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Issue 13, 2019
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Dialkylaluminum 2-substituted 6,6-dimethylcyclopentylpyridin-7-oxylates toward structural-differentiation of the ring-opening polymerization of ε-caprolactone and L-lactides

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Abstract

Herein, a series of dialkylaluminum 2-substituted 6,6-dimethylcyclopentyl pyridin-7-oxylates Al1–Al7 were synthesized and characterized by 1H- and 13C-NMR spectroscopy and elemental analysis. The molecular structure of Al3 was proven to be a dimer of an aluminum complex. These aluminum complexes could efficiently initiate the ring-opening polymerization (ROP) of ε-caprolactone (CL), and the structural differentiations of the resultant PCL were strongly dependent on the amount of BnOH (PhCH2OH) used. In the absence of BnOH, the resultant PCL showed a cyclic structure, whereas BnO-capped linear PCL was obtained in the presence of >2.0 equivalents of BnOH; the resultant PCL was a mixture of linear and cyclic PCLs in the presence of 1.0 equivalent of BnOH. Moreover, these aluminum complexes exhibited high efficiency towards the ROP of L-lactide (LLA); however, the activities were lower than those for the ROP of ε-CL. Without BnOH, the resultant PLLA showed a highly linear structure with the alkyl-end group from aluminum complexes; on the other hand, PLLA displayed a major cyclic structure and minor BnO-capped linear PLLA if 1.0 equivalent of BnOH was employed, and the percentage of BnO-capped linear PLLA was increased by increasing the amount of BnOH.

Graphical abstract: Dialkylaluminum 2-substituted 6,6-dimethylcyclopentylpyridin-7-oxylates toward structural-differentiation of the ring-opening polymerization of ε-caprolactone and l-lactides

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Publication details

The article was received on 10 Jan 2019, accepted on 13 Feb 2019 and first published on 13 Feb 2019


Article type: Paper
DOI: 10.1039/C9DT00137A
Citation: Dalton Trans., 2019,48, 4157-4167

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    Dialkylaluminum 2-substituted 6,6-dimethylcyclopentylpyridin-7-oxylates toward structural-differentiation of the ring-opening polymerization of ε-caprolactone and L-lactides

    D. Zhu, L. Guo, W. Zhang, X. Hu, K. Nomura, A. Vignesh, X. Hao, Q. Zhang and W. Sun, Dalton Trans., 2019, 48, 4157
    DOI: 10.1039/C9DT00137A

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