Effect of Solvent Hydrogen Bonding on Excited-State Properties of Luminol: A Combined Fluorescence and DFT Study

Abstract

The effect of solvent on the photoluminescence behavior of luminol was studied by steady-state fluorescence spectroscopy. The fluorescence spectral behavior of luminol is markedly different in polar protic solvents compared to that in aprotic solvents. A quantitative estimation of the contribution from different solvatochromic parameters, like solvent polarizibility (pi*), hydrogen-bond donor (alpha), and hydrogen-bond acceptor (beta), was made using the linear free energy relationship based on the Kamlet-Taft equation. The analysis reveals that the hydrogen-bond-donating ability (acidity) of the solvent is the most important parameter to characterize the excited-state behavior of luminol. Quantum mechanical calculations using density functional theory (DFT) predict the most stable structure, out of several possible tautomeric conformers of luminol with varying degrees of hydration. In the excited state, charge localization at specific points of the luminol phthalhydrazide moiety causes the solvent to interact primarily through hydrogen-bond donation.

Spectroscopic Study of Solvent Effects on the Electronic Absorption Spectra of Flavone and 7-Hydroxyflavone in Neat and Binary Solvent Mixtures

“…These flavones have potential applications as highly sensitive environmental probes in micellar systems [18]. There have been a large number of studies on solvatochromism of different probe molecules like fluorenones, anthraquinones and luminol [19–21]. Nevertheless, the information on the solvatochromic behavior of flavones is rather scarce.…”

Structural Basis and Mechanism of Chiral Benzedrine Molecules Interacting With Third Dopamine Receptor

“…The single‐residue RAT (or SAT) pairs were extracted from the optimized D 3 R structures within 6.0 Å distance around RAT. Two H atoms were added to close the carbonyl and amino terminals of extracted single‐residue RAT pairs, which were calculated with MP2/6‐31G(d,p) to obtain E b . The basis set superposition error (BSSE) was evaluated by the counterpoise method, where E b includes E BSSE : …”

“…Two H atoms were added to close the carbonyl and amino terminals of extracted single-residue RAT pairs, [93][94][95][96][97][98] which were calculated with MP2/6-31G(d,p) to obtain E b . 110,111 The basis set superposition error (BSSE) was evaluated by the counterpoise method, 112,113 where E b includes E BSSE :…”

Investigation of contrasting hydrogen bonding pattern of 3-(phenylamino)-cyclohexen-1-one with solvents in the ground and excited states

“…The s, a and b are the coefficient of the corresponding solvent parameters. The Kamlet-Taft analysis has been reported to be useful in predicting the contribution of different solvent parameters [39][40][41][42][43][44]. The choice of cyclohexane as a reference for this investigation can be justified as it is a unique medium that has p ⁄ , a and b values of zero.…”