Intermolecular bonding and vibrations of phenol⋅oxirane

Abstract

High-resolution ultraviolet spectroscopy of p -fluorostyrene-water: Evidence for a σ -type hydrogen-bonded dimerThe supersonically cooled hydrogen-bonded phenol•oxirane complex was studied using mass-and isomer-selective laser spectroscopic techniques. The S 1 ←S 0 vibronic spectrum was measured by mass-selective two-color resonant two-photon ionization. UV/UV-hole-burning experiments prove that the whole observed spectrum is due to only one isomer. High-resolution fluorescence emission spectra yielded five different intermolecular S 0 state vibrational fundamentals as 15, 27, 39, 83, and 177 cm Ϫ1 , which are assigned as the 1 Љ , ␤ 1 Љ , Љ, ␤ 2 Љ , and Љ modes, respectively, based on ab initio calculations. The analogous S 1 state intermolecular vibrations were also assigned, based on frequency and Franck-Condon activity. The observation of the 1 and intermolecular vibrational transitions in both excitation and emission implies that phenol•oxirane is asymmetric ͑chiral͒, even though the H-donor is C s and the acceptor C 2v symmetric. Four different ab initio structure optimizations and normal-mode calculations were made, to compare the performance of the self-consistent field ͑SCF͒ and Becke-Lee-Yang-Parr ͑B-LYP͒ density functional methods, using the 6-31G(d, p) and 6-311ϩϩG(d, p) basis sets. The SCF/6-31G(d,p) method and the B-LYP method with both basis sets indeed predict chiral minimum-energy structures. The B-LYP/6-311ϩϩG(d, p) and SCF/6-31G(d,p) normal mode frequencies agree well with the experimental S 0 state frequencies, with rms deviations of 4%. The MP2/6-31G(d, p) hydrogen bond well depth is D e ϭ6.9 kcal/mol and the dissociation energy is D 0 ϭ5.7 kcal/mol.

Internal Rotation of the Hydroxyl Group in Isopropanol and the Chirality of the Gauche Form: Fourier Transform Microwave Spectroscopy of (CH3)2CHOD

“…Quite recently Al-Rabaa et al (15) reported enantiodifferentiation in jet-cooled van der Waals complexes: (R)-(+)-and (S)-(−)-α-methyl-2-naphthalenemethanol solvated with (S)-(+)-chloro-1-propanol by using laser induced fluorescence spectroscopy and Sarfati et al (16) a successful enatiometric differentiation of saturated chiral alkanes dissolved in a chiral polypeptide liquid crystal, by deuterium NMR spectroscopy. Leutwyler and his collaborators examined the chirality of a few hydrogen-bonded oxirane complexes by laser spectroscopic techniques (17) or by ab initio calculations (18). Vardi (19) discussed the effect of intermolecular interactions on coherent tunneling racemization within the framework of a double minimum model like gauche; namely, he set up equations of motion which were nonlinear due to the difference between homochiral and heterochiral interactions and showed that the nonlinearity contributed much to the chiral stability.…”

Chiral self-recognition in the gas phase: the case of glycidol dimers

“…Oxiranes have been recognized previously as being well suited in this context. 13,14,18 The availability of two complementary functional groups in each monomer helps to reduce the dimer Ñexibility and can be expected to enhance the chiral recognition e †ect.10 Glycidol 2,3-epoxypropan-1-ol, (C 3 H 6 O 2 , oxiranemethanol), a cyclic ether with an additional alcohol functionality, fulÐlls these requirements. While it also has two torsional degrees of freedom, two of the monomer conformations are strongly favored over the others due to the formation of a weak internal hydrogen bond.…”

Monitoring the polymerization of a diglycidyl ether bisphenol-A/2,2′-dimethyl-4,4′-methylenebis (cyclohexylamine) matrix with a Fourier transform infrared optical fibre sensor

“…Némec et al [10] have defined the rCH 3 vibration from 1133 to 1136 cm 21 by FT-IR and at 1132 cm 21 by FT-Raman. Inauen et al [23] described the vibration frequencies of phenol-oxirane at 1112 cm 21 , the (1 þ 3t) at 1167 cm 21 and the (1 þ d) at 1176 cm 21 from fluorescence emersion spectra.…”