Preparation And Electrocatalytic Properties Of Isoheptyloxy, Aminophthalocyanine/carbon Nanotubes

In recent years,carbon nanotube(CNTs)have attracted much attention as electrochemical sensing materials due to its huge surface area,specific structure,high electrical conductivity and excellent thermal stability.However,pristine(unfunctionalized)CNTs often cause low sensitivity and poor reproducibility of the electrocatalysis properties.Recent studies have shown that functionalizing CNTs with metal phthalocyanines can bring a notable improvement to the electrocatalytic properties,in comparison with the free CNTs or MPcs.In this paper,three metal phthalocyanines,viz tetra-?-isoheptyloxyphthalocyanine cobalt(II)(THPcCo),tetra-?-(p-nitrophenoxy)phthalocyanine cobalt(II)(TNPPcCo),and tetra-?-(p-aminophenoxy)phthalocyanine cobalt(II)(TAPPcCo),were synthesized by template-reaction method at the present of 1,8-diazabicyclo[5,4,0]undec-7-ene.Then,three novel metal(II)phthalocyanine/acid-treated multi-walled carbon nanotube(aMWCNT)composites,THPcCo/aMWCNT,TNPPcCo/aMWCNT and TAPPcCo/aMWCNT,were prepared by noncovalent and covalent method respectively.The products and their intermediates were characterized by 1H NMR,MALDI-TOF-MS,FT-IR,UV-vis,TGA,XPS,SEM and TEM,respectively.Three sensitive electrochemical sensors was designed and prepared by immobilization of the as-prepared composites on the suface of the glassy carbon electrode(GCE)via the drop coating method.The electrocatalytic behaviors of the composite modified electrodes were investigated.The results are as follws:1.The electrochemical sensor for ascorbic acid(AA)based on THPcCo/aMWCNT.The results of various characterizations revealed that the successful self-assembly between THPcCo and aMWCNT via ?-? stacking interaction,and the THPcCo/aMWCNT composite appears uniform network-like structure on the GCE surface due to the four peripheral isoheptyl substituents of PcCo.Such structure can effectively increase electrode area,facilitate mass transport of analytes and provide continuous conducting pathways for the transportation of electron.Synchronously,benefited from the synergistic effect between PcCo and aMWCNT,the obtained electrochemical sensor has a higher current and lower potential for the oxidation of AA,compared with bare GCE,THPcCo/GCE and aMWCNT/GCE sensors.The linear relationship between anodic or cathodic peak currents and the scan rate were obtained,demonstrating that the electrochemical reaction of AA on the composite modified electrodes is a surface-controlled process.The linear range for the AA detection is from 10 ?M to 1.2 mM and the detection limit is as low as 4.0 ?M.The developed biosensor exhibited fast response(2 s),good reproducibility and acceptable stability,providing a simple method for the analysis of AA.2.The electrochemical sensor for paracetamol(PCT)based on TNPPcCo/aMWCNT is designed:it investigate the electrocatalytic activity of TNPPcCo/aMWCNT/GCE towards PCT by cyclic voltammetry,the results show that there are relations between its electrocatalytic activity and metal phthalocyanine center.It has a lower overpotential,which compared with TNPPcCo/GCE and aMWCNT/GCE.The effect of the scanning speed to the peak current and peak potential on the TNPPcCo/aMWCNT/GCE,and the results show that the modified electrode is controlled by surface absorption.The response between TNPPcCo/aMWCNT/GCE and different concentrations of PCT by differential pulse voltammetry is studied,the results show that the modified electrode to PCT has excellent electrochemical response performance,sensitive response(0.1387 ?A ?M-1),low limit of detection(0.4 ?M),high selectivity and stability.3.The electrochemical sensor for dopamine(DA)based on TAPPcCo/aMWCNT is designed:it investigate the electrocatalytic activity of TAPPcCo/aMWCNT/GCE towards DA by cyclic voltammetry,the results show that there are relations between its electrocatalytic activity and metal phthalocyanine center.It has a higher peak current,which compared with TAPPcCo/GCE and aMWCNT/GCE.The effect of the scanning speed to the peak current and peak potential on the TAPPcCo/aMWCNT/GCE,and the results show that the modified electrode is controlled by diffusion.The response between TAPPcCo/aMWCNT/GCE and different concentrations of DA by differential pulse voltammetry is studied and the results show that the modified electrode to DA has excellent electrochemical response performance,strong response signal,low limit of detection(1.0 ?M)and high selectivity.