Structure, electrochemistry and photochromism of [Cu(RaaiR′)(PPh3)X] (RaaiR′=1-alkyl-2-(arylazo)imidazole; X=Cl, Br, I) and correlation with theoretical calculations

Autor: Kamal Sarkar, Dibakar Sardar, Gunomoni Saha, Tian-Huey Lu, Jack Cheng, Chittaranjan Sinha
Rok vydání: 2012
Předmět:
Zdroj: Polyhedron. 45:158-169
ISSN: 0277-5387
DOI: 10.1016/j.poly.2012.07.039
Popis: The reaction between CuX (X = Cl, Br, I), PPh 3 and 1-alkyl-2-(arylazo)imidazole (RaaiR′) has synthesized [Cu(RaaiR′)(PPh 3 )X]. The composition has been established by spectroscopic (UV–Vis, IR, 1 H NMR) data and the single crystal X-ray diffraction study of [Cu(MeaaiH)(PPh 3 )Cl] and [Cu(MeaaiH)(PPh 3 )Br] (MeaaiH = 2-( p -tolylazo)imidazole) have confirmed the structures. These complexes show trans -to- cis (E-to-Z) photoisomerisation upon UV light irradiation. Quantum yields ( ϕ E→Z ) of [Cu(RaaiR′)(PPh 3 )X] are lower than the free ligand values. The rate of isomerisation follows the sequence [Cu(RaaiR′)(PPh 3 )Cl] 3 )Br] 3 )I]. The cis -to- trans (Z-to-E) isomerisation is very slow upon light irradiation and has been achieved by a thermal route. The activation energy ( E a ) of the Z-to-E isomerisation has been calculated by a controlled temperature reaction. DFT calculations of the optimized geometry of representative complexes have been used to determine the composition and energy of the molecular levels.
Databáze: OpenAIRE