Combining Topological and Steric Constraints for the Preparation of Heteroleptic Copper(I) Complexes. Issue 38 (23rd July 2014)

• Record Type: Journal Article
• Authors: Mohankumar, Meera; Monti, Filippo; Holler, Michel; Niess, Frédéric; Delavaux‐Nicot, Béatrice; Armaroli, Nicola; Sauvage, Jean‐Pierre; Nierengarten, Jean‐François
• Is Part Of: Chemistry. Volume 20:Issue 38(2014)
• Page Start: 12083
• Page End: 12090
• Publication Date: 2014-07-23
• Subjects: Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.201402429
• Languages: English
• ISSNs: 0947-6539

Abstract

<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p>Heteroleptic copper(I) complexes have been prepared from a macrocyclic ligand incorporating a 2, 9‐diphenyl‐1, 10‐phenanthroline subunit (<bold>M30</bold>) and two bis‐phosphines, namely bis[(2‐diphenylphosphino)phenyl] ether (POP) and 1, 3‐bis(diphenylphosphino)propane (dppp). In both cases, the diphenylphosphino moieties of the PP ligand are too bulky to pass through the 30‐membered ring of <bold>M30</bold> during the coordination process, hence the formation of <italic>C</italic><sub>2<italic>v</italic></sub>‐symmetrical pseudo‐rotaxanes is prevented. When POP is used, X‐ray crystal structure analysis shows the formation of a highly distorted [Cu(<bold>M30</bold>)(POP)]<sup>+</sup> complex in which the POP ligand is only partially threaded through the <bold>M30</bold> unit. This compound is poorly stable as the Cu<sup>I</sup> cation is not in a favorable coordination environment due to steric constraints. By contrast, in the case of dppp, the bis‐phosphine ligand undergoes both steric and topological constraints and adopts a nonchelating coordination mode to generate [Cu<sub>2</sub>(<bold>M30</bold>)<sub>2</sub>(μ‐dppp)](BF<sub>4</sub>)<sub>2</sub>. This compound exhibits metal‐to‐ligand charge transfer (MLCT) emission characterized by a very large Stokes' shift (≈200 nm) that is not attributed to a dramatic structural distortion between the ground and the emitting states but to very weak MLCT absorption transitions at longer wavelengths. Accordingly, [Cu<sub>2</sub>(<bold>M30</bold>)<sub>2</sub>(μ‐dppp)](BF<sub>4</sub>)<sub>2</sub> shows unusually high luminescence quantum yields for Cu<sup>I</sup> complexes, both in solution and in the solid state (0.5 and 7 %, respectively).</p> </abstract>