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摘要
We report the preparation and spectroscopic properties of [Os(bpy)(2)(pySO)](2+) and [Os(bpy)(2)(pySOCF(3))](2+) where bpy is 2,2'-bipyridine, pySO is 2-(propane-2-sulfinylmethyl)pyridine, and pySOCF(3) is 2-[(trifluoroethylsulfinyl)methyl]pyridine. The charge-transfer absorption spectra of [Os(bpy)(2)-(pySO)](2+) and [Os(bpy)(2)(pySOCF(3))](2+) are 378 and 367 nm, respectively. Charge-transfer excitation of [Os(bpy)(2)-(pySOCF(3))](2+) shows substantial changes in the UV/Vis spectrum with a shift in the lowest energy absorption maximum from 367 to 415 nm, which is consistent with phototriggered S -> O isomerization. Irradiation of [Os(bpy)(2)(pySO)](2+) shows no evidence of isomerization. Cyclic voltammograms of [Os(bpy)(2)(pySO)(2+) and [Os(bpy)2(pySOCF(3))](2+) feature reversible one-electron couples that are ascribed to 0s3+/2+ reduction potentials (E degrees') at 1.01 V (vs Ag/AgCl; (v) over tilde = 0.1 V/s; CH3CN; 0.1 n't TBAPF(6)) and 1.17 V, respectively. Femtosecond to nanosecond transient absorption spectra for [Os(bpy)(2)(pySOCF(3))](2+) are reported. For [Os(bpy)(2)(pySOCF3)](2+), fits of data obtained at 370 nm yield lifetimes of 0.20 (0.02) and 19.7 (8) ps, whereas for [Os(bpy)(2)(pySO)](2+) lifetimes of 0.47 (0.2) and 12.7 (11) ps are obtained at 378 nm. These lifetimes are ascribed to the formation of a (MLCT)-M-3 state and solvent reorganization, respectively. Excited state lifetimes of 331(+/- 4) and 348 (+/- 25) ns are found for [Os(bpy)(2)(pySO)](2+) and [Os(bpy)(2)(pySOCF(3))](2+), respectively. The time constant for isomerization is 213 is for [Os(bpy)(2)(pySOCF(3))](2+). Transient absorption spectra reveal an excited state sulfoxide to Os3+ transition. The electrochemical and spectroscopic data can be combined to yield electronic state diagrams for [Os(bpy)(2)(pySO)](2+) and [Os(bpy)(2)(pySOCF(3))](2+)
- 出版日期2013-3
