TY - JOUR

T1 - Conformational preference determined by inequivalent n-pairs

T2 - Rotational studies on acetophenone and its monohydrate

AU - Lei, Juncheng

AU - Zhang, Jiaqi

AU - Feng, Gang

AU - Grabow, Jens-Uwe

AU - Gou, Qian

N1 - Funding Information: We are grateful for support from: National Natural Science Foundation of China (Grant No. 21703021 and U1931104); Fundamental and Frontier Research Fund of Chongqing (Grant No. cstc2017jcyjA0068 and cstc2018jcyjA0050); Venture & Innovation Support Program for Chongqing Overseas Returns (Grant No. cx2018064); Fundamental Research Funds for the Central Universities (Grant No. 106112017CDJQJ228807 and 2018CDQYHG0009); Foundation of 100 Young Chongqing University (Grant No. 0220001104428). J.-U. G. acknowledges funding from the Deutsche Forschungsgemeinschaft (GR 1344) and the Land Niedersachsen.

PY - 2019/11/7

Y1 - 2019/11/7

N2 - Acetophenone and its complex with water have been investigated by using pulsed jet Fourier transform microwave spectroscopy complemented with quantum chemical calculations. Rotational spectra of the acetophenone monomer comprising nine isotopologues were measured and assigned, enabling the accurate structural description of the carbon skeleton. The most stable isomer of the monohydrate of acetophenone was detected in the supersonic jet expansion. Water serves as a proton donor and acceptor forming an O-H⋯OC hydrogen bond and a secondary C-H⋯O-H weak hydrogen bond with acetophenone through a six-membered ring. The water molecule lies almost in the plane of the aromatic ring. Bader's quantum theory of atoms in molecules, Johnson's non-covalent interaction, electron localization function and natural bond orbital analyses were applied to characterize the nature of the non-covalent interactions in the target complex. All rotational transitions are split into two components arising from the hindered methyl internal rotation. Upon the complexation, the V3 barrier to internal rotation of-CH3 slightly decreases, with 7.50(3) kJ mol-1 for the monomer, and 7.04(5) kJ mol-1 for the acetophenone-H2O dimer, respectively.

AB - Acetophenone and its complex with water have been investigated by using pulsed jet Fourier transform microwave spectroscopy complemented with quantum chemical calculations. Rotational spectra of the acetophenone monomer comprising nine isotopologues were measured and assigned, enabling the accurate structural description of the carbon skeleton. The most stable isomer of the monohydrate of acetophenone was detected in the supersonic jet expansion. Water serves as a proton donor and acceptor forming an O-H⋯OC hydrogen bond and a secondary C-H⋯O-H weak hydrogen bond with acetophenone through a six-membered ring. The water molecule lies almost in the plane of the aromatic ring. Bader's quantum theory of atoms in molecules, Johnson's non-covalent interaction, electron localization function and natural bond orbital analyses were applied to characterize the nature of the non-covalent interactions in the target complex. All rotational transitions are split into two components arising from the hindered methyl internal rotation. Upon the complexation, the V3 barrier to internal rotation of-CH3 slightly decreases, with 7.50(3) kJ mol-1 for the monomer, and 7.04(5) kJ mol-1 for the acetophenone-H2O dimer, respectively.

UR - http://www.scopus.com/inward/record.url?scp=85074117777&partnerID=8YFLogxK

U2 - 10.1039/c9cp03904j

DO - 10.1039/c9cp03904j

M3 - Article

C2 - 31595918

AN - SCOPUS:85074117777

VL - 21

SP - 22888

EP - 22894

JO - Physical Chemistry Chemical Physics

JF - Physical Chemistry Chemical Physics

SN - 1463-9076

IS - 41

ER -