Solvent effect on the type (red-shifted or blue-shifted) of hydrogen bond

Solvent (liquid xenon) effect on the four hydrogen-bonded complexes F3C-H⋯NH3, F3C-H⋯N(CH3)3, F3C-H⋯NCH, and F3C-H⋯O(CH3)2 as well as on the two intramolecular hydrogen-bonded configurations, TG(T∣G′) conformer of 1-methoxy-2-(dimethylamino)-ethane (in which the C-H⋯O hydrogen bond is involved) and Z-conformer of 2-(N-methoxyl iminomethyl)-4(1H)-pyridinone (in which the N-H⋯O hydrogen bond is involved), is investigated with polarized continuum model at B3LYP/6-311 + G(d, p) level of theory. Solvent effect on the type (red-shifted or blue-shifted) of hydrogen bond can be generally divided into six classes (A-F). The solvent effect does not change the type of hydrogen bond when the frequency shift of the ν(X-H) (X = C or N) of the hydrogen bond donor caused by hydrogen bond formation in gas phase is considerably larger than both that of the hydrogen bond donor and that of the hydrogen-bonded complex caused by solvent effect. Classes B-E belong to this situation. The type of hydrogen bond will probably change when the former is considerably smaller than either value of the latter. Classes A and F belong to this situation. Our calculations show that solvent effect on the first to fifth hydrogen-bonded system belongs to class C, C, D, D, and E, respectively. For the sixth system, solvent effect changes the N-H⋯O hydrogen bond from the red-shifted type of the gas phase (Δν(N-H) = −17.1 cm−1) to the blue-shifted type of the solution phase (Δν(N-H) = 21.8 cm−1). This is the second theoretical instance of class A.