Browsing by Author "Carmona Vargas, Christian C."
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Item Determination of the binding constants of propeller-like metal complexes of picolinaldehyde-2-pyridylhydrazone(Elsevier S.A., 2018-12-13) Carmona Vargas, Christian C.; Aristizábal, Sandra L.; Belalcázar, María I.; D'Vries, Richard F.; Chaur, Manuel N.Herein, we determined the binding constants for transition metal complexes of Cu2+, Co2+, Fe2+, Ni2+, and Zn2+ ions formed with the ligand picolinaldehyde-2-pyridylhydrazone (PapyH) using the Benesi-Hildebrand method. Stoichiometry 2:1 (ligand: metal) was previously determined by the Job’s method and confirmed by single-crystal X-ray diffraction finding a propeller-like structure of the [Fe(Papy)2] compound. PapyH and the metal complexes were characterized by 1H NMR and UV-Vis spectroscopy, respectively. The Cu2+ complex exhibited the highest stability constant, which was confirmed by competitive reaction of different metal ions with the ligand PapyH.Item Photochemical and Electrochemical Triggered Bis(hydrazone) Switch(Wiley-VCH Verlag, 2017-08-17) Gordillo, Mónica A.; Soto Monsalve, Mónica; Carmona Vargas, Christian C.; Gutiérrez, Gustavo; D'vries, Richard F.; Lehn, Jean Marie; Chau, Manuel N.Herein, we report the synthesis of a double hydrazone capable of undergoing photochemical E/Z isomerization through the imine double bonds. The bis(hydrazone) 1‐E,E can be considered as a “two‐arm” system in which the controlled movement of each arm is obtained by photo‐modulation, making possible the appearance of two isolable metastable isomeric states 1‐E,Z and 1‐Z,Z. Such states are characterized by very specific structural, optical, and electrochemical properties. The latter allows the reversible return from either 1‐E,Z or 1‐Z,Z to the 1‐E,E state. Our results are of great importance in the further development of molecular machines and photochemically controlled reactions by introducing for the first time double hydrazones as tunable photochemical switches.Item Synthesis, characterization, and redox potential properties of a new double-stranded Ni-bis(hydrazone)-based helicate(Academic Press Inc., 2020-08-25) Villada, Juan D.; Carmona Vargas, Christian C.; Alcides Ellena, Javier; Ayala, Alejandro P.; Ramírez Pradilla, Juan S.; Combariza, M. Y.; Galarza, Esperanza; D'Vries, Richard Fernando; Chaur, Manuel N.Herein we report the synthesis and structural characterization of a new Ni-bis(hydrazone) complex with the chemical formula [Ni2(L)2(Cl)2](Cl)2·2H2O (L = 2-(heptylthio)-4,6-bis(2-((E)-pyridin-2-ylmethylene)hydrazineyl)pyrimidine). Suitable crystals for X-ray diffraction showed the supramolecular interactions of this complex to exhibit a helical structure coordinating two Ni2+ metal ions bounded by two 2-(heptylthio)-4,6-bis(2-((E)-pyridin-2-ylmethylene)hydrazineyl)pyrimidine ligands. In addition, exploitation of the electrochemical properties by cyclic voltammetry, for this helicate, showed catalyzing ability for the reduction of H+ to H2.