2-(1-(Arylimino)ethyl)-8-arylimino-5,6,7-trihydroquinolylcobalt dichloride: Synthesis and polyethylene wax formation

A series of 2-(1-(arylimino)ethyl)-8-arylimino-5,6,7-trihydroquinolylcobalt dichloride (aryl = 2,6-R1-4-R2C6H2) pre-catalysts were synthesized and structurally characterized by FT-IR and elemental analyses. The molecular structures of Co1 (R1 = Me, R 2 = H), Co2 (R1 = Et, R2 = H) and Co5 (R 1 = Et, R2 = Me) were determined by single-crystal X-ray diffraction analysis, and confirmed Co1 as a distorted trigonal bipyramidal geometry at the metal, whilst in Co2 and Co5 the metal is square-pyramidal. Upon treatment with either MAO or MMAO, all cobalt pre-catalysts exhibited highest activities at 60 °C for ethylene polymerization. The resultant polyethylenes, under optimization reaction parameters, possessed low molecular weight (waxes) and narrow polydispersity. © 2012 Elsevier B.V

Collagen–Hyaluronic Acid Composite Hydrogels with Applications for Chronic Diabetic Wound Repair

Chronic diabetic wounds have become a major healthcare challenge worldwide. Improper treatment may lead to serious complications. Current treatment methods including biological and physical methods and skin grafting have limitations and disadvantages, such as poor efficacy, inconvenience of use, and high cost. Therefore, developing a more effective and feasible treatment is of great significance for the repair of chronic diabetic wounds. Hydrogels can be designed to serve multiple functions to promote the repair of chronic diabetic wounds. Furthermore, 3D bioprinting enables hydrogel customization to fit chronic diabetic wounds, thus facilitating the healing process. This paper reports a study of 3D printing of a collagen–hyaluronic acid composite hydrogels with application for chronic diabetic wound repair. In situ printed hydrogels were developed by a macromolecular crosslinking network using methacrylated recombinant human collagen (RHCMA) and methacrylated hyaluronic acid (HAMA), both of which can respond to ultraviolet (UV) irradiation. The hydrogels were also loaded with silver nanoclusters (AgNCs) with ultra-small-size nanoparticles, which have the advantages of deep penetration ability and broad-spectrum high-efficiency antibacterial properties. The results of this study show that the developed RHCMA, HAMA, and AgNCs (RHAg) composite hydrogels present good UV responsiveness, porosity, mechanical properties, printability, and biocompatibility, all of which are beneficial to wound healing. The results of this study further show that the developed RHAg hydrogels not only effectively inhibited Staphylococcus aureus and Pseudomonas aeruginosa but also promoted the proliferation and migration of fibroblasts in vitro and tissue regeneration and collagen deposition in vivo, thus producing a desirable wound repair effect and can be used as an effective functional biomaterial to promote chronic diabetic wound repair

Enhancing the Activity and Thermal Stability of Nickel Complex Precatalysts Using 1‑[2,6-Bis(bis(4-fluorophenyl)methyl)-4-methyl phenylimino]-2-aryliminoacenaphthylene Derivatives

The series of acenaphthylene-1-[2,6-bis­(bis­(4-fluorophenyl)­methyl)-4-methylphenylimino]-2-arylimine derivatives and their dichloronickel complexes were synthesized and fully characterized as well as the single-crystal X-ray diffraction of representative nickel complexes, revealing a distorted tetrahedral geometry. Upon activation with either MAO or Et₂AlCl, all nickel complexes showed high activities in ethylene polymerization; moreover, their catalytic systems showed better thermal stabilities on being manipulated at 80 °C as the industrial operating temperature