Host - Guest Complexes of Bicyclic Hexaamine Cryptands - Prediction of Ion Selectivity by Quantum Chemical Calculations. III

2007 ◽  
Vol 60 (12) ◽  
pp. 889 ◽  
Author(s):  
Ralph Puchta ◽  
Roland Meier ◽  
Rudi van Eldik
Keyword(s):  
Density Functional Theory ◽  
Complex Formation ◽  
Quantum Chemical Calculations ◽  
Quantum Chemical ◽  
Density Functional ◽  
Alkaline Earth ◽  
Ion Selectivity ◽  
Cavity Size ◽  
Functional Theory ◽  
Formation Energies

Density functional theory (B3LYP/LANL2DZp) calculations on the structures and complex formation energies were performed to predict the alkali and alkaline earth ion selectivity of the cryptands 1,4,7,10,13,16,21,24-octaazabicyclo(8.8.8)hexacosane (N2N2N2) 1, 3,6,10,13,16,19-hexaazabicyclo(6.6.6)icosane (sarcophagine) 2 and 1,3,6,8,10,13,16,19-octaazabicyclo(6.6.6)icosane (sepulchrate) 3. Compounds 2 and 3 favour binding of Li+ and Mg2+ and exhibit a cavity size similar to [2.1.1], whereas cryptand 1 has a cavity size similar to [2.2.2] and prefers the selective binding of K+ and Ba2+. The cryptand flexibility of 1 is attributed mainly to the groups adjacent to the bridgehead nitrogens, whereas the main guiding feature for the flexibility of 2 and 3 can be traced back to the coordination of the ethylenediamine spacer.

scholarly journals Host–guest complexes of mixed glycol-bipyridine cryptands: prediction of ion selectivity by quantum chemical calculations, part V

2013 ◽  
Vol 9 ◽  
pp. 1252-1268 ◽  
Author(s):  
Svetlana Begel ◽  
Ralph Puchta ◽  
Rudi van Eldik
Keyword(s):  
Complex Formation ◽  
Metal Ions ◽  
Quantum Chemical ◽  
Alkaline Earth ◽  
Ion Selectivity ◽  
Earth Metal ◽  
Building Blocks ◽  
Cavity Size ◽  
Bridgehead Nitrogen ◽  
Formation Energies

The selectivity of the cryptands [2.2.bpy] and [2.bpy.bpy] for the endohedral complexation of alkali, alkaline-earth and earth metal ions was predicted on the basis of the DFT (B3LYP/LANL2DZp) calculated structures and complex-formation energies. The cavity size in both cryptands lay between that for [2.2.2] and [bpy.bpy.bpy], such that the complexation of K+, Sr2+ and Tl3+ is most favorable. While the [2.2.bpy] is moderately larger, preferring Rb+ complexation and demonstrating equal priority for Sr2+ and Ba2+, the slightly smaller [2.bpy.bpy] yields more stable cryptates with Na+ and Ca2+. Although the CH2-units containing molecular bars fixed at the bridgehead nitrogen atoms determine the flexibility of the cryptands, the twist angles associated with the bipyridine and glycol building blocks also contribute considerably.

A density functional theory insight into the structure and reactivity of diphenyltin(IV) derivative of glycylphenylalanine

2016 ◽  
Vol 39 (3-4) ◽  
Author(s):  
Sandeep Pokharia ◽  
Rachana Joshi ◽  
Mamta Pokharia ◽  
Swatantra Kumar Yadav ◽  
Hirdyesh Mishra
Keyword(s):  
Density Functional Theory ◽  
Quantum Chemical Calculations ◽  
Quantum Chemical ◽  
Density Functional ◽  
Functional Theory ◽  
Insight Into

AbstractThe quantum-chemical calculations based on density functional theory (DFT) have been performed on the diphenyltin(IV) derivative of glycyl-phenylalanine (H

scholarly journals Quantum Chemical Calculations on Locked Nucleic Acid based Modifications: A Density Functional Theory (DFT) Study

2020 ◽  
Author(s):  
Mallikarjunachari Uppuladinne ◽  
Dikshita Dowerah ◽  
Uddhavesh Sonavane ◽  
Suvendra Kumar Ray ◽  
Ramesh Deka ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Nucleic Acid ◽  
Quantum Chemical Calculations ◽  
Quantum Chemical ◽  
Density Functional ◽  
Locked Nucleic Acid ◽  
Dft Study ◽  
Functional Theory

Can silylenes rival transition metal systems in bond-strengthening π-back donation? A computational investigation

2014 ◽  
Vol 50 (62) ◽  
pp. 8522-8525 ◽  
Author(s):  
Amrita Pal ◽  
Kumar Vanka
Keyword(s):  
Density Functional Theory ◽  
Transition Metal ◽  
Quantum Chemical Calculations ◽  
Quantum Chemical ◽  
Density Functional ◽  
Computational Investigation ◽  
Functional Theory ◽  
Silylene Complexes ◽  
Back Donation ◽  
Full Quantum

Full quantum chemical calculations with density functional theory (DFT) show that bond-strengthening back-donation to a π-diborene, recently discovered for transition metal systems (Braunschweig and co-workers, Nat. Chem., 2013, 5, 115–121), would be just as favored for Main Group silylene complexes.

scholarly journals SYNTHESIS, STRUCTURE, TAUTOMERISM AND INVESTIGATION OF SOME QUANTUM CHEMICAL PARAMETERS OF COMPOUND 2-(4,6-DIOXO-1,3,5-TRIAZINAN-2- YLIDENE)HYDRAZINECARBOXYAMIDE

2020 ◽  
Vol 5 (7(76)) ◽  
pp. 65-68
Author(s):  
Bakhtiyor Ganiyev ◽  
Bako Umarov ◽  
Gulyayra Kholikova ◽  
Furqat Salimov ◽  
Ferangiz Aslonova
Keyword(s):  
Density Functional Theory ◽  
Quantum Chemical Calculations ◽  
Elemental Analysis ◽  
Quantum Chemical ◽  
Density Functional ◽  
Chemical Parameters ◽  
Dft Methods ◽  
Functional Theory ◽  
Quantum Chemical Parameters ◽  
Composite Methods

This article describes the synthesis and tautomerism of 2- (4,6-dioxo-1,3,5-triazinan-2-ylidene) hydrazinecarboxyamide. The synthesized compound was investigated using elemental analysis methods, and quantum chemical calculations performed in ChemCraft 1.8 and Gaussian programs. Composite methods of the Gaussian family (G4) and density functional theory (DFT) methods (BLYP / 6-311 + G (d, p)) were used. The data obtained indicate that the BLYP / 6-311 + G (d, p) well suited for describing such systems in order to save 66 machine resources. Based on the calculated resistance series, it was established that the main form is diketoenolform.

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