Adsorption of 4-nitrophenol onto Amberlite® IRA-900 modified with metallophthalocyanines
- Marais, Eloïse A, Nyokong, Tebello
- Authors: Marais, Eloïse A , Nyokong, Tebello
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/268576 , vital:54211 , xlink:href="https://doi.org/10.1016/j.jhazmat.2007.06.096"
- Description: The adsorption of 4-nitrophenol using commercially available Amberlite® IRA-900 modified with metal phthalocyanines (MPc) was investigated. The metallophthalocyanines immobilised onto the surface of Amberlite® IRA-900 include Fe (FePcS4), Co (CoPcS4) and Ni (NiPcS4) tetrasulphophthalocyanines, and differently sulphonated phthalocyanine mixtures of Fe (FePcSmix), Co (CoPcSmix) and Ni (NiPcSmix). Adsorption rates were fastest for the modified adsorbents at a loading of 1 × 10−3 g MPc/g Amberlite, at pH 9. The highest amount of 4-NP removal was obtained on FePcSmix modified Amberlite® IRA-900 with Qt = 42.9 mmol g−1 and adsorption efficiency of 86%. The recovery efficiency of 4-NP within 150 min was 76%. Using the Langmuir–Hinshelwood kinetic model, the complexes showed an order of 4-nitrophenol adsorption to be as follows: CoPcSmix > NiPcS4 > NiPcSmix > FePcS4 > FePcSmix > CoPcS4. The MPc modified Amberlite® IRA-900 was used repeatedly, following removal of 4-NP by nitric acid, without any significant loss of activity.
- Full Text:
- Date Issued: 2008
- Authors: Marais, Eloïse A , Nyokong, Tebello
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/268576 , vital:54211 , xlink:href="https://doi.org/10.1016/j.jhazmat.2007.06.096"
- Description: The adsorption of 4-nitrophenol using commercially available Amberlite® IRA-900 modified with metal phthalocyanines (MPc) was investigated. The metallophthalocyanines immobilised onto the surface of Amberlite® IRA-900 include Fe (FePcS4), Co (CoPcS4) and Ni (NiPcS4) tetrasulphophthalocyanines, and differently sulphonated phthalocyanine mixtures of Fe (FePcSmix), Co (CoPcSmix) and Ni (NiPcSmix). Adsorption rates were fastest for the modified adsorbents at a loading of 1 × 10−3 g MPc/g Amberlite, at pH 9. The highest amount of 4-NP removal was obtained on FePcSmix modified Amberlite® IRA-900 with Qt = 42.9 mmol g−1 and adsorption efficiency of 86%. The recovery efficiency of 4-NP within 150 min was 76%. Using the Langmuir–Hinshelwood kinetic model, the complexes showed an order of 4-nitrophenol adsorption to be as follows: CoPcSmix > NiPcS4 > NiPcSmix > FePcS4 > FePcSmix > CoPcS4. The MPc modified Amberlite® IRA-900 was used repeatedly, following removal of 4-NP by nitric acid, without any significant loss of activity.
- Full Text:
- Date Issued: 2008
Synthesis and photophysical properties of lead phthalocyanines
- Modibane, D.K., Nyokong, Tebello
- Authors: Modibane, D.K. , Nyokong, Tebello
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/268636 , vital:54216 , xlink:href="https://doi.org/10.1016/j.poly.2007.12.004"
- Description: This work reports on the synthesis and photophysical parameters of tetra-and octa-substituted new lead phthalocyanines. The complexes synthesized are: 1,4-(tetraphenoxyphthalocyaninato)lead (7a), 1,4-(tetra-tert-butylphenoxyphthalocyaninato)lead (7b), 2,3-(tetraphenoxyphthalocyaninato)lead (8a), 2,3-(tetra-tert-butylphenoxyphthalocyaninato)lead (8b), 2,3-octaphenoxyphthalocyaninatolead (9a) 2,3-[octakis(4-t-butylphenoxyphthalocyaninato)]lead (9b). Photophysical properties were studied for these complexes in a dimethylsulfoxide, dimethylformamide, toluene, tetrahydrofuran and chloroform. The fluorescence spectra were different from excitation spectra due to demetallation upon excitation. High triplet quantum yields ranging from 0.70 to 0.88 (in DMSO, DMF and toluene) and low triplet lifetimes (20–50 μs in DMSO, and more than 10 μs in the rest of the solvents) were observed due to the presence of heavy atom.
- Full Text:
- Date Issued: 2008
- Authors: Modibane, D.K. , Nyokong, Tebello
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/268636 , vital:54216 , xlink:href="https://doi.org/10.1016/j.poly.2007.12.004"
- Description: This work reports on the synthesis and photophysical parameters of tetra-and octa-substituted new lead phthalocyanines. The complexes synthesized are: 1,4-(tetraphenoxyphthalocyaninato)lead (7a), 1,4-(tetra-tert-butylphenoxyphthalocyaninato)lead (7b), 2,3-(tetraphenoxyphthalocyaninato)lead (8a), 2,3-(tetra-tert-butylphenoxyphthalocyaninato)lead (8b), 2,3-octaphenoxyphthalocyaninatolead (9a) 2,3-[octakis(4-t-butylphenoxyphthalocyaninato)]lead (9b). Photophysical properties were studied for these complexes in a dimethylsulfoxide, dimethylformamide, toluene, tetrahydrofuran and chloroform. The fluorescence spectra were different from excitation spectra due to demetallation upon excitation. High triplet quantum yields ranging from 0.70 to 0.88 (in DMSO, DMF and toluene) and low triplet lifetimes (20–50 μs in DMSO, and more than 10 μs in the rest of the solvents) were observed due to the presence of heavy atom.
- Full Text:
- Date Issued: 2008
Synthesis, electrochemical characterization of tetra-and octa-substituted dodecyl-mercapto tin phthalocyanines in solution and as self-assembled monolayers
- Khene, Samson M, Geraldo, Daniela A, Togo, Chamunorwa A, Limson, Janice L, Nyokong, Tebello
- Authors: Khene, Samson M , Geraldo, Daniela A , Togo, Chamunorwa A , Limson, Janice L , Nyokong, Tebello
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/264541 , vital:53743 , xlink:href="https://doi.org/10.1016/j.electacta.2008.08.018"
- Description: Non-peripherally (α) tetra- (9) and octa-(7) substituted dodecyl-mercapto tin(IV) phthalocyanines were synthesized and their electrochemical behavior studied. Cyclic voltammetry and spectroelectrochemistry show ring-based reductions for 7 and 9, the former shows two ring oxidations, while the latter shows only one ring-based oxidation. The adsorption kinetics of (7) and (9) on gold electrode were investigated by electrochemical impedance spectroscopy (EIS). The equilibrium constant (K) for the adsorption and the Gibbs free energy (ΔGads) of the SAMs were evaluated based on the Frumkin isotherm.
- Full Text:
- Date Issued: 2008
- Authors: Khene, Samson M , Geraldo, Daniela A , Togo, Chamunorwa A , Limson, Janice L , Nyokong, Tebello
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/264541 , vital:53743 , xlink:href="https://doi.org/10.1016/j.electacta.2008.08.018"
- Description: Non-peripherally (α) tetra- (9) and octa-(7) substituted dodecyl-mercapto tin(IV) phthalocyanines were synthesized and their electrochemical behavior studied. Cyclic voltammetry and spectroelectrochemistry show ring-based reductions for 7 and 9, the former shows two ring oxidations, while the latter shows only one ring-based oxidation. The adsorption kinetics of (7) and (9) on gold electrode were investigated by electrochemical impedance spectroscopy (EIS). The equilibrium constant (K) for the adsorption and the Gibbs free energy (ΔGads) of the SAMs were evaluated based on the Frumkin isotherm.
- Full Text:
- Date Issued: 2008
Synthesis, photophysical and photochemical studies on long chain zinc phthalocyanine derivatives
- Ogunsipe, Abimbola, Durmus, Mahmut, Atilla, Devrim, Gürek, Ayşe Gül, Ahsen, Vefa, Nyokong, Tebello
- Authors: Ogunsipe, Abimbola , Durmus, Mahmut , Atilla, Devrim , Gürek, Ayşe Gül , Ahsen, Vefa , Nyokong, Tebello
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/266019 , vital:53910 , xlink:href="https://doi.org/10.1016/j.synthmet.2008.06.007"
- Description: The synthesis and characterization of 2,9,16,23-chloro-3,10,17,24-triethyleneoxysulphanylphthalocyaninato zinc(II) (CTESZnPc) is described. The photophysics and photochemistry of CTESZnPc and those of tetrakis(triethyleneoxysulphanyl)zinc phthalocyanine (TTESZnPc) and octakis(triethyleneoxysulphanyl)zinc phthalocyanine (OTESZnPc), are presented and compared with those of unsubstituted zinc phthalocyanine (ZnPc). The presence of triethyleneoxysulphanyl substituents on the ZnPc ring gave rise to higher values of singlet oxygen (ΦΔ) and photodegradation (ΦPd) quantum yields in DMF. However, TTESZnPc, OTESZnPc and CTESZnPc are less fluorescent than ZnPc, judging from their fluorescence quantum yield (ΦF) values. Fluorescence was lower in toluene than in DMF due to aggregation in the former solvent. Triplet quantum yield (ΦT) values were found to increase with the presence of substituents on the ZnPc ring, while triplet lifetimes (τT) were found to vary linearly with the logarithms of solvent viscosities. The fluorescences of the substituted ZnPc complexes were effectively quenched by benzoquinone (BQ), and the quenching data analyzed by the Stern–Volmer equation. The Stern–Volmer constants and the diffusion-controlled bimolecular rate constants were calculated.
- Full Text:
- Date Issued: 2008
- Authors: Ogunsipe, Abimbola , Durmus, Mahmut , Atilla, Devrim , Gürek, Ayşe Gül , Ahsen, Vefa , Nyokong, Tebello
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/266019 , vital:53910 , xlink:href="https://doi.org/10.1016/j.synthmet.2008.06.007"
- Description: The synthesis and characterization of 2,9,16,23-chloro-3,10,17,24-triethyleneoxysulphanylphthalocyaninato zinc(II) (CTESZnPc) is described. The photophysics and photochemistry of CTESZnPc and those of tetrakis(triethyleneoxysulphanyl)zinc phthalocyanine (TTESZnPc) and octakis(triethyleneoxysulphanyl)zinc phthalocyanine (OTESZnPc), are presented and compared with those of unsubstituted zinc phthalocyanine (ZnPc). The presence of triethyleneoxysulphanyl substituents on the ZnPc ring gave rise to higher values of singlet oxygen (ΦΔ) and photodegradation (ΦPd) quantum yields in DMF. However, TTESZnPc, OTESZnPc and CTESZnPc are less fluorescent than ZnPc, judging from their fluorescence quantum yield (ΦF) values. Fluorescence was lower in toluene than in DMF due to aggregation in the former solvent. Triplet quantum yield (ΦT) values were found to increase with the presence of substituents on the ZnPc ring, while triplet lifetimes (τT) were found to vary linearly with the logarithms of solvent viscosities. The fluorescences of the substituted ZnPc complexes were effectively quenched by benzoquinone (BQ), and the quenching data analyzed by the Stern–Volmer equation. The Stern–Volmer constants and the diffusion-controlled bimolecular rate constants were calculated.
- Full Text:
- Date Issued: 2008
Volcano correlations for the reactivity of surface-confined cobalt N4-macrocyclics for the electrocatalytic oxidation of 2-mercaptoacetate
- Claußen, Jan A, Ochoa, Gonzalo, Páez, Maritza, Costamagno, Juan, Gulppi, Miguel, Nyokong, Tebello, Bedioui, Fethi, Zagal, José H
- Authors: Claußen, Jan A , Ochoa, Gonzalo , Páez, Maritza , Costamagno, Juan , Gulppi, Miguel , Nyokong, Tebello , Bedioui, Fethi , Zagal, José H
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/268688 , vital:54222 , xlink:href="https://doi.org/10.1007/s10008-007-0336-y"
- Description: We have investigated the electrocatalytic activity of several substituted and unsubstituted cobalt–phthalocyanines of substituted tetraphenyl porphyrins and of vitamin B12, for the electro-oxidation of 2-mercaptoacetate, with the complexes pre-adsorbed on a pyrolytic graphite electrode. Several N4-macrocyclic were used to have a wide variety of Co(II)/(I) formal potentials. The electrocatalytic activity, measured as current at constant potential, increases with the Co(II)/(I) redox potential for porphyrins as Co–pentafluorotetraphenylporphyrin larger than Co–tetrasulfonatotetraphenylporphyrin larger than Co-2,2′,2″,2‴tetra-aminotetraphenylporphyrin and decreases for cobalt phthalocyanines as Co-3,4-octaethylhexyloxyphthalocyanine > Co–octamethoxyphthalocyanine > Co–tetranitrophthalocyanine Co–tetraaminophthalocyanine > Co–unsubstituted phthalocyanine > Co–tetrasulfonatophthalocyanine > Co–perfluorinated phthalocyanine. Vitamin B12 exhibits the maximum activity. A correlation of log I (at constant potential) versus the Co(II)/(I) formal potential of the catalysts gives a volcano curve. This clearly shows that the search for better catalysts for this reaction point to those N4-macrocyclic complexes with Co(II)/(I) formal potentials close to −0.84 V versus SCE, which correspond to an optimum situation for the interaction of the thiol with the active site.
- Full Text:
- Date Issued: 2008
- Authors: Claußen, Jan A , Ochoa, Gonzalo , Páez, Maritza , Costamagno, Juan , Gulppi, Miguel , Nyokong, Tebello , Bedioui, Fethi , Zagal, José H
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/268688 , vital:54222 , xlink:href="https://doi.org/10.1007/s10008-007-0336-y"
- Description: We have investigated the electrocatalytic activity of several substituted and unsubstituted cobalt–phthalocyanines of substituted tetraphenyl porphyrins and of vitamin B12, for the electro-oxidation of 2-mercaptoacetate, with the complexes pre-adsorbed on a pyrolytic graphite electrode. Several N4-macrocyclic were used to have a wide variety of Co(II)/(I) formal potentials. The electrocatalytic activity, measured as current at constant potential, increases with the Co(II)/(I) redox potential for porphyrins as Co–pentafluorotetraphenylporphyrin larger than Co–tetrasulfonatotetraphenylporphyrin larger than Co-2,2′,2″,2‴tetra-aminotetraphenylporphyrin and decreases for cobalt phthalocyanines as Co-3,4-octaethylhexyloxyphthalocyanine > Co–octamethoxyphthalocyanine > Co–tetranitrophthalocyanine Co–tetraaminophthalocyanine > Co–unsubstituted phthalocyanine > Co–tetrasulfonatophthalocyanine > Co–perfluorinated phthalocyanine. Vitamin B12 exhibits the maximum activity. A correlation of log I (at constant potential) versus the Co(II)/(I) formal potential of the catalysts gives a volcano curve. This clearly shows that the search for better catalysts for this reaction point to those N4-macrocyclic complexes with Co(II)/(I) formal potentials close to −0.84 V versus SCE, which correspond to an optimum situation for the interaction of the thiol with the active site.
- Full Text:
- Date Issued: 2008
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