1‐Alkyl‐2‐{(O‐Thioalkyl)Phenylazo}Imidazole Complexes of PbII and Their Photochromic Property. Issue 10 (19th June 2013)

• Record Type: Journal Article
• Authors: Saha Halder, Shefali; Roy, Suman; Kumar Mondal, Tapan; Saha, Rajat; Sinha, Chittaranjan
• Is Part Of: Zeitschrift für anorganische und allgemeine Chemie. Volume 639:Issue 10(2013)
• Page Start: 1861
• Page End: 1870
• Publication Date: 2013-06-19
• Subjects: Chemistry, Inorganic -- Periodicals; Chemistry -- Periodicals; 540
• DOI: 10.1002/zaac.201300173
• Languages: English
• ISSNs: 0044-2313

Abstract

<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p>Pb^II complexes of 1‐alkyl‐2‐{(<italic>o</italic>‐thioalkyl)phenylazo}imidazole (SRaaiNR'), [Pb(SRaaiNR')₂X₂] were characterized by spectroscopic studies. The single‐crystal X‐ray structure of [Pb(SEtaaiNEt)₂Cl₂] (SEtaaiNEt = 1‐ethyl‐2‐{(<italic>o</italic>‐thioalkyl)phenylazo}imidazole) proved imidazolyl‐N and –SEt coordination forming unusual puckered eight member chelate rings. UV light irradiation of the complexes in DMF solution shows E‐to‐Z (E and Z refer to <italic>trans</italic> and <italic>cis</italic>‐configuration about –N=N–, respectively) photoisomerization of the coordinated azoimidazole. The rate of isomerization follows the sequence: [Pb(SRaaiNR')₂Cl₂] &lt; [Pb(SRaaiNR')₂Br₂] &lt; [Pb(SRaaiNR')₂I₂]. Quantum yields (φ_E→Z) and the activation energy (<italic>E</italic>_a) of the isomerization of the complexes are lower than observed for the free ligand. This can be explained by considering the molecular assembly and the thus observed increase in mass and rotor volume of the complexes. DFT and TDDFT calculations of optimized geometry could explained the spectral properties and photochromic activity.</p> </abstract>