Relative stabilities and the spectral signatures of stacked and hydrogen-bonded dimers of serotonin

Abstract

The O-HsssN hydrogen-bonded dimer of serotonin is shown to be more stable than the stacked dimer in its ground electronic state, by using the M?ller-Plesset second-order perturbation theory (MP2) and the 6-31g??basis set. The vertical excitation energy for the lowest ? ? ?? transition for the monomer as well as the dimer is predicted by time-dependent density functional theory. The experimentally observed red shift of excitation wavelength on oligomerisation is explained in terms of the change in the HOMO-LUMO energy gap due to complex formation. The impact of dimer formation on the proton magnetic resonance spectrum of serotonin monomer is also examined. ? 2015 Taylor and Francis.