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Highly selective and immortal magnesium calixarene complexes for the ring-opening polymerization of rac-lactide

Lancaster, Simon J.; Walton, Mark J.; Redshaw, Carl


Simon J. Lancaster

Mark J. Walton

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Professor Carl Redshaw
Professor of Inorganic Materials Chemistry and REF Lead for Chemistry


The lithiation of 1,3-dipropoxy-p-tert-butylcalix[4]arene (LH₂) followed by reaction with nBuMgBr in THF resulted in the formation of the hetero-bimetallic complex [Li(THF)Mg(nBu)L] (1). By contrast, the treatment of tripropoxy-p-tert-butylcalix[4]arene (L′H) with nBu₂Mg afforded a mononuclear complex [L′Mg(nBu)] (2). Single-crystal XRD studies revealed that in both structures the calix[4]arene adopts a cone conformation, and a Li cation resides in the cavity for 1. Both 1 and 2 were active for the ring-opening polymerisation of rac-lactide. Compound 2 displayed not only exceptional activity (100 equivalents, 3 min, 92 % conversion, BnOH, room temperature) but also high selectivity (probability to form an r dyad, Pᵣ=0.85) and exhibited an immortal character in THF. Surprisingly, compound 2 also showed isotactic bias (Pr=0.30–0.36) and an immortal character if toluene was employed as the solvent; 2 D J-resolved ¹H NMR spectroscopy was employed for the assignment of the stereoselectivity.


Walton, M. J., Lancaster, S. J., & Redshaw, C. (2014). Highly selective and immortal magnesium calixarene complexes for the ring-opening polymerization of rac-lactide. ChemCatChem, 6(7), 1892-1898.

Acceptance Date Feb 12, 2014
Online Publication Date May 21, 2014
Publication Date 2014-07
Deposit Date Apr 22, 2015
Publicly Available Date Apr 22, 2015
Journal ChemCatChem
Print ISSN 1867-3880
Electronic ISSN 1867-3899
Publisher Wiley
Peer Reviewed Peer Reviewed
Volume 6
Issue 7
Pages 1892-1898
Keywords Calixarenes, Heterometallic complexes, Magnesium, NMR spectroscopy, Ring-opening polymerization
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Additional Information This is the peer reviewed version of the following article: ChemCatChem, 2014, v.6, issue 7, which has been published in final form at This article may be used for non-commercial purposes in accordance With Wiley-VCH Terms and Conditions for self-archiving.


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