1,2,3-Triazole-derived mesoionic biscarbenes bridged by a pyridylene group were synthesized and their structures were determined. Bulky substituents on the carbene rings stabilized the carbenes, which enabled their crystal structures to be determined. As implied by DFT calculations and the experimental results, the carbenes are partly reduced to anionic radical species in the presence of strong bases. This suggests that the pyridylene and triazolylidene moieties endow molecules with both electron-acceptor and -donor properties. A rare example of an iron complex with a pincer carbene was synthesized.

The homopolymerization reactions of several lactones, as well as the copolymerization reactions of DL-lactide with these lactones were investigated using tridentate Schiff base aluminum complexes as the initiators. ε-Caprolactone and δ-valerolactone polymerized efficiently at room temperature to afford polyesters, whereas β-butyrolactone only gave the corresponding oligomer. The copolymerization reactions of DL-lactide with caprolactone and valerolactone yielded gradient block copolymers where the lactyl blocks formed crystalline stereoblocks as a consequence of the stereoselective polymerization of DL-lactide in the presence of the aluminum complexes. These polymerization processes were highly controlled in nature, and block copolymerization where caprolactone copolymerized using poly(DL-lactide)-Al complex proceeded. The obtained gradient copolymer containing stereoblock lactyl blocks and caproyl blocks were analyzed using WAXD analysis to uncover existence of the crystalline stereoblock lactyl blocks in the copolymer. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 2536–2544

Cobalt(II) iodide, bromide, and chloride react with 1 equiv. of IPr [1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene] to form a series of tetrahedral dimeric (30e) complexes of cobalt(II) in good yields. These were transformed into the monomeric forms in the presence of pyridine. These complexes were characterized by SQUID, XPS, UV/Vis spectroscopy, elemental analysis, and X-ray crystallography, and were found to have high catalytic activity for Kumada–Tamao–Corriu cross-coupling reactions of aryl halides.

Ring-opening polymerization of D,L-lactide was stereoselectively achieved using newly designed aluminum alkoxide complexes as initiators. These half-SALEN aluminum complexes bearing tridentate nonchiral Schiff-base ligands are racemates, which provide chirality in the aluminum centers, efficiently afforded a stereoblock copolymer of D,L-LA. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012

The first C^∧C^∧N cyclometalated complexes of iridium that bear tridentate pyridylbiphenylene ligands are reported herein. These complexes were synthesized in good yields by means of the directed C–C bond activation of biphenylene with the assistance of pyridyl group precoordination. Their photoluminescent performances were also studied and show unique luminescent properties at longer wavelengths in the near-infrared range than that of previously synthesized C^∧N^∧C cyclometalated iridium complexes.

Radical polymerization of styrene derivatives having a series of amino acid, alanine, glycine, leucine, valine, Boc-leucine, and Boc-valine, in the side chain bound at the C-terminal was conducted to regulate the stereoinduction system in the propagation step. Isotacticity increased in the polymer main chain, especially in the polymerization of monomers bearing N-free L-leucyl and L-valyl esters in THF or DMF at 50 °C, by the synergic stereoregulation with chirality control and hydrogen bonding between the radical polymer terminal and the monomer. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010

The preparation of several new o-amine-substituted anilines was achieved according to a new bifunctional molecular design, and their reactions with glyoxal were conducted. Cannizzaro reactions of glyoxal proceeded using specifically designed anilines, such as 2,6-dipyrrolidinyl-, 2,6-dipiperidinyl-, 2,6-dimorpholinyl-, and 2-pyrrolidinyl-aniline, which are new and can easily be synthesized by substitution of halogen-substituted nitrobenzene with amines and subsequent reduction with hydrogen, to form α-hydroxy acetamide and α-amino acetamide derivatives, as a result of the Cannizzaro reaction. In comparison with the reaction of glyoxal with p-pyrrolidinylaniline to form a common diimine product, the reaction with o-pyrrolidinylaniline leads only to α-hydroxy amides, strongly suggesting that the abnormal Cannizzaro reactions are attributed to the existence of basic nitrogen atoms at the o-positions, which suppress diimine formation and assist the generation of acetamides.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

We successfully developed phosphorescent cyclometallated iridium-containing metallopolymers, which are near-red luminescent iridium complexes bearing phosphine-containing copolymers used as polymer ligands, and investigated their photoluminescence and electroluminescence behavior. The phosphine copolymer ligand made from methyl methacrylate and 4-styryldiphenylphosphine can be used as an anchor, which coordinates luminescent iridium units to form the metallopolymer easily. Organic light-emitting diodes were fabricated from the metallopolymer and its nonpolymer analog, [IrCl(piq)₂PPh₃]. These complexes exhibited quite similar luminescence behavior, except for emission from the free-phosphine-units in the polymer side chain and their energy-transferring properties from host to guest materials. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4366–4378, 2009

We prepared an iridium polymer complex having 2-phenylpyridine as a η²-cyclometallated ligand, a new OLED containing a solution-processible iridium polymer as a host, and a phosphorescent iridium complex, [Ir(piq-^tBu)₃] as a guest. This is the first example to apply a phosphorescent iridium complex polymer to a host material in a phosphorescent OLED. A phosphine copolymer ligand made from methyl methacrylate (MMA) and 4-styryldiphenylphosphine can be used as an anchor polymer, which coordinates to luminescent iridium units to form a host metallopolymer easily. The OLED containing the host iridium-complex polymer film, in which the guest, 2 wt % Ir(piq-^tBu)₃, was doped, showed red electroluminescence as a result of efficient energy transfer from the iridium polymer host to the iridium guest. The maximum current efficiency of the device was 1.00, suggesting that a soluble iridium complex polymer can be used as a solution-processible polymer host in EL devices. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4358–4365, 2009