ABSTRACT
In the present paper, the authors study the photolumimescence spectra of the novel 2,3-tetra-(2-isopropyl-5-methylbenzoyl) hydrogen phthalocyanine casting film and vacuum-deposited film. Photolumimescence spectras of casting film on the quartz substrate were measured at 10, 77, 177 and 300 K, and the photolumimescence spectra of vacuum-deposited film with a thickness of about 200 nm on the silicon substrate was studied at room temperature (300 K). For 2,3-tetra-(2-isopropyl-5-methylbenzoyl) hydrogen phthalocyanine, the casting films all show fluorescence peaks at 942, 937, 942 and 942 nm and phosphorescence peaks at 1114, 1057, 1114 and 1114 nm in the photolumimescence spectra at 10, 77, 177 and 300 K, respectively. In the cases of 2,3-tetra-(2-isopropyl-5-methyl -benzoyl) hydrogen phthalocyanine, the peaks of excimers, which are related with the resistance ability of molecular aggregation, were found around 1673 nm as observed from photolumimescence spectra of the novel phthalocyanine casting films at 177 and 300 K. And the peak of excimers at 300 K is stronger than at 177 K also as can be seen from photolumimescence spectra of its casting films. With the increase in the temperature, the fluorescence peak was weakened and the peaks of excimers became stronger from the photoluminescence spectra of 2,3-tetra-(2-isopropyl-5-methylbenzoyl) hydrogen phthalocyanine casting films at 10, 77, 177 and 300 K. At the same time, the authors discussed the reason for coming into being 2,3-tetra-(2-isopropyl-5-methylbenzoyl) hydrogen phthalocyanine excimers as can be concluded from the structure of 2,3-tetra-(2-isopropyl-5-methylbenzoyl) hydrogen phthalocyanine molecules through the parameters of Chem 3D Ultra 9.0 MM2 calculation and simulated diagram of C4h isomer of 2,3-tetra-(2-isopropyl-5-methylbenzoyl) hydrogen phthalocyanine. The peaks of casting film and vacuum-deposited film of 2,3-tetra-(2-isopropyl-5-methyl -benzoyl) hydrogen phthalocyanine presented different maximum emission wavelength and full width at half maximum. The peak of 2,3-tetra-(2-isopropyl-5-methyl-benzoyl) hydrogen phthalocyanine vacuum-deposited films displays the maximum emission wavelengths around 1140 nm, while the maximum emission wavelengths of casting films show obvious differences compared with the vacuum-deposited films. The usual full width at half maximum is approximately 300 nm for casting film, which is in contrasts with that the full width at half maximum is about 100 nm for the vacuum-deposited film as can be seen from photolumimescence spectra of 2,3-tetra-(2-isopropyl-5-methylbenzoyl) hydrogen phthalocyanine casting film and photolumimescence spectra of 2,3-tetra-(2-isopropyl-5-methylbenzoyl) hydrogen phthalocyanine vacuum-deposited film.
ABSTRACT
Electrochemistry and electrocatalysis of binuclear cobalt phthalocyaninehexasulfonate sodium salt (bi-CoPc) were investigated successfully in liquid crystal films of didodecyldimethylammonium bromide (DDAB) on pyrolytic graphite (PG) electrodes in aqueous solution. This new bi-CoPc-surfactant film modified electrode could reduce aggregation of bi-CoPc in aqueous solution, which was confirmed by the electronic absorption spectra in the visible region and images of transmission electron microscopy (TEM). The charge transport diffusion coefficient (D(ct)) and apparent heterogeneous electrode reaction rate constant (k(s)) for this modified electrode were estimated. The reduction of bi-CoPc ligand showed excellent electrocatalytic ability for the reduction of trichloroacetic acid (TCA) and catalytic current had a linear relationship with the concentration of TCA in the range of 3x10(-5)-7.5x10(-3) M. The reduction of bi-Co(III)Pc/bi-Co(II)Pc couple exhibited new pattern of catalytic reactivity in the reduction of oxygen. Peak current for the cathodic reduction of oxygen is proportion to the square root of the scan rate in the range of 5-1000 mV s(-1) in oxygen-saturated solution.
