Gas-Phase Geometry Optimization of Biological Molecules as a Reasonable Alternative to a Continuum Environment Description: Fact, Myth, or Fiction?†

2009 ◽  
Vol 113 (52) ◽  
pp. 14231-14236 ◽  
Author(s):  
Sérgio Filipe Sousa ◽  
Pedro Alexandrino Fernandes ◽  
Maria João Ramos
Keyword(s):  
Gas Phase ◽  
Geometry Optimization ◽  
Biological Molecules ◽  
Reasonable Alternative

Molecular orbital structures of sulfones

1982 ◽  
Vol 60 (6) ◽  
pp. 730-734 ◽  
Author(s):  
Russell J. Boyd ◽  
Jeffrey P. Szabo
Keyword(s):  
Crystal Structure ◽  
Gas Phase ◽  
Molecular Orbital ◽  
Geometry Optimization ◽  
Membered Ring ◽  
Molecular Orbital Calculations ◽  
Bond Lengths ◽  
Comparison With Experiment ◽  
The Difference

Abinitio molecular orbital calculations are reported for several cyclic and acyclic sulfones. The geometries of XSO2Y, where X, Y = H, F, or CH3 are optimized at the STO-3G* level. Similar calculations are reported for the smallest cyclic sulfone, thiirane-1,1 -dioxide, as well as the corresponding sulfoxide, thiirane-1-oxide, and the parent sulfide, thiirane. Where comparison with experiment is possible, the agreement is satisfactory. In order to consider the possibility of substantial differences between axial and equatorial S—O bonds in the gas phase, as observed in the crystal structure of 5H,8H-dibenzo[d,f][1,2]-dithiocin-1,1-dioxide, STO-3G* calculations are reported for a six-membered ring, thiane-1,1-dioxide, and a model eight-membered ring. Limited geometry optimization of the axial and equatorial S—O bonds in the chair conformations of the six- and eight-membered rings leads to bond lengths of 1.46 Å with the difference being less than 0.01 Å.

scholarly journals Synthesis, Characterization, Catalytic Activity, and DFT Calculations of Zn(II) Hydrazone Complexes

Molecules ◽  
2020 ◽  
Vol 25 (18) ◽  
pp. 4043 ◽  
Author(s):  
Temiloluwa T. Adejumo ◽  
Nikolaos V. Tzouras ◽  
Leandros P. Zorba ◽  
Dušanka Radanović ◽  
Andrej Pevec ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Gas Phase ◽  
Molecular Orbital ◽  
Density Functional ◽  
Chemical Potential ◽  
Chemical Reactivity ◽  
Geometry Optimization ◽  
Coupling Reaction ◽  
Functional Theory ◽  
Reactivity Descriptors

Two new Zn(II) complexes with tridentate hydrazone-based ligands (condensation products of 2-acetylthiazole) were synthesized and characterized by infrared (IR) and nuclear magnetic resonance (NMR) spectroscopy and single crystal X-ray diffraction methods. The complexes 1, 2 and recently synthesized [ZnL3(NCS)2] (L3 = (E)-N,N,N-trimethyl-2-oxo-2-(2-(1-(pyridin-2-yl)ethylidene)hydrazinyl)ethan-1-aminium) complex 3 were tested as potential catalysts for the ketone-amine-alkyne (KA2) coupling reaction. The gas-phase geometry optimization of newly synthesized and characterized Zn(II) complexes has been computed at the density functional theory (DFT)/B3LYP/6–31G level of theory, while the highest occupied molecular orbital and lowest unoccupied molecular orbital (HOMO and LUMO) energies were calculated within the time-dependent density functional theory (TD-DFT) at B3LYP/6-31G and B3LYP/6-311G(d,p) levels of theory. From the energies of frontier molecular orbitals (HOMO–LUMO), the reactivity descriptors, such as chemical potential (μ), hardness (η), softness (S), electronegativity (χ) and electrophilicity index (ω) have been calculated. The energetic behavior of the investigated compounds (1 and 2) has been examined in gas phase and solvent media using the polarizable continuum model. For comparison reasons, the same calculations have been performed for recently synthesized [ZnL3(NCS)2] complex 3. DFT results show that compound 1 has the smaller frontier orbital gap so, it is more polarizable and is associated with a higher chemical reactivity, low kinetic stability and is termed as soft molecule.

scholarly journals The formation of urea in space

2018 ◽  
Vol 610 ◽  
pp. A26 ◽  
Author(s):  
Flavio Siro Brigiano ◽  
Yannick Jeanvoine ◽  
Antonio Largo ◽  
Riccardo Spezia
Keyword(s):  
Activation Energy ◽  
Interstellar Medium ◽  
Gas Phase ◽  
Organic Molecules ◽  
Peptide Bond ◽  
Biological Molecules ◽  
Gas Phase Reactions ◽  
Molecule Reaction ◽  
Quantum Chemistry Calculations ◽  
Highly Correlated

Context. Many organic molecules have been observed in the interstellar medium thanks to advances in radioastronomy, and very recently the presence of urea was also suggested. While those molecules were observed, it is not clear what the mechanisms responsible to their formation are. In fact, if gas-phase reactions are responsible, they should occur through barrierless mechanisms (or with very low barriers). In the past, mechanisms for the formation of different organic molecules were studied, providing only in a few cases energetic conditions favorable to a synthesis at very low temperature. A particularly intriguing class of such molecules are those containing one N–C–O peptide bond, which could be a building block for the formation of biological molecules. Urea is a particular case because two nitrogen atoms are linked to the C–O moiety. Thus, motivated also by the recent tentative observation of urea, we have considered the synthetic pathways responsible to its formation. Aims. We have studied the possibility of forming urea in the gas phase via different kinds of bi-molecular reactions: ion-molecule, neutral, and radical. In particular we have focused on the activation energy of these reactions in order to find possible reactants that could be responsible for to barrierless (or very low energy) pathways. Methods. We have used very accurate, highly correlated quantum chemistry calculations to locate and characterize the reaction pathways in terms of minima and transition states connecting reactants to products. Results. Most of the reactions considered have an activation energy that is too high; but the ion-molecule reaction between NH2OHNH2OH2+ and formamide is not too high. These reactants could be responsible not only for the formation of urea but also of isocyanic acid, which is an organic molecule also observed in the interstellar medium.

scholarly journals Structural Diversity of Di-Metalized Arginine Evidenced by Infrared Multiple Photon Dissociation (IRMPD) Spectroscopy in the Gas Phase

Molecules ◽  
2021 ◽  
Vol 26 (21) ◽  
pp. 6546
Author(s):  
Ruxia Feng ◽  
Yicheng Xu ◽  
Xianglei Kong
Keyword(s):  
Gas Phase ◽  
Theoretical Study ◽  
Molecular Level ◽  
Structural Diversity ◽  
Laser Desorption ◽  
Biological Molecules ◽  
Laser Desorption Ionization ◽  
Irmpd Spectroscopy ◽  
Infrared Multiple Photon Dissociation ◽  
Isomerization Energy

Although metal cations are prevalent in biological media, the species of multi-metal cationized biomolecules have received little attention so far. Studying these complexes in isolated state is important, since it provides intrinsic information about the interaction among them on the molecular level. Our investigation here demonstrates the unexpected structural diversity of such species generated by a matrix-assisted laser desorption ionization (MALDI) source in the gas phase. The photodissociation spectroscopic and theoretical study reflects that the co-existing isomers of [Arg+Rb+K−H]+ can have energies ≥95 kJ/mol higher than that of the most stable one. While the result can be rationalized by the great isomerization energy barrier due to the coordination, it strongly reminds us to pay more attention to their structural diversities for multi-metalized fundamental biological molecules, especially for the ones with the ubiquitous alkali metal ions.

scholarly journals Potential Energy Surface (PES) Scan of Gas-Phase L-Proline

2014 ◽  
Vol 38 ◽  
pp. 26-34
Author(s):  
Anouar el Guerdaoui ◽  
Yassine el Kahoui ◽  
Malika Bourjila ◽  
Rachida Tijar ◽  
Abderrahman el Gridani
Keyword(s):  
Potential Energy ◽  
Potential Energy Surface ◽  
Gas Phase ◽  
Density Functional ◽  
Energy Surface ◽  
Conformational Stability ◽  
Geometry Optimization ◽  
Basis Set ◽  
Absolute Minimum ◽  
Pes Scan

We performed here a systematic ab initio calculations on neutral gas-phase L-proline. A total of 8 local minima were located by geometry optimization of the trial structures using density functional theory (DFT) with B3LYP three parameter hybrid potential coupled with the 6-31G)d( basis set. The absolute minimum obtained will be subject to a rigid potential energy surface (PES) scan by rotating its carboxylic group using the same method with more accurate basis set B3LYP/6-311++G(d,p), to get a deeper idea about its conformational stability. The main aim of the present work was the study of the rigidity of the L-proline structure and the puckering of its pyrrolidine ring.

A Quantitative Basis for a Scale of Na+Affinities of Organic and Small Biological Molecules in the Gas Phase

1999 ◽  
Vol 121 (38) ◽  
pp. 8864-8875 ◽  
Author(s):  
S. Hoyau ◽  
K. Norrman ◽  
T. B. McMahon ◽  
G. Ohanessian
Keyword(s):  
Gas Phase ◽  
Biological Molecules ◽  
Quantitative Basis

scholarly journals The Computational Calculation and Molecular Docking of Aeroplysinin-1 As Antibacterial

2021 ◽  
Vol 9 (2) ◽  
pp. 124-128
Author(s):  
Mirella Fonda Maahury ◽  
Veliyana Londong Allo
Keyword(s):  
Hydrogen Bond ◽  
Molecular Docking ◽  
Binding Energy ◽  
Gas Phase ◽  
Geometry Optimization ◽  
Dna Gyrase ◽  
Marine Sponges ◽  
E Coli ◽  
Free Binding Energy ◽  
Computational Calculation

Aeroplysinin-1 is naturally found from marine sponges as an anti-bacterial compound. Computational calculation and molecular docking were performed for aeroplysinin. Aeroplysinin as an inhibitor has optimized in the gas phase using DFT with 6-31G(d) functional. The structure from geometry optimization of aeroplysinin-1is, not in one plane. The interaction of aeroplysinin-1 with two different DNA gyrase from E. Coli and S. Aureus. In this research,aeroplysinin-1 can inhibit the protein with the free binding energy of about -5.7 kcal/mol and -6.35 kcal/mol, respectively, for E. Coli and S. Aureus. The dominant molecular interaction is the hydrogen bond.

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