Electrochemical Detection of 4-Chlorophenol Using Glassy Carbon Electrodes Modified with Thulium Double-Decker Phthalocyanine Salts

摘要

This paper presents newly developed electrochemical sensors based on green and blue lanthanide double-decker phthalocyanines (LnPc(2)), with the green LnPc(2) derivative referred to as 2 a while the blue counterpart is designated 2 b. The modified glassy carbon electrode (GCE) based on the blue LnPc(2) complex is referred to as 2 b-GCE while that which is based on the green LnPc(2) complex is named 2 a-GCE. The oxidation of 4-chlorophenol is extensively investigated and found to differ from one modified electrode to the next. Interestingly, the electrode modified with blue LnPc(2) complex (2 b-GCE) showed lower peak potential 0.88 V vs AgAgCl and higher catalytic current of 593 mu A compared to that based on the green LnPc(2) counterpart (2 b-GCE) which exhibited similar to 1.05 V vs AgAgCl and 65 mu A, respectively. Remarkable differences in Tafel slopes were also found to be complimented by high rate constants in the order: 2 b-GCE>2 a-GCE. The lowest limit of detection (LOD) was found for 2 b-GCE at 4.16 x10(-8) M in comparison to that for 2 a-GCE at 6.14 x10(-6) M. When investigating the electrochemical behavior, it was found that the first one-electron oxidation minus the first one-electron reduction differences were very low at 0.36 V and 0.55 V vs AgAgCl for 2 b and 2 a, respectively. Such values are comparable to the literature values for lutetium bisphthalocyanines.