Synthesis and electrochemical characterisation of benzylmercapto and dodecylmercapto tetra substituted cobalt, iron, and zinc phthalocyanines complexes
- Nyokong, Tebello, Ozoemena, Kenneth I, Agboola, Bolade O
- Authors: Nyokong, Tebello , Ozoemena, Kenneth I , Agboola, Bolade O
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:6580 , http://hdl.handle.net/10962/d1004143
- Description: The work reports on cyclic voltammetry (CV), square wave voltammetry and spectroelectrochemistry of the following complexes: tetrakis (benzyl mercapto) phthalocyanine complexes of Zn(II) (ZnTBMPc, 4a ), Co(II) (CoTBMPc, 5a ), Fe(II) (FeTBMPc 6a ); and tetrakis (dodecylmercapto) phthalocyanine complexes of Zn(II) (ZnTDMPc, 4b), Co(II) (CoTDMPc, 5b) and Fe(II) (FeTDMPc, 6b). More reversible CV couples were observed for complexes 4a, 5a and 6a containing thiol phenyl ring substituents. Complexes 4b, 5b and 6b containing long chain thiol substituents showed less reversible couples. Complexes 6a and 6b showed a relatively large number of redox processes (5 for 6a and 6 for 6b) within the potential window employed in this work. The processes for FePc derivatives (6a) are assigned to FeIIIPc-1/FeIIIPc-2, FeIIIPc-2/FeIIPc-2, FeIIPc-2/FeIPc-2, FeIPc-2/FeIPc-3 and FeIPc-3/FeIPc-4 and for the CoPc derivative (5a) to CoIIIPc-1/CoIIIPc-2, CoIIIPc-2/CoIIPc-2, CoIIPc-2/CoIPc-2 and CoIPc-2/CoIPc-3.
- Full Text:
- Date Issued: 2006
- Authors: Nyokong, Tebello , Ozoemena, Kenneth I , Agboola, Bolade O
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:6580 , http://hdl.handle.net/10962/d1004143
- Description: The work reports on cyclic voltammetry (CV), square wave voltammetry and spectroelectrochemistry of the following complexes: tetrakis (benzyl mercapto) phthalocyanine complexes of Zn(II) (ZnTBMPc, 4a ), Co(II) (CoTBMPc, 5a ), Fe(II) (FeTBMPc 6a ); and tetrakis (dodecylmercapto) phthalocyanine complexes of Zn(II) (ZnTDMPc, 4b), Co(II) (CoTDMPc, 5b) and Fe(II) (FeTDMPc, 6b). More reversible CV couples were observed for complexes 4a, 5a and 6a containing thiol phenyl ring substituents. Complexes 4b, 5b and 6b containing long chain thiol substituents showed less reversible couples. Complexes 6a and 6b showed a relatively large number of redox processes (5 for 6a and 6 for 6b) within the potential window employed in this work. The processes for FePc derivatives (6a) are assigned to FeIIIPc-1/FeIIIPc-2, FeIIIPc-2/FeIIPc-2, FeIIPc-2/FeIPc-2, FeIPc-2/FeIPc-3 and FeIPc-3/FeIPc-4 and for the CoPc derivative (5a) to CoIIIPc-1/CoIIIPc-2, CoIIIPc-2/CoIIPc-2, CoIIPc-2/CoIPc-2 and CoIPc-2/CoIPc-3.
- Full Text:
- Date Issued: 2006
Tetracarboxylic acid cobalt phthalocyanine SAM on gold: Potential applications as amperometric sensor for H2O2 and fabrication of glucose biosensor
- Mashazi, Philani N, Ozoemena, Kenneth I, Nyokong, Tebello
- Authors: Mashazi, Philani N , Ozoemena, Kenneth I , Nyokong, Tebello
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:6578 , http://hdl.handle.net/10962/d1004141
- Description: This report describes the applications of cobalt tetracarboxylic acid phthalocyanine (CoTCAPc) self-assembled monolayer (SAM) immobilized onto a preformed 2-mercaptoethanol (Au-ME) SAM on gold surface (Au-ME-CoTCAPc SAM) as a potential amperometric sensor for the detection of hydrogen peroxide (H[subscript 2]O[subscript 2]) at neutral pH conditions. The Au-ME-CoTCAPc SAM sensor showed a very fast amperometric response time of approximately 1 s, good linearity at the studied concentration range of up to 5 μM with a coefficient R² = 0.993 and a detection limit of 0.4 μM oxidatively. Also reductively, the sensor exhibited a very fast amperometric response time (~1 s), linearity up to 5 μM with a coefficient R² = 0.986 and a detection limit of 0.2 μM. The cobalt tetracarboxylic acid phthalocyanine self-assembled monolayer was then evaluated as a mediator for glucose oxidase (GOx)-based biosensor. The GOx (enzyme) was immobilized covalently onto Au-ME-CoTCAPc SAM using coupling agents: N-ethyl-N(3-dimethylaminopropyl) carbodiimide (EDC) and N-hydroxy succinimide (NHS), and the results demonstrated a good catalytic behavior. Kinetic parameters associated with the enzymatic and mediator reactions were estimated using electrochemical versions of Lineweaver–Burk and Hanes equation, and the stability of the sensor was tested. The biosensor (Au-ME-CoTCAPc-GOx SAM) electrode showed good sensitivity (7.5 nA/mM) with a good detection limit of 8.4 μM at 3σ, smaller Michaelis–Menten constant (4.8 mM from Hanes plot) and very fast response time of approximately 5 s.
- Full Text:
- Date Issued: 2006
- Authors: Mashazi, Philani N , Ozoemena, Kenneth I , Nyokong, Tebello
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:6578 , http://hdl.handle.net/10962/d1004141
- Description: This report describes the applications of cobalt tetracarboxylic acid phthalocyanine (CoTCAPc) self-assembled monolayer (SAM) immobilized onto a preformed 2-mercaptoethanol (Au-ME) SAM on gold surface (Au-ME-CoTCAPc SAM) as a potential amperometric sensor for the detection of hydrogen peroxide (H[subscript 2]O[subscript 2]) at neutral pH conditions. The Au-ME-CoTCAPc SAM sensor showed a very fast amperometric response time of approximately 1 s, good linearity at the studied concentration range of up to 5 μM with a coefficient R² = 0.993 and a detection limit of 0.4 μM oxidatively. Also reductively, the sensor exhibited a very fast amperometric response time (~1 s), linearity up to 5 μM with a coefficient R² = 0.986 and a detection limit of 0.2 μM. The cobalt tetracarboxylic acid phthalocyanine self-assembled monolayer was then evaluated as a mediator for glucose oxidase (GOx)-based biosensor. The GOx (enzyme) was immobilized covalently onto Au-ME-CoTCAPc SAM using coupling agents: N-ethyl-N(3-dimethylaminopropyl) carbodiimide (EDC) and N-hydroxy succinimide (NHS), and the results demonstrated a good catalytic behavior. Kinetic parameters associated with the enzymatic and mediator reactions were estimated using electrochemical versions of Lineweaver–Burk and Hanes equation, and the stability of the sensor was tested. The biosensor (Au-ME-CoTCAPc-GOx SAM) electrode showed good sensitivity (7.5 nA/mM) with a good detection limit of 8.4 μM at 3σ, smaller Michaelis–Menten constant (4.8 mM from Hanes plot) and very fast response time of approximately 5 s.
- Full Text:
- Date Issued: 2006
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