A new application for bis­(cyclometalated) iridium­(III) species containing ancillary acyclic diaminocarbene ligands, viz. for sensing of mercury­(II) ions, is disclosed. A family of bis­(cyclometalated) iridium­(III) species supported by both parent isocyanide and acyclic diaminocarbene ligands was prepared, and their electrochemical and photophysical properties were evaluated, revealing efficient blue-green phosphorescence in solution with quantum yields of up to 55%. We uncovered that the photophysical properties of these complexes are dramatically altered by the presence of metal ions and that the complex [Ir­(ppy)2(CN)­{C­(NH2)­(NHC6H4-4-X)}] with an ADC ligand reacts selectively with Hg2+ ions, enabling its use for sensing of mercury­(II) ions in solution. The limit of detection was as low as 2.63 × 10–7 M, and additional mechanistic studies indicated the formation of an unusual dinuclear iridium­(III) cyclometalated intermediate, bridged by a mercury dicyano fragment as a driving force of mercury sensing.

In the past decades, silicone-based technology has evolved from specialty, high-performance applications into broad industrial usage.1 Cured silicone coatings have substantial thermal, weather corrosion, biofouling, and abrasion resistance. These coatings accounted for almost three quarters of contemporary paper and film coating production; 3 they are also used for metal 3b and glass protection, 4 and as substrates for pressure-sensitive adhesives. 5The conventional preparation of silicone coating involves metal-catalysed hydrosilylative cross-linking (curing) of vinyland hydrogen-functional polyIJdimethylsiloxanes).2c,3a,6 Ideally, coating composition should not gel at RT but cure rapidly at a temperature above 100°C allowing the coated substrate to be further processed without cooling down. 3aAlthough these requirements can be addressed by application of a suitable catalyst, the commonly used Karstedt's catalyst (a platinumIJ0) complex with 1,3-divinyl-1,1,3,3-tetramethyldisiloxane, Fig. 1a) shows limited chemical and thermal stability and excessive activity. The use of inhibitors is required to prevent immediate cross-linking even at RT; therefore, its application at higher temperatures is not straightforward. 7 Marciniec et al. 7 first reported iridiumIJI)-based siloxide catalysts (Fig. 1b) that cure siloxanes at ca. 200°C; however, the properties of the thus prepared rubbers were not rationalized.In the current study, we scrutinised a series of alternative iridiumIJIII) complexes 1-6 (Scheme 1) as catalysts for the cross-linking of α,ω-diIJvinyldimethylsiloxy)polyIJdimethylsiloxane) (PDMS) with trimethylsilyl-terminated polyIJdimethylsiloxane-co-ethylhydrosiloxane) (EHDMS). We established the temperature-curing profile for these complexes and evaluated the properties of the silicone compositions obtained. In addition, we measured the luminescence emission profiles of 2-6 and of the corresponding rubbers prepared, and developed a procedure for immediate measurement of the coating thickness based upon optical detection. ), were prepared from a chloro-bridged dimer, [IrIJppy) 2 IJμ-Cl)] 2 (1, Scheme 1). Thus, the reaction of 1 with two equiv. of isocyanide CNR (R = Xyl, R = Mes) in CH 2 Cl 2 at RT afforded 2 or 3 in 82-85% isolated yield. Further reaction of 1 equiv. of 2 or 3 with 1 equiv. of CNR in the presence of 1 equiv. of AgOTf in CH 2 Cl 2 at RT gave 4 or 5 in 74-85% yield. Complex fac-[IrIJppy) 3 ] (6) was prepared via a known procedure starting from 1 and ppy. Synthesis and characterization of catalysts8 Complexes 2-5 were obtained as pale yellow

A new reactivity mode for acyclic diaminocarbene ligands, viz. competitive cleavage of either C–NH2 or C–NHR bonds in the aminocarbene fragment, is recognized.

Solvent-rich dichloromethane solvate of

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