An efficient Cp*Rh(III)-catalyzed selective bis-cyanation of arylimidazo[1,2-α]pyridines with N-cyano-N-phenyl-p-methylbenzenesulfonamide via N-directed ortho double C–H activation has been developed. The reaction proceeds with broad functional group tolerance to furnish various cyanated imidazopyridines in high yields. The current methodology exhibits unique characteristics, including high bis-cyanation selectivity, operational convenience, and gram-scale production.

In an effort to exert more precise control over structural features of supramolecules, a series of giant concentric hexagons were assembled as discrete structures using tetratopic terpyridine (tpy) ligands. In preparation of tetratopic ligand, pyrylium and pyridinium salts chemistry significantly facilitated synthesis. The key compounds were obtained by condensation reactions of pyrylium salts with corresponding primary amine derivatives in good yields. These discrete metallo-supramolecular concentric hexagons were fully characterized by NMR, ESI–MS, TWIM–MS, and TEM, establishing their hexagon-in-hexagon architectures. The combination of different tetratopic ligands also assembled hybrid concentric hexagons with increasing diversity and complexity. Furthermore, these concentric hexagon supramolecules with precisely controlled shapes and sizes were utilized as building blocks to hierarchically self-assemble supramolecular metal–organic nanoribbons (SMON) at solid–liquid interfaces. Ambient STM imaging showed the formation of long 1D SMON rather than 2D assembly on the basal plane of highly oriented pyrolytic graphite (HOPG) surface after simple dropcasting of the solution of preassembled concentric hexagons onto a freshly cleaved surface of HOPG. This wet chemical method based on self-assembly may offer simple, economical, and scalable routes to deliver complex materials.

The transformation of aldoximes to primary amides has been evaluated using pincer ruthenium complexes a–c, among which the ionic Ru catalyst a proved to be the most efficient in water under air atmosphere. A variety of (hetero)arene aldoximes proceeded smoothly to afford amides in high yields with good functional group compatibilities. Furthermore, a direct synthetic route of amides from aldehydes, hydroxylamine hydrochloride and sodium carbonate was also described with broad substrates including conjugated and aliphatic aldehydes. This protocol is operationally simple and proceeds with a low catalyst loading (0.5 mol%).

Two water-soluble monophosphine [PPh3 and 2-dicyclohexylphosphino-2′,6′-dimethoxybiphenyl(Sphos)]-palladacycles containing hydroxymethyl groups 2–3 were prepared by cyclopalladation and chloride bridge-splitting reactions. The complexes were characterized by elemental analysis, ESI–MS and NMR. In addition, single-crystal X-ray analysis reveals that they have one-dimensional lamellar structures involving intermolecular hydrogen bonds and π–π interactions. The use of these palladacycles as catalysts for amination and Suzuki coupling of aryl chlorides in water was investigated. Complex 3 was found to be very efficient for these coupling reactions. Additionally, it was also successfully used in Suzuki coupling of (hydroxymethyl)phenylboronic acid for the synthesis of substituted 2-N-heterocyclic biarylmethanols.

A novel iron-involved tosylmethylation of imidazo[1,2-α]pyridines with p-toluenesulfonylmethyl isocyanide in a solvent mixture of H2O and PEG400 under an Ar atmosphere has been developed. This protocol provides a facile synthetic route for the functionalization of the imidazo[1,2-α]pyridine scaffold with broad substrate compatibility, which is less expensive and environmentally friendly. The current methodology could further enable regioselective C–H tosylmethylation of indole at the C3 position. Also, p-toluenesulfonylmethyl isocyanide was utilized as the tosylmethylating reagent for the first time.

A catalyst free Friedel–Crafts (F–C) hydroxyalkylation of imidazo[1,2-α]pyridines with ethyl trifluoropyruvate is herein described using isopropyl ether as a solvent. Electron-donating and electron-withdrawing functional groups at various aromatic positions were well tolerated under our optimized conditions. The method enabled the generation of desired products in moderate to excellent yields under mild conditions, which makes this transformation an attractive, environmentally benign alternative for the synthesis of the target compounds.

•NHC-palladacycles 3–10 display fluorescence in the solid state at rt.•X-ray structures of four NHC-palladacycles 5–7 and 9.•Pyrazine ligands 1–2 and their NHC-palladacycles 3–10 have been synthesized and characterized.Two pyrazine ligands 1–2 and their NHC-palladacycles 3–10 have been synthesized and fully characterized. Additionally, the detailed structures of 5–7 and 9 have been determined by X-ray diffraction and intermolecular π⋯π and C–H⋯X (Cl, N) interactions were found in their crystal structures. These palladacycles are fluorescent in both the solid state and solution at room temperature.Two pyrazine ligands 1–2 and their NHC-palladacycles 3–10 have been synthesized and fully characterized. These palladacycles are fluorescent in both the solid state and solution at room temperature.

A series of naphtho[1′,2′:4,5]imidazo[1,2-a]pyridines were synthesized smoothly from 2-arylimidazo[1,2-a]pyridines and alkynes involving rhodium(III)-catalyzed C–H bond functionalization. The process selected Co(OAc)2·4H2O as the co-catalyst for the first time and minimized the reaction time to 2 h under air atmosphere. Some products exhibited deep blue luminescence properties.

Two 2-dicyclohexylphosphino-2′,6′-dimethoxybiphenyl (Sphos) adducts of cyclopalladated arylpyrazine complexes have been synthesized and characterized. Additionally, the structures of both complexes were determined by single-crystal X-ray analysis. These palladacycles are fluorescent in CH2Cl2 at room temperature. They have been applied to the double Suzuki coupling of N-heteroaryl halides with 1,4-benzenediboronic acid, giving the desired products in good yields.

Neutral and cationic ruthenium(II) complexes bearing a symmetrical 2,6-bis(imidazo[1,2-a]pyridin-2-yl)pyridine were synthesized and structurally characterized by NMR analysis and X-ray crystallographic determinations. These complexes have exhibited good catalytic activity in the transfer hydrogenation of ketones. In refluxing isopropyl alcohol, the conversion of the substrates reached up to 99%, and a TOF value of 356 400 h–1 with 0.1 mol % catalyst was achieved.

Using a series of tritopic 2,2′:6′,2″-terpyridine (tpy) ligands constructed on adamantane, three discrete 3D metallo-supramolecular architectures were assembled, i.e., trigonal bipyramidal, tetrahedron, and cube. The self-assembly used tritopic ligands as corner directing units and metal ions as glue units at the edge. The angles of the linkers between adamantane and tpy head play a critical role in guiding the assembled structures, which have the general formula of M3nL2n, where M denotes metal ion and L denotes ligand. All complexes were fully characterized by 1H, 13C NMR, diffusion-ordered NMR spectroscopy, ESI-MS, and traveling-wave ion mobility-mass spectrometry. The binary mixtures of LA and LC or LB and LC underwent a self-sorting process that led to the self-assembly of discrete 3D structures. The self-sorting behavior is solely based on the angles precoded within the arm of tritopic ligands. Moreover, kinetic study of preassembled cube and tetrahedron demonstrated a slow ligand exchange process toward a statistical mixture of hetero tetrahedrons with LA and LB.

A series of cyclopalladated 2-(4-bromophenyl)pyridine (bpp) complexes [Pd(bpp)(NHC)Cl] 1–3, [Pd(bpp)(acac)] 4, cyclometalated iridium(III) complexes [Ir(bpp)2Cl]25 and [Ir(bpp)2(acac)] 6 have been synthesized and characterized. Their detailed structures have been determined by X-ray diffraction and many intermolecular C–H⋯X (Cl, Br, π) and π⋯π interactions were found in their crystals. Cyclometalated complexes 1–4 and 6 exhibit luminescence with emission peaks of 390–543 nm in dichloromethane solution under UV irradiation. Their application to coupling reactions of aryl chlorides containing hydroxymethyl was also investigated. An efficient 3/Cu cocatalyzed oxidation/Suzuki reaction for the synthesis of biarylaldehydes from chloro-phenylmethanol and arylboronic acids in air has been developed. In addition, a 6/3-cocatalyzed one-pot reaction of acetylferrocene, (2-amino-5-chlorophenyl)methanol, and arylboronic acids provided 6-aryl-2-ferrocenylquinolines in moderate to good yields.

Two new NHC adducts of cyclopalladated ferrocenylpyrazine complexes 1–2 have been prepared and characterized. An efficient NHC-modulated Pd/Cu cocatalyzed three-component coupling reaction for the synthesis of 2,6-diarylquinolines from aminobenzyl alcohols, aryl ketones, and arylboronic acids in air is described. The reaction involves oxidation, cyclization and Suzuki reactions. The luminescence of the resulting arylquinolines 3–30 was also investigated.

Primary aromatic amides can be synthesized from aldehydes and hydroxylamine hydrochloride in the presence of Cs2CO3. Various aromatic aldehydes (include some heteroaromatic aldehydes) are able to generate the corresponding aromatic amides in moderate to excellent yields.

Two new NHC adducts of cyclopalladated ferrocenylpyrazine complexes 1–2 have been prepared and characterized. An efficient NHC-modulated Pd/Cu cocatalyzed three-component coupling reaction for the synthesis of 2,6-diarylquinolines from aminobenzyl alcohols, aryl ketones, and arylboronic acids in air is described. The reaction involves oxidation, cyclization and Suzuki reactions. The luminescence of the resulting arylquinolines 3–30 was also investigated.

A series of cyclopalladated 2-(4-bromophenyl)pyridine (bpp) complexes [Pd(bpp)(NHC)Cl] 1–3, [Pd(bpp)(acac)] 4, cyclometalated iridium(III) complexes [Ir(bpp)2Cl]25 and [Ir(bpp)2(acac)] 6 have been synthesized and characterized. Their detailed structures have been determined by X-ray diffraction and many intermolecular C–H⋯X (Cl, Br, π) and π⋯π interactions were found in their crystals. Cyclometalated complexes 1–4 and 6 exhibit luminescence with emission peaks of 390–543 nm in dichloromethane solution under UV irradiation. Their application to coupling reactions of aryl chlorides containing hydroxymethyl was also investigated. An efficient 3/Cu cocatalyzed oxidation/Suzuki reaction for the synthesis of biarylaldehydes from chloro-phenylmethanol and arylboronic acids in air has been developed. In addition, a 6/3-cocatalyzed one-pot reaction of acetylferrocene, (2-amino-5-chlorophenyl)methanol, and arylboronic acids provided 6-aryl-2-ferrocenylquinolines in moderate to good yields.