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ID 38063
file
creator
Hontama, Naoya
Aprà, Edoardo
Xantheas, Sotiris S.
NDC
Chemistry
abstract
The structure of the calix[4]arene(C4A)-Arn complexes has been investigated by laser induced fluorescence spectroscopy, mass-selected resonant two-color two-photon ionization (2C-R2PI) spectroscopy, fragment detected IR photodissociation (FDIRPD) spectroscopy, and high level first principles electronic structure calculations at the MP2 and CCSD(T) levels of theory. C4A has a very high ability of forming van der Waals complexes with rare gas atoms. For the C4A-Ar dimer, two isomers are found. A major species shows a 45 cm-1 red-shift of its band origin with respect to the monomer, while that of a minor species is 60 cm-1. The binding energy the major species is determined to be in the range of 350 - 2250 cm-1 from 2C-R2PI spectroscopy and FDIRPD spectroscopy. Two isomers are also identified in the quantum chemical calculation, depending on whether the Ar atom resides inside (endo) or outside (exo) the C4A. We propose a novel scheme to derive CCSD(T)-quality binding energies for the C4A-Ar complex based on the ratio of CCSD(T)/MP2 energies for the smaller model systems Benzene-Ar and Phenol-Ar. Our best computed estimates for the binding energies of the C4A-Ar endo- and endo-complexes are 1560 cm-1 and 510 cm-1, respectively, at the CCSD(T)/Complete Basis Set (CBS) level of theory. For the C4A-Ar2 trimer, we again identified two isomers in the calculation: one is the {2:0} endo-complex in which the Ar2 dimer is encapsulated inside the C4A cavity and the other is the {1:1} endo-exo-complex in which one Ar resides inside and the other outside the C4A cavity. The calculated binding energies for the two C4A-Ar2 isomers are nearly identical. However, the experimental evidence strongly suggests that the observed species is the {2:0} endo-complex. The endo structural motif is also suggested for the larger C4A-Arn complexes because of the systematic red-shifts of the complexes with the number of bound Ar atoms, that is the Arn complex is encapsulated inside the C4A cavity. The formation of the endo-complex structures is attributed to the anisotropy of the interaction with C4A during the complex formation in the expansion region.
description
This is a postprint of an article published by Royal Society of Chemistry in Physical Chemistry Chemical Physics, 2010, available online: http://pubs.rsc.org/en/Content/ArticleLanding/2010/CP/b927441c#!divAbstract
This study is supported from JSPS through a Grant-in-Aid project (No. 18205003) and from MEXT through a Grant-in-Aid for the Scientific Research on Priority Area “Molecular Science for Supra Functional Systems” (No. 477).
journal title
Physical Chemistry Chemical Physics
volume
Volume 12
issue
Issue 18
start page
4569
end page
4579
date of issued
2010-03-22
publisher
Royal Society of Chemistry
issn
1463-9076
publisher doi
language
eng
nii type
Journal Article
HU type
Journal Articles
DCMI type
text
format
application/pdf
text version
author
rights
Copyright (c) the Owner Societies 2010
relation is version of URL
http://dx.doi.org/10.1039/B927441C
department
Graduate School of Science