Chirality-dependent balance between hydrogen bonding and London dispersion in isolated (±)-1-indanol clusters

Abstract

The aggregation behavior of racemic and enantiopure 1-indanol has been studied by FTIR spectroscopy, resonant ion dip IR spectroscopy, and spontaneous Raman scattering in supersonic jets. This triple experimental approach, augmented by homology to related molecular fragments and dispersion-corrected DFT predictions, allows disentangling the complex spectroscopic signature in the OH stretch range. Evidence for chirality-sensitive aggregation via isolated OH···π bonds in competition with cooperative ···OH···OH···π patterns is collected. An accurate description of London dispersion forces provides the key to its explanation.

Molecular Docking via Olefinic OH···π Interactions: A Bulky Alkene Model System and Its Cooperativity

“…This systematic discrepancy between the predictive power of harmonic hydrogen bond shifts to O and π acceptors has been noted before 45,46 and could be due to anharmonic effects or deficiencies at the electronic structure level. Without dispersion correction, the harmonic B3LYP shift prediction for TT is coincidentally perfect, 47 and that for TPe is too low.…”

Diastereo-specific conformational properties of neutral, protonated and radical cation forms of (1R,2S)-cis- and (1R,2R)-trans-amino-indanol by gas phase spectroscopy

“…Besides the presence or absence of the H-bond, the diastereomers also differ in the shape of the potential along the puckering motion, which has been shown to be very sensitive to small perturbations. 40,81,91,92 As a result, neutral cis-and trans-AI differ by the number of populated conformers under supersonic jet conditions. While the ax-eq and eq-ax positions of the OH-NH 2 substituents are isoenergetic in cis-AI, equatorial preference manifests itself by a large energy difference between the ax-ax and eq-eq conformations in trans-AI.…”

Chirality effects in gas-phase spectroscopy and photophysics of molecular and ionic complexes: contribution of low and room temperature studies

“…It is especially precious in the case of highly symmetrical species like alcohol cyclic trimers or pseudo-centro symmetric dimers, as propensity rules intervene. Observation of alternating IR and Raman active frequencies favours the assignment of the observed species to a highly symmetrical structure [126,127]. Ion or fluorescence dip techniques resting on Stimulated Raman have not been applied to chiral systems, though they elegantly complement IR spectroscopy in the 3 μm region [128,129] and give access to the fingerprint region of neutral species [130], as dip techniques resting in Stimulated-Emission Pumping also do [131,132].…”

“…However, the barrier between I eq and I ax is low enough that relaxation between them takes place in some particular cooling conditions [230,231,234]. As a result, only the equatorial conformer is observed in argon expansion, as International Reviews in Physical Chemistry confirmed by microwave spectroscopy [234], while both of them coexist when less efficient cooling gases such as neon or helium are used [127,230].…”

“…The use of mode-dependent scaling factors allows correcting for the overestimated frequency shifts upon hydrogen-bond formation [175,177]. A good option is to resort to the dispersion-corrected B3LYP-D3 which combines the good frequency description of the hybrid functional B3LYP with refined description of dispersion [24,127,[172][173][174]. As frequencies also intervene in the thermal corrections to the energy, and in the calculations of dissociation constants within the frame of statistical methods like the RRKM theory, good description of the frequencies including anharmonicity effects is especially important for room-temperature experiments such as CID and IRMPD.…”