Synthesis, characterization, photochromism and theoretical interpretation of bis-(triphenylphosphine)-Cu(I)- and Ag(I)-(1-alkyl-2-(arylazo)imidazole) complexes

Department of Chemistry, Jadavpur University, Kolkata-700 032, India
E-mail: crsjuchem@gmail.com
Department of Chemistry, Mrinalini Datta Mahavidyapith, Birati, Kolkata-700 051, India
E-mail: dmchemmdm51@gmail.com
Department of Chemistry, Sripat Singh College, Murshidabad-742 123, West Bengal, India
Department of Chemistry, Mahadevananda Mahavidyalaya, S. N. Banerjee Rd., Monirampore,
Kolkata-700 120, India
Manuscript received 09 January 2018, revised 07 March 2018, accepted 08 March 2018

[Cu(PPh₃)₂(RaaiR')]ClO₄ and [Ag(PPh₃)₂(RaaiR')]NO₃ (RaaiR', 1-alkyl-2-(arylazo)imidazole)) complexes are spectroscopically characterised and in one case, [Cu(PPh₃)₂(HaaiMe)]ClO₄ (3a), the structure is confirmed by single crystal X-ray diffraction measurement. UV light irradiation to the solution of the complexes in DMF (free ligand in MeOH) show trans-to-cis isomerisation about -N=N-C₆H₄-R. The reverse transformation, cis-to-trans, is carried out under thermal condition. Quantum yields (\(\Phi\)_t→_c) of trans-to-cis
isomerisation of free ligand is higher than their complex phase. The activation energy (E_a) of cis-to-trans isomerisation is calculated by controlled temperature experiment and is found that E_a (ligands) > E_a (complexes). The Density Functional Theory has been used to calculate electronic structure of the optimized geometry and hence the interpretation of the spectral and photochromic properties.