More Like this

1. Investigation of a zirconium compound for redox switchable ring opening polymerization

   https://doi.org/10.1039/C9DT00212J  

   Dai, Ruxi; Diaconescu, Paula L. (February 2019, Dalton Transactions)

   A zirconium compound, (salfen)Zr(O i Pr) 2 (salfen = N , N ′-bis(2,4-di- tert -butylphenoxy)-1,1′-ferrocenediimine), was tested as a redox switchable catalyst for the ring opening polymerization of cyclic esters and epoxides. Different activities were observed in the reduced and oxidized state, and an orthogonal switch on monomer activities could be achieved. Diblock and triblock copolymers were synthesized using an in situ redox switch of the catalyst oxidation state. 

   more » « less
2. Hydrogen atom abstraction as a synthetic route to a square planar Co ^II complex with a redox-active tetradentate PNNP ligand

   https://doi.org/10.1039/D4SC03364G  

   Miller, Justin D; Walsh, Mitchell M; Lee, Kyounghoon; Moore, Curtis E; Thomas, Christine M (January 2024, Chemical Science)

   Dehydrogenation of the ligand backbone of a bis(amido)bis(phosphine) Co complex is achieved through hydrogen atom abstraction. The new unsaturated backbone of the tetradentate ligand renders the ligand in the resulting Co complex redox-active. 

   more » « less
3. An Electrochemical Approach to Aluminum‐Based Redox Switchable Ring Opening Polymerization

   https://doi.org/10.1002/cctc.202401534  

   Hern, Zachary_C; Lai, Amy; Massad, Ramzi_N; Diaconescu, Paula_L (April 2025, ChemCatChem)

   Abstract We report the electrochemically switchable reactivity of (salfen)Al(OⁱPr) (salfen = 1,1′‐di(2,4‐bis‐tert‐butyl‐salicylimino)ferrocene) toward the ring‐opening polymerization of various cyclic esters, ethers, and carbonates. Using a recently developed electrochemical system comprised of an H‐cell and a glassy carbon working electrode, an applied potential can alternate between the two redox states of the catalyst and alter monomer incorporation during ring‐opening polymerization. We discuss differences in activity and control under electrochemical conditions compared to previously studied chemical redox methods and discuss the necessity of a redox switch during certain copolymerization reactions. 

   more » « less
4. Host–Guest Interactions and Redox Activity in Layered Conductive Metal–Organic Frameworks

   https://doi.org/10.1021/acs.chemmater.0c01007  

   Stolz, Robert M.; Mahdavi-Shakib, Akbar; Frederick, Brian G.; Mirica, Katherine A. (July 2020, Chemistry of Materials)

   This paper describes the identification of specific host–guest interactions between basic gases (NH3, CD3CN, and pyridine) and four topologically similar 2-dimensional (2D) metal–organic frameworks (MOFs) comprising copper and nickel bis(diimine) and bis(dioxolene) linkages of triphenylene-based ligands using diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), X-ray photoelectron spectroscopy (XPS), electron paramagnetic resonance spectroscopy (EPR), and powder X-ray diffraction (PXRD). This contribution demonstrates that synthetic bottom-up control over surface chemistry of layered MOFs can be used to impart Lewis acidity or a mixture of Brønsted and Lewis acidities, through the choice of organic ligand and metal cation. This work also distinguishes differences in redox activity within this class of MOFs that contribute to their ability to promote electronic transduction of intermolecular interactions. Future design of structure–function relationships within multifunctional 2D MOFs will benefit from the insights this work provides. 

   more » « less
5. A switchable dimeric yttrium complex and its three catalytic states in ring opening polymerization

   https://doi.org/10.1039/d0qi01479f  

   Deng, Shijie; Diaconescu, Paula L. (April 2021, Inorganic Chemistry Frontiers)

   null (Ed.)

   A dimeric yttrium phenoxide complex supported by a ferrocene Schiff base ligand, [(salfen)Y(OPh)] 2 (salfen = ( N,N ′-bis(2,4-di- tert -butylphenoxy)-1,1′-ferrocenediimine), was synthesized and characterized. According to electrochemical studies and 1 H NMR spectroscopy, [(salfen)Y(OPh)] 2 can be oxidized in a stepwise fashion to access three oxidation states. The catalytic activity of the three states toward the ring opening polymerization of cyclic esters and epoxides was investigated. The activity toward cyclic esters decreases upon oxidation while the opposite trend was observed in epoxide polymerization. Block copolymer syntheses using a redox switch were also performed. 

   more » « less