Tannaz Ebrahimi

Dinucleating Ligand Platforms Supporting Indium and Zinc Catalysts for Cyclic Ester Polymerization

The synthesis of the first alkoxide-bridged indium complex supported by a chiral dinucleating ligand platform (1), along with its zinc analogue (2), is reported. Both complexes are synthesized in a one-pot reaction starting from a chiral dinucleating bis(diamino)phenolate ligand platform, sodium ethoxide, and respective metal salts. The dinucleating indium analogue (7) based on an achiral ligand backbone is also reported. Indium complexes bearing either the chiral or achiral ligand catalyze the ring-opening polymerization of racemic lactide (rac-LA) to afford highly heterotactic poly(lactic acid) (PLA; Pr > 0.85). The indium complex bearing an achiral ligand affords essentially atactic PLA from meso-LA. The role of the dinucleating ligand structure in catalyst synthesis and polymerization activity is discussed.

The Role of Nitrogen Donors in Zinc Catalysts for Lactide Ring-Opening Polymerization

The electronic effects of nitrogen donors in zinc catalysts for ring-opening polymerization of cyclic esters were investigated. Alkyl and benzyloxy zinc complexes supported by tridentate diamino- and aminoimino phenolate ligands were synthesized, and their solid-state and solution structures characterized. The solution-state structures showed that the alkyl complexes are mononuclear, while the alkoxy complexes are dimeric with the ligands coordinated with different denticities depending on the nature of the ligand donors. The catalytic activities of these compounds toward the ring-opening polymerization of racemic lactide were studied and showed that catalysts with secondary and imine nitrogen donors are more active than analogues with tertiary amines.

Coupling of Epoxides and Lactones by Cationic Indium Catalysts To Form Functionalized Spiro-Orthoesters

We prepared a cationic indium catalyst for the conversion of epoxides and lactones into spiro‐orthoesters (SOEs), a family of expanding monomers. The cationic indium alkyl complexes [(NNiO)In(CH2SiMe3)(S)][B{3,5‐(CF3)2C6H3}4] (2⋅Solv; H(NNiO)=2,4‐dicumyl‐6‐({[2‐(dimethylamino)cyclohexyl]imino}methyl)phenol, S=OEt2 or THF) were synthesized and fully characterized. The reaction of ϵ‐caprolactone with 1,2‐epoxy‐7‐octene resulted in the formation of 2‐(hex‐5‐en‐1‐yl)‐1,4,6‐trioxaspiro[4.6]undecane (SOE1) with full conversion of both components. We extended the substrate scope to five‐ and six‐membered lactones as well as to a number of functionalized epoxides. The reactivity of the SOEs was explored.

CCDC 1492149: Experimental Crystal Structure Determination

Related Article: Tannaz Ebrahimi, Dinesh Aluthge, Savvas Hatzikiriakos, Parisa Mehrkhodavandi|2016|Macromolecules|49|8812|doi:10.1021/acs.macromol.6b01908

CCDC 1492151: Experimental Crystal Structure Determination

Related Article: Tannaz Ebrahimi, Dinesh Aluthge, Savvas Hatzikiriakos, Parisa Mehrkhodavandi|2016|Macromolecules|49|8812|doi:10.1021/acs.macromol.6b01908

CCDC 1492150: Experimental Crystal Structure Determination

Related Article: Tannaz Ebrahimi, Dinesh Aluthge, Savvas Hatzikiriakos, Parisa Mehrkhodavandi|2016|Macromolecules|49|8812|doi:10.1021/acs.macromol.6b01908

CCDC 1492148: Experimental Crystal Structure Determination

Related Article: Tannaz Ebrahimi, Dinesh Aluthge, Savvas Hatzikiriakos, Parisa Mehrkhodavandi|2016|Macromolecules|49|8812|doi:10.1021/acs.macromol.6b01908