title: Spectroscopic studies on the intermolecular charge transfer interaction of Fe(II)- and Fe(III)-phthalocyanines with 2,3,5,6-tetrachloro-1,4-benzoquinone and its application in colorimetric sensing of amino acids and amines.
abstract: The interactions of Fe(II)Pc and Fe(III)Pc with π-acceptor 2,3,5,6-tetrachloro-1,4-benzoquinone (p-chloranil, p-CHL) have been investigated spectroscopically (UV/vis and FT-IR) and spectrofluorimetrically at three different temperatures. The stoichiometry of the complexes was found to be 1:1. The results of electronic spectral studies indicated that the formation constant for Fe(II)Pc-p-CHL system is found to be higher than that for Fe(III)Pc-p-CHL system. This observation is well supported by the results of fluorescence quenching studies and the association constants calculated for Fe(II)Pc-p-CHL system is 4.2 × 10(3) mol L(-1) and that for Fe(III)Pc-p-CHL system is 2.2 × 10(3) mol L(-1). The data are discussed in terms of physico-chemical parameters viz. molar extinction coefficient, oscillator strength, dipole moment, ionization potential, dissociation energy and thermodynamic parameters. The results indicated that the formation of π-π CT complex is spontaneous and endothermic. Preliminary studies indicated that the CT complex can effectively be used as a colorimetric agent for sensing amino acids and amines.
authors.affiliation: Department of Chemistry, Gandhigram Rural Institute (Deemed University), Gandhigram 624 302, India.
authors.forename: Chellamuthu
authors.initials: C
authors.lastname: Balraj
authors.forename: Kuppanagounder P
authors.initials: KP
authors.lastname: Elango
mesh_terms: D000588:Amines / Q000032:analysis*; D000596:Amino Acids / Q000032:analysis*; D002703:Chloranil / Q000737:chemistry*; D003124:Colorimetry / Q000379:methods*; D004126:Dimethylformamide / Q000737:chemistry; D004583:Electrons; D005296:Ferrous Compounds / Q000737:chemistry*; D007211:Indoles / Q000737:chemistry*; D007700:Kinetics; D008968:Molecular Conformation; D013050:Spectrometry, Fluorescence; D017550:Spectroscopy, Fourier Transform Infrared; D013816:Thermodynamics
chemical_list: D000588:Amines; D000596:Amino Acids; D005296:Ferrous Compounds; D007211:Indoles; C493990:iron phthalocyanine; D002703:Chloranil; D004126:Dimethylformamide