500716-28-9Relevant articles and documents
Unimolecular Anion-Binding Catalysts for Selective Ring-Opening Polymerization of O-carboxyanhydrides
Li, Maosheng,Zhang, Shuai,Zhang, Xiaoyong,Wang, Yanchao,Chen, Jinlong,Tao, Youhua,Wang, Xianhong
, p. 6003 - 6012 (2021/02/01)
Anion-binding can regulate anion transport in chloride channels through dynamic non-covalent interactions, which gives insights into the designing of new organocatalytic transformations but is surprisingly unexplored in polymerization catalysis. Herein, we describe an effective unimolecular anion-binding organocatalysis where 4-(dimethylamino)pyridine is anchored to a thiourea for ring-opening polymerization of O-carboxyanhydrides (OCAs) to furnish highly isotactic poly(phenyllactic acid) (Ph-PLA) with molecular weight (MW) up to 150.0 kDa, which well addresses the formidable challenge of synthesizing high MW stereoregular polyesters. Calculations and experimental studies indicate a dynamic cooperative anion-binding mechanism, where the dynamic anion-binding interaction of thiourea moiety to propagating species facilitates efficient chain propagation and the synergetic decarboxylation retains high selectivity for OCA ring-opening over side reactions (such as cyclization, epimerization, and transesterification).
Synthesis and Characterization of the Most Active Copper ATRP Catalyst Based on Tris[(4-dimethylaminopyridyl)methyl]amine
Ribelli, Thomas G.,Fantin, Marco,Daran, Jean-Claude,Augustine, Kyle F.,Poli, Rinaldo,Matyjaszewski, Krzysztof
supporting information, p. 1525 - 1534 (2018/02/09)
The tris[(4-dimethylaminopyridyl)methyl]amine (TPMANMe2) as a ligand for copper-catalyzed atom transfer radical polymerization (ATRP) is reported. In solution, the [CuI(TPMANMe2)Br] complex shows fluxionality by variable-temperature NMR, indicating rapid ligand exchange. In the solid state, the [CuII(TPMANMe2)Br][Br] complex exhibits a slightly distorted trigonal bipyramidal geometry (τ = 0.89). The UV-vis spectrum of [CuII(TPMANMe2)Br]+ salts is similar to those of other pyridine-based ATRP catalysts. Electrochemical studies of [Cu(TPMANMe2)]2+ and [Cu(TPMANMe2)Br]+ showed highly negative redox potentials (E1/2 = -302 and -554 mV vs SCE, respectively), suggesting unprecedented ATRP catalytic activity. Cyclic voltammetry (CV) in the presence of methyl 2-bromopropionate (MBrP; acrylate mimic) was used to determine activation rate constant ka = 1.1 × 106 M-1 s-1, confirming the extremely high catalyst reactivity. In the presence of the more active ethyl α-bromoisobutyrate (EBiB; methacrylate mimic), total catalysis was observed and an activation rate constant ka = 7.2 × 106 M-1 s-1 was calculated with values of KATRP ≈ 1. ATRP of methyl acrylate showed a well-controlled polymerization using as little as 10 ppm of catalyst relative to monomer, while side reactions such as CuI-catalyzed radical termination (CRT) could be suppressed due to the low concentration of L/CuI at a steady state.
