Quenching of Luminescent Ruthenium(II) Complexes by Water and Polymer-Based Relative Humidity Sensors

Abstract

Water quenching of luminescent [Ru(phen)(2)dppz]Cl(2), [Ru(phen)(2)dppn]Cl(2), and [Ru(4,7-Ph(2)phen)(2) dppz]Cl(2) (phen = 1,10-phenanthroline; 4,7-Ph(2)phen = 4; 4,7-diphenyl-1,10-phenanthroline; dppz = dipyrido[3,2-a:2'3'-c]phenazine; dppn = benzodipyrido(a:3,2-h:2',3'-j)phenazine) complexes was studied in acetonitrile and in polymers. The polymers contained hydrophobic and hydrophilic components to control mechanical properties and were designed to absorb water with changing humidity and, thus, affect the emission intensity and lifetime. Quenching by water in mixed solvents and in polymers was shown to arise from a combination of diffusional and static ground-state associational quenching. The factors controlling polymer properties are discussed. The systems can be tailored to give a wide range of responses or function as a binary sensor at a fixed humidity level.

Dual-Action Ru(II) Complexes with Bulky π-Expansive Ligands: Phototoxicity without DNA Intercalation

“…30 Related complexes that underwent either PCT or PDT alone showed minimal, if any, cytotoxicity in these 2D and 3D culture models, proving that dual-action PCT/PDT creates and promotes efficacy of Ru(II) compounds against cancer cells. Aside from dual-action PCT/PDT agents, derivatives of the ligand dppn (Figure 2) have been incorporated into Ru(II) and related metal complexes for research in photochemistry, solar energy capture, 31 sensing, 32 and biology, including anticancer 20,33−35 and antibacterial 36,37 applications, among other works not cited here. Derivatives of dppn are underexplored, as opposed to other π-expansive ligands such as dipyrido[3,2-a:2′,3′-c]phenazine (dppz, Figure 2); a Sci-Finder search shows >100 analogs of dppz have been reported.…”

“…Aside from dual-action PCT/PDT agents, derivatives of the ligand dppn (Figure ) have been incorporated into Ru­(II) and related metal complexes for research in photochemistry, solar energy capture, sensing, and biology, including anticancer ,− and antibacterial , applications, among other works not cited here. Derivatives of dppn are underexplored, as opposed to other π-expansive ligands such as dipyrido­[3,2- a :2′,3′- c ]­phenazine (dppz, Figure ); a SciFinder search shows >100 analogs of dppz have been reported.…”

Inert cationic iridium(iii) complexes with phenanthroline-based ligands: application in antimicrobial inactivation of multidrug-resistant bacterial strains

“…31,32,36 The decrease of the emission intensity of the complexes with respect to highly emissive Ir1, could be explained by the increase of the non-radiative process due to the interaction of the solvent with the two uncoordinated basic nitrogens of the phenazine ligands. 37,38 Dppz-based complexes possess two triplet excited states: a "bright" (emissive) 3 MLCT state involving the proximal bipyridine (bpy) portion of the dppz ligand and a "dark" (non-emissive) 3 MLCT state involving the phenazine moiety of dppz distal to the metal. In aqueous solution, the dark state is lower in energy than the bright state; the latter is not thermally accessible at room temperature, such that the complex is weakly emissive or even non-emissive.…”

Dual optical and electrochemical saccharide detection based on a dipyrido[3,2-a:2′3′-c]phenazine (DPPZ) ligand

“…[1][2][3] Such sensors allow for versatile detection of analytes and reduce the possibilities of false positives. Ligands based on dipyrido[3,2-a: 2',3'-c]phenazine (DPPZ (1)) have been widely used in the coordination of various transition metals and the resulting complexes have been studied in DNA intercalation, 4 optical probes, 5 and in dye-sensitized solar cells. 6 Surprisingly, little has been done towards developing DPPZ-based ligands as detection units, though their optical 7,8 and electrochemical properties 8 provide a unique approach to tailor these ligands as tunable sensors.…”