Effects of microsolvation and aqueous solvation on the tautomers of histidine: a computational study on energy, structure and IR spectrum

2009 ◽  
Vol 124 (1-2) ◽  
pp. 37-47 ◽  
Author(s):  
Amareshwar Kumar Rai ◽  
Weixin Fei ◽  
Zhiwen Lu ◽  
Zijing Lin
Keyword(s):  
Ir Spectrum ◽  
Computational Study ◽  
Energy Structure ◽  
Aqueous Solvation

Comparison of P- and As-core-modified porphyrins with the parental porphyrin: a computational study

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Aleksey E. Kuznetsov
Keyword(s):  
Computational Study ◽  
Electron Delocalization ◽  
Energy Structure ◽  
Frontier Molecular Orbitals ◽  
The Core ◽  
Potential Applications ◽  
Noticeable Reduction ◽  
Internal Electron ◽  
Porphyrin Core ◽  
Homo Lumo

Abstract The first comparative DFT (B3LYP/6-31G*) study of the Zn-porphyrin and its two derivatives, ZnP(P)4 and ZnP(As)4, is reported. For all three species studied, ZnP, ZnP(P)4 and ZnP(As)4, the singlet was calculated to be the lowest-energy structure and singlet-triplet gap was found to decrease from ca. 41—42 kcal/mol for N to ca. 17—18 kcal/mol for P and to ca. 10 kcal/mol for As. Both ZnP(P)4 and ZnP(As)4 were calculated to attain very pronounced bowl-like shapes. The frontier molecular orbitals (MOs) of the core-modified porphyrins are quite similar to the ZnP frontier MOs. For the HOMO-2 of the core-modified porphyrins due to the ZnP(P)4/ZnP(As)4 bowl-like shapes we might suppose the existence of “internal” electron delocalization inside the ZnP(P)4/ZnP(As)4 “bowls”. Noticeable reduction of the HOMO/LUMO gaps was calculated for ZnP(P)4 and ZnP(As)4, by ca. 1.10 and 1.47 eV, respectively, compared to ZnP. The core-modification of porphyrins by P and especially by As was found to result in significant decrease of the charge on Zn-centers, by ca. 0.61—0.67e for P and by ca. 0.69—0.76e for As. Charges on P- and As-centers were computed to have large positive values, ca. 0.41—0.45e and ca. 0.43—0.47e, for P and As, respectively, compared to significant negative values, ca. −0.65 to −0.66e for N. The porphyrin core-modification by heavier N congeners, P and As, can noticeably modify the structures, electronic, and optical properties of porphyrins, thus affecting their reactivity and potential applications.

Computational Study of Aqueous Solvation of Vanadium (V) Complexes

2018 ◽  
pp. 147-156
Author(s):  
Francisco J. Melendez ◽  
María Eugenia Castro ◽  
Jose Manuel Perez-Aguilar ◽  
Norma A. Caballero ◽  
Lisset Noriega ◽  
...  
Keyword(s):  
Computational Study ◽  
Aqueous Solvation

scholarly journals Valence tautomerism and recyclisation of type B mesoionic tetrazoles: a computational study

2021 ◽  
Author(s):  
Wojciech Piotr Oziminski ◽  
Christopher Antony Ramsden
Keyword(s):  
Solvent Effect ◽  
Ring Opening ◽  
Continuum Model ◽  
Computational Study ◽  
Reaction Pathway ◽  
Type B ◽  
Valence Tautomerism ◽  
Energy Profiles ◽  
Aqueous Solvation ◽  
Influence Of Solvent

AbstractThe energy profiles for ring opening of representative type B mesoionic 2,3-diphenyl-1,2,3,4-tetrazolium-5-olates, -thiolates, -aminides and –methylides and for alternative recyclisation pathways are investigated using ab initio MP2 calculations. The energetics of initial ring opening are found to be comparable for all systems, but the tetrazolium-5-olates are anomalous in that no alternative reaction pathway is accessible. The influence of solvent is explored using the polarised continuum model (PCM) method to simulate aqueous solvation. The only significant solvent effect is found to be solvation of the mesoionic precursors. This solvent effect correlates with dipole moment and disfavours initial valence tautomerism both kinetically and thermodynamically.

scholarly journals Computational Study of Geometry, IR Spectrum and Molecular Properties of Acetanilide

2016 ◽  
Vol 19 (2) ◽  
pp. 170-178 ◽  
Author(s):  
Mohammad Firoz Khan ◽  
Rahatullah Razan ◽  
Ridwan Bin Rashid ◽  
Faiza Tahia ◽  
Mohammad A Rashid
Keyword(s):  
Ir Spectrum ◽  
Chemical Potential ◽  
Computational Study ◽  
Pharmaceutical Journal ◽  
Molecular Properties ◽  
Basis Sets ◽  
Mulliken Charge ◽  
Chemical Hardness ◽  
Reactivity Descriptors ◽  
Ir Frequencies

In this paper an effort has made to conduct and repot the computational study of geometry, IR spectrum and different molecular properties like Molecular Electrostatic Potential (MESP), Mulliken Charge Distribution, Global Reactivity Descriptors such as chemical hardness, softness, chemical potential, electronegativity, and electrophilicity index of acetanilide. All calculations were performed on Hartee-Fock (HF), Becke and 3-parameter, Lee-Yang-Parr (B3LYP) with 6-31G(d) and 6-31+G(d,p) basis sets. The calculated geometries (bond length, bond angle and dihedral angle) were in a good agreement with the experimental data for both level of theories and basis sets. In case of IR frequencies the scaled calculated frequencies agreed reasonably well with the experimental results.Bangladesh Pharmaceutical Journal 19(2): 170-178, 2016

THE JET-COOLED HIGH-RESOLUTION IR SPECTRUM OF FORMIC ACID CYCLIC DIMER

2017 ◽  
Author(s):  
Manuel Goubet ◽  
Robert Georges ◽  
P. Roy ◽  
Atef Jabri ◽  
Pascale Soulard ◽  
...  
Keyword(s):  
High Resolution ◽  
Formic Acid ◽  
Ir Spectrum ◽  
Cyclic Dimer
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