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Updated: Apr 26, 2026

Synthesis of pH Dependent Pyrazole, Imidazole, and Isoindolone Dipyrrinone Fluorophores using a Claisen-Schmidt Condensation Approach
Published on: June 10, 2021
Vertically π-expanded coumarin--synthesis via the Scholl reaction and photophysical properties
Mariusz Tasior1, Irena Deperasińska, Karolina Morawska
1Institute of Organic Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, Warsaw, Poland. dtgryko@icho.edu.pl.
Abstract:
A short and efficient access to a unique type of π-expanded coumarin is achieved. The strategic placement of naphthalene at the 4-position of coumarin allowed us to fuse these two moieties via aromatic dehydrogenation under Scholl conditions. The intriguing optical properties of this π-expanded coumarin are discussed on the basis of quantum chemical calculations. The fluorescence quantum yield (∼20%) is significantly higher than that obtained for the classical 7-hydroxycoumarin. The ratio of emission versus radiationless deactivation is governed by the following factors: decrease in the oscillator strength of the SS transition (vs. perylene), low yield of intersystem crossing and strong internal conversion originating from the activity of the number of vibronic states.
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