Synthesis and Characterization of Ru(II) Tris(1,10-phenanthroline)-Electron Acceptor Dyads Incorporating the 4-Benzoyl-N-methylpyridinium Cation or N-Benzyl-N‘-methyl Viologen. Improving the Dynamic Range, Sensitivity, and Response Time of Sol−Gel-Based Optical Oxygen Sensors

Abstract

The title compounds were synthesized by Sonogashira coupling reactions of appropriate Ru(II) complexes with the electron acceptors. Characterization was conducted in solution and in frozen matrixes. Finally, the title compounds were evaluated as dopants of sol-gel materials. It was found that the intramolecular quenching efficiency of 4-benzoyl-Nmethylpyridinium cation in solution depends on the solvent: photoluminescence is quenched completely in CH 3 CN, but not in methanol or ethanol. On the other hand, intramolecular emission quenching by 4-benzyl-N-methyl viologen is complete in all solvents. The difference between the two quenchers is traced electrochemically to the solvation of the 4-benzoyl-Nmethylpyridiniums by alcohol. In frozen matrixes or adsorbed on the surfaces of silica aerogel, both Ru(II) complex/electron acceptor dyads of this study are photoluminescent, and the absence of quenching has been traced to the environmental rigidity. When doped aerogels are cooled at 77 K, the emission intensity increases by ∼4×, and the spectra shift to the blue, analogous to what is observed with Ru(II) complexes in solutions undergoing fluidto-rigid transition. However, in contrast to frozen solutions, the luminescent moieties in the bulk of aerogels kept at low temperatures are still accessible to gas-phase quenchers diffusing through the mesopores, leading to more sensitive platforms for sensors than other room-temperature configurations. Thus, the photoluminescence of our Ru(II) complex dyads adsorbed on aerogel is quenchable by O 2 both at room temperature and at 77 K. Furthermore, it was also found that O 2 modulates the photoluminescence of aerogels doped with 4-benzoyl-N-methylpyridinium -based dyads over a wider dynamic range compared with aerogels doped with either our viologen-based dyads or with Ru(II) tris(1,10-phenanthroline) itself.

Polyelectrolyte‐Induced Self‐Assembly of Positively Charged Alkynylplatinum(II)–Terpyridyl Complexes in Aqueous Media

“…Synthesis of the metal complexes : [Pt(tpy)(CC‐CCCH 2 OH)][OTf] ( 1 ) was synthesized as reported previously 20. The compounds Me 3 SiCCC 6 H 4 CH 2 Br,21 Me 3 SiCC‐CCCH 2 Br,22 [Pt(tpy)Cl][OTf],23 and [Pt(tpy)(CH 3 CN)][OTf] 2 14, 24 were synthesized according to literature methods.…”

“…(1) was synthesized as reported previously. [20] The compounds Me 3 Si-CCC 6 H 4 CH 2 Br, [21] Me 3 SiCC-CCCH 2 Br, [22] [23] and [14,24] were synthesized according to literature methods.…”

Mesoporous Silicate Materials in Sensing

“…Oxygen sensing has been accomplished through quenching of the fluorescence of N -(3-trimethoxysilylpropyl)-2,7-diazapyrenium bromide incorporated into a highly porous aerogel through direct co-condensation and post-synthesis grafting [91, 92]. It was found that co-condensation provided a more uniform distribution of the dye and more effective interrogation of the resulting photoluminescence.…”

“…It was found that co-condensation provided a more uniform distribution of the dye and more effective interrogation of the resulting photoluminescence. The incorporation of ruthenium complexes into a variety of materials has been applied to detection and quantification of oxygen [82, 92-95]. In the case of the ruthenium complexes, covalent modification techniques were found to yield notably more linear Stern-Volmer plots (I 0 /I vs. oxygen concentration) than techniques that employed entrapment of the dyes [93].…”

Synthesis of a Highly Luminescent Three-Dimensional Pyrene Dye Based on the Spirobifluorene Skeleton

“…Many studies have been conducted on strategies for synthesizing a highly efficient dye. For example, rod- [ 1 , 2 ] and star-shaped [ 3 , 4 , 5 , 6 ] hydrocarbons that expand π-conjugation to two dimensions can be used to control the emission color of a dye with high efficiency.…”