4 documents found, page 1 of 1
Estudos fotoluminescentes em compostos de íons terras raras coordenados por um ...
Martins,Renata Figueredo; Neri,Cláudio Roberto; Sousa Filho,Paulo Cesar de; Serra,Osvaldo Antonio; Oliveira,Kleber Thiago de[RE(czb)3(H2O)2] complexes (where RE = Eu3+, Tb3+, Gd3+; and czb = 4-(9H-carbazol-9-yl)benzoato) have been synthesized and characterized. The Gd3+ complex was used to determine the triplet state energy of the czb ligand. Photoluminescence measurements of the complexes have been carried out under UV excitation. The Tb3+ complex exhibited a strong green luminescence indicating an efficient antenna effect, whereas...
Extração e purificação de clorofila a, da alga Spirulina maxima: um experimento...
Maestrin,Ana Paula Jecks; Neri,Cláudio Roberto; Oliveira,Kleber Thiago de; Serra,Osvaldo Antonio; Iamamoto,YassukoThis work describes a simple and economical experiment for the extraction and purification of chlorophyll a from Spirulina maxima. Extraction and purification of natural compounds can be considered one of the most illustrative experiments that can be performed in Organic Chemistry courses. Particularly, the chromatography of dyes and pigments allows students to have a better comprehension of the chromatography ...
Aromaticidade: evolução histórica do conceito e critérios quantitativos
Caramori,Giovanni Finoto; Oliveira,Kleber Thiago deIn this paper the evolution of the concept of aromaticity is discussed. It considers not only historical aspects of the aromaticity concept but also the different criteria (theoretical and experimental) that have appeared to explain the properties of the aromatic compounds. The topics range from the isolation of benzene by Faraday (1825) until the modern criteria based on geometries, magnetic properties, resona...
Reatividade em reações de Diels-Alder: uma prática computacional
Lacerda Júnior,Valdemar; Oliveira,Kleber Thiago de; Silva,Rodrigo Costa e; Constantino,Mauricio Gomes; Silva,Gil Valdo José daA computational quantum chemistry experiment is described of Diels-Alder reactions between 2-cycloenones and cyclopentadiene. The effects of FMO-Frontier Molecular Orbitals (HOMO-LUMO) and of the withdrawing nature of substituents at the C=C bond of cycloenones were evaluated. The calculations were made using HF/STO-3G and B3LYP/6-31+G(d,p) methods. The FMO based indexes are in agreement with the experimentally...