Luminol: Extended hydrogen bond network in water solution

Density functional theory at the B3LYP/6-311G (d, p) level was used to obtain the optimised geometries of a series of luminol-water complexes with stoichiometric ratios ranging from 1:1 to 1:5 both in the gas phase and in aqueous solution. All the calculations show that there are strong hydrogen bond interactions between luminol and water due to the existence of C=O, N-H, and N-H-2 groups in luminol molecule. By comparing the relative energy and binding energy, the most stable hydrogen bond complex is suggested, which involves extended hydrogen-bonding networks. Then the changes of luminol geometry structure, charge distribution, frontier orbital properties, and the absorption spectrums induced by hydrogen bond and solvent effects were investigated. The results show that the hydrogen bonds increase the planarity of system, which further decrease the HOMO-LUMO energy gap, and induce maximum absorption shift. This work will be helpful for understanding the effect of hydrogen bond on hydrazide chemiluminescence reagents. (C) 2013 Elsevier B.V. All rights reserved.