Water Arrangements upon Interaction with a Rigid Solute: Multiconfigurational Fenchone-(HO) Hydrates.

Insight into the arrangements of water molecules around solutes is important to understand how solvation proceeds and to build reliable models to describe water-solute interactions. We report the stepwise solvation of fenchone, a biogenic ketone, with 4-7 water molecules. Multiple hydrates were observed using broadband rotational spectroscopy, and the configurations of four fenchone-(HO), three fenchone-(HO), two fenchone-(HO), and one fenchone-(HO) complexes were characterized from the analysis of their rotational spectra in combination with quantum-chemical calculations.

Microwave spectra of dinitrotoluene isomers: a new step towards the detection of explosive vapors.

The spectroscopic characterization of explosive taggants used for TNT detection is a research topic of growing interest. We present a gas-phase rotational spectroscopic study of weakly volatile dinitrotoluene (DNT) isomers. The pure rotational spectra of 2,4-DNT and 2,6-DNT were recorded in the microwave range (2-20 GHz) using a Fabry-Perot Fourier-transform microwave (FP-FTMW) spectrometer coupled to a pulsed supersonic jet.

Insights into the non-covalent interactions of hydrogen sulfide with fenchol and fenchone from a gas-phase rotational study.

The gas-phase non-covalent interactions in the -fenchol-HS and fenchone-HS complexes have been unveiled using rotational spectroscopy in a supersonic jet expansion and quantum chemical calculations. In -fenchol, the hydrogen bond HSH⋯OH together with dispersive interactions stabilizes the system. In fenchone, the weak interaction HSH⋯OC allows an internal dynamic of HS.

Disentangling the complex network of non-covalent interactions in fenchone hydrates rotational spectroscopy and quantum chemistry.

The hydrates of the monoterpenoid fenchone (CHO)·(HO) ( = 1, 2, 3) were investigated by both computational chemistry and microwave spectroscopy. Two monohydrates, three dihydrates and for the first time three trihydrates were identified through the observation of the parent and O isotopologues in the rotational spectrum from 2 to 20 GHz. For each hydrate, the sets of rotational constants enabled the determination of the substitution coordinates of the oxygen water atoms as well as an effective structure accounting for the arrangement of the water molecules around fenchone.

Microsolvation of myrtenal studied by microwave spectroscopy highlights the role of quasi-hydrogen bonds in the stabilization of its hydrates.

Hydrates of myrtenal (CHO) · (HO) (n = 1, 2, 3) were experimentally investigated in a molecular jet using a cavity-based Fourier transform microwave spectrometer in the 2.6 GHz-15 GHz frequency range. The assignment of the spectra was made possible, thanks to computationally optimized structures at the B3LYP-D3BJ/def2-TZVP and MP2/6-311++G(d,p) levels using the Gaussian 16 software.

Gas-Phase Hydration of Perillaldehyde Investigated by Microwave Spectroscopy Assisted by Computational Chemistry.

The microsolvated complexes of two equatorial conformers of perillaldehyde were experimentally investigated in a supersonic molecular jet coupled to a cavity-based Fourier transform microwave spectrometer, in the 2.3-8 GHz frequency range. The structures of hydrates CHO·(HO) ( = 1,2,3) were first optimized at the MP2/6-311++G(d,p) and B3LYP-D3BJ/def2-TZVP levels of theory.

Microhydration of verbenone: how the chain of water molecules adapts its structure to the host molecule.

The microsolvation of verbenone (C10H14O)·(H2O)n (n = 1, 2, 3) was experimentally investigated in a supersonic expansion using a cavity-based Fourier transform microwave spectrometer, in the 2.8-14 GHz frequency range. Thanks to computationally optimized structures at the B3LYP-D3BJ/def2-TZVP and MP2/6-311++G(d,p) levels using the Gaussian 16 software, the spectra of two mono- and two dihydrates, and that of the lowest energy conformer among the four expected trihydrates, could be assigned.

Rotational spectrum of NSF3 in the ground and v5 = 1 vibrational states: observation of Q-branch perturbation-allowed transitions with delta(k - l) = 0, +/-3, +/-6 and anomalies in the rovibrational structure of the v5 = 1 state.

The rotational spectrum of NSF3 in the ground and v5 = 1 vibrational states has been investigated in the centimeter- and millimeter-wave ranges. R-branch (J + 1 <-- J) transitions for J = 0, 1 and Q-branch rotational transitions for the v5 = 1 vibrational state have been measured by waveguide Fourier transform microwave spectroscopy in the range 8-26.5 GHz.

Millimeter wave spectrum of bromomethyl radical, CH2Br.

The rotational spectra of the two isotopic species of the bromomethyl radical, CH2 79Br and CH2 81Br, have been observed in their ground electronic state 2B1 in the 180-470 GHz frequency region, corresponding to a-type transitions from N=8-7 to N=21-20. The radical was produced by hydrogen abstraction of methylbromide (CH3Br) either by chlorine or by fluorine atoms in a free space cell. Hyperfine structure due to the bromine nucleus has been resolved in the observed spectra, and the rotational constants as well as the fine and hyperfine interaction constants were accurately determined for both isotopomers.