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Updated: Apr 16, 2026

Synthesis of pH Dependent Pyrazole, Imidazole, and Isoindolone Dipyrrinone Fluorophores using a Claisen-Schmidt Condensation Approach
Published on: June 10, 2021
Synthesis, photophysical studies, solvatochromic analysis and TDDFT calculations of diazaspiro compounds
Komal Aggarwal1, Jitender M Khurana1
1Department of Chemistry, University of Delhi, Delhi 110007, India.
Abstract:
Diazaspiro[5.5]undecane-1,3,5,9-tetraones and 3-thioxo-diazaspiro[5.5]undecane-1,5,9-trione have been synthesized via double Michael addition of 1,5-diphenyl-1,4-pentadien-3-one with active methylene heterocycles N,N-dimethyl barbituric acid, barbituric acid and thiobarbituric acid in water:ethanol (1:1) using TBAB as catalyst. The solvent effect on photophysical behavior of these compounds showed that stokes shift increases with increase in polarity of solvents. The solvent effect on the spectral properties has been investigated by using the Lippert-Mataga and Reichardt methods. The solvatochromism is analyzed by linear solvation energy relationship using the new four-parameter Catalán polarity scales. The relative fluorescence quantum yield of these diazaspiro compounds varies in solvents of different polarity. The HOMO and LUMO energies have been calculated by TDDFT (B3LYP/6-311G (d, p)) approach. TDDFT calculations were also used to compare the experimental and theoretical absorption spectra.
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