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Malhan AH, Thirumoorthy K. Global minimum and a heap of low-lying isomers with planar tetracoordinate carbon in the CAl 3MgH 2- system. Phys Chem Chem Phys 2024; 26:3804-3809. [PMID: 38240304 DOI: 10.1039/d3cp05841g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2024]
Abstract
A global minimum and a heap of low-lying isomers with planar tetracoordinate carbon (ptC) are identified in the CAl3MgH2- system by computational quantum chemical investigations. The nature of the chemical bonding in the global minimum ptC isomer is examined using the conceptual quantum chemical tools. The atoms in molecule (AIM) analysis reveals that the global minimum isomer possesses a ptC geometry. Additionally, the adaptive natural density partitioning (AdNDP), electron localization function (ELF), and nucleus-independent chemical shifts (NICS) analysis corroborate the presence of delocalization in the ptC isomer. The delocalization of electron density in the global minimum ptC isomer contributes to attaining structural stability. The results also suggest that the bridging hydrogen plays a crucial role in stabilizing the ptC system. Furthermore, the ab initio molecular dynamics study supports the structural stability of the ptC isomer.
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Affiliation(s)
- Abdul Hamid Malhan
- Department of Chemistry, School of Advanced Sciences, Vellore Institute of Technology, Vellore 632 014, Tamil Nadu, India.
| | - Krishnan Thirumoorthy
- Department of Chemistry, School of Advanced Sciences, Vellore Institute of Technology, Vellore 632 014, Tamil Nadu, India.
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Vásquez-Espinal A, Pino-Rios R. Strong carbon - noble gas covalent bond and fluxionality in hypercoordinate compounds. Phys Chem Chem Phys 2023; 25:27468-27474. [PMID: 37800185 DOI: 10.1039/d3cp03576j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/07/2023]
Abstract
Thermodynamic, kinetic, and chemical bonding analysis at the coupled cluster level has been carried out for a series of hypercoordinated carbon compounds with formula CH4Ng2+ (Ng = He-Rn). Results show that these compounds could be stable at room temperature and Born-Oppenheimer molecular dynamics simulations (BOMD) in conjunction with activation energies indicate high kinetic stability. In addition, all chemical bonding descriptors agree with a strong C-Ng covalent bond and a bonding pattern similar to that of CH5+. Finally, BOMD simulations showed that these compounds are fluxional, with a continuous formation/breaking of H-H and C-H bonds. To the best of the authors' knowledge, these results represent the first series of fluxional compounds possessing a covalent bond between a main group element and a noble gas atom.
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Affiliation(s)
- Alejandro Vásquez-Espinal
- Química y Farmacia, Facultad de Ciencias de la Salud, Universidad Arturo Prat. Casilla 121, Iquique 1100000, Chile.
| | - Ricardo Pino-Rios
- Química y Farmacia, Facultad de Ciencias de la Salud, Universidad Arturo Prat. Casilla 121, Iquique 1100000, Chile.
- Instituto de Estudios de la Salud, Universidad Arturo Prat, Iquique, 1100000, Chile
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Structural Factors That Determine the Activity of the Xenobiotic Reductase B Enzyme from Pseudomonas putida on Nitroaromatic Compounds. Int J Mol Sci 2022; 24:ijms24010400. [PMID: 36613844 PMCID: PMC9820340 DOI: 10.3390/ijms24010400] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Revised: 12/09/2022] [Accepted: 12/13/2022] [Indexed: 12/28/2022] Open
Abstract
Xenobiotic reductase B (XenB) catalyzes the reduction of the aromatic ring or nitro groups of nitroaromatic compounds with methyl, amino or hydroxyl radicals. This reaction is of biotechnological interest for bioremediation, the reuse of industrial waste or the activation of prodrugs. However, the structural factors that explain the binding of XenB to different substrates are unknown. Molecular dynamics simulations and quantum mechanical calculations were performed to identify the residues involved in the formation and stabilization of the enzyme/substrate complex and to explain the use of different substrates by this enzyme. Our results show that Tyr65 and Tyr335 residues stabilize the ligands through hydrophobic interactions mediated by the aromatic rings of these aminoacids. The higher XenB activity determined with the substrates 1,3,5-trinitrobenzene and 2,4,6-trinitrotoluene is consistent with the lower energy of the highest occupied molecular orbital (LUMO) orbitals and a lower energy of the homo orbital (LUMO), which favors electrophile and nucleophilic activity, respectively. The electrostatic potential maps of these compounds suggest that the bonding requires a large hydrophobic region in the aromatic ring, which is promoted by substituents in ortho and para positions. These results are consistent with experimental data and could be used to propose point mutations that allow this enzyme to process new molecules of biotechnological interest.
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Thimmakondu VS, Sinjari A, Inostroza D, Vairaprakash P, Thirumoorthy K, Roy S, Anoop A, Tiznado W. Why an integrated approach between search algorithms and chemical intuition is necessary? Phys Chem Chem Phys 2022; 24:11680-11686. [PMID: 35506427 DOI: 10.1039/d2cp00315e] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Though search algorithms are appropriate tools for identifying low-energy isomers, fixing several constraints seems to be a fundamental prerequisite to successfully running any structural search program. This causes some potential setbacks as far as identifying all possible isomers, close to the lowest-energy isomer, for any elemental composition. The number of explored candidates, the choice of method, basis set, and availability of CPU time needed to analyze the various initial test structures become necessary restrictions in resolving the issues of structural isomerism reasonably. While one could arrive at new structures through chemical intuition, reproducing or achieving those exact same structures requires increasing the number of variables in any given program, which causes further constraints in exploring the potential energy surface in a reasonable amount of time. Thus, it is emphasized here that an integrated approach between search algorithms and chemical intuition is necessary by taking the C12O2Mg2 system as an example. Our initial search through the AUTOMATON program yielded 1450 different geometries. However, through chemical intuition, we found eighteen new geometries within 40.0 kcal mol-1 at the PBE0-D3/def2-TZVP level. These results indirectly emphasize that an integrated approach between search algorithms and chemical intuition is necessary to further our knowledge in chemical space for any given elemental composition.
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Affiliation(s)
- Venkatesan S Thimmakondu
- Department of Chemistry and Biochemistry, San Diego State University, San Diego, CA 92182-1030, USA.
| | - Aland Sinjari
- School of Mathematics, Biological, Exercise & Physical Sciences, San Diego Miramar College, San Diego, CA, 92126-2910, USA
| | - Diego Inostroza
- Computational and Theoretical Chemistry Group, Departamento de Ciencias Química, Facultad de Ciencias Exactas, Universidad Andres Bello, República 498, Santiago, Chile. .,Universidad Andres Bello, Programa de Doctorado en Fisicoquímica Molecular, Facultad de Ciencias Exactas, Santiago, Chile
| | - Pothiappan Vairaprakash
- Department of Chemistry, School of Chemical and Biotechnology, SASTRA Deemed University, Thanjavur 613 401, Tamil Nadu, India
| | - Krishnan Thirumoorthy
- Department of Chemistry, School of Advanced Sciences, Vellore Institute of Technology, Vellore - 632 014, Tamil Nadu, India
| | - Saikat Roy
- Department of Chemistry, Indian Institute of Technology Kharagpur, Kharagpur 721 302, West Bengal, India.
| | - Anakuthil Anoop
- Department of Chemistry, Indian Institute of Technology Kharagpur, Kharagpur 721 302, West Bengal, India.
| | - William Tiznado
- Computational and Theoretical Chemistry Group, Departamento de Ciencias Química, Facultad de Ciencias Exactas, Universidad Andres Bello, República 498, Santiago, Chile.
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