scholarly journals Energetic Study of Clusters and Reaction Barrier Heights from Efficient Semilocal Density Functionals

Computation ◽  
2017 ◽  
Vol 5 (4) ◽  
pp. 27 ◽  
Author(s):  
Guocai Tian ◽  
Yuxiang Mo ◽  
Jianmin Tao
Keyword(s):  
Density Functionals ◽  
Reaction Barrier ◽  
Barrier Heights

scholarly journals A Computational Investigation of the Uncatalysed and Water-Catalysed Acyl Rearrangements in Ingenol Esters

2018 ◽  
Vol 71 (4) ◽  
pp. 212 ◽  
Author(s):  
Asja A. Kroeger ◽  
Amir Karton
Keyword(s):  
Ring Opening ◽  
Density Functional ◽  
Skin Lesions ◽  
Functional Theory ◽  
Reaction Barrier ◽  
Barrier Heights ◽  
Rate Determining Step ◽  
Proton Transfers ◽  
Biological Potency ◽  
Hybrid Density Functional

Ingenol esters have been identified as potent anticancer and HIV latency reversing agents. Ingenol-3-angelate was recently approved as a topical treatment for precancerous actinic keratosis skin lesions. It was found, however, that ingenol esters can undergo a series of acyl rearrangements, which may affect their biological potency and the shelf-life of drug formulations. We use double-hybrid density functional theory to explore the mechanisms for the uncatalysed and water-catalysed acyl migrations in a model ingenol ester. The uncatalysed reaction may proceed either via a concerted mechanism or via a stepwise mechanism that involves a chiral orthoester intermediate. We find that the stepwise pathway is kinetically preferred by a significant amount of ΔΔH‡298 = 44.5 kJ mol−1. The uncatalysed 3-O-acyl to 5-O-acyl and 5-O-acyl to 20-O-acyl stepwise rearrangements involve cyclisation and ring-opening steps, both concomitant with a proton transfer. We find that the ring-opening step is the rate-determining step for both rearrangements, with reaction barrier heights of ΔH‡298 = 251.6 and 177.1 kJ mol−1 respectively. The proton transfers in the cyclisation and ring-opening steps may be catalysed by a water molecule. The water catalyst reduces the reaction barrier heights of these steps by over 90 kJ mol−1.

scholarly journals Reactivity of arsenoplatin complex versus water and thiocyanate: a DFT benchmark study

2020 ◽  
Vol 139 (12) ◽  
Author(s):  
Iogann Tolbatov ◽  
Cecilia Coletti ◽  
Alessandro Marrone ◽  
Nazzareno Re
Keyword(s):  
Theoretical Study ◽  
Structural Parameters ◽  
Platinum Complexes ◽  
Molecular Structures ◽  
Geometrical Parameters ◽  
Density Functionals ◽  
Arsenic Compounds ◽  
Energy Barriers ◽  
Barrier Heights ◽  
Benchmark Study

AbstractSeven different density functionals, including GGAs, meta-GGAs, hybrids and range-separated hybrids, and considering Grimme’s empirical dispersion correction (M06-L, M06-2X, PBE0, B3LYP, B3LYP-D3, CAM-B3LYP, ωB97X) have been tested for their performance in the prediction of molecular structures, energies and energy barriers for a class of newly developed antitumor platinum complexes involving main group heavy elements such as arsenic. The calculated structural parameters, energies and energy barriers have been compared to the available experimental data. The results show that range-separated hybrid functionals CAM-B3LYP and ωB97X give good results in predicting both geometrical parameters and isomerization energies and barrier heights and are promising new tools for the theoretical study of novel platinum(II) arsenic compounds.

Assessment of Multireference Perturbation Methods for Chemical Reaction Barrier Heights

2015 ◽  
Vol 119 (21) ◽  
pp. 5490-5495 ◽  
Author(s):  
Francesco Fracchia ◽  
Renzo Cimiraglia ◽  
Celestino Angeli
Keyword(s):  
Chemical Reaction ◽  
Perturbation Methods ◽  
Reaction Barrier ◽  
Barrier Heights
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