Related Experiment Video
Updated: Sep 21, 2026

Synthesis of pH Dependent Pyrazole, Imidazole, and Isoindolone Dipyrrinone Fluorophores using a Claisen-Schmidt Condensation Approach
Published on: June 10, 2021
Positional isomerism and short hydrogen bonds govern photochromic behaviour in dipyridyl-NDI⋯formic acid co-crystals
Adnan Ishaq1, Louise Male1, Neil R Champness1
1School of Chemistry, University of Birmingham Edgbaston Birmingham B15 2TT UK n.champness@bham.ac.uk.
Abstract:
Positional isomerism in pyridyl naphthalene diimide formic acid co-crystals controls crystal symmetry, yielding centrosymmetric (I2/a) and polar (Pc) structures from 4- and 2-pyridyl isomers respectively. Both materials function as reversible photochromic switches upon UV irradiation via a proton-coupled electron transfer type mechanism, generating NDI radical anions, as confirmed by UV-vis and ATR-FTIR spectroscopy.
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