title: Solvent-Free Lipase-Catalyzed Synthesis: Unique Properties of Enantiopure D- and L- Polyaspartates and Their Complexation.
abstract: Amino acids are attractive monomers for the large-scale preparation of chiral polyamides. For enzymatic polymerization of amino acids using protease in aqueous environment as the catalysis system, one main restriction is oligomer formation, usually along with other displayed advantages. Herein we developed an efficient solvent-free lipase-catalyzed polymerization of diethyl D- or L-aspartate, providing chiral D- and L-polyaspartates with an average degree of polymerization (DPavg) up to 60 and having about 96% β-linkages. Additionally, their distinct chemical and physical properties were characterized by circular dichroism (CD) spectra, X-ray powder diffraction (XRD), microscopic observation, and thermal analysis. Poly(β-D-AspEt) and Poly(β-L-AspEt) showed vertically mirrored negative and positive CD signals, high crystallinity, and entirely different microscopic morphology. They are thermal stable while having different decomposition (Td), melting (Tm), and cold crystallization temperatures (Tcc), respectively. Our results also showed that the complexation of enantiopure D- and L-polyaspartates was not stereocomplex but homocomplex.
authors.affiliation: Department of Chemistry, Zhejiang University , Hangzhou 310027, People's Republic of China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Department of Chemistry, Zhejiang University , Hangzhou 310027, People's Republic of China.
authors.forename: Bo
authors.initials: B
authors.lastname: Xia
authors.affiliation: Department of Chemistry, Zhejiang University , Hangzhou 310027, People's Republic of China.
authors.forename: Yanyan
authors.initials: Y
authors.lastname: Li
authors.affiliation: Department of Chemistry, Zhejiang University , Hangzhou 310027, People's Republic of China.
authors.forename: Yuanyuan
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Department of Chemistry, Zhejiang University , Hangzhou 310027, People's Republic of China.
authors.forename: Xianfu
authors.initials: X
authors.lastname: Lin
authors.affiliation: Department of Chemistry, Zhejiang University , Hangzhou 310027, People's Republic of China.
authors.forename: Qi
authors.initials: Q
authors.lastname: Wu
mesh_terms: D001224:Aspartic Acid / Q000737:chemistry*; D002384:Catalysis; D002942:Circular Dichroism / Q000379:methods; D008049:Lipase / Q000737:chemistry / Q000378:metabolism*; D009757:Nylons / Q000138:chemical synthesis*; D010447:Peptide Hydrolases / Q000378:metabolism*; D010455:Peptides / Q000138:chemical synthesis* / Q000737:chemistry*; D058105:Polymerization; D011108:Polymers / Q000138:chemical synthesis / Q000737:chemistry; D012997:Solvents / Q000737:chemistry; D014961:X-Ray Diffraction / Q000379:methods
chemical_list: D009757:Nylons; D010455:Peptides; D011108:Polymers; D012997:Solvents; C017645:polyaspartate; D001224:Aspartic Acid; D008049:Lipase; D010447:Peptide Hydrolases