Adsorption of imidazole on Au(111) surface: Dispersion corrected density functional study

We use density functional theory in the generalized gradient approximation to study the adsorption of imidazole on the Au(111) surface and account for dispersion effect using Grimme's empirical dispersion correction technique. Our results show that the adsorption energy of imidazole depends on the slab size and on the adsorption site. In agreement with other studies, we find the largest adsorption energy for imidazole on a top site of Au(111). However, we also note that the adsorption energy at other sites is substantial

Theoretical study of the CO2 adsorption by Zeolitic Imidazolate Frameworks (ZIFs)

Density functional theory with Grimme's empirical correction, DFT-D3, has been used to examine the adsorption of a carbon dioxide molecule by different sets of zeolitic imidazolate framework materials (ZIF-1 to -4, -6 to -10, and -zni). We have calculated the interaction energy, the dipole moment variation, and the charge density difference for the different CO 2 @ZIF structures. Our study shows a strong relationship between the CO 2 adsorption energy and the volume of the cavities of the ZIFs: the capture of carbon dioxide depends on the shape and size of the ZIFs pore in which CO 2 has been inserted. The physisorption phenomena that govern the adsorption of CO 2 molecule require both π-stacking interactions and hydrogen-like bonding. We have found that adsorption does not change the geometry of CO 2 , but it induces a significant structural change in some ZIF structures

Theoretical spectroscopic study of acetyl (CH3CO), vinoxy (CH2CHO), and 1-methylvinoxy (CH3COCH2) radicals. Barrierless formation processes of acetone in the gas phase

Background: Acetone is present in the earth´s atmosphere and extra-terrestrially. The knowledge of its chemical history in these environments represents a challenge with important implications for global tropospheric chemistry and astrochemistry. The results of a search for efficient barrierless pathways producing acetone from radicals in the gas phase are described in this paper. The spectroscopic properties of radicals needed for their experimental detection are provided. Methods: The reactants were acetone fragments of low stability and small species containing C, O and H atoms. Two exergonic bimolecular addition reactions involving the radicals CH3, CH3CO, and CH3COCH2, were found to be competitive according to the kinetic rates calculated at different temperatures. An extensive spectroscopic study of the radicals CH3COCH2 and CH3CO, as well as the CH2CHO isomer, was performed. Rovibrational parameters, anharmonic vibrational transitions, and excitations to the low-lying excited states are provided. For this purpose, RCCSD(T)-F12 and MRCI/CASSCF calculations were performed. In addition, since all the species presented non-rigid properties, a variational procedure of reduced dimensionality was employed to explore the far infrared region. Results: The internal rotation barriers were determined to be V3=143.7 cm-1 (CH3CO), V2=3838.7 cm-1 (CH2CHO) and V3=161.4 cm-1 and V2=2727.5 cm-1 (CH3COCH2).The splitting of the ground vibrational state due to the torsional barrier have been computed to be 2.997 cm-1, 0.0 cm-1, and 0.320 cm-1, for CH3CO, CH2CHO, and CH3COCH2, respectively. Conclusions: Two addition reactions, H+CH3COCH2 and CH3+CH3CO, could be considered barrierless formation processes of acetone after considering all the possible formation routes, starting from 58 selected reactants, which are fragments of the molecule. The spectroscopic study of the radicals involved in the formation processes present non-rigidity. The interconversion of their equilibrium geometries has important spectroscopic effects on CH3CO and CH3COCH2, but is negligible for CH2CHO.This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 872081. This work was also supported by the Ministerio de Ciencia, Innovación y Universidades of Spain through the grants EIN2019-103072 and FIS2016-76418-P; the CSIC i-coop+2018 program under the grant number COOPB20364; the CTI (CSIC) and CESGA and to the “Red Española de Computación” for the grants AECT-2020-2-0008 and RES- AECT-2020-3-0011 for computing facilities. MC also acknowledges the financial support from the Spanish National Research, Development, and Innovation plan (RDI plan) under the project PID2019-104002GB-C21 and the Consejerı́a de Conocimiento, Investigación y Universidad, Junta de Andalucı́a and European Regional Development Fund (ERDF), Ref. SOMM17/6105/UGR. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

Ab Initio and DFT Studies on CO 2 Interacting with Zn q + -Imidazole ( q =0, 1, 2) Complexes: Prediction of Charge Transfer through σ- or π-Type Models

International audienc

The Microwave Rotational Electric Resonance (RER) Spectrum of Benzothiazole

The microwave spectra of benzothiazole were measured in the frequency range 2–26.5 GHz using a pulsed molecular jet Fourier transform microwave spectrometer. Hyperfine splittings arising from the quadrupole coupling of the 14N nucleus were fully resolved and analyzed simultaneously with the rotational frequencies. In total, 194 and 92 hyperfine components of the main species and the 34S isotopologue, respectively, were measured and fitted to measurement accuracy using a semi-rigid rotor model supplemented by a Hamiltonian accounting for the 14N nuclear quadrupole coupling effect. Highly accurate rotational constants, centrifugal distortion constants, and 14N nuclear quadrupole coupling constants were deduced. A large number of method and basis set combinations were used to optimize the molecular geometry of benzothiazole, and the calculated rotational constants were compared with the experimentally determined constants in the course of a benchmarking effort. The similar value of the χcc quadrupole coupling constant when compared to other thiazole derivatives indicates only very small changes of the electronic environment at the nitrogen nucleus in these compounds. The small negative inertial defect of −0.056 uÅ2 hints that low-frequency out-of-plane vibrations are present in benzothiazole, similar to the observation for some other planar aromatic molecules