An electrochemically controlled synthesis of multiblock copolymers by alternating the redox states of (salfan)Zr-(O t Bu) 2 (salfan = 1,1′-di(2-tert-butyl-6-N-methylmethylenephenoxy)ferrocene) is reported. Aided by electrochemistry with a glassy carbon working electrode, an in situ potential switch alters the catalyst's oxidation state and its subsequent monomer (Llactide, β-butyrolactone, or cyclohexene oxide) selectivity in one pot. Various multiblock copolymers were prepared, including an ABAB tetrablock copolymer, poly(cyclohexene oxide-b-lactide-bcyclohexene oxide-b-lactide), and an ABC triblock copolymer, poly(hydroxybutyrate-b-cyclohexene oxide-b-lactide). The polymers produced using this technique are similar to those produced via a chemical redox reagent method, displaying moderately narrow dispersities (1.1−1.5) and molecular weights ranging from 7 to 26 kDa.
An aluminum(III) iso‐propoxide complex supported by salfen (1, salfen=1,1′‐di(2,4‐bis‐tert‐butyl‐salicylimino)ferrocene) was synthesized and characterized. Compound 1 can be reversibly oxidized and reduced, and both redox species were surveyed as ring‐opening polymerization catalysts for cyclic esters and cyclohexene oxide. Based on the observed reactivity behavior, 1 could be used as a redox‐switchable catalyst for the formation of AB and ABC type di‐ and triblock copolymers of lactide, cyclohexene oxide, and trimethylene carbonate.
We introduce a new unsymmetric ligand, PDIpCy (PDI = pyridyldiimine; Cy = cyclam), that offers two distinct, noncoupled coordination sites. A series of homo- and heterobimetallic complexes, [Zn(PDIpCy)(THF)(OTf)] (1; THF = tetrahydrofuran and OTf = triflate), [Ni(PDIpCy)(THF)(OTf)](OTf) (2), and [NiZn(PDIpCy)(THF)(OTf)] (3), are described. The one-electron-reduced compounds, [Zn(PDIpCy)(OTF)] (4), [Ni(PDIpCy)(OTf)](OTf) (5), and [NiZn(PDIpCy)(OTf)] (6), were isolated, and their electronic structures were characterized. The reduced compounds are charge-separated species, with electron storage at either the PDI ligand (4) or at the PDI-bound metal ion (5 and 6).
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.