RESUMO
Peripherally and non-peripherally terminal alkynyl substituted manganese phthalocyanines (MnPc) were synthesized and characterized and then used as functional materials in modified electrodes. MnPcs were substituted with alkynyl groups, which are reactive moieties in click electrochemistry (CEC) reactions. Mn(iii) cations were incorporated into the cavity of the Pc ring in order to increase the redox activity of the complexes. Electrochemical characterizations of the complexes were determined by voltammetric and in situ spectroelectrochemical measurements in order to determine their possible technological applications. MnPc complexes illustrated five redox couples and these redox couples were assigned as [Cl-MnIIIPc2-]/[Cl-MnIIPc2-]1-, [Cl-MnIIPc2-]1-/[Cl-MnIPc2-]2-, [Cl-MnIPc2-]2-/[ Cl-MnIPc3-]3-, and [Cl-MnIIIPc2-]/[Cl-MnIIIPc1-]1+ redox processes. The position of the substituents affected the mechanism of the redox reactions and influenced the tendency to react with the molecular oxygen. Moreover, changing the position of the substituents slightly influenced the peak potentials and reversibility of the redox processes. For the applications, modified electrodes (ITO/PANI-N3-MnPc and GCE/PANI-N3-MnPc) were constructed with CEC reaction between azido functionalized polyaniline (PANI-N3) and terminally alkynyl substituted MnPcs and these electrodes. Voltammetric characterizations of the modified electrodes illustrated suitable redox activity and conductivity for the practical applications. Finally, the GCE/PANI-N3-MnPc electrode was tested as a potential electrocatalyst for water splitting reaction. Although the GCE/PANI-N3-MnPc electrode did not catalyze the hydrogen evolution reaction (HER), it significantly catalyzed the oxygen evolution reaction (OER) in aqueous solution.
RESUMO
BACKGROUND: The role of carotid endarterectomy for the treatment of atherosclerotic carotid bifurcation disease is now well established. The aim of this study was to compare durability, postoperative death, stroke, minor strokes, cranial nerve injuries, neck hematomas, myocardial infarctions, or surgical defects and restenosis at the operative site following short- and mid-term duration of the advantages eversion carotid endarterectomy (E-CEA) compared to conventional carotid endarterectomy (C-CEA). PATIENTS AND METHODS: Between March 2003 and November 2012, primary CEAs were performed in 380 consecutive patients by the same surgical groups. These patients were evaluated retrospectively. C-CEA was performed in 202 patients, and E-CEA was performed in 178 patients. Carotid duplex ultrasonography was performed in all patients at 1, 6, 12 and 24 months after CEA to identify residual atherosclerotic carotid disease. RESULTS: Mean age was 67.3±13.4 years in the E-CEA group and 64.8±14.8 years in the C-CEA group. Mean cross-clamping time in the E-CEA group was 9.54±2.6 minutes and 12.62±2.7 minutes for C-CEA group (P=0.236). Three postoperative strokes occurred (one after E-CEA and two after C-CEA). In the E-CEA group and C-CEA group respectively, carotid stenosis rates were found in 4 patients (2.24%) and in 5 (2.97%) at a follow-up period of 26 months. CONCLUSION: Classical endarterectomy still remains the gold standard surgical technique for patients who are selected for coronary artery disease surgery. Nevertheless, we believe that eversion endarterectomy, which has some advantages, must be kept in mind as an alternative approach.
