Ana Gallardo - Academia.edu (original) (raw)
Papers by Ana Gallardo
CrystEngComm, 2015
Unravelling the Cu(ii) coordination chemistry of a thermally tunable tetracarboxylate.
Tetrahedron Letters, 1987
Computational and Theoretical Chemistry, 2013
We have studied the 1,2,3-triazole system with a set of 25 substituents of different electronic f... more We have studied the 1,2,3-triazole system with a set of 25 substituents of different electronic features using several methods. Our aim is to find out a calculation method for the analysis of these molecules in biological systems. The combined AIM and NBO study permitted us to justify the observed tautomeric preferences. The absolute predominance of the 2H-tautomer forms is greatly changed when the substituent group possesses anionic character; therefore the pH of the medium is relevant. When the calculations were carried out in solution, noteworthy changes in the behavior of charged substituents were observed. These facts may be relevant when studying the interactions of these molecules with biological receptors. Keyword 1,2,3-triazol, tautomerism, NBO analysis, AIM charges, group electronegativity, resonance. interactions as concerned in Van der Waals or π-staking. 2. Material and methods Calculations were performed using Gaussian 03W version 6.1 [11]. Optimized geometries were calculated at MP2 [12], B3LYP [13], MPW1PW91[14] and MPWB1K [15] level of theory using 6-31+G* basis set. In addition 6-311++G* basis set was used for specific hydrogen bond analysis. Electronic densities obtained at partial and full MP2/6-311++G* and MPW1PW91/6-311++G* levels served as input for Atom in Molecules (AIM) [16] Bader analysis helped with the AIM2000 [17] program. Natural Resonance Theory Analysis (NRT) was performed using NBO5.0 [18] program. 3. Results and discussions 3.1. The influence of C-substituents in 1,2,3-triazoles (gas phase) on the tautomeric equilibrium Unsubstituted 1,2,3-triazole can exist in two tautomeric forms: the 1H-tautomer, with C s symmetry, and the 2H-tautomer with C 2v symmetry. The presence of a 5(4)-substituent increases the number of these forms at three, or even more, if the substituent group is OH, NH 2 or SH (Scheme 1. In brackets the nomenclature used in this work). The investigation of tautomeric equilibrium in triazoles has been usually focused on Nsubstituted derivatives [19] rather of C-substituted derivatives[20-24]. Oziminski et all performed the most complete study on 5(4)-substituted-1,2,3-triazole systems with a quite high basis sets and DFT (B3PW91/6-311++G**) [24]. A higher level of calculus (CCSD(T)/CBS) for the two unsubstituted imidazole tautomers was reported by Denis [25] Scheme 1. 1,2,3 triazole nomenclature
Phytochemistry, 1989
... HALOGENATED HYDROPYRAN FROM LAURENCIA CAESPI TOSA MAYLAND CHANG, JESUS T. VAZQUEZ, Koji NAKAN... more ... HALOGENATED HYDROPYRAN FROM LAURENCIA CAESPI TOSA MAYLAND CHANG, JESUS T. VAZQUEZ, Koji NAKANISHI, FERNANDO CATALDO,t ... enhancement, Circular dichroic studies [26] of the bromobenzoylated sesquiterpenes showed a negative Cotton effect at ...
CrystEngComm, 2015
Unravelling the Cu(ii) coordination chemistry of a thermally tunable tetracarboxylate.
Tetrahedron Letters, 1987
Computational and Theoretical Chemistry, 2013
We have studied the 1,2,3-triazole system with a set of 25 substituents of different electronic f... more We have studied the 1,2,3-triazole system with a set of 25 substituents of different electronic features using several methods. Our aim is to find out a calculation method for the analysis of these molecules in biological systems. The combined AIM and NBO study permitted us to justify the observed tautomeric preferences. The absolute predominance of the 2H-tautomer forms is greatly changed when the substituent group possesses anionic character; therefore the pH of the medium is relevant. When the calculations were carried out in solution, noteworthy changes in the behavior of charged substituents were observed. These facts may be relevant when studying the interactions of these molecules with biological receptors. Keyword 1,2,3-triazol, tautomerism, NBO analysis, AIM charges, group electronegativity, resonance. interactions as concerned in Van der Waals or π-staking. 2. Material and methods Calculations were performed using Gaussian 03W version 6.1 [11]. Optimized geometries were calculated at MP2 [12], B3LYP [13], MPW1PW91[14] and MPWB1K [15] level of theory using 6-31+G* basis set. In addition 6-311++G* basis set was used for specific hydrogen bond analysis. Electronic densities obtained at partial and full MP2/6-311++G* and MPW1PW91/6-311++G* levels served as input for Atom in Molecules (AIM) [16] Bader analysis helped with the AIM2000 [17] program. Natural Resonance Theory Analysis (NRT) was performed using NBO5.0 [18] program. 3. Results and discussions 3.1. The influence of C-substituents in 1,2,3-triazoles (gas phase) on the tautomeric equilibrium Unsubstituted 1,2,3-triazole can exist in two tautomeric forms: the 1H-tautomer, with C s symmetry, and the 2H-tautomer with C 2v symmetry. The presence of a 5(4)-substituent increases the number of these forms at three, or even more, if the substituent group is OH, NH 2 or SH (Scheme 1. In brackets the nomenclature used in this work). The investigation of tautomeric equilibrium in triazoles has been usually focused on Nsubstituted derivatives [19] rather of C-substituted derivatives[20-24]. Oziminski et all performed the most complete study on 5(4)-substituted-1,2,3-triazole systems with a quite high basis sets and DFT (B3PW91/6-311++G**) [24]. A higher level of calculus (CCSD(T)/CBS) for the two unsubstituted imidazole tautomers was reported by Denis [25] Scheme 1. 1,2,3 triazole nomenclature
Phytochemistry, 1989
... HALOGENATED HYDROPYRAN FROM LAURENCIA CAESPI TOSA MAYLAND CHANG, JESUS T. VAZQUEZ, Koji NAKAN... more ... HALOGENATED HYDROPYRAN FROM LAURENCIA CAESPI TOSA MAYLAND CHANG, JESUS T. VAZQUEZ, Koji NAKANISHI, FERNANDO CATALDO,t ... enhancement, Circular dichroic studies [26] of the bromobenzoylated sesquiterpenes showed a negative Cotton effect at ...