Construction of copper chains with new fluorescent guanidino-functionalized naphthyridine ligands

• Published in: Dalton transactions : an international journal of inorganic chemistry Vol. 45; no. 42; pp. 16966 - 16983
• Main Authors: Krämer, Christoph, Leingang, Simone, Hübner, Olaf, Kaifer, Elisabeth, Wadepohl, Hubert, Himmel, Hans-Jörg
• Format: Journal Article
• Language: English
• Published: England 01.01.2016
• Subjects: Absorption; Copper; Electronics; Fluorescence; Ligands; Mathematical analysis; Optical properties; Time dependence
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/c6dt03166h

The three new blue-fluorescent ligands 2,7-bis(tetramethylguanidino)-1,8-naphthyridine (1), 2,7-bis(N,N'-dimethylethylene-guanidino)-1,8-naphthyridine (2) and 2,7-bis(N,N'-diisopropylguanidino)-1,8-naphthyridine (3) are synthesized, and their optical properties (electronic absorption and emission spectroscopy) studied. Reactions of 1 or 2 with [Cu(CH CN) ]BF yield the Cu chain compounds [Cu (1) ](BF ) (that crystallizes as [Cu (1) (CH CN) ](BF ) ·2CH Cl ) and [Cu (2) ](BF ) . The variations of the optical properties upon coordination are evaluated, and the electronic transitions identified by time-dependent DFT (TD-DFT) calculations. Then the redox properties of the new Cu chain complexes are studied. In the course of these experiments, the new Cu complex [Cu (1) (CuCl ) ] , in which two CuCl units coordinate to the Cu chain in [Cu (1) ] , was fully characterized. In addition, the Cu chain complexes [Cu (1) ] and [Cu (1) ] were isolated as products of redox-induced degradation processes. Finally, we show by quantum chemical calculations that in [M (1) ] complexes (M = coinage metal), the HOMO changes from a ligand-centered to a metal-centered orbital for replacement of M = Cu by Au.