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 (Ea) of cis-to-trans isomerisation is calculated by controlled temperature experiment and is found that Ea (ligands) > Ea (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