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Updated: Sep 5, 2025

Synthesis of pH Dependent Pyrazole, Imidazole, and Isoindolone Dipyrrinone Fluorophores using a Claisen-Schmidt Condensation Approach
Published on: June 10, 2021
Spiroindeno-pyridineindoles (SIPIs) as new visible colorimetric pH indicators
Ghodsi Mohammadi Ziarani1, Maedeh Bagheri1, Shahriar Bahar1
1Department of Chemistry, Faculty of Physics and Chemistry, Alzahra University, Vanak Square, P.O. Box 1993893973, Tehran, Iran.
Abstract:
Some new, highly selective, and sensitive colorimetric pH indicators, spiro[4H-indeno-[1,2-b]pyridine-4,3'-[3H]indoles] (SIPIs) in aqueous solution were developed. SIPIs were synthesized via a one-pot four-component condensation of isatin derivatives, β-diketones 1,3-indandione, and ammonium acetate using FSi-PrNH-BuSO3H as a nanocatalyst in EtOH. According to the experimental evaluations, it was found that SIPI derivatives are pH indicators for naked-eye detection of OH- ion with intense color changes from orange to purple in the pH range of 10.3-12.
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