title: Substitution effect on phenalenyl backbone in the rate of organozinc catalyzed ROP of cyclic esters.
abstract: A series of zinc complexes (1-6) supported by substituted phenalenyl ligands was synthesized by reacting the phenalenyl ligands with diethyl zinc under ethane evolution. The solid state structures of these complexes (1-6) were determined by single crystal X-ray crystallography. Furthermore, the organozinc complexes (4-6) were tested for the polymerization of cyclic esters as efficient catalysts for the ring-opening polymerization of ε-caprolactone (ε-CL) and rac-lactide (rac-LA) in the presence of benzyl alcohol (BnOH) as initiator. Complex 4 exhibited remarkably higher rate of polymerization under identical reaction condition than complexes 5 and 6. The polymerization of ε-caprolactone produced polymer with narrow polydispersities (M(w)/M(n) = 1.06 to 1.22), while the polymerization of lactide monomers afforded polylactides with polydispersity values ranging from 1.08 to 1.8. The kinetic experiments unravelled a controlled polymerization. The controlled nature of polymerization was further utilized in the preparation of the block copolymer poly(CL)block-poly(rac-LA).
authors.affiliation: Department of Chemical Sciences, Indian Institute of Science Education and Research-Kolkata, Mohanpur-741252, India.
authors.forename: Tamal K
authors.initials: TK
authors.lastname: Sen
authors.forename: Arup
authors.initials: A
authors.lastname: Mukherjee
authors.forename: Arghya
authors.initials: A
authors.lastname: Modak
authors.forename: Swadhin K
authors.initials: SK
authors.lastname: Mandal
authors.forename: Debasis
authors.initials: D
authors.lastname: Koley
mesh_terms: D019905:Benzyl Alcohol / Q000737:chemistry; D002208:Caproates / Q000737:chemistry; D002384:Catalysis; D056831:Coordination Complexes / Q000138:chemical synthesis / Q000737:chemistry*; D018360:Crystallography, X-Ray; D004146:Dioxanes / Q000737:chemistry; D004952:Esters; D007783:Lactones / Q000737:chemistry; D008968:Molecular Conformation; D058105:Polymerization; D015032:Zinc / Q000737:chemistry*
chemical_list: D002208:Caproates; D056831:Coordination Complexes; D004146:Dioxanes; D004952:Esters; D007783:Lactones; C121056:caprolactone; C091880:dilactide; D015032:Zinc; D019905:Benzyl Alcohol