Supersonic jet studies of solvation effects on the spectroscopy and photophysics of 4-diethylaminopyridine

Abstract

We present the results of spectroscopic and photophysical investigations of 4-diethylaminopyridine (DEAP) and its 1 : 1 complexes with a number of protic solvents such as water and various alcohols of different acidity isolated under supersonic jet conditions. While a double resonance vibrational spectroscopic method was employed to investigate the size and geometrical structure of jet-cooled clusters, laser-induced fluorescence spectroscopy was used to examine the changes of photophysics induced by complexation of DEAP with solvent molecule(s). The results obtained from ab initio calculations enable the assignment of geometries and of the vibrational spectra of the clusters in the OH-stretch region. The comparison of the experimental and calculated vibrational spectra indicates that the solvent molecule is hydrogen-bonded to the pyridine nitrogen atom. Dual luminescence is observed only for the complexes with alcohols of relatively strong acidity.

Quantum chemical study of the ground-state alcoholic complexation of selected dual luminescent compounds

“…They supposed that this structure favours the formation of the twisted ICT exited state. However, our calculation indicates that in the primary complexation step the hydrogen bond formation must occur on the pyridine nitrogen, in accordance with the results of Szydlowska et al 14,32,33 In evaluation of the data of spectroscopic experiments (as for example solvatochromic measurements) the knowledge of the ground state dipole moments is essential. The dipole moments of the complexes are given in Table 6.…”

Structure and Hydrogen-Bond Vibrations of Water Complexes of Azaaromatic Compounds: 7-(3′-Pyridyl)indole

“…The weak band at 3436 cm −1 can generally be treated in terms of either a Fermi resonance or a combination band or another hydrate isomer. A Fermi resonance is improbable, because water bending overtones, Fermi-resonant with the stretching fundamentals for the 2-aminopyridine and 4-(diethylamino)pyridine hydrates, are observed at 3343 and 3344 cm −1 , respectively. The water bending frequency may increase with the strength of the H-bond donated by the water OH .…”