Accurate dissociation energies of O–H⋯O hydrogen-bonded 1-naphthol⋅solvent complexes

Abstract

Accurate O–H⋯O hydrogen-bond dissociation energies were measured for the supersonic-jet-cooled complexes 1-naphthol⋅S with S=D2O, ethanol, oxirane, and oxetane. A mass-selective pump–dump–probe method was used, combining stimulated emission pumping with resonant two-photon ionization and ion-dip techniques. The ground-state dissociation energies D0(S0) are 5.83±0.13 kcal/mol for d1-1-naphthol⋅D2O, 7.94±0.02 kcal/mol for 1-naphthol⋅ethanol, 7.71±0.14 kcal/mol for 1-naphthol⋅oxirane and >8.17 kcal/mol for 1-naphthol⋅oxetane. The D0’s increase by 5%–7% upon excitation of 1-naphthol to the S1 state. These dissociation energies are compared to those of the analogous complexes with S=H2O, methanol, NH3, and ND3 [Chem. Phys. Lett. 246, 291 (1996)]. The trends in D0 are compared to the electric dipole moments μ, molecular polarizabilities ᾱ, and gas-phase proton affinities of the H bond acceptor molecules. For the O-containing acceptors, the D0’s correlate well with ᾱ, but the only good overall correlation for both O- and N-containing acceptors was found between the dissociation energies and proton affinities.

Intermolecular dissociation energies of dispersively bound 1-naphthol⋅cycloalkane complexes

“…43 Similarly, the face isomer of 1NpOH·cyclopropane exhibits a small spectral shift to the blue, δν = +2 cm −1 . 28 In contrast, the spectral shifts are always to the red and larger if the solvent molecule is H-bonded to the naphthol OH group, as in the complexes 25,27,32 The nonclassically H-bonded edge isomer of 1NpOH·cyclopropane exhibits a red shift of −71.5 cm −1 , about half that of the 1NpOH·H 2 O complex. 28 .…”

“…12,[23][24][25][26][27][30][31][32] Detailed descriptions have been reported elsewhere. 12,28 Briefly, a pulsed pump laser (∼ 5 ns pulse width) is fixed at the S 0 → S 1 electronic origin (0 0 0 band) and excites the jet-cooled M·X complex from the vibrationless S 0 to the vibrationless S 1 state.…”

Accurate dissociation energies of two isomers of the 1-naphthol⋅cyclopropane complex

“…This triply-resonant method is abbreviated as SEP-R2PI, 9,[17][18][19]22,[38][39][40][41] a scheme is shown in Figure 1. First, a pump laser (1), fixed at the S 0 → S 1 origin of the aromatic chromophore M, excites the jet-cooled M·S complex to the vibrationless S 1 state.…”

Experimental and Theoretical Determination of Dissociation Energies of Dispersion-Dominated Aromatic Molecular Complexes

“…The detection occurs after a time delay ∆t that is long enough for M ̸ = ·S to undergo intramolecular vibrational redistribution and VP (∆t = 0.1 − 10 µs). [39][40][41] The pump, dump and probe steps are induced by three independently tunable UV lasers, as shown in The SEP-R2PI method has been applied to dispersively bound M·S complexes, 39,43 to complexes involving nonclassical OH· · · π hydrogen bonds, to aromatic and aliphatic acceptors, 41,44 and to classically H-bonded complexes. 40,41 The dissociation energies D 0 (S 0 ) of 10 complexes have been determined with a relative accuracy of ≈ 1%, [38][39][40][41]43,44 and are given in Table 3.…”