Revisiting structure and conformational stability of ethanethiol

Infrared Spectroscopy of Ethanethiol Monomers and Dimers at MP2 Level: Characterizing the Dimer Formation and Hydrogen Bond

Ethanethiol, also known as ethyl mercaptan, is an organosulfur compound that appears as a colorless liquid with a distinctive odor. It has been detected in the interstellar medium, and its self-association has been the subject of a few known experimental studies, where the SH vibrational mode was used. However, unlike the analogous ethanol dimer, the ethanethiol dimer has not been thoroughly explored theoretically. In this study, ethanethiol and dimers were investigated using the MP2 method with various basis sets to determine the properties and stability of these structures. For the monomer, both trans and gauche structures were computed, with the gauche conformer being more stable, consistent with the available data in the literature. Local mode decomposition analysis of monomers showed that the CH2 rocking mode, associated with the CSH bending, is present only for the gauche isomer aligning with the experimental assignments. Furthermore, eight stable dimer configurations were identified and categorized into three groups: trans-trans, gauche-gauche, and trans-gauche isomers. Among these, the trans-gauche isomer was found to be the most stable. Dispersion is the dominant term for the ethanethiol dimer.

Conformational and structural stability of n and 2-propylthiols: a revisit

The conformational and structural stability of n-propanethiol (nP) is revisited owing to the prevailing ambiguity in the literature reported hitherto, and the rationale for 2-propanethiol's (2P) most stable conformers is analyzed. Based on the rotation around the C-C and C-S bonds, four conformers for nP and two conformers for 2-propanethiol (2P) were found to have the lowest energies at the CCSD/cc-pVDZ level of theory. The two conformers of 2P are anti (T), and gauche (G), and those of nP are T-G, G-G, T-T, and G-T. Rotational barriers, geometrical parameters, fundamental vibrational modes, and energy parameters reported herein agree exceedingly well with the reported experimental values for nP and 2P molecules. Furthermore, natural bond orbital (NBO), frontier molecular orbital (FMO), Mulliken charge (MC), electrostatic potential charge (ESP), and vibrational mode analyses were carried out to get a better understanding of both the thiols.

Study of membrane fouling mechanism during the phenol degradation in microbial fuel cell and membrane bioreactor coupling system

This study evaluated the feasibility of phenol degradation in microbial fuel cell (MFC) and membrane bioreactor (MBR) coupling system, and explored the mechanism of MBR membrane fouling. Four aspects were researched in open and closed circuit conditions: the degradation capacity of the coupling system, the increase of trans-membrane pressure (TMP), and the adhesion of phenol degradation products and microorganisms on the membrane. The results showed that the degradation of phenol and COD in the closed circuit coupling system was higher than that in the open circuit. The micro-electric field can inhibit the growth of TMP and keep dodecamethylcyclohexasiloxane away from the membrane, meanwhile can also reduce the abundance and species diversity of microorganisms. Nevertheless, the micro-electric field could not completely eliminate the membrane fouling due to the fact that the phenol degradation product of ethanethiol, microorganisms of Proteobacteria and Actinobacteria were more favorable on the membrane.

Conformational stability and structural analysis of methanethiol clusters: a revisit

B3LYP/cc-pV(D/T/Q)Z and CCSD/cc-pVDZ levels of theory predict three minima for both dimers and trimers of methanethiol. Predictions at B3LYP/cc-pVDZ corroborates exceedingly well with the earlier reported experimental value but significantly differ from the previous computational predictions. Interaction energy between the molecules decreases with an increase in the size of the basis set for both the dimer and trimer. The dipole moment of methanethiol dimer gets reduced at the B3LYP/cc-pVDZ level of theory relative to all minima configurations, and the same is seen for trimer also. These new predictions are well supported by atoms in molecules (AIM), frontier molecular orbital (FMO), Mulliken charge (MC), and natural bond orbital (NBO) analysis.

B3LYP/cc-pV(D/T/Q)Z and CCSD/cc-pVDZ levels of theory predict three minima for both dimers and trimers of methanethiol.