Premium
Revisiting the photochemistry 2,5‐dihydroxy benzoic acid (gentisic acid): Solvent and pH effect
Author(s) -
Adhikari Meena,
Joshi Neeraj K.,
Joshi Hem C.,
Mehata Mohan S.,
Mishra Hirdyesh,
Pant Sanjay
Publication year - 2021
Publication title -
journal of physical organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.325
H-Index - 66
eISSN - 1099-1395
pISSN - 0894-3230
DOI - 10.1002/poc.4168
Subject(s) - chemistry , photochemistry , aqueous solution , benzoic acid , solvent , intramolecular force , deprotonation , excited state , conformational isomerism , gentisic acid , proton , fluorescence , organic chemistry , molecule , ion , biochemistry , salicylic acid , physics , quantum mechanics , nuclear physics
In the present study, we have reinvestigated photochemistry of 2,5‐dihydroxy benzoic acid (DHBA) in a series of organic solvents of different polarities and the aqueous solution of varying pH from 1 to 14. The investigation was carried out using steady‐state and nanosecond (ns) time‐domain fluorescence measurement techniques at room temperature. Some hitherto not explored spectral features with new insight on different forms of DHBA are reported. It is found that DHBA exists as monoanionic and neutral forms in various polar protic, aprotic, and nonpolar solvents. In aqueous solution (pH 1 to 14), neutral, monoanionic, and dianion forms are found to be responsible for the observed optical spectral profiles. The observed significant Stokes shift in emission is attributed to species undergoing excited‐state intramolecular proton transfer (ESIPT) in different solvents. The analysis presented in this work elucidates and validate the presence of various species and conformers of DHBA.