Interactions of promazine with selected biomolecules: Photophysical and computational investigation

Abstract

Abstract Charge transfer complexes formed by electron transfer processes are important components of many biochemical processes. Donor-acceptor complex formation between promazine and dopamine, serotonin and melatonin was investigated using experimental and computational methods. UV–Vis absorption, fluorescence spectroscopy and cyclic voltammetry measurements were carried out to investigate the intermolecular interactions and donor-acceptor properties. Geometry optimizations were completed at ωB97XD/6-31G(d,p) level and electronic transitions were performed by the time-dependent density functional theory with CAM-B3LYP, B3LYP, and ωB97XD functionals using 6-311++G(d,p) basis set. Complex formation with promazine is in the order as melatonin\u202f>\u202fserotonin\u202f>\u202fdopamine in water especially by H-bond formation. Experimental and calculated values for UV–Vis absorption spectra and HOMO, LUMO energies were compared and found in agreement in water. Serotonin was determined as the best donor among studied molecules forming H-bond and π-π∗ interactions with promazine. Investigated complexes may be useful for the design of organic-biological hybrid components acting as donor-acceptor systems.