Jump to main content
Jump to site search
SCHEDULED MAINTENANCE Close the message box

Maintenance work is planned for Monday 16 August 2021 from 07:00 to 23:59 (BST).

Website performance may be temporarily affected and you may not be able to access some PDFs or images. If this does happen, refreshing your web browser should resolve the issue. We apologise for any inconvenience this might cause and thank you for your patience.


Issue 48, 2014

Zinc calixarene complexes for the ring opening polymerization of cyclic esters

Author affiliations

Abstract

Reaction of Zn(C6F5)2·toluene (two equivalents) with 1,3-dipropoxy-p-tert-butyl-calix[4]arene (L1H2) led to the isolation of the complex [{Zn(C6F5)}2L1] (1), whilst similar use of Zn(Me)2 resulted in the known complex [{Zn(Me)}2L1] (2). Treatment of L1H2 with in situ prepared Zn{N(SiMe3)2}2 in refluxing toluene led to the isolation of the compound [(Na)ZnN(SiMe3)2L1] (3). The stepwise reaction of L1H2 and sodium hydride, followed by ZnCl2 and finally NaN(SiMe3)2 yielded the compound [Zn{N(SiMe3)2}2L1] (4). The reaction between three equivalents of Zn(C6F5)2·toluene and oxacalix[3]arene (L2H3) at room temperature formed the compound {[Zn(C6F5)]3L2} (5); heating of 5 in acetonitrile caused the ring opening of the parent oxacalix[3]arene and rearrangement to afford the complex [(L2)Zn6(C6F5)(R)(RH)OH]·5MeCN R = C6F5CH2-(p-tBuPhenolate-CH2OCH2–)2p-tBuPhenolate-CH2O)3− (6). The molecular structures of the new complexes 1, 3 and 6, together with that of the known complex 2, whose solid state structure has not previously been reported, have been determined. Compounds 1, 3–5 have been screened for the ring opening polymerization (ROP) of ε-caprolactone (ε-CL) and rac-lactide. Compounds featuring a Zn–C6F5 fragment were found to be poor ROP pre-catalysts as they did not react with benzyl alcohol to form an alkoxide. By contrast, compound 4, which contains a zinc silylamide linkage, was the most active of the zinc-based calix[4]arene compounds screened and was capable of ROP at ambient temperature with 65% conversion over 4 h.

Graphical abstract: Zinc calixarene complexes for the ring opening polymerization of cyclic esters

Supplementary files

Article information


Submitted
23 Jul 2014
Accepted
15 Oct 2014
First published
15 Oct 2014

Dalton Trans., 2014,43, 18001-18009
Article type
Paper
Author version available

Zinc calixarene complexes for the ring opening polymerization of cyclic esters

M. J. Walton, S. J. Lancaster, J. A. Wright, M. R. J. Elsegood and C. Redshaw, Dalton Trans., 2014, 43, 18001 DOI: 10.1039/C4DT02226B

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.


Social activity

Search articles by author

Spotlight

Advertisements