Redox switchable catalysis utilizing a fluorescent dye

Silver-mediated, direct phosphorylation of BODIPY dyes at the 3- or 3,5-positions with H-phosphonates

A direct and regioselective C-H/P-H cross-coupling of dialkyl phosphites, and diphenylphosphine oxide to easily available BODIPYs through an Ag-mediated radical addition, resulted in a series of new α-phosphorylated BODIPY fluorophores under mild conditions. Hydrolysis of the phosphonate gave the corresponding BODIPY phosphoric acid, which is soluble and fluorescent in water with a high quantum yield of 0.83.

Redox-Switchable Cycloisomerization of Alkynoic Acids with Napthalenediimide-Derived N-Heterocyclic Carbene Complexes

Two naphthalene-diimide (NDI) bis-imidazolium salts have been used as N-heterocyclic carbene (NHC) precursors for the preparation of NDI-functionalized complexes of rhodium and iridium of general formula [MCl(NDI-NHC)(COD)] (M=Rh, Ir; NDI-NHC=NDI-functionalized NHC ligand). Comparison of the IR spectra of the complexes [IrCl(NDI-NHC)(CO)2 ] and their related one- and two-electron reduced forms, reveal that each one-electron reduction produces a decrease of the average ν(CO) of 9-10 cm-1 , indicating a significant enhancement of the electron-richness of the metal. The [MCl(NDI-NHC)(COD)] complexes were tested in the catalytic cycloisomerization of alkynoic acids. The one-electron reduced forms showed greatly enhanced activities. For the cyclization of 5-hexynoic acid, the two-electron reduction of the ligand produced further enhancement of the catalytic activity, therefore showing that the catalyst can switch between three redox species with three distinct catalytic activities.

Supramolecular Regulation of Catalytic Activity for an Amphiphilic Pyrene-Ruthenium Complex in Water

A switchable catalytic system has been designed and constructed with a host-guest interaction between cucurbituril (CB) and an amphiphilic metal complex pyrene-ruthenium (Py-Ru). Py-Ru can self-assemble into positively charged nanoparticles in water, and exhibits an enhanced catalytic efficiency in the transfer hydrogenation of NAD⁺ to NADH. After forming an inclusion complex with CB, Py-Ru aggregates are broken, leading to a decrease in catalytic efficiency, which can be recovered by competitive replacement with amantadine. This supramolecular strategy provides an efficient and flexible method for constructing reversible catalytic system, which also extends the application scope of the host-guest interaction.

Cu2O hydrides promote the selective semihydrogenation of alkynes on Pd–Cu2O/TiO2 under mild conditions

High activity, chemoselectivity and stereoselectivity were unveiled by the synergy of the p–n heterojunctions with Pd⁰ in a novel Pd–Cu₂O/TiO₂ catalyst for spillover semihydrogenations.

Additive- and column-free synthesis of rigid bis-coumarins as fluorescent dyes for G-quadruplex sensing via disaggregation-induced emission

A novel and efficient method to synthesize rigid bis-coumarins based on the dimerization of coumarinyl aldehydes was developed. This procedure is additive- and column-free, providing a facile and environment-friendly way to prepare fluorophores. The prepared novel fluorescent bis-coumarins exhibit favorable photophysical properties with good sensitivity and selectivity towards G-quadruplexes (G4s).