Rácz Dávid,
Lázár László,
Purgel Mihály,
Ditrói Tamás,
Zsuga Miklós,
Kéki Sándor
Publication year - 2014
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.201402310
Subject(s) - fluorescence , pyridine , fluorophore , chemistry , photochemistry , solvatochromism , hydrogen bond , quenching (fluorescence) , quantum yield , stacking , deprotonation , solvent , molecule , organic chemistry , ion , physics , quantum mechanics
Mono‐ and dialkylated derivatives of 1‐amino‐5‐isocyanonaphthalene (ICAN) were studied as new members of a multifunctional, easy‐to‐prepare fluorophore family, which showed excellent solvatochromic properties. The monoallyl derivative and the starting ICAN exhibited strong fluorescence quenching in the presence of small amounts of pyridine. The formation of a hydrogen‐bonded ground‐state pyridine complex was detected; however, analysis of quantum chemical calculations suggested the presence of an additional π‐stacked pyridine complex. The Stern–Volmer plot of the quenching process exhibited a downward curvature and after reaching a minimum the fluorescence intensity increased back to a significant level at high pyridine concentrations. Significant fluorescence was observed even in pure pyridine. A new mechanism and a simple mathematical equation were derived to explain the downward curvature and the remaining fluorescence by the formation of a fluorescent π‐stacked complex.