Chemoselective guest-triggered shaping of a polynuclear CuII calix[6]complex into a molecular host. Issue 44 (25th October 2017)

• Record Type: Journal Article
• Authors: Richard, Sarah; Le Duc, Gaëtan; Le Poul, Nicolas; Le Mest, Yves; Reinaud, Olivia; Rebilly, Jean-Noël
• Is Part Of: Dalton transactions. Volume 46:Issue 44(2017)
• Page Start: 15249
• Page End: 15256
• Publication Date: 2017-10-25
• Subjects: Chemistry, Inorganic -- Periodicals; Chemistry, Physical and theoretical -- Periodicals; Chemistry, Inorganic -- Periodicals; 546.05
• DOI: 10.1039/c7dt03375c
• Languages: English
• ISSNs: 1477-9226

Abstract

Abstract : A molecular host is selectively shaped by amines to yield a tetranuclear system where the guest faces three Cu II complexes. Abstract : A new calix[6]arene scaffold bearing a tris-imidazole binding site at the small rim and three tetradentate aza ligands at the large rim was synthesized. The system binds three Cu II ions at the large rim sites and is unable to bind a fourth one, which remains in solution. The charge repulsion between the complexes, together with the flexibility of the scaffold, disorganizes the small rim site for binding and prevents its use for host–guest studies. Although the presence of MeCN or DMF guests does not alter this state, the addition of a heptylamine guest, which further displays Brønsted basicity, restores its receptor ability by stabilizing the extra Cu II ion at the tris-imidazole site with concomitant guest encapsulation and binding of an exo hydroxo ligand. This chemoselective nuclearity switch yields a tetranuclear complex in which the guest backbone is preorganized in front of three potentially reactive Cu(ii ) complexes, reminiscent of polynuclear Cu II enzyme active sites.