Metin Özer

Novel 4,4′-{(diphenylmethylene) bis(4,1-phenylene)bis(oxy)}-bridged ball-type phthalocyanines: Electrochemical, electrocatalytic oxygen reducing and heavy metals ions sensing properties

Novel 4,4′-{(diphenylmethylene)bis(4,1-phenylene)bis(oxy)} bridged ball-type metal-free, zinc(II), cobalt(II) and iron(II) ball-type metallophthalocyanines were achieved by the reaction of the bisphthalonitrile derivative in 2-dimetylaminoethanol. The isolation of the metal-free and metallophthalocyanines were carried out by both planar and column chromatography and also by hot soxhalet extraction. Their structures have been characterized by infrared, ultraviolet-visible, 1H nuclear magnetic resonance and matrix assisted laser desorption/ionization mass spectroscopies. The redox characters of the ball-type metallophthalocyanines have been investigated by cyclic voltammetry, square wave voltammetry, controlled potential coulometry and spectroelectrochemistry in nonaqueous media. The investigation suggested that the ball-type complexes form ring-based and/or metal-based mixed-valence species as a result of the remarkable interaction between the two Pc rings and/or metal centers. Furthermore, these species were found to be stable as evidenced by the splitting of the relevant redox processes. The electrocatalytic oxygen reducing performances of the dinuclear ball-type complexes were also studied. The compound involving Fe(II) centers at the phthalocyanine cores displayed higher catalytic performance towards oxygen reduction than those of other ones. By using these compounds as sensing materials, a flow type quartz crystal microbalance sensor was developed for the detection of small concentrations of heavy metal ions. A cadmium ion sensitivity of 2.85 × 104 Hz/mg.L−1 was observed with ball-type iron(II) phthalocyanine coated quartz crystal microbalance sensor. Detection of other metal ions including Fe2+, Zn2+, Ag2+ and Sn2+ were also performed. The results indicated that 1– 4 functionalized quartz crystal microbalance sensors can be used for the detection of heavy metal ions in aqueous solution. Partition coefficients obtained from the linear response regimes of the calibration curves are in the 8.6 × 104–5.4 × 105 range. Results show that the minor structural difference between metal free and metallophthalocyanine poses significant impact on metal ion partitioning.

The Effect of Ambient Conditions on the Impedance Spectra of Newly Synthezised Organic Semiconductor Thin Films

A detailed study of the effect of the film preparation conditions on the d.c conductivity and impedance spectra of a newly synthesized trinuclear phthalocyanine (ZnPc) derivative were carried out at the temperatures between 290 K and 420 K. We find that the experimental data are described by thermally activated conductivity dependence on temperature. A quassi‐vertical line was observed in Nyquist plot for all films at room temperature. Both the complex impedance and Bode plots showed that the ZnPc coated IDT can be represented by different equivalent circuits as depend on temperature.