1, 2, 4, 5‐Tetrakis(tetramethylguanidino)‐3, 6‐diethynyl‐benzenes: Fluorescent Probes, Redox‐Active Ligands and Strong Organic Electron Donors. Issue 45 (10th July 2020)

• Record Type: Journal Article
• Authors: Wagner, Conrad; Kreis, Franka; Popp, Dennis; Hübner, Olaf; Kaifer, Elisabeth; Himmel, Hans‐Jörg
• Is Part Of: Chemistry. Volume 26:Issue 45(2020)
• Page Start: 10336
• Page End: 10347
• Publication Date: 2020-07-10
• Subjects: copper -- guanidine -- organic electron donors -- redox chemistry -- redox-active ligand; Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.202001557
• Languages: English
• ISSNs: 0947-6539

Abstract

Abstract: In this work, the change of reactivity induced by the introduction of two para ‐ethynyl substituents (CCSi( i Pr)3 or CCH) to the organic electron‐donor 1, 2, 4, 5‐tetrakis(tetramethylguanidino)‐benzene is evaluated. The redox‐properties and redox‐state dependent fluorescence are evaluated, and dinuclear Cu I and Cu II complexes synthesized. The Lewis‐acidic B(C6 F5 )3 substitutes the proton of the ethynyl −CCH groups to give new anionic −CCB(C6 F5 )3 − substituents, leading eventually to a novel dianionic strong electron donor in its diprotonated form. Its two‐electron oxidation with dioxygen in the presence of a copper catalyst yields the first redox‐active guanidine that is neutral (instead of cationic) in its oxidized form. Abstract : The diverse chemistry of redox‐active guanidines is enriched by compounds with alkynyl groups, showing redox‐state‐dependent fluorescence, and allowing the synthesis of the first redox‐active guanidine that is neutral in its oxidized form (see figure).