The interactions of square platinum(II) complexes with guanine and adenine: a quantum-chemical ab initio study of metalated tautomeric forms

2000 ◽  
Vol 5 (2) ◽  
pp. 178-188 ◽  
Author(s):  
J. V. Burda ◽  
J. Šponer ◽  
J. Leszczynski
Keyword(s):  
Ab Initio ◽  
Quantum Chemical ◽  
Ab Initio Study ◽  
Tautomeric Forms ◽  
Guanine And Adenine

A quantum chemical ab initio study of the polymerization to polyhydridophosphazenes

2006 ◽  
Vol 325 (2-3) ◽  
pp. 291-298 ◽  
Author(s):  
Rebecca Fondermann ◽  
Michael Dolg ◽  
Michael Raab ◽  
Edgar Niecke
Keyword(s):  
Ab Initio ◽  
Quantum Chemical ◽  
Ab Initio Study

Ab Initio Quantum Chemical Calculations on the Stability of Different Tautomers of 6- and 7-Phenacetyl Pterin

Pteridines ◽  
1993 ◽  
Vol 4 (1) ◽  
pp. 23-26 ◽  
Author(s):  
Gilbert Reibnegger ◽  
Brian J. Denny ◽  
Helmut Wachter
Keyword(s):  
Ab Initio ◽  
Quantum Chemical ◽  
Population Analysis ◽  
Carbonyl Oxygen ◽  
Side Chain ◽  
Keto Form ◽  
Tautomeric Forms ◽  
Amide Form ◽  
Planar Molecules ◽  
The Stability

Summary In order to investigate the stabilities of different tautomeric forms of pteridine derivatives with a phenacetyl side chain in the 6- or 7-position, we have performed ab initio quantum chemical geometry optimizations of both the keto form and the vinylogous amide form of 6- and 7-phenacetyl pterin. The results are in accordance with experimental expectations: the keto form is slightly more stable for the 6-substituted derivative (1 .8 kcal per mol). while the vinylogous amide form is substantially more stable for the 7-substituted compound (8 .7 kcal per mol). The vinylogous amide forms are planar molecules, and this geometry enables the interaction between the hydrogen atom at N-5 (or N-8) and the carbonyl function of the side chain. Inspection of the calculated electron densities (population analysis) underlines the suggestion that the vinylogous amide form of 7-phenacetyl pterin is stabilized by a shift of electron density from the nitrogen bonded to C-2 to the carbonyl oxygen atom of the side chain (resonance stabilization via an additional highly conjugated vinylogous amide structure).

Mutagenic Properties of 5-Halogenuracils:  Correlated Quantum Chemical ab Initio Study†

Biochemistry ◽  
2005 ◽  
Vol 44 (5) ◽  
pp. 1701-1707 ◽  
Author(s):  
Michal Hanus ◽  
Martin Kabeláč ◽  
Dana Nachtigallová ◽  
Pavel Hobza
Keyword(s):  
Ab Initio ◽  
Quantum Chemical ◽  
Ab Initio Study

Density functional and ab initio study of the tautomeric forms of 3-acetyl tetronic and 3-acetyl tetramic acids

2003 ◽  
Vol 293 (3) ◽  
pp. 355-363 ◽  
Author(s):  
Chris-Kriton Skylaris ◽  
Olga Igglessi-Markopoulou ◽  
Anastasia Detsi ◽  
John Markopoulos
Keyword(s):  
Ab Initio ◽  
Density Functional ◽  
Ab Initio Study ◽  
Tautomeric Forms ◽  
Tetramic Acids

scholarly journals Ab initio study of the electronic spectrum of BeO

1999 ◽  
Vol 64 (12) ◽  
pp. 721-735 ◽  
Author(s):  
Ivana Adamovic ◽  
Maja Parac ◽  
Michael Hanrath ◽  
Miljenko Peric
Keyword(s):  
Energy Range ◽  
Ab Initio ◽  
Electronic Spectrum ◽  
Quantum Chemical ◽  
Electronic States ◽  
Vibrational Structure ◽  
Ab Initio Method ◽  
Ab Initio Study

Low-lying singlet and triplet electronic states of the BeO molecule are calculated by means of the quantum chemical ab initio method. It was found that all states in the energy range from 0 to 50000 cm-1 are of valence character. Particular attention was paid to the investigation of the dissociative behavior of the states considered. The vibrational structure of the A 1P ? X1S and B 1S+ ? X1S+ spectral systems was calculated.

Quantum-Chemical ab initio Study of Side Chain pKa of Linear and Cyclic Lysine Dipeptides

2020 ◽  
pp. 1-9
Author(s):  
Mohsen Sargolzaei ◽  
Hossein Nikoofard ◽  
Majid Namayandeh Jorabchi
Keyword(s):  
Experimental Data ◽  
Hydrogen Bond ◽  
Ab Initio ◽  
Quantum Chemical ◽  
Biological Activities ◽  
Side Chain ◽  
Ab Initio Study ◽  
Cyclic Dipeptides ◽  
Pka Values ◽  
Pka Value

Cyclic dipeptides show interesting biological activities such as antitumor, antiviral and so on. In biological systems, the bioavailability of drugs is determined by several parameters such as pKa values. In this study, we used DFT and thermodynamics cycle to determine pKa value of side chain of lysine in linear and cyclic dipeptides. All considered dipeptides were optimized using B3LYP and RMSD tool was used to compare the optimized structures. The calculated pKa values were compared with the available experimental data. Our results show that pKa of side chain of lysine increases for cyclic dipeptides compared to the linear ones. To justify the reason of increasing of pKa of cyclic dipeptides, we used NBO and AIM analyses. The analyses showed that a hydrogen bond in cyclic lysine dipeptides is responsible for increasing of pKa.

Ab initio study of the tautomeric forms of some quinolinediones

1995 ◽  
Vol 330 (1-3) ◽  
pp. 431-435 ◽  
Author(s):  
Monica Bartolomei ◽  
Maurizio Cignitti ◽  
Marina Cotta Ramusino ◽  
Gianfranco La Manna
Keyword(s):  
Ab Initio ◽  
Ab Initio Study ◽  
Tautomeric Forms
Sign in / Sign up

Export Citation Format

Share Document