TY - JOUR
T1 - A combined theoretical and experimental study of phenol-(acetylene)n (n ≤ 7) clusters
AU - Singh, Gurmeet
AU - Nandi, Apurba
AU - Gadre, Shridhar R.
AU - Chiba, Takashi
AU - Fujii, Asuka
N1 - Funding Information:
We acknowledge Dr. Takahito Nakajima and Dr. Michio Katouda in RIKEN, AICS, for their helpful discussion and support. This work is supported by India-Japan Cooperative Science Program (No. DST/INT/JSPS/P-193/2015). S.R.G. thanks the Department of Science and Technology (DST), New Delhi, India, for the award of a J. C. Bose National Fellowship and the Centre for Development of Advanced Computing (CDAC), Pune, India for support. G.S. is grateful to the Council of Scientific and Industrial Research (CSIR), New Delhi, India, for the award of Senior Research Fellowship. A.F. thanks the partial financial support by the Grant-in-Aid for Scientific Research (Project No. 26288002) from JSPS.
Publisher Copyright:
© 2017 Author(s).
PY - 2017/4/21
Y1 - 2017/4/21
N2 - Structures and vibrational spectra of phenol-(acetylene)n (Ph(Ac)n) clusters are studied by a combination of theoretical calculations and infrared (IR) spectroscopy. The molecular electrostatic potential features are utilized for generating trial geometries of the medium-sized Ph(Ac)n (n = 1, 2, 4, 6, and 7) clusters. These initial geometries are subjected to geometry optimization within the second-order Møller-Plesset (MP2) theory, employing correlation consistent aug-cc-pVDZ (aVDZ) basis set. Minimal nature of the reported structures is confirmed by doing vibrational frequency run at MP2/aVDZ level of theory using full calculations for n = 1 and 2 and employing grafting based molecular tailoring approach for the n = 4, 6, and 7. Several isomers for n ≥ 4 are found to lie in an energy window of 1 kcal mol−1 of each other. Considering the formidability of MP2 level investigation for the large number of isomers for n = 6 and 7, B97-D level theory is used for studying their energetics and IR spectra. It is seen that the number of energetically close isomers increases with increasing n. Moderately size-selected IR spectra of Ph(Ac)n (n = 4 and 7), prepared by a supersonic jet expansion, are measured for the acetylenic C-H and phenolic O-H stretch regions by infrared-ultraviolet (IR-UV) double resonance spectroscopy combined with time-of-flight mass spectrometry. Asymmetric line shape of the C-H stretch band and remarkable line broadening and weakening of the O-H stretch band are noteworthy features of the observed spectra. These findings of the experimental spectra are explained by the theoretical studies. The averaging of the vibrational spectrum of low-lying isomers of the Ph(Ac)n clusters lying in a narrow energy range is found to be responsible for the broadening and weakening of the O-H band.
AB - Structures and vibrational spectra of phenol-(acetylene)n (Ph(Ac)n) clusters are studied by a combination of theoretical calculations and infrared (IR) spectroscopy. The molecular electrostatic potential features are utilized for generating trial geometries of the medium-sized Ph(Ac)n (n = 1, 2, 4, 6, and 7) clusters. These initial geometries are subjected to geometry optimization within the second-order Møller-Plesset (MP2) theory, employing correlation consistent aug-cc-pVDZ (aVDZ) basis set. Minimal nature of the reported structures is confirmed by doing vibrational frequency run at MP2/aVDZ level of theory using full calculations for n = 1 and 2 and employing grafting based molecular tailoring approach for the n = 4, 6, and 7. Several isomers for n ≥ 4 are found to lie in an energy window of 1 kcal mol−1 of each other. Considering the formidability of MP2 level investigation for the large number of isomers for n = 6 and 7, B97-D level theory is used for studying their energetics and IR spectra. It is seen that the number of energetically close isomers increases with increasing n. Moderately size-selected IR spectra of Ph(Ac)n (n = 4 and 7), prepared by a supersonic jet expansion, are measured for the acetylenic C-H and phenolic O-H stretch regions by infrared-ultraviolet (IR-UV) double resonance spectroscopy combined with time-of-flight mass spectrometry. Asymmetric line shape of the C-H stretch band and remarkable line broadening and weakening of the O-H stretch band are noteworthy features of the observed spectra. These findings of the experimental spectra are explained by the theoretical studies. The averaging of the vibrational spectrum of low-lying isomers of the Ph(Ac)n clusters lying in a narrow energy range is found to be responsible for the broadening and weakening of the O-H band.
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U2 - 10.1063/1.4979953
DO - 10.1063/1.4979953
M3 - Article
C2 - 28433025
AN - SCOPUS:85018653741
VL - 146
JO - Journal of Chemical Physics
JF - Journal of Chemical Physics
SN - 0021-9606
IS - 15
M1 - 154303
ER -