Synthesis, crystal structure, and cytotoxicity studies of titanacalix[4 and 8]arene complexes

David M. Miller-Shakesby, Shubhanchi Nigam, David L. Hughes, Enrique Lopez-Estelles, Mark R. J. Elsegood, Christopher J. Cawthorne, Stephen J. Archibald, Carl Redshaw

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Reaction of 5,11,17,23-tetra-tert-butyl-dihydroxy-26,28-bis(2-pentoxy)calix[4]arene (L(OH)2(Opentyl)2) with [TiCl4] afforded the dichlorotitanoacalix[4]arene complex [TiCl2L(O)2(Opentyl)2] (1) in good yield. Hydrolysis of 1 led to the isolation of the complex {[TiL(O)3(Opentyl)]2(μ-OH)(μ-Cl)} (2). Reaction of 5,11,17,23,29,35,41,47-p-tert-butyl-49,50,51,52,53,54,55,56-octapropoxycalix[8]arene (L′(Opropyl)8) with [TiCl4] in refluxing toluene afforded, following work-up, a 35:65 mixture (3) of the complex [Ti(NCMe)Cl]2[TiCl(μ-O)]2L′ and the silicone grease derived complex [Ti(NCMe)Cl]2[Ti(μ-O)]2[OSi(CH3)2OSi(CH3)2O]L′ in which the grease replaces two chloride ligands. The molecular structures of 1·2MeCN, 2·7MeCN, and 3·10MeCN have been determined. The complexes were studied using in vitro cell assays and were found to have CC50 values in the range 111-186 μM, i.e. they have low toxicity.

Original languageEnglish
Pages (from-to)8992-8999
Number of pages8
JournalDalton Transactions
Issue number27
Early online date12 Jun 2018
Publication statusPublished - 21 Jul 2018

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