D. S. Bolotin, V. Korzhikov-Vlakh, E. Sinitsyna, S. N. Yunusova, V. V. Suslonov, A. Shetnev, A. Osipyan, M. Krasavin, V. Yu. Kukushkin, Biocompatible zinc(II) 8-(dihydroimidazolyl)quinoline complex and its catalytic application for synthesis of poly(L,L-lactide), J. Catal., 372 (2019) 362–369; DOI: 10.1016/j.jcat.2019.03.002.

Abstract

A 1:1 reaction of 8-(dihydroimidazolyl)quinoline (abbreviated as L) with MCl₂·2H₂O (M = Co^II, Ni^II, Cu^II, Zn^II) conducted in EtOAc (for Zn^II and Cu^II) or MeOH (Ni^II and Co^II) at 50 °C for 10 min provided the respective air- and shelf-stable [MCl₂L] complexes (94–96%). The catalytic activity of these well-defined species was evaluated in L-lactide ring-opening polymerization (ROP) that was conducted in the presence of 2-hydroxyethylmethacrylate (HEMA) as a nucleophilic initiator. The biocompatible zinc(II) complex was found to be more catalytically active in ROP compared to the other three complexes as well as SnOct₂, a common reference catalyst. The zinc(II)-catalyzed ROP also gives the macromolecular product with the lowest polydispersity index (1.2). The applicability of the HEMA-terminated PLA, prepared in the presence of the [ZnCl₂L] complex, was demonstrated when PLA was converted into amphiphilic copolymer PLA-PEG via the thiol-ene click reaction. The PLA-PEG copolymer was shown to form nanospheres (calculated mean diameter 95 ± 10 nm) characterized by low particle size distribution. This – along with anticipated lower toxicity of [ZnCl₂L] traces in the polymer – makes these nanospheres potentially applicable as vehicles for intravenous drug delivery.

Lijun Fu, Qunting Qu, Rudolf Holze, Veniamin V. Kondratiev and Yuping Wu, Composites of metal oxides and intrinsically conducting polymers as supercapacitor electrodes: The best of both worlds? J. Mater. Chem. A, 2019. DOI:10.1039/C8TA10587A.

Abstract

Composite materials combining intrinsically conducting polymers and metal oxides suggested as electrode materials in supercapacitors are reviewed with attention to achieved stability and specific functions and effects both components contribute to performance of the materials.

Mikhail V.Dobrynin, Carla Pretorius, Dumisani V.Kama, Andreas Roodt, Vadim P.Boyarskiy, Regina M.Islamova, Rhodium(I)-catalysed cross-linking of polysiloxanes conducted at room temperature, J. Catal., V. 372, 2019, 193-200. DOI: 10.1016/j.jcat.2019.03.004.

Abstract

Acetylacetonate and 4-arylimino-2-pentanonate carbonyl complexes of rhodium(I) [Rh(RC(O)C(R')C(O)R“)(CO)₂] (1: R = Me, R' = H, R'' = Me; 2: R = Me, R' = Cl, R'' = Me; 3: R = Me, R' = H, R'' = CO₂Me; 4: R = Ph, R' = H, R'' = Me; 5: R = Ph, R' = H, R'' = Ph) and [Rh(MeC(NR''')CHC(O)Me)(CO)₂] (6: R''' = Ph; 7: R''' = 2,6-Me₂C₆H₃) were examined as hydrosilylation cross-linking catalysts at RT for the reaction of poly(dimethylsiloxane-co-ethylhydrosiloxane) copolymer with vinyl terminated poly(dimethylsiloxane) or vinyl terminated poly(dimethylsiloxane-co-styrene) copolymer. All complexes allow cross-linking of vinyl- and hydride-containing polysiloxanes and copolymers at RT without inhibitor addition. Complexes 1–7possess catalytic activity comparable to the industrially used complex of Pt⁰ and divinyltetramethyldisiloxane (Karstedt’s catalyst). 1 is the most active among the studied rhodium complexes at 1.0 × 10⁻⁴ mol⋅L⁻¹ and 1.0 × 10⁻⁵ mol⋅L⁻¹. Silicone rubbers obtained with the rhodium catalysts compared to Karstedt’s catalyst possess no visible defects (bubbles or cracks), and differed by improved elastic properties (the elongation at break increased from 160 to 255%) The activity and improved silicone rubber properties using 1 renders it one of the suitable alternatives to Karstedt’s catalyst.