Victor K Outlaw1, Jiawang Zhou2, Arthur E Bragg2, Craig A Townsend2. 1. Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, WI 53706, USA. 2. Department of Chemistry, The Johns Hopkins University, Remsen Hall, 3400 N. Charles Street, Baltimore, MD 21218, USA.
Abstract
6-Amino-8-cyanobenzo[1, 2-b]indolizines, a new class of photoluminescent materials, exhibit reversible pH-dependent optical properties characterized by an uncommon and dramatic blue shift in fluorescence emission when protonated. Acid titration and NMR spectroscopy experiments reveal that, rather than the anticipated N-protonation, C-protonation and loss of aromaticity is responsible for the observed photophysical changes. Efficient synthesis from indole-2-carboxaldehydes makes variously substituted versions of this nucleus readily available to tune optical and pH effects.
6-Amino-8-cyanobenzo[1, 2-b]indolizines, a new class of photoluminescent materials, exhibit reversible pH-dependent optical properties characterized by an uncommon and dramatic blue shift in fluorescence emission when protonated. Acid titration and n class="Chemical">NMR spectroscopy experiments reveal that, rather than the anticipated N-protonation, C-protonation and loss of aromaticity is responsible for the observed photophysical changes. Efficient synthesis from indole-2-carboxaldehydes makes variously substituted versions of this nucleus readily available to tune optical and pH effects.
Authors: Heiko Ihmels; Andreas Meiswinkel; Christian J Mohrschladt; Daniela Otto; Michael Waidelich; Michael Towler; Rick White; Martin Albrecht; Alexander Schnurpfeil Journal: J Org Chem Date: 2005-05-13 Impact factor: 4.354