QUENCHING OF FLUORESCENCE FROM PYRENE-LABELED POLY(N-ISOPROPYLACRYLAMIDE) SOLUTIONS HEATED ABOVE THEIR LOWER CRITICAL SOLUTION TEMPERATURE

Fluorescence quenching experiments were carried out on aqueous solutions of pyrene-labeled poly(N-isopropylacrylamide)s in dilute solution and in the presence of unlabeled poly(N-isopropy-lacrylamide), below and above their lower critical solution temperature (LCST). The quenchers of fluorescence were two water-soluble compounds: ethylpyridinium bromide (EPB) and nitromethane (CH3N02). Above the LCST the pyrene labels experience a remarkable protection against quenching by EPB and CH3N02. Below the LCST the fluorescence of pyrene is quenched, but the simple Stern-Volmer model is not obeyed. © 1990, American Chemical Society. All rights reserved.