Chiral (1S)- and (1R)-camphyl α-diimine nickel complexes were synthesized respectively with (1S)-(+) camphorquinone and (1R)-(−) camphorquinone as raw reagents and used as catalyst precursors for olefin polymerizations. It is found that the ligand chirality has no influence on catalytic activity and regioselectivity for olefin polymerizations. Ethylene, propylene, 1-hexene, and 4-methyl-1-pentene polymerizations with the camphyl α-diimine nickel activated by AlEt2Cl can exhibit some living characteristics under the optimized conditions. The resultant polypropylenes and poly(1-hexene)s have significantly narrow molecular weight distributions (PDI < 1.2) in a wide temperature range, even at an elevated temperature of 70 °C. Sustainable period of the linear relationship of M n vs polymerization time depends on temperature for propylene and 1-hexene polymerizations. Additionally, high 1,3-enchainment fraction of 45% is observed even at −60 °C for propylene polymerization using the camphyl α-diimine catalyst due to 2,1-insertion of propylene and chain walking.

CO/styrene copolymerization by α-diimine palladium catalysts is a promising method for direct synthesis of polyketones. The effect of the catalyst backbone structure on CO/styrene copolymerization has been studied with the aim of developing robust α-diimine palladium catalysts able to improve the polymerization productivity and controllability. Dibenzobarrelene derived α-diimine palladium catalysts without o-aryl substituents were designed and synthesized for CO/styrene alternating copolymerization. Introduction of the rigid and bulky dibenzobarrelene backbone enhanced the thermal stability and the productivity of palladium catalyst. The dibenzobarrelene ligand backbone also improved the polymerization controllability, and living CO/styrene copolymerizations were achieved at 15 °C using α-diimine palladium catalysts in CH 2 Cl 2 . The steric hindrance of backbone and the π−π stacking between the dibenzobarrelene backbone and the aniline played crucial roles in stereocontrol and productivity.

Development of low-cost nontraditional intrinsic luminescence (NTIL) polymers containing auxochromophores and understanding their luminescence characteristics are highly desirable. In this paper, alternating vinylarene−carbon monoxide copolymers (PK-X, X = H, Ph, t Bu, O t Bu, F, and Cl) were, for the first time, reported as simple and efficient NTIL polymers, which were facilely and precisely prepared by palladium-catalyzed coordination copolymerization of vinylarene and CO. These nonconjugated polymers emitted intrinsic blue light in both concentrated solutions and solid powders by the clusterizationtriggered emission mechanism. Theoretical calculations and singlecrystal analysis of the small molecular model clearly confirmed that through-space intra-and interchain interactions by n−π and π−π modes between the carbonyl and the phenyl groups collectively formed clusteroluminogens. The copolymer quantum yields greatly improved regardless of the introduction of an electron acceptor or donor. The chloride-substituted copolymer had a high quantum yield of up to 44.8% and showed great potential as a photoluminescent material for improving the utilization of sunlight.

Polymerization of polar vinyl monomers by a coordination− insertion approach is a topic of fundamental importance to the field of polymer synthesis. Herein, we initially report the coordination−insertion polymerization of para-alkoxystyrene (pAOS) monomers by the dibenzobarrelene-based αdiimine palladium catalysts. The unprecedented polymerization characteristics including rapid initiation, fast chain growth, controlled chain transfer, and highmolecular-weight polymer with a narrow distribution (M w > 1000 kg/mol, PDI < 1.32) reflected previously unrecognized aspects of palladium-catalyzed pAOS polymerization. Chain-end analysis and characterization of palladium intermediates showed that the pAOS monomer was rapidly inserted into the primary palladium species in a full 1,2-regioselectivity, and the chain transfer took place by monomer-assisted β-H abstraction at high monomer concentrations. The resultant polymers showed improved mechanical properties and thermal stabilities and were also attractive candidates of hydrophilic styrenic resin.

To better understand the substituent effects of vinyl arene, a series of substituted styrenes with different groups and locations (n-X-St, n = 2, 3, 4; X = H, Me, t Bu, MeO, t BuO, F, Cl, and Br) were used as comonomers for palladium-catalyzed vinyl arene/CO copolymerization. Dibenzobarrelene-based α-diimine palladium catalyst Pd1 was capable of catalyzing alternating copolymerizations of substituted styrene comonomers and CO in a living fashion, which excluded the effect of the palladium catalyst. Electronic effects of comonomer substituents were quantitatively examined by Hammet constants (σ) of substituents and highest occupied molecular orbital (HOMO) energies of comonomers. Experimental results clearly showed that the turnover number (TON) of copolymerization, copolymer molecular weight, and stereoregularity were greatly affected by the inserted substituent. The steric effect of 4-substituents was presented and clearly proved in addition to a widely acceptable electronic effect. Strikingly, the unprecedented positioning effects of comonomer substituents were initially discovered. Whatever substituents were located on 3-position, vinyl arene/CO alternating copolymerization was greatly promoted because of the neglectable steric effect of 3-substituents.