Studies of hydrogen-bonded complexes of 4-methoxybenzonitrile in ground and lowest triplet states by IR, phosphorescence, and 15N NMR spectra

Abstract

The formation of hydrogen-bonded complexes between 4-methoxybenzonitrile and various OH proton donors was studied in solution in the ground electronic state by means of IR absorption spectra, and the ΔH values were measured. The upfield shift of purely electronic 0–0 transition is observed in low temperature phosphorescence spectra under the interaction, the values of this shift for different proton donor molecules being correlated with the chemical shifts of 15N NMR signals under the complex formation. The nature of observed anomalous N signal shift in NMR spectra was explained by a decrease of paramagnetic deshielding because of the mixing of ground and lowest triplet electronic states of the nitrile studied.