| Luminescent water-soluble oxygen sensors have been prepared by bonding iridium complexes to inexpensive water-soluble polymers, such as poly(ethylene glycol) methyl ether-aldehyde (PEGME-Aldehyde) or Silamine D208-EDA. The luminescent iridium complexes, [Ir(fppy)2(t-Bu-iCN)2 ][CF3SO3], [Ir(C6)2(acacacid)], [Ir(ppy)2(amppy)Cl], [Ir(ppy)2(phendiald)][PF6 ], where fppy 4-(2-pyridyl)benzaldehyde, t-Bu-iCN = tert-butyl isocyanide, C6 = 3-(2'-benzothiazolyl)-7-N, N-diethylaminocoumarin, acacacid = 4,6-dioxoheptanoic acid, ppy = 2-phenylpyridine, amppy = 5-aminomethyl-2-phenylpyridine, and phendiald = 1,10phenanthroline-2,9-dicarboxaldehyde, have been synthesized and characterized by nuclear magnetic resonance, absorption and emission spectroscopies. These complexes along with [Ir(tpy)2( t-Bu-iCN)2][CF3SO3] and [Ir(ppy) 2(fppy)], where tpy = 2-(p-tolyl) pyridine, were dispersed in or covalently attached to functionalized water-soluble polymers by reductive amination or coupling reactions. Aqueous blends of these water-soluble luminophores with colloidal microcrystalline cellulose (MC) were used to prepare oxygen sensor films, otherwise known as pressure sensitive paints (PSPs). Oxygen sensitivities of these PSPs were determined as a function of blended MC and obeyed Stern-Volmer kinetics. These novel materials offer an environmentally friendly alternative to non-aqueous PSP formulations and provide improved workplace safety, and lower contamination.;The temperature dependence of luminescence was examined between 10 to 40°C for a number of PSPs and gave temperature sensitivities (percent emission intensity loss per degree) of between -0.8% and -1.6% °C -1 at 1 bar atmospheric pressure.;Oxygen quenching sensitivity data (slope of a linear fit to the modified Stern-Volmer plot) for water-soluble luminophores composed of Silamine-attached [Ir(fppy)2(t-Bu-iCN)2][CF3SO 3] and [Ir(ppy)2(fppy)] are between 0.4 and 0.5, which are appropriate for pressure sensitive paint applications. Investigation of luminescence microscopy and solid state lifetime measurements revealed that the preferential binding of the luminophore to MC increased its luminescence lifetime and was primarily responsible for the improved oxygen quenching sensitivity of PSP films that include MC. |
