Please use this identifier to cite or link to this item:
Title: Arylazoimidazole complexes of lead(II)-halide and their photochromism
Authors: Mallick, Debashis
Chowdhury, Bharati
Sen, Chandana
Sarkar, Kamal Krishna
Jana, Srikanta
Mondal, Sudipa
Sinha, Chittaranjan
Keywords: Photochromism;Density functional calculations;Arylazoimidazoles;Lead halide complexes
Issue Date: Mar-2018
Publisher: NISCAIR-CSIR, India
Abstract: Lead(II) complexes of 1-alkyl-2-(arylazo)imidazole (Raai-CnH2n+1), [Pb(Raai-CnH2n+1)X2] (X = Cl, Br, I; and Raai-CnH2n+1, R = H, Me and n = 4, 6, 8) have been characterized by UV-vis, IR and 1H-NMR spectroscopy. The coordinated Raai-CnH2n+1 in the complexes undergoes E-to-Z (trans-to-cis) isomerisation about the –N=N– group upon being irradiated with UV light in DMF solution. The rate and quantum yields of E-to-Z photoisomerisation (φE→Z) of the complexes are poorer than the respective free ligand response and are also affected by the nature of halide present (Cl-, Br- and I-). Variation in physicochemical parameters may be correlated with the effective mass of the photochrome. The rate of isomerisation follows the sequence: [Pb(Raai-CnH2n+1)Cl2] < [Pb(Raai-CnH2n+1)Br2] < [Pb(Raai-CnH2n+1)I2]. The Z-to-E isomerisation has been carried out at varying temperatures (298–308 K) to determine the activation energy of Z-to-E (cis-to-trans) isomerisation (Ea: 47.09–63.42 kJ mol-1) and the entropy of activation (S : 166.52 to –109.0 J mol-1 K-1) which is a large negative in the complexes. Theoretical calculation supports cleavage of Pb(II)-N(azo) bond followed by the –N=N– rotation in a three-coordinated symmetry rather than the four-coordinated symmetry.
Page(s): 418-426
ISSN: 0975-0975(Online); 0376-4710(Print)
Appears in Collections:IJC-A Vol.57A(03) [March 2018]

Files in This Item:
File Description SizeFormat 
IJCA 57A(3) 418-426.pdfMain Article474.47 kBAdobe PDFView/Open
IJCA 57A(3) 418-426_Suppl Data.pdfSupplementary Data1.11 MBAdobe PDFView/Open

Items in NOPR are protected by copyright, with all rights reserved, unless otherwise indicated.