"Oxidative addition" of halogens to uranium(IV) bis(amidophenolate) complexes.

A series of U(IV) complexes, ((R)ap)2U(THF)2 [R = tert-butyl (t-Bu) (1), adamantyl (Ad) (2), diisopropylphenyl (dipp) (3)], supported by the redox-active 4,6-di-tert-butyl-2-(R)amidophenolate ligand, have been synthesized by salt metathesis of 2 equiv of the alkali metal salt of the ligand, M2[(R)ap] [M = K (1 and 2), Na (3)], with UCl4. Exposure of these uranium complexes to 1 equiv of PhICl2 results in oxidative addition to uranium, forming the bis-(4,6-di-tert-butyl-2-(R)iminosemiquinone) ([(R)isq](1-)) uranium(IV) dichloride dimer, [((R)isq)2UCl]2(μ(2)-Cl)2 [R = t-Bu (4), Ad (5), dipp (6)]. The addition of iodine to 1 forms ((tBu)isq)2UI2(THF) (7), while the reactivity of I2 with 2 and 3 results in decomposition.

Wide dynamic range sensing with single quantum dot biosensors.

Single-particle analysis of biosensors that use charge transfer as the means for analyte-dependent signaling with semiconductor nanoparticles, or quantum dots, was examined. Single-particle analysis of biosensors that use energy transfer show analyte-dependent switching of nanoparticle emission from off to on. The charge-transfer-based biosensors reported here show constant emission, where the analyte (maltose) increases the emission intensity.