title: Solvatochromic study of highly fluorescent alkylated isocyanonaphthalenes, their π-stacking, hydrogen-bonding complexation, and quenching with pyridine.
abstract: 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.
authors.affiliation: Department of Applied Chemistry, University of Debrecen, 4032 Debrecen, Egyetem tér 1 (Hungary), Fax: (+36) 52-518662.
authors.forename: Miklós
authors.initials: M
authors.lastname: Nagy
authors.forename: Dávid
authors.initials: D
authors.lastname: Rácz
authors.forename: László
authors.initials: L
authors.lastname: Lázár
authors.forename: Mihály
authors.initials: M
authors.lastname: Purgel
authors.forename: Tamás
authors.initials: T
authors.lastname: Ditrói
authors.forename: Miklós
authors.initials: M
authors.lastname: Zsuga
authors.forename: Sándor
authors.initials: S
authors.lastname: Kéki
mesh_terms: D000478:Alkylation; D005456:Fluorescent Dyes / Q000737:chemistry*; D006860:Hydrogen Bonding; D009281:Naphthalenes / Q000737:chemistry*; D011725:Pyridines / Q000737:chemistry*; D011789:Quantum Theory; D012997:Solvents / Q000737:chemistry*; D013050:Spectrometry, Fluorescence
chemical_list: D005456:Fluorescent Dyes; D009281:Naphthalenes; D011725:Pyridines; D012997:Solvents; C023666:pyridine
keywords: complexes; density functional calculations; fluorescence; quenching; solvatochromism