The influence of the implicit solvent model on transition state structures of two S N2 reactions of biochemical importance is presented. In the considered methyl transfer reaction, we show experimentally that the rate constant in blood serum is about 60% slower than in the aqueous solution and that the implicit solvent model with slightly modified parameters for water captures correctly the energetics of this reaction. With the example of the reaction between 4-methyl-1,2,4-triazol-3-thione and ethyl bromoacetate, we show that relative stabilities of the conformationally different transition states depend upon the solvent inclusion strategy.
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http://dx.doi.org/10.1021/jp8035956 | DOI Listing |
J Phys Chem B
January 2025
Department of Chemistry, Institute for Advanced Studies in Basic Sciences (IASBS), Zanjan 45137-66731, Iran.
The studies on ionic liquids (ILs) and their interaction with different solvents have always been an interesting topic for experimental and computational chemists. Recently, however, deep insights on the molecular structures of the IL-water binary mixtures have been mainly performed through classical simulations. Here, a comprehensive quantum mechanical study is presented on seven 1-butyl-3-methylimidazolium-based ILs in the absence and presence of water.
View Article and Find Full Text PDFPhys Chem Chem Phys
January 2025
School of Materials Science and Engineering, Jiangxi University of Science and Technology, Ganzhou 341000, P. R. China.
First-principles calculations, particularly density functional theory (DFT) combined with D3 dispersion correction (DFT+D3), have proven to be valuable tools in simulating the adsorption of lead ions on TiCO surfaces. However, conventional theoretical models assume electrically neutral systems under vacuum conditions, neglecting the solvent environment and electrode potential's crucial effects. This study employed an implicit solvent model, treating the solvent as a continuous and homogeneous medium to capture the influence of different solvents by varying their dielectric constants.
View Article and Find Full Text PDFJ Chem Theory Comput
January 2025
Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan.
The complete active space second-order perturbation theory (CASPT2) is valuable for accurately predicting electronic structures and transition energies. However, optimizing molecular geometries in the solution phase has proven challenging. In this study, we develop analytic first-order derivatives of CASPT2 using an implicit solvation model, specifically the polarizable continuum model, within the open-source package OpenMolcas.
View Article and Find Full Text PDFJ Chem Theory Comput
January 2025
University of Bremen, Institute for Physical and Theoretical Chemistry, Leobener Str. 6, D-28359 Bremen, Germany.
To simulate the effects of high pressure on molecular and electronic structure, methods based on the polarizable continuum model have emerged as a serious contender to the conventionally employed periodic boundary conditions. In this work, we present a highly efficient integral-direct algorithm for the Gaussians On Surface Tesserae Simulate HYdrostatic Pressure (GOSTSHYP) method. We examine the efficiency of this implementation on large chains of α-d-glucose units.
View Article and Find Full Text PDFJ Comput Chem
January 2025
Scuola Superiore Meridionale, Napoli, Italy.
Light-driven molecular rotary motors are nanometric machines able to convert light into unidirectional motions. Several types of molecular motors have been developed to better respond to light stimuli, opening new avenues for developing smart materials ranging from nanomedicine to robotics. They have great importance in the scientific research across various disciplines, but a detailed comprehension of the underlying ultrafast photophysics immediately after photo-excitation, that is, Franck-Condon region characterization, is not fully achieved yet.
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