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Trinuclear zinc calix[4]arenes: synthesis, structure, and ring opening polymerization studies

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posted on 2022-08-22, 09:50 authored by Tian Xing, Josef Frese, Max Derbyshire, Mollie A Glenister, Mark ElsegoodMark Elsegood, Carl Redshaw

The trinuclear zinc calix[4]arene complexes [Zn3(O2CCH3)2(L(O)2(OMe)2)2·xMeCN (x = 7.5, 1; x = 6, 1′), [Zn3(O2CCH3)2(L(O)2(OnPr)2)2·5MeCN (2·5MeCN), [Zn3(OEt)2(L(O)2(OMe)2)2]·4MeCN (3·4MeCN), [Zn3(OEt)2(L(Opentyl)2)2]·4.5MeCN (4·4.5MeCN) and [Zn3(OH)2(L(O)2(On-pentyl)2]·8MeCN (5·8MeCN) have been isolated from reaction of [(ZnEt)2(L(O)2(OR)2)2] (L(OH)2(OR)2 = 1,3-dialkoxy-4-tert-butylcalix[4]arene; R = methyl, n-propyl or pentyl) and the reagents acetic acid, ethanol, and presumed adventitious water, respectively. Attempts to make 5via a controlled hydrolysis led only to the isolation of polymorphs of (L(OH)2(Opentyl)2·MeCN. Reaction of [Zn(C6F5)2] with L(OH)2(Opentyl)2, in the presence of K2CO3, led to the isolation of the complex [Zn6(L(On-pentyl))2(OH)3(C6F5)3(NCMe)3]·3MeCN (6·3MeCN). The molecular structures of 1–6 reveal they all contain a near linear (163 to 179°) Zn3 motif. In 1–5, a central tetrahedral Zn centre is flanked by trigonal bipyramidal Zn centres, whilst in 6, for the linear Zn3 unit, a central distorted octahedral zinc centre is flanked by trigonal planar and a tetrahedral zinc centres. Screening for the ring opening polymerization (ROP) of ε-caprolactone at 90 °C revealed that they are active with moderate to good conversion affording low to medium molecular weight products with at least two series of ions. For comparative studies, the trinuclear aminebis(phenolate) complex [Zn3(Oi-Pr)2L/] (L/ = n-propylamine-N,N-bis(2-methylene-4,6-di-tert-butylphenolate) I was prepared. Kinetics revealed the rate order I > 4 > 6 ≈ 2 ≈ 1 > 3.

Funding

Evolving a circular plastics ecomony

Engineering and Physical Sciences Research Council

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History

School

  • Science

Department

  • Chemistry

Published in

Dalton Transactions

Volume

51

Issue

31

Pages

11776-11786

Publisher

Royal Society of Chemistry

Version

  • VoR (Version of Record)

Rights holder

Journal is © The Royal Society of Chemistry

Publisher statement

This is an Open Access Article. It is published by Royal Society of Chemistry under the Creative Commons Attribution 3.0 Unported Licence (CC BY). Full details of this licence are available at: https://creativecommons.org/licenses/by/3.0/

Acceptance date

2022-07-11

Publication date

2022-07-11

Copyright date

2022

ISSN

1477-9226

eISSN

1477-9234

Language

  • en

Depositor

Dr Mark Elsegood. Deposit date: 19 July 2022

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