Papers by Keyword: Ru(II) Complex

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Authors: Maria Milanova, Joana Zaharieva, Salzitsa Anastasova, Dimitar Todorovsky
Abstract: A short review of recent investigations of the authors on the Ru(II)-based optical oxygen sensors is presented focused on the influence of: (i) type of the supporting matrix (SiO2 or polymethylmetacrylate based), (ii) precursors used (tetraethoxysilane, ormosil-type alkoxosilanes, methylmetacrylate, polymethylmetacrylate), (iii) method applied for the matrix synthesis, (iv) method for films deposition (dip- and spin coating), (v) chromophore leaching as a result of storage of the films in potentially aggressive media (water, diluted acidic and basic solutions) and (vi) working environment nature on the: a) films morphology, b) the analytical characteristics of the sensing component (linearity of the Stern-Volmer dependence, sensitivity of the device, reproducibility of the results), c) admissible parameters (pH, temperature) of the working medium. Special attention is paid on the effect of sol-sonication (as a tool against dye microcrystallization). The results obtained permit optimal precursors, sol preparation conditions and coating procedure to be recommended for gas and for dissolved oxygen measurement, respectively. The sonication of the sol ensures a rather significant improvement of the sensor performance. The strong quenching of the chromophore in the case of in-situ polymerization of the methylmetacrylate is observed.The sensing films are successfully applied for oxygen determination in natural lake waters and beer.
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Authors: Tomohiro Ozawa, Y. Kishi, K. Miyamoto, Y. Wasada-Tsutsui, Yasuhiro Funahashi, Koichiro Jitsukawa, Hideki Masuda
Abstract: Two new bipyridine derivative ligands with an extended π electron system and a triple hydrogen bond group, 2,4-diaminopyrimido[5,6-b]dipyrido[2,3-f:2’,3’-h]quinoxaline (DAPQ) and 2,4(1H,3H)-pyrimidinedion[5,6-b]dipyrido[2,3-f:2’3’-h]quinoxaline (PDPQ), were synthesized in order to construct high-performance Ru(II) complexes. The two Ru(II) complexes composed of dapq or pdpq and two 2,2’-bipyridine (BPY) ligands showed characteristic luminescent spectra with a peak maximum at ca. 610 nm. The octahedral Ru(II) complexes with a D-A-D (D: proton donor; A: proton acceptor) type triple hydrogen bond indicated intense luminescence in comparison with the corresponding Ru(II) complex composed of three BPY ligands. When the triple hydrogen bond was formed with a Co(III) complex with the D-A-D type hydrogen bonding group, the luminescence was quenched. This result was explained in terms of an energy transfer from an excited Ru(II) complex to the Co(III) complex.
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