ABSTRACT The dithiocarbamate complexes [Ni{S2CNR(R1)}2] (1), [Pd{S2CNR(R1)}2] (2), [Pt{S2CNR(R1)}... more ABSTRACT The dithiocarbamate complexes [Ni{S2CNR(R1)}2] (1), [Pd{S2CNR(R1)}2] (2), [Pt{S2CNR(R1)}2] (3), [Ni{S2CNR(R2)}2] (4), [Pd{S2CNR(R2)}2] (5), [Pt{S2CNR(R2)}2] (6), {R = Me; R1 = CH2CH(OMe)2 and R2 = 2-methyl-1,3-dioxolane} have been prepared and characterized. The structure of (1), (2) and (3) have been authenticated by X-ray diffraction. The antifungal activities of (1) - (6) have been screened against Aspergillus flavus, Aspergillus niger, Aspergillus parasiticus and Penicillium citrinum.
The influence of pH during hydrolysis of titanium(IV) isopropoxide on the morphological and elect... more The influence of pH during hydrolysis of titanium(IV) isopropoxide on the morphological and electronic properties of TiO2nanoparticles prepared by the sol-gel method is investigated and correlated to the photoelectrochemical parameters of dye-sensitized solar cells (DSCs) based on TiO2films. Nanoparticles prepared under acid pH exhibit smaller particle size and higher surface area, which result in higher dye loadings and better short-circuit current densities than DSCs based on alkaline TiO2-processed films. On the other hand, the product of charge collection and separation quantum yields in films with TiO2obtained by alkaline hydrolysis is c.a. 27% higher than for the acid TiO2films. The combination of acid and alkaline TiO2nanoparticles as mesoporous layer in DSCs results in a synergic effect with overall efficiencies up to 6.3%, which is better than the results found for devices employing one of the nanoparticles separately. These distinct nanoparticles can be also combined by us...
The formation and structure of four different Cu(II)–clupeine Z complexes have been studied using... more The formation and structure of four different Cu(II)–clupeine Z complexes have been studied using potentiometric and spectroscopic (ir and visible absorption, and CD) measurements. The results thus obtained indicate the presence of up to 8 binding sites in the pH range from 6.5 to 10.5. The spectroscopic evidence suggests that the strongest site available contains the α‐amino terminal and the adjacent peptide nitrogen, which bind to copper from pH 5 to 6.5 to form the first complex. The stability constant of this first complex has a value of (9.5 ± 0.9) × 103 mol−1 1. From pH 6.5 to 8.5, two intervening guanidinium nitrogens of arginine residues occupy the two other corners of the coordination square, giving rise to the second complex. The other sites potentially available from pH 6.5 to 10.5 are formed by two amino nitrogens of arginine residues and two contiguous peptide nitrogens. The first intervene up to pH 8.5, forming the third complex, and the latter from this pH to 10.5, forming the fourth complex. Although the ligands intervening at sites 2–8 appear to be the same, the sites are by no means equivalent. The spectroscopic data enable one to distinguish three different types of binding sites.
The 1:2 molar reaction of Cu(II) perchlorate and glycinehydroxamic acid in aqueous solution at pH... more The 1:2 molar reaction of Cu(II) perchlorate and glycinehydroxamic acid in aqueous solution at pH ∼8 leads to the dihydrate of the octahedral complex (I).
The formation constants of the species formed in metal/glycinehydroxamic acid systems with Mn, Co... more The formation constants of the species formed in metal/glycinehydroxamic acid systems with Mn, Co, Ni, Cu, Zn and Cd ions are determined by potentiometric measurements.
The full speciation of the vanadium(V) complexation systems with two aminohydroxamic acids, aspar... more The full speciation of the vanadium(V) complexation systems with two aminohydroxamic acids, asparticb-and glutamic-c-hydroxamic acid, has been determined using potentiometric and spectroscopic techniques. Formation constants were calculated in a systematic study at different ligand to metal molar ratios and the coordination types are proposed. An almost constant value of the 51 V NMR signal in neutral medium can be attributed to two (1:1 and 1:2 metal to ligand ratios) similar structures, both of which can be either protonated or deprotonated. The two ligands have a carboxylic group in the structure and show comparable biological activities. In this work analogous complexation behavior at physiological conditions was found despite the presence of two or three methylenic groups between the amino and hydroxamate groups. The carboxylic groups are quite distant from the hydroxamic groups and are not involved directly in the coordination process. Therefore the coordination structures are related to that found in the vanadium(V)-b-alaninehydroxamic acid in which there is not a carboxylic group.
Molekularer Sauerstoff reagiert mit Ni(II)‐peptid‐Verbindungen in wäßriger Lösung durch einen ein... more Molekularer Sauerstoff reagiert mit Ni(II)‐peptid‐Verbindungen in wäßriger Lösung durch einen einfachen autokatalytischen Prozeß, in dem Ni(III)‐Intermediärverbindungen die Hauptrolle spielen.
Journal of the Chemical Society D Chemical Communications, 1971
ABSTRACT Tetra- and penta-peptide complexes of NiII consume O2 in neutral solutions as the metal ... more ABSTRACT Tetra- and penta-peptide complexes of NiII consume O2 in neutral solutions as the metal ion catalyses the oxidation of peptide to give a number of products including amides of amino-acids and of peptides, oxo-acids, and CO2.
ChemInform Abstract Die Oxidation von Tetrapeptiden mit Sauerstoff wird in neutraler Lösung durch... more ChemInform Abstract Die Oxidation von Tetrapeptiden mit Sauerstoff wird in neutraler Lösung durch Cu2(+) beschleunigt, dagegen durch Belichtung (420 nm) inhibiert.
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
ABSTRACT The dithiocarbamate complexes [Ni{S2CNR(R1)}2] (1), [Pd{S2CNR(R1)}2] (2), [Pt{S2CNR(R1)}... more ABSTRACT The dithiocarbamate complexes [Ni{S2CNR(R1)}2] (1), [Pd{S2CNR(R1)}2] (2), [Pt{S2CNR(R1)}2] (3), [Ni{S2CNR(R2)}2] (4), [Pd{S2CNR(R2)}2] (5), [Pt{S2CNR(R2)}2] (6), {R = Me; R1 = CH2CH(OMe)2 and R2 = 2-methyl-1,3-dioxolane} have been prepared and characterized. The structure of (1), (2) and (3) have been authenticated by X-ray diffraction. The antifungal activities of (1) - (6) have been screened against Aspergillus flavus, Aspergillus niger, Aspergillus parasiticus and Penicillium citrinum.
The influence of pH during hydrolysis of titanium(IV) isopropoxide on the morphological and elect... more The influence of pH during hydrolysis of titanium(IV) isopropoxide on the morphological and electronic properties of TiO2nanoparticles prepared by the sol-gel method is investigated and correlated to the photoelectrochemical parameters of dye-sensitized solar cells (DSCs) based on TiO2films. Nanoparticles prepared under acid pH exhibit smaller particle size and higher surface area, which result in higher dye loadings and better short-circuit current densities than DSCs based on alkaline TiO2-processed films. On the other hand, the product of charge collection and separation quantum yields in films with TiO2obtained by alkaline hydrolysis is c.a. 27% higher than for the acid TiO2films. The combination of acid and alkaline TiO2nanoparticles as mesoporous layer in DSCs results in a synergic effect with overall efficiencies up to 6.3%, which is better than the results found for devices employing one of the nanoparticles separately. These distinct nanoparticles can be also combined by us...
The formation and structure of four different Cu(II)–clupeine Z complexes have been studied using... more The formation and structure of four different Cu(II)–clupeine Z complexes have been studied using potentiometric and spectroscopic (ir and visible absorption, and CD) measurements. The results thus obtained indicate the presence of up to 8 binding sites in the pH range from 6.5 to 10.5. The spectroscopic evidence suggests that the strongest site available contains the α‐amino terminal and the adjacent peptide nitrogen, which bind to copper from pH 5 to 6.5 to form the first complex. The stability constant of this first complex has a value of (9.5 ± 0.9) × 103 mol−1 1. From pH 6.5 to 8.5, two intervening guanidinium nitrogens of arginine residues occupy the two other corners of the coordination square, giving rise to the second complex. The other sites potentially available from pH 6.5 to 10.5 are formed by two amino nitrogens of arginine residues and two contiguous peptide nitrogens. The first intervene up to pH 8.5, forming the third complex, and the latter from this pH to 10.5, forming the fourth complex. Although the ligands intervening at sites 2–8 appear to be the same, the sites are by no means equivalent. The spectroscopic data enable one to distinguish three different types of binding sites.
The 1:2 molar reaction of Cu(II) perchlorate and glycinehydroxamic acid in aqueous solution at pH... more The 1:2 molar reaction of Cu(II) perchlorate and glycinehydroxamic acid in aqueous solution at pH ∼8 leads to the dihydrate of the octahedral complex (I).
The formation constants of the species formed in metal/glycinehydroxamic acid systems with Mn, Co... more The formation constants of the species formed in metal/glycinehydroxamic acid systems with Mn, Co, Ni, Cu, Zn and Cd ions are determined by potentiometric measurements.
The full speciation of the vanadium(V) complexation systems with two aminohydroxamic acids, aspar... more The full speciation of the vanadium(V) complexation systems with two aminohydroxamic acids, asparticb-and glutamic-c-hydroxamic acid, has been determined using potentiometric and spectroscopic techniques. Formation constants were calculated in a systematic study at different ligand to metal molar ratios and the coordination types are proposed. An almost constant value of the 51 V NMR signal in neutral medium can be attributed to two (1:1 and 1:2 metal to ligand ratios) similar structures, both of which can be either protonated or deprotonated. The two ligands have a carboxylic group in the structure and show comparable biological activities. In this work analogous complexation behavior at physiological conditions was found despite the presence of two or three methylenic groups between the amino and hydroxamate groups. The carboxylic groups are quite distant from the hydroxamic groups and are not involved directly in the coordination process. Therefore the coordination structures are related to that found in the vanadium(V)-b-alaninehydroxamic acid in which there is not a carboxylic group.
Molekularer Sauerstoff reagiert mit Ni(II)‐peptid‐Verbindungen in wäßriger Lösung durch einen ein... more Molekularer Sauerstoff reagiert mit Ni(II)‐peptid‐Verbindungen in wäßriger Lösung durch einen einfachen autokatalytischen Prozeß, in dem Ni(III)‐Intermediärverbindungen die Hauptrolle spielen.
Journal of the Chemical Society D Chemical Communications, 1971
ABSTRACT Tetra- and penta-peptide complexes of NiII consume O2 in neutral solutions as the metal ... more ABSTRACT Tetra- and penta-peptide complexes of NiII consume O2 in neutral solutions as the metal ion catalyses the oxidation of peptide to give a number of products including amides of amino-acids and of peptides, oxo-acids, and CO2.
ChemInform Abstract Die Oxidation von Tetrapeptiden mit Sauerstoff wird in neutraler Lösung durch... more ChemInform Abstract Die Oxidation von Tetrapeptiden mit Sauerstoff wird in neutraler Lösung durch Cu2(+) beschleunigt, dagegen durch Belichtung (420 nm) inhibiert.
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
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