A rare case of dual emission in a neutral heteroleptic iridium(III) complex

Herein we describe the synthesis and characterization of a neutral heteroleptic iridium complex bearing an unusual 2-pyridyl-6-methylthiazine dioxide ligand (pythdo). X-ray crystallographic analysis reveals that in the complex, the pythdo ligand is twisted and puckered, resulting in very low photoluminescent quantum efficiency. The emission profile is structured. Excited state lifetime measurements along with oxygen quenching studies point to a rare case of dual emission from different excited states whereby the high energy bands possess significant ligand-centered ((LC)-L-3) character while the lower energy bands are predominantly characterized as a mixture of charge transfer ((CT)-C-3) states. A detailed computational analysis corroborates the unusual photophysical behavior.</p

Direct Route to Well-Defined Poly(ionic liquid)s by Controlled Radical Polymerization in Water

The precision synthesis of poly(ionic liquid)s (PILs) in water is achieved for the first time by the cobalt-mediated radical polymerization (CMRP) of N-vinyl-3-alkylimidazolium-type monomers following two distinct protocols. The first involves the CMRP of various 1-vinyl-3-alkylimidazolium bromides conducted in water in the presence of an alkyl cobalt(III) complex acting as a monocomponent initiator and mediating agent. Excellent control over molar mass and dispersity is achieved at 30 degrees C. Polymerizations are complete in a few hours, and PIL chain-end fidelity is demonstrated up to high monomer conversions. The second route uses the commercially available bis(acetylacetonato)cobalt(II) (Co(acac)2) in conjunction with a simple hydroperoxide initiator (tertbutyl hydroperoxide) at 30, 40, and 50 degrees C in water, facilitating the scaling-up of the technology. Both routes prove robust and straightforward, opening new perspectives onto the tailored synthesis of PILs under mild experimental conditions in water

'Click'-inspired chemistry in macromolecular science: matching recent progress and user expectations

This year, it has been a decade that the concept of click chemistry was pioneered in polymer and material science by the exploration of the synthetic scope of copper-catalyzed azide/alkyne cycloaddition (CuAAC), the click benchmark. The impact on the endeavors of polymer chemists has been substantial because the power of this concept, featuring modularity, orthogonality, and versatility for the design and synthesis of polymeric materials, was recognized very soon in macromolecular research groups worldwide. After this first burst of research activity, challenging the boundaries of CuAAC in terms of attainable polymer constructs, ongoing method development, and implementation, in response to the need for metal-free alternatives, resulted in a valuable toolbox of click-inspired conjugation methods. Because of the large diversity of employable reactions, applied in various polymeric systems, the first-time or occasional click user will be confronted with a burden of choice. Therefore, the principal aim of this Perspective is to clearly denote the recent progress of click-inspired chemistry in macromolecular science by detailed conceptual analysis and to provide some selection procedures, allowing potential users to readily match their expectations of click chemistry to the state-of-the-art. Consequently, first-time or occasional users should be able to identify and select the most appropriate click-inspired reaction for their purposes and eventually contribute to the next generations of advanced polymeric materials