Whole microwave syntheses of pyridylpyrazole and of Re and Ru luminescent pyridylpyrazole complexes

Abstract

The synthesis of 3-(2pyridyl)pyrazole (pypzH) by conventional methods requires refluxing at high temperatures during more than 16 h, but this is reduced to two consecutive steps of 2 h at 100 °C, and of 10 min at 50 °C in a microwave (MW) assisted synthesis. Its coordination as chelating ligand to the “fac-ReIBr(CO)3” and “RuII(bipy)2” fragments also occurs MW assisted in 5 or 10 min, respectively. A new MW assisted synthetic method is also described for the synthesis of the starting material [Ru(bipy)2Cl2]·2H2O. Both pypzH complexes are characterized by X-ray crystallography, and the study of their photophysical properties support their phosphorescence. The electrochemistry of the Ru complex indicates that electrochemical oxidation is followed by a chemical process.