Controlling Lanthanide Exchange in Triple‐Stranded Helicates: A Way to Optimize Molecular Light‐Upconversion. Issue 46 (16th October 2017)

• Record Type: Journal Article
• Authors: Zare, Davood; Suffren, Yan; Nozary, Homayoun; Hauser, Andreas; Piguet, Claude
• Is Part Of: Angewandte Chemie international edition. Volume 56:Issue 46(2017)
• Page Start: 14612
• Page End: 14617
• Publication Date: 2017-10-16
• Subjects: helicates -- heterometallic complexes -- keystone mechanism -- kinetics -- molecular upconversion; Chemistry -- Periodicals; 540
• DOI: 10.1002/anie.201709156
• Languages: English
• ISSNs: 1433-7851

Abstract

Abstract: The kinetic lability of hexadentate gallium‐based tripods is sufficient to ensure thermodynamic self‐assembly of luminescent heterodimetallic [GaLn(L3 )3 ] 6+ helicates on the hour time scale, where Ln is a trivalent 4f‐block cation. The inertness is, however, large enough for preserving the triple‐helical structure when [GaLn(L3 )3 ] 6+ is exposed to lanthanide exchange. The connection of a second gallium‐based tripod further slows down the exchange processes to such an extent that spectroscopically active [CrErCr(L4 )3 ] 9+ can be diluted into closed‐shell [GaYGa(L4 )3 ] 9+ matrices without metal scrambling. This feature is exploited for pushing molecular‐based energy‐transfer upconversion (ETU) at room temperature. Abstract : Inert noncovalent [GaL 3 ] 3+ ions promote an unprecedented keystone mechanism for the capture/release of labile trivalent lanthanides on hour time scales. The cooperative operation of two [GaL 3 ] 3+ tripods pushes the limit of inertness to over months, which makes these new materials compatible with the preparation of solid‐state solutions displaying molecular‐based energy‐transfer upconversion at room temperature.