Spectral shifts and structures of phenol⋯Arn clusters

Armentano, Antonio; Černý, Jiří; Riese, Mikko; Taherkhani, Mehran; Yezzar, Med Ben; Müller‐Dethlefs, Klaus

doi:10.1039/c0cp01370f

Cited by 9 publications

(28 citation statements)

References 38 publications

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“…Calculations at moderate theoretical levels are however consistent with this assignment. 29,31,39 Although spectra of the related benzene-Ar 2 and aniline-Ar 2 clusters exhibit also significant signals from a less stable (20) structure, this type of isomer has escaped identification in the PhOH-Ar 2 spectra for a long time owing to its weak intensity in most REMPI spectra. Only very recently, an empirical additivity model developed for the DS 1 shifts of PhOH-Ar n suggested a tentative assignment of the S 1 origin of (20) to a weak transition at DS 1 = À2 cm À1 (Fig.…”

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confidence: 99%

“…During the course of the present work, REMPI spectra of n = 5 and n = 6 were reported, and weak peaks on top of a broad and largely unstructured signal at DS 1 = À20 and À44 cm À1 were interpreted as S 1 origins of (50) and (60) isomers by comparison with corresponding shifts of aniline-Ar n , although calculations suggested structures with solvation on both sides to be more stable. 39 This discrepancy was attributed to expansion conditions favouring the production of PhOH-Ar n clusters with singlesided Ar solvation for the size range n Z 3.…”

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confidence: 99%

“…39,43 The origin of the broad background in the n = 4 spectrum is unclear. It may arise from fragmentation of larger clusters (n Z 5) or spectral congestion due to signals from other n = 4 isomers.…”

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confidence: 99%

“…39 For completeness, it is noted that there are a variety of related (20)-type isomers, which are obtained from the most stable one shown in Fig. 1 by internal rotation of Ar 2 above the aromatic plane (see Fig.…”

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confidence: 99%

“…Only vibrationally-resolved IR and UV spectra were reported, 37,39,40 and the REMPI spectra are shown in Fig. 2.…”

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confidence: 99%

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Structures and IR/UV spectra of neutral and ionic phenol–Arn cluster isomers (n≤ 4): competition between hydrogen bonding and stacking

Schmies

Patzer

Fujii

et al. 2011

Phys. Chem. Chem. Phys.

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The structures, binding energies, and vibrational and electronic spectra of various isomers of neutral and ionic phenol-Ar n clusters with n r 4, PhOH (+) -Ar n , are characterized by quantum chemical calculations. The properties in the neutral and ionic ground electronic states (S 0 , D 0 ) are determined at the M06-2X/aug-cc-pVTZ level, whereas the S 1 excited state of the neutral species is investigated at the CC2/aug-cc-pVDZ level. The Ar complexation shifts calculated for the S 1 origin and the adiabatic ionisation potential, DS 1 and DIP, sensitively depend on the Ar positions and thus the sequence of filling the first Ar solvation shell. The calculated shifts confirm empirical additivity rules for DS 1 established recently from experimental spectra and enable thus a firm assignment of various S 1 origins to their respective isomers. A similar additivity model is newly developed for DIP using the M06-2X data. The isomer assignment is further confirmed by Franck-Condon simulations of the intermolecular vibrational structure of the S 1 ' S 0 transitions. In neutral PhOH-Ar n , dispersion dominates the attraction and p-bonding is more stable than H-bonding. The solvation sequence of the most stable isomers is derived as (10), (11), (30), and (31) for n r 4, where (km) denotes isomers with k and m Ar ligands binding above and below the aromatic plane, respectively. The p interaction is somewhat stronger in the S 1 state due to enhanced dispersion forces. Similarly, the H-bond strength increases in S 1 due to the enhanced acidity of the OH proton. In the PhOH + -Ar n cations, H-bonds are significantly stronger than p-bonds due to additional induction forces. Consequently, one favourable solvation sequence is derived as (H00), (H10), (H20), and (H30) for n r 4, where (Hkm) denotes isomers with one H-bound ligand and k and m p-bonded Ar ligands above and below the aromatic plane, respectively. Another low-energy solvation motif for n = 2 is denoted (11) H and involves nonlinear bifurcated H-bonding to both equivalent Ar atoms in a C 2v structure in which the OH group points toward the midpoint of an Ar 2 dimer in a T-shaped fashion. This dimer core can also be further solvated by p-bonded ligands leading to the solvation sequence (H00),

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“…Only vibrationally-resolved IR and UV spectra were reported, 37,39,40 and the REMPI spectra are shown in Fig. 2.…”

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confidence: 99%