Date/Time Date(s) - 23/09/20211:30 pm - 2:30 pm
Title: Te…O Chalcogen Bonding in Supramolecular Chemistry
Date: Thursday, September 23, 2021
Time: 1:30-2:30
Zoom link- contact macchem@mcmaster.ca
Host: Dr. Ignacio Vargas-Baca
Abstract: Iso-tellurazole N-oxides (1, 2Te)have been hailed as “particularly impressive,” “fascinating and promising”1compounds in the fast-expanding area2 of chalcogen bonding.Iso-tellurazole N-oxides are heterocycles that spontaneously assemblesupramolecular structures through reversible Te…Ointeractions. In solution, their macrocyclic tetramers (14)and hexamers (16) exist in equilibrium. These rings as wellas supramolecular polymers have been authenticated by single-crystal X-raydiffraction. Despite the reversibility of the Te…O link, themacrocycles display properties of typical covalent macrocycles, being able tocoordinate metal ions, host small molecules, and form adducts with fullerenes.3–7They are stable to partial or full tellurium halogenation and unreactive toLewis bases.8 However, they are readily cleaved by Bronsted andLewis acids.9,10
We have recently extended the supramolecular chemistryof iso-tellurazoles to a new family of building blocks (3o,m,p)designed by formal insertion of an aromatic bridge between the nitrogen andoxygen atoms of 1.11 In solution, 3o,m,pparallel the behaviour of 1. Crystallization enabled the isolation of eitherpolymeric or macrocyclic aggregates. Among the latter, 3oassembled a calixarene-like trimer while 3p built amacrocyclic tetramer akin to a molecular square.
Reference
(1) Gleiter, R.; Haberhauer, G.; Werz,D. B.; Rominger, F.; Bleiholder, C. Chem. Rev. 2018, 118,2010–2041.
(2) Ho, P. C.; Wang, J. Z.; Meloni, F.;Vargas-Baca, I. Coord. Chem. Rev. 2020, 422, 213464.
(3) Kübel, J.; Elder, P. J. W.; Jenkins, H. A.; Vargas-Baca, I. Dalton Trans.2010, 39, 11126–11128.
(4) Ho, P. C.; Szydlowski, P.; Sinclair,J.; Elder, P. J. W.; Kübel, J.; Gendy, C.; Lee, L. M.; Jenkins, H.; Britten, J.F.; Morim, D. R.; Vargas-Baca, I. Nat. Commun. 2016, 7,11299.
(5) Ho, P. C.; Rafique, J.; Lee, J.;Lee, L. M.; Jenkins, H. A.; Britten, J. F.; Braga, A. L.; Vargas-Baca, I. DaltonTrans. 2017, 46, 6570–6579.
(6) Ho, P. C.; Bui, R.; Cevallos, A.;Sequeira, S.; Britten, J. F.; Vargas-Baca, I. Dalton Trans. 2019,48, 4879–4886.
(7) Wang, J.; Ho, P. C.; Britten, J. F.;Tomassetti, V.; Vargas-Baca, I. New J. Chem. 2019, 43,12601–12608.
(8) Ho, P. C.; Lomax, J.; Tomassetti,V.; Britten, J. F.; Vargas-Baca, I. Chem. Eur. J. 2021, 27,10849–10853.
(9) Ho, P. C.; Lee, L. M.; Jenkins, H.;Britten, J. F.; Vargas-Baca, I. Can. J. Chem. 2016, 94,453–457.
(10) Ho, P.C.; Jenkins, H. A.; Britten, J. F.; Vargas-Baca, I. Faraday Discuss. 2017,203, 187–199.
(11) Ho, P. C.; Tomassetti, V.; Britten, J. F.; Vargas-Baca, I. Submitted.