Photophysical and photochemical studies of sulfur containing phthalocyanine derivatives in the presence of folic acid
- Nombona, Nolwazi, Nyokong, Tebello
- Authors: Nombona, Nolwazi , Nyokong, Tebello
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/243180 , vital:51124 , xlink:href="https://doi.org/10.1016/j.ica.2012.03.051"
- Description: The syntheses of zinc and magnesium 9,16,23-tris-(5-trifluoromethyl-2-mercaptopyridine)-2-(carboxy)phthalocyaninato complexes are described for the first time. The photophysical and photochemical parameters of these molecules in the absence or presence of folic acid are compared to the corresponding oxygen bridged complexes and to 2,9,17,23-tetrakis-[(1,6-hexanedithiol)phthalocyaninato]zinc(II), [8,15,22-tris-(naptho)-2-(amidoethanethiol)phthalocyaninato]zinc(II) and zinc phthalocyanine tetrasulfonate. In the absence of folic acid, the complexes show relatively good triplet quantum yields (ranging from 0.52 to 0.88) in DMSO with reasonable triplet lifetime between 140 and 470 μs. The complexes showed high singlet oxygen quantum yield values ranging from 0.27 to 0.66 in the absence of folic acid. In the presence of folic acid, the triplet quantum yield values were between 0.37 and 0.75 and the lifetimes were significantly reduced (70–320 μs).
- Full Text:
- Date Issued: 2012
- Authors: Nombona, Nolwazi , Nyokong, Tebello
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/243180 , vital:51124 , xlink:href="https://doi.org/10.1016/j.ica.2012.03.051"
- Description: The syntheses of zinc and magnesium 9,16,23-tris-(5-trifluoromethyl-2-mercaptopyridine)-2-(carboxy)phthalocyaninato complexes are described for the first time. The photophysical and photochemical parameters of these molecules in the absence or presence of folic acid are compared to the corresponding oxygen bridged complexes and to 2,9,17,23-tetrakis-[(1,6-hexanedithiol)phthalocyaninato]zinc(II), [8,15,22-tris-(naptho)-2-(amidoethanethiol)phthalocyaninato]zinc(II) and zinc phthalocyanine tetrasulfonate. In the absence of folic acid, the complexes show relatively good triplet quantum yields (ranging from 0.52 to 0.88) in DMSO with reasonable triplet lifetime between 140 and 470 μs. The complexes showed high singlet oxygen quantum yield values ranging from 0.27 to 0.66 in the absence of folic acid. In the presence of folic acid, the triplet quantum yield values were between 0.37 and 0.75 and the lifetimes were significantly reduced (70–320 μs).
- Full Text:
- Date Issued: 2012
Physico-chemical properties of lutetium phthalocyanine complexes in solution and in solid polystyrene polymer fibers and their application in photoconversion of 4-nitrophenol
- Zugle, Ruphino, Nyokong, Tebello
- Authors: Zugle, Ruphino , Nyokong, Tebello
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/243520 , vital:51160 , xlink:href="https://doi.org/10.1016/j.molcata.2012.02.010"
- Description: The photophysical and photochemical behavior of two phthalocyanine complexes of lutetium peripherally substituted with tetraphenoxy and tetra-2-pyridiloxy groups were studied in solution and when dispersed in polystyrene polymer fiber. The phthalocyanines were found not to fluoresce significantly in solution and not at all within the fiber matrix as compared with standard unsubstituted zinc phthalocyanine. They showed very promising photoactivity in solution with high singlet oxygen quantum yields. Their photoactivity within the polymer fiber matrix was also demonstrated with the photoconversion of 4-nitrophenol, a water pollutant. The photodegradation process with both phthalocyanines follows first order kinetics similar to that observed for the zinc phthalocyanine and the photo-products were found to be hydroquinone, benzoquinone and 4-nitrocatechol.
- Full Text:
- Date Issued: 2012
- Authors: Zugle, Ruphino , Nyokong, Tebello
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/243520 , vital:51160 , xlink:href="https://doi.org/10.1016/j.molcata.2012.02.010"
- Description: The photophysical and photochemical behavior of two phthalocyanine complexes of lutetium peripherally substituted with tetraphenoxy and tetra-2-pyridiloxy groups were studied in solution and when dispersed in polystyrene polymer fiber. The phthalocyanines were found not to fluoresce significantly in solution and not at all within the fiber matrix as compared with standard unsubstituted zinc phthalocyanine. They showed very promising photoactivity in solution with high singlet oxygen quantum yields. Their photoactivity within the polymer fiber matrix was also demonstrated with the photoconversion of 4-nitrophenol, a water pollutant. The photodegradation process with both phthalocyanines follows first order kinetics similar to that observed for the zinc phthalocyanine and the photo-products were found to be hydroquinone, benzoquinone and 4-nitrocatechol.
- Full Text:
- Date Issued: 2012
Reverse saturation absorption spectra and optical limiting properties of chlorinated tetrasubstituted phthalocyanines containing different metals
- Tuhl, Ahmad, Manaa, Hacene, Makhseed, Saad, Al-Awadi, Nouria, Matthew, Jacob, Ibrahim, Hamada Mohamed, Nyokong, Tebello, Behbehani, Haider
- Authors: Tuhl, Ahmad , Manaa, Hacene , Makhseed, Saad , Al-Awadi, Nouria , Matthew, Jacob , Ibrahim, Hamada Mohamed , Nyokong, Tebello , Behbehani, Haider
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/243498 , vital:51158 , xlink:href="https://doi.org/10.1016/j.optmat.2012.05.018"
- Description: A highly non-aggregated series of peripherally tetra(2,6-diisopropylphenoxy) substituted phthalocyanines (Pcs) containing different metals (Al, Ga, In and Zn) were prepared and their nonlinear optical properties (NLO), including the optical limiting behavior were investigated. This study explores the effect of the implanted metals along with the peripheral chlorine atoms on the NLO of the prepared complexes, thereby improving their optical limiting performance. The best wavelength at which the Pc complex exhibits the strongest nonlinear effect was determined over the low absorption window region (420–590 nm) comprised between the Q and B bands using a nanosecond pulsed laser with the aid of a Z-scan technique. The excited state absorption cross sections (σeff) have been found to be wavelength dependent with common double peaks at 505 nm and around 485 nm and the highest value was calculated for Pc1–In (1.1 × 10−16 cm2). The figure of merit spectra show different spectral structure when compared to the excited state absorption spectra and the largest figure of merit value was found to be around 107 for Pc1–In derivative. In full agreement with reverse saturation results, the optical limiting measurements, carried out at 485 nm and 532 nm for each derivative, show very low optical limiting thresholds at the former wavelength. In the continuous wave excitation regime, the Z-scan measurements, which were carried out at 632.8 and 532 nm, showed strong refractive and absorptive nonlinear effects.
- Full Text:
- Date Issued: 2012
- Authors: Tuhl, Ahmad , Manaa, Hacene , Makhseed, Saad , Al-Awadi, Nouria , Matthew, Jacob , Ibrahim, Hamada Mohamed , Nyokong, Tebello , Behbehani, Haider
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/243498 , vital:51158 , xlink:href="https://doi.org/10.1016/j.optmat.2012.05.018"
- Description: A highly non-aggregated series of peripherally tetra(2,6-diisopropylphenoxy) substituted phthalocyanines (Pcs) containing different metals (Al, Ga, In and Zn) were prepared and their nonlinear optical properties (NLO), including the optical limiting behavior were investigated. This study explores the effect of the implanted metals along with the peripheral chlorine atoms on the NLO of the prepared complexes, thereby improving their optical limiting performance. The best wavelength at which the Pc complex exhibits the strongest nonlinear effect was determined over the low absorption window region (420–590 nm) comprised between the Q and B bands using a nanosecond pulsed laser with the aid of a Z-scan technique. The excited state absorption cross sections (σeff) have been found to be wavelength dependent with common double peaks at 505 nm and around 485 nm and the highest value was calculated for Pc1–In (1.1 × 10−16 cm2). The figure of merit spectra show different spectral structure when compared to the excited state absorption spectra and the largest figure of merit value was found to be around 107 for Pc1–In derivative. In full agreement with reverse saturation results, the optical limiting measurements, carried out at 485 nm and 532 nm for each derivative, show very low optical limiting thresholds at the former wavelength. In the continuous wave excitation regime, the Z-scan measurements, which were carried out at 632.8 and 532 nm, showed strong refractive and absorptive nonlinear effects.
- Full Text:
- Date Issued: 2012
Spectroscopic and physicochemical behavior of magnesium phthalocyanine derivatives mono-substituted with a carboxylic acid group
- Nombona, Nolwazi, Chidawanyika, Wadzanai J U, Nyokong, Tebello
- Authors: Nombona, Nolwazi , Chidawanyika, Wadzanai J U , Nyokong, Tebello
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/244450 , vital:51258 , xlink:href="https://doi.org/10.1016/j.molstruc.2011.12.051"
- Description: This work reports on the synthesis of novel unsymmetrically substituted magnesium phthalocyanine complexes containing one carboxyl group. The physicochemical behavior of these complexes were compared with those of their unmetallated and zinc counterparts. The MgPcs showed interesting absorption spectra with [8,15,22-Tris-(naphtho)-4,5-(3-carboxy-1,2-dioxyphenyl)phthalocyaninato]magnesium (II) showing a large split in the Q band whereas [8,15,22-Tris-(naphtho)-2-(carboxy) phthalocyaninato]magnesium(II) presented only a small splitting. The magnesium phthalocyanine derivatives displayed higher fluorescence quantum yields compared to unmetallated and zinc phthalocyanine counterparts. The latter gave admirable triplet and singlet oxygen quantum yields. These molecules can distinctly be employed in the field of photodynamic therapy in combination with fluorescence imaging.
- Full Text:
- Date Issued: 2012
- Authors: Nombona, Nolwazi , Chidawanyika, Wadzanai J U , Nyokong, Tebello
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/244450 , vital:51258 , xlink:href="https://doi.org/10.1016/j.molstruc.2011.12.051"
- Description: This work reports on the synthesis of novel unsymmetrically substituted magnesium phthalocyanine complexes containing one carboxyl group. The physicochemical behavior of these complexes were compared with those of their unmetallated and zinc counterparts. The MgPcs showed interesting absorption spectra with [8,15,22-Tris-(naphtho)-4,5-(3-carboxy-1,2-dioxyphenyl)phthalocyaninato]magnesium (II) showing a large split in the Q band whereas [8,15,22-Tris-(naphtho)-2-(carboxy) phthalocyaninato]magnesium(II) presented only a small splitting. The magnesium phthalocyanine derivatives displayed higher fluorescence quantum yields compared to unmetallated and zinc phthalocyanine counterparts. The latter gave admirable triplet and singlet oxygen quantum yields. These molecules can distinctly be employed in the field of photodynamic therapy in combination with fluorescence imaging.
- Full Text:
- Date Issued: 2012
Synthesis and photophysical behavior of a novel zinc phthalocyanine containing a single carboxylic acid and three phenylthio substituents
- Forteath, Shaun, Antunes, Edith M, Chidawanyika, Wadzanai J U, Nyokong, Tebello
- Authors: Forteath, Shaun , Antunes, Edith M , Chidawanyika, Wadzanai J U , Nyokong, Tebello
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/243207 , vital:51127 , xlink:href="https://doi.org/10.1016/j.jlumin.2012.03.050"
- Description: Zinc 2, (3)-tri-(phenylthio)-2, (3)-carboxy phthalocyanine (ZnPc(COOH)(SPh)3), zinc 2, (3)-tetra-(phenylthio) phthalocyanine (ZnPc(SPh)4) and 2, (3)-tetra-(phenylthio) phthalocyanine (H2Pc(SPh)4) were synthesized and their photophysical behavior were compared with those of a number of zinc phthalocyanine (ZnPc) derivatives. ZnPc(COOH)(SPh)3 and ZnPc(SPh)4 had similar fluorescence (ΦF=0.14) and triplet state (ΦT=0.65) quantum yields in dimethylsulfoxide, hence showing no effects of the replacement of one of the phenylthio groups with a carboxylic acid group. ZnPc(COOH)(SPh)3 displayed a slightly shorter triplet lifetime (τT=331 μs) than ZnPc (τT=350 μs) in DMSO, but within the range of ZnPc derivatives. The triplet lifetime for ZnPc(COOH)(SPh)3 is much longer than for the symmetrical derivative (ZnPc(SPh)4) with τT=149 μs in DMSO.
- Full Text:
- Date Issued: 2012
- Authors: Forteath, Shaun , Antunes, Edith M , Chidawanyika, Wadzanai J U , Nyokong, Tebello
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/243207 , vital:51127 , xlink:href="https://doi.org/10.1016/j.jlumin.2012.03.050"
- Description: Zinc 2, (3)-tri-(phenylthio)-2, (3)-carboxy phthalocyanine (ZnPc(COOH)(SPh)3), zinc 2, (3)-tetra-(phenylthio) phthalocyanine (ZnPc(SPh)4) and 2, (3)-tetra-(phenylthio) phthalocyanine (H2Pc(SPh)4) were synthesized and their photophysical behavior were compared with those of a number of zinc phthalocyanine (ZnPc) derivatives. ZnPc(COOH)(SPh)3 and ZnPc(SPh)4 had similar fluorescence (ΦF=0.14) and triplet state (ΦT=0.65) quantum yields in dimethylsulfoxide, hence showing no effects of the replacement of one of the phenylthio groups with a carboxylic acid group. ZnPc(COOH)(SPh)3 displayed a slightly shorter triplet lifetime (τT=331 μs) than ZnPc (τT=350 μs) in DMSO, but within the range of ZnPc derivatives. The triplet lifetime for ZnPc(COOH)(SPh)3 is much longer than for the symmetrical derivative (ZnPc(SPh)4) with τT=149 μs in DMSO.
- Full Text:
- Date Issued: 2012
Synthesis and photophysical properties of peripherally and non-peripherally mercaptopyridine substituted metal free, Mg (II) and Al (III) phthalocyanines
- Arslanoğlu, Yasin, Idowu, Mopelela, Nyokong, Tebello
- Authors: Arslanoğlu, Yasin , Idowu, Mopelela , Nyokong, Tebello
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/243248 , vital:51131 , xlink:href="https://doi.org/10.1016/j.saa.2012.04.004"
- Description: The syntheses and photophysical properties of metallophthalocyanines containing Mg2+ and Al3+ as central metal ions and their unmetallated derivative (complexes 3–8) tetra- substituted at the non-peripheral (α) and peripheral (β) positions with 2-mercaptopyridine are reported. The trends in triplet and fluorescence quantum yields are described for these compounds. The complexes exhibited relatively high triplet quantum yields (ΦT) ranging from 0.33 to 0.54 and fluorescence quantum yields (ΦF) ranging from 0.02 to 0.29. Triplet state lifetimes of the complexes were long ranging from 120 to 460 μs, indicating a potential use of these complexes as photosensitizers.
- Full Text:
- Date Issued: 2012
- Authors: Arslanoğlu, Yasin , Idowu, Mopelela , Nyokong, Tebello
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/243248 , vital:51131 , xlink:href="https://doi.org/10.1016/j.saa.2012.04.004"
- Description: The syntheses and photophysical properties of metallophthalocyanines containing Mg2+ and Al3+ as central metal ions and their unmetallated derivative (complexes 3–8) tetra- substituted at the non-peripheral (α) and peripheral (β) positions with 2-mercaptopyridine are reported. The trends in triplet and fluorescence quantum yields are described for these compounds. The complexes exhibited relatively high triplet quantum yields (ΦT) ranging from 0.33 to 0.54 and fluorescence quantum yields (ΦF) ranging from 0.02 to 0.29. Triplet state lifetimes of the complexes were long ranging from 120 to 460 μs, indicating a potential use of these complexes as photosensitizers.
- Full Text:
- Date Issued: 2012
Synthesis and photophysicochemical properties of novel zinc phthalocyanines mono substituted with carboxyl containing functional groups
- Rapulenyane, Nomasonto, Antunes, Edith M, Masilela, Nkosiphile, Nyokong, Tebello
- Authors: Rapulenyane, Nomasonto , Antunes, Edith M , Masilela, Nkosiphile , Nyokong, Tebello
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/242389 , vital:51037 , xlink:href="https://doi.org/10.1016/j.jphotochem.2012.09.007"
- Description: This work reports on the synthesis and the physicochemical properties of novel unsymmetrically substituted zinc phthalocyanines (complexes 8, 10 and 11) and their symmetrically substituted counterparts (complexes 9, 12 and 13). The new complexes and their counterparts were successfully structurally characterized by IR, NMR, mass spectral and elemental analyses. Low fluorescence quantum yields (0.032) and lifetimes (0.91 ns) were obtained for the symmetrical ZnOTPc (complex 9) compared to the higher fluorescence quantum yields (0.15, 0.13, 0.10, 0.09 and 0.29) and lifetimes (4.4, 1.69, 1.69, 2.16 and 3.23 ns) obtained for ZnMPCPc (8), ZnTDTPc (12), ZnMCapPc (10), ZnMCafPc (11) and ZnTCPPc (13), respectively. All the complexes showed the ability to produce singlet oxygen with the highest triplet quantum yields obtained for 8 and 10 (0.80 and 0.65 respectively). High triplet lifetimes (109–286 μs) were obtained for all complexes. Complex 8 showed the longest triplet and fluorescence lifetimes as well the largest triplet state and singlet oxygen quantum yields.
- Full Text:
- Date Issued: 2012
- Authors: Rapulenyane, Nomasonto , Antunes, Edith M , Masilela, Nkosiphile , Nyokong, Tebello
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/242389 , vital:51037 , xlink:href="https://doi.org/10.1016/j.jphotochem.2012.09.007"
- Description: This work reports on the synthesis and the physicochemical properties of novel unsymmetrically substituted zinc phthalocyanines (complexes 8, 10 and 11) and their symmetrically substituted counterparts (complexes 9, 12 and 13). The new complexes and their counterparts were successfully structurally characterized by IR, NMR, mass spectral and elemental analyses. Low fluorescence quantum yields (0.032) and lifetimes (0.91 ns) were obtained for the symmetrical ZnOTPc (complex 9) compared to the higher fluorescence quantum yields (0.15, 0.13, 0.10, 0.09 and 0.29) and lifetimes (4.4, 1.69, 1.69, 2.16 and 3.23 ns) obtained for ZnMPCPc (8), ZnTDTPc (12), ZnMCapPc (10), ZnMCafPc (11) and ZnTCPPc (13), respectively. All the complexes showed the ability to produce singlet oxygen with the highest triplet quantum yields obtained for 8 and 10 (0.80 and 0.65 respectively). High triplet lifetimes (109–286 μs) were obtained for all complexes. Complex 8 showed the longest triplet and fluorescence lifetimes as well the largest triplet state and singlet oxygen quantum yields.
- Full Text:
- Date Issued: 2012
Synthesis and physicochemical behavior of new low symmetry Ge, Ti and Sn phthalocyanines
- Masilela, Nkosiphile, Nyokong, Tebello
- Authors: Masilela, Nkosiphile , Nyokong, Tebello
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/242421 , vital:51040 , xlink:href="https://doi.org/10.1016/j.synthmet.2012.07.028"
- Description: The synthesis and photophysicochemical properties of new low symmetrically Ge, Sn and Ti phthalocyanines substituted with one carboxy containing group are reported. Broading and splitting in the absorption spectra were observed for some of the complexes in particular for both the titanium Pcs due to loss of symmetry. Higher fluorescence quantum yields and lifetimes were obtained for the Pcs substituted with three benzyloxy (5–7) compared to their corresponding counterparts substituted with six 2-diethylaminoethylthiol groups (9–11). The germanium Pc complexes gave the highest triplet and singlet oxygen quantum yields compared to all the other complexes studied in DMF. All the complexes showed reasonable ability to generate singlet oxygen with quantum yields ranging from 0.54 to 0.69.
- Full Text:
- Date Issued: 2012
- Authors: Masilela, Nkosiphile , Nyokong, Tebello
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/242421 , vital:51040 , xlink:href="https://doi.org/10.1016/j.synthmet.2012.07.028"
- Description: The synthesis and photophysicochemical properties of new low symmetrically Ge, Sn and Ti phthalocyanines substituted with one carboxy containing group are reported. Broading and splitting in the absorption spectra were observed for some of the complexes in particular for both the titanium Pcs due to loss of symmetry. Higher fluorescence quantum yields and lifetimes were obtained for the Pcs substituted with three benzyloxy (5–7) compared to their corresponding counterparts substituted with six 2-diethylaminoethylthiol groups (9–11). The germanium Pc complexes gave the highest triplet and singlet oxygen quantum yields compared to all the other complexes studied in DMF. All the complexes showed reasonable ability to generate singlet oxygen with quantum yields ranging from 0.54 to 0.69.
- Full Text:
- Date Issued: 2012
Synthesis and physicochemical behaviour of aluminium trikis and tetrakis (diaquaplatinum) octacarboxyphthalocynine
- Malinga, Nduduzo, Dolotova, Olga V, Bulgakov, Roman, Antunes, Edith M, Nyokong, Tebello
- Authors: Malinga, Nduduzo , Dolotova, Olga V , Bulgakov, Roman , Antunes, Edith M , Nyokong, Tebello
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/242687 , vital:51068 , xlink:href="https://doi.org/10.1016/j.dyepig.2012.05.011"
- Description: The combination of chemotherapy and photodynamic therapy was investigated by the synthesis and characterisation of phthalocyanine conjugates with Pt complexes. The complexes synthesized are: hydroxoaluminum trikis(diaquaplatinum) octacarboxyphthalocyanine (OHAlOCPc(Pt)3) and hydroxoaluminum tetrakis(diaquaplatinum) octacarboxyphthalocyanine (OHAlOCPc(Pt)4). The platinated phthalocyanine complexes gave long triplet lifetimes of 577 and 526 μs for OHAlOCPc(Pt)3 and OHAlOCPc(Pt)4, respectively. The triplet quantum yields were found to be 0.45 for OHAlOCPc(Pt)3 and 0.57 OHAlOCPc(Pt)4 while the singlet oxygen quantum yields were found to be 0.38 and 0.48, respectively.
- Full Text:
- Date Issued: 2012
- Authors: Malinga, Nduduzo , Dolotova, Olga V , Bulgakov, Roman , Antunes, Edith M , Nyokong, Tebello
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/242687 , vital:51068 , xlink:href="https://doi.org/10.1016/j.dyepig.2012.05.011"
- Description: The combination of chemotherapy and photodynamic therapy was investigated by the synthesis and characterisation of phthalocyanine conjugates with Pt complexes. The complexes synthesized are: hydroxoaluminum trikis(diaquaplatinum) octacarboxyphthalocyanine (OHAlOCPc(Pt)3) and hydroxoaluminum tetrakis(diaquaplatinum) octacarboxyphthalocyanine (OHAlOCPc(Pt)4). The platinated phthalocyanine complexes gave long triplet lifetimes of 577 and 526 μs for OHAlOCPc(Pt)3 and OHAlOCPc(Pt)4, respectively. The triplet quantum yields were found to be 0.45 for OHAlOCPc(Pt)3 and 0.57 OHAlOCPc(Pt)4 while the singlet oxygen quantum yields were found to be 0.38 and 0.48, respectively.
- Full Text:
- Date Issued: 2012
Synthesis of phthalocyanine conjugates with gold nanoparticles and liposomes for photodynamic therapy
- Nombona, Nolwazi, Maduray, Kaminee, Antunes, Edith M, Karsten, Aletta, Nyokong, Tebello
- Authors: Nombona, Nolwazi , Maduray, Kaminee , Antunes, Edith M , Karsten, Aletta , Nyokong, Tebello
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/245798 , vital:51406 , xlink:href="https://doi.org/10.1016/j.jphotobiol.2011.11.007"
- Description: The efficiency of [2,9,17,23-tetrakis-(1,6-hexanedithiol)phthalocyaninato]zinc(II) as a photodynamic therapy (PDT) agent was investigated. This compound belongs to the second generation of photosensitizers currently tested for the cellular photo-damage of cancer cells. The production of reactive oxygen species (ROS) and phototoxicity of the photosensitizer were assessed. Healthy fibroblast cells and breast cancer (MCF-7) cells were treated with either free phthalocyanine or phthalocyanine bound to either gold nanoparticles or encapsulated in liposomes. Cell viability studies showed the optimum phototoxic effect on non-malignant cells to be 4.5 J cm−2. The PDT effect of the liposome bound phthalocyanine showed extensive damage of the breast cancer cells. Gold nanoparticles only showed a modest improvement in PDT activity.
- Full Text:
- Date Issued: 2012
- Authors: Nombona, Nolwazi , Maduray, Kaminee , Antunes, Edith M , Karsten, Aletta , Nyokong, Tebello
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/245798 , vital:51406 , xlink:href="https://doi.org/10.1016/j.jphotobiol.2011.11.007"
- Description: The efficiency of [2,9,17,23-tetrakis-(1,6-hexanedithiol)phthalocyaninato]zinc(II) as a photodynamic therapy (PDT) agent was investigated. This compound belongs to the second generation of photosensitizers currently tested for the cellular photo-damage of cancer cells. The production of reactive oxygen species (ROS) and phototoxicity of the photosensitizer were assessed. Healthy fibroblast cells and breast cancer (MCF-7) cells were treated with either free phthalocyanine or phthalocyanine bound to either gold nanoparticles or encapsulated in liposomes. Cell viability studies showed the optimum phototoxic effect on non-malignant cells to be 4.5 J cm−2. The PDT effect of the liposome bound phthalocyanine showed extensive damage of the breast cancer cells. Gold nanoparticles only showed a modest improvement in PDT activity.
- Full Text:
- Date Issued: 2012
Synthesis, density functional theory, molecular dynamics and electrochemical studies of 3-thiopheneacetic acid-capped gold nanoparticles
- Sosibo, Ndabenhle M, Mdluli, Phumlane S, Mashazi, Philani N, Dyan, Busiswa, Revaprasadu, Neerish, Nyokong, Tebello, Tshikhudo, Robert T, Skepu, Amanda, Van Der Lingen, Elma
- Authors: Sosibo, Ndabenhle M , Mdluli, Phumlane S , Mashazi, Philani N , Dyan, Busiswa , Revaprasadu, Neerish , Nyokong, Tebello , Tshikhudo, Robert T , Skepu, Amanda , Van Der Lingen, Elma
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/246446 , vital:51477 , xlink:href="https://doi.org/10.1016/j.molstruc.2011.09.057"
- Description: Gold nanoparticles capped with a bifunctional ligand, 3-thiopheneacetic acid (3-TAA) were synthesised by borohydride reduction at room temperature. The transmission electron microscopy (TEM) analysis showed that the particle aggregates and had semi-linear partial linkages that could be attributed to multi-modal binding of the ligand with various gold nanoparticles through the terminal thiolether (–S–) group and oxygen of the carboxylic (–COOH) group. This bimodal interaction led to limited stability of the resultant nanoparticles when tested using highly electrolytic media. To investigate further, density functional theory (DFT) quantum chemical and molecular dynamic calculations were conducted. The energetically favorable binding modes of the ligand to gold nanoparticle surfaces using the Gaussian program were studied. The DFT results showed kinetic stability of Au–3-TAA–Au interactions leading to inter-particle coupling or aggregation. Electrochemical analysis of the resultant nature of the capping agent revealed that 3-thiopheneacetic acid did not form a polymer during the preparation of Au–3-TAA. The cyclic voltammograms of Au–3-TAA nanoparticles coated glassy carbon electrode showed a typical gold character with the oxidation and reduction peaks at 1.4 V and 0.9 V, respectively.
- Full Text:
- Date Issued: 2012
- Authors: Sosibo, Ndabenhle M , Mdluli, Phumlane S , Mashazi, Philani N , Dyan, Busiswa , Revaprasadu, Neerish , Nyokong, Tebello , Tshikhudo, Robert T , Skepu, Amanda , Van Der Lingen, Elma
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/246446 , vital:51477 , xlink:href="https://doi.org/10.1016/j.molstruc.2011.09.057"
- Description: Gold nanoparticles capped with a bifunctional ligand, 3-thiopheneacetic acid (3-TAA) were synthesised by borohydride reduction at room temperature. The transmission electron microscopy (TEM) analysis showed that the particle aggregates and had semi-linear partial linkages that could be attributed to multi-modal binding of the ligand with various gold nanoparticles through the terminal thiolether (–S–) group and oxygen of the carboxylic (–COOH) group. This bimodal interaction led to limited stability of the resultant nanoparticles when tested using highly electrolytic media. To investigate further, density functional theory (DFT) quantum chemical and molecular dynamic calculations were conducted. The energetically favorable binding modes of the ligand to gold nanoparticle surfaces using the Gaussian program were studied. The DFT results showed kinetic stability of Au–3-TAA–Au interactions leading to inter-particle coupling or aggregation. Electrochemical analysis of the resultant nature of the capping agent revealed that 3-thiopheneacetic acid did not form a polymer during the preparation of Au–3-TAA. The cyclic voltammograms of Au–3-TAA nanoparticles coated glassy carbon electrode showed a typical gold character with the oxidation and reduction peaks at 1.4 V and 0.9 V, respectively.
- Full Text:
- Date Issued: 2012
The direct use value of municipal commonage goods and services to urban households in the Eastern Cape, South Africa
- Davenport, Nicholas A, Shackleton, Charlie M, Gambiza, James
- Authors: Davenport, Nicholas A , Shackleton, Charlie M , Gambiza, James
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/181071 , vital:43696 , xlink:href="https://doi.org/10.1016/j.landusepol.2011.09.008"
- Description: To redress past racial discrepancies in ownership and tenure, the ANC government of South Africa initiated programmes to make land accessible to the previously disadvantaged. A key component of the national land reform programme was the provision of commonage lands to urban municipalities for use by the urban poor. However, there has been no assessment of the contribution that urban commonage makes to previously disadvantaged households. This study assessed the economic benefits of the commonage programme to local households, through an in-depth survey of 90 households across three small towns in the Eastern Cape of South Africa. We examined the marketed and non-marketed consumptive direct-use values of land-based livelihoods on commonage, calculated via the ‘own reported values’ approach. The results indicate that a proportion of South Africa's urban population rely to some degree on municipal commonage for part of their livelihoods. Commonage contributions to total livelihood incomes ranged between 14 and 20%. If the contributions from commonage were excluded, the incomes of over 10% of households in each study town would drop below the poverty line. Overall, the value of harvests from commonage was worth over R1 000 (US$ 142) per hectare per year and over R4.7 million (US$ 0.68 million) per commonage per year. However, the extent and nature of use and reliance was not uniform among households, so that we developed a typology of commonage users, with four types being identified. However, rapidly growing urban populations and high levels of poverty potentially threaten the sustainability of commonage resource use. Yet the national land reform programme focuses largely on the transfer of land to municipalities and not on sustainable management. Municipalities, in turn, invest relatively little in commonage management, and the little they do is focussed on livestock production. Non-timber forest products are not considered at all, even though this study shows that they are a vital resource for the urban poor, notably for energy and construction materials.
- Full Text:
- Date Issued: 2012
- Authors: Davenport, Nicholas A , Shackleton, Charlie M , Gambiza, James
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/181071 , vital:43696 , xlink:href="https://doi.org/10.1016/j.landusepol.2011.09.008"
- Description: To redress past racial discrepancies in ownership and tenure, the ANC government of South Africa initiated programmes to make land accessible to the previously disadvantaged. A key component of the national land reform programme was the provision of commonage lands to urban municipalities for use by the urban poor. However, there has been no assessment of the contribution that urban commonage makes to previously disadvantaged households. This study assessed the economic benefits of the commonage programme to local households, through an in-depth survey of 90 households across three small towns in the Eastern Cape of South Africa. We examined the marketed and non-marketed consumptive direct-use values of land-based livelihoods on commonage, calculated via the ‘own reported values’ approach. The results indicate that a proportion of South Africa's urban population rely to some degree on municipal commonage for part of their livelihoods. Commonage contributions to total livelihood incomes ranged between 14 and 20%. If the contributions from commonage were excluded, the incomes of over 10% of households in each study town would drop below the poverty line. Overall, the value of harvests from commonage was worth over R1 000 (US$ 142) per hectare per year and over R4.7 million (US$ 0.68 million) per commonage per year. However, the extent and nature of use and reliance was not uniform among households, so that we developed a typology of commonage users, with four types being identified. However, rapidly growing urban populations and high levels of poverty potentially threaten the sustainability of commonage resource use. Yet the national land reform programme focuses largely on the transfer of land to municipalities and not on sustainable management. Municipalities, in turn, invest relatively little in commonage management, and the little they do is focussed on livestock production. Non-timber forest products are not considered at all, even though this study shows that they are a vital resource for the urban poor, notably for energy and construction materials.
- Full Text:
- Date Issued: 2012
The effect of harvesting approaches on fruit yield, embelin concentration and regrowth dynamics of the forest shrub, Embelia tsjeriam-cottam, in central India
- Pandey, Ashok K, Shackleton, Charlie M
- Authors: Pandey, Ashok K , Shackleton, Charlie M
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/181094 , vital:43698 , xlink:href="https://doi.org/10.1016/j.foreco.2011.11.015"
- Description: Embelia tsjeriam-cottam Roem and Schult A. DC. (Myrsinaceae), popularly known as Vaividang, is a vulnerable forest species because of the high demand of fruits for medicinal purposes. It is in great demand in ayurveda and the pharmaceutical industry (>100 t/yr), which has imposed tremendous pressure on some natural populations. The fruits contain embelin (a benzoquinone derivative), which has wide clinical applications. Considering the importance, growing use and decreasing populations in some areas of its natural habitat, a study on development of sustainable harvesting practices of E. tsjeriam-cottam fruits was conducted in Chhattisgarh, in central India. Experiments were laid out in Dhamtari, Marvahi and Bilaspur forest divisions of the state covering both protected and open forests in a randomized design with three replications. At each site, quadrats of 40 × 20 m were laid out to study the effect of two fruit harvesting methods and four harvesting intensities on fruit yield, and regeneration of the species. Fruits were analyzed for their embelin content by HPLC method. This study is the first to experimentally assess the consequences of harvesting of E. tsjeriam-cottam fruits from India. It was found that up to 70% fruits could be hand plucked at the right time of maturity (December) to obtain quality produce without impacting the current population size. Since every year is not a good fruiting year, it is difficult to develop universal harvest regime for sustainable management of E. tsjeriam-cottam. The embelin content increased as fruits ripened, ranging from 1.01% to 5.63%. The adoption of sustainable harvesting practices will be helpful in sustainable management of E. tsjeriam-cottam and also provide income and livelihood opportunities to rural people on a sustainable basis.
- Full Text:
- Date Issued: 2012
- Authors: Pandey, Ashok K , Shackleton, Charlie M
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/181094 , vital:43698 , xlink:href="https://doi.org/10.1016/j.foreco.2011.11.015"
- Description: Embelia tsjeriam-cottam Roem and Schult A. DC. (Myrsinaceae), popularly known as Vaividang, is a vulnerable forest species because of the high demand of fruits for medicinal purposes. It is in great demand in ayurveda and the pharmaceutical industry (>100 t/yr), which has imposed tremendous pressure on some natural populations. The fruits contain embelin (a benzoquinone derivative), which has wide clinical applications. Considering the importance, growing use and decreasing populations in some areas of its natural habitat, a study on development of sustainable harvesting practices of E. tsjeriam-cottam fruits was conducted in Chhattisgarh, in central India. Experiments were laid out in Dhamtari, Marvahi and Bilaspur forest divisions of the state covering both protected and open forests in a randomized design with three replications. At each site, quadrats of 40 × 20 m were laid out to study the effect of two fruit harvesting methods and four harvesting intensities on fruit yield, and regeneration of the species. Fruits were analyzed for their embelin content by HPLC method. This study is the first to experimentally assess the consequences of harvesting of E. tsjeriam-cottam fruits from India. It was found that up to 70% fruits could be hand plucked at the right time of maturity (December) to obtain quality produce without impacting the current population size. Since every year is not a good fruiting year, it is difficult to develop universal harvest regime for sustainable management of E. tsjeriam-cottam. The embelin content increased as fruits ripened, ranging from 1.01% to 5.63%. The adoption of sustainable harvesting practices will be helpful in sustainable management of E. tsjeriam-cottam and also provide income and livelihood opportunities to rural people on a sustainable basis.
- Full Text:
- Date Issued: 2012
The photophysical and energy transfer behaviour of low symmetry phthalocyanine complexes conjugated to coreshell quantum dots
- Masilela, Nkosiphile, Nyokong, Tebello
- Authors: Masilela, Nkosiphile , Nyokong, Tebello
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/243051 , vital:51111 , xlink:href="https://doi.org/10.1016/j.jphotochem.2012.07.016"
- Description: This work reports on the synthesis of new coreshell quantum dots (QDs)-low symmetry phthalocyanines conjugates. The energy transfer from QDs (donor) to phthalocyanines (acceptor) was investigated when the two are mixed together or chemically linked to each other. Ti monocarboxy phthalocyanine QDs-linked and Sn monocarboxy phthalocyanine QDs-linked gave the smallest centre-to-centre separation distance (r) corresponding to their higher Förster resonance energy transfer efficiencies which are estimated at 0.76 and 0.85 respectively. Higher energy transfer behaviour was achieved for all the covalently linked conjugates compared to their corresponding mixed counterparts. An improvement in triplet quantum yields and lifetimes was achieved for all the complexes in the presence of quantum dots, with the linked counterparts displaying excellent triplet state behaviour.
- Full Text:
- Date Issued: 2012
- Authors: Masilela, Nkosiphile , Nyokong, Tebello
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/243051 , vital:51111 , xlink:href="https://doi.org/10.1016/j.jphotochem.2012.07.016"
- Description: This work reports on the synthesis of new coreshell quantum dots (QDs)-low symmetry phthalocyanines conjugates. The energy transfer from QDs (donor) to phthalocyanines (acceptor) was investigated when the two are mixed together or chemically linked to each other. Ti monocarboxy phthalocyanine QDs-linked and Sn monocarboxy phthalocyanine QDs-linked gave the smallest centre-to-centre separation distance (r) corresponding to their higher Förster resonance energy transfer efficiencies which are estimated at 0.76 and 0.85 respectively. Higher energy transfer behaviour was achieved for all the covalently linked conjugates compared to their corresponding mixed counterparts. An improvement in triplet quantum yields and lifetimes was achieved for all the complexes in the presence of quantum dots, with the linked counterparts displaying excellent triplet state behaviour.
- Full Text:
- Date Issued: 2012
The syntheses and photophysical properties of 4, 4′-isopropylidendioxydiphenyl substituted ball-type dinuclear Mg (II) and Zn (II) phthalocyanines
- Canlıca, Mevlüde, Nyokong, Tebello
- Authors: Canlıca, Mevlüde , Nyokong, Tebello
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/243554 , vital:51163 , xlink:href="https://doi.org/10.1016/j.poly.2011.10.024"
- Description: The syntheses of ball-type dinuclear Zn(II) and Mg(II) phthalocyanines containing four 4,4′-isopropylidendioxydiphenyl substituents at the peripheral and non-peripheral positions are presented. The structures of the synthesized compounds were characterized using elemental analyses, and UV–Vis, FT-IR, 1H NMR and mass spectroscopies. The ΦF values were 0.14, 0.11, 0.22, 0.15 and ΦT values were 0.84, 0.88, 0.62, 0.74, for 6–9, respectively. The largest triplet yields were observed for the non-peripherally substituted complexes 6 and 7, showing that non-peripheral substitution favors increased population of the triplet state. All complexes showed reasonably long triplet lifetimes with τT 510, 310, 910 and 350 μs in DMSO, respectively.
- Full Text:
- Date Issued: 2012
- Authors: Canlıca, Mevlüde , Nyokong, Tebello
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/243554 , vital:51163 , xlink:href="https://doi.org/10.1016/j.poly.2011.10.024"
- Description: The syntheses of ball-type dinuclear Zn(II) and Mg(II) phthalocyanines containing four 4,4′-isopropylidendioxydiphenyl substituents at the peripheral and non-peripheral positions are presented. The structures of the synthesized compounds were characterized using elemental analyses, and UV–Vis, FT-IR, 1H NMR and mass spectroscopies. The ΦF values were 0.14, 0.11, 0.22, 0.15 and ΦT values were 0.84, 0.88, 0.62, 0.74, for 6–9, respectively. The largest triplet yields were observed for the non-peripherally substituted complexes 6 and 7, showing that non-peripheral substitution favors increased population of the triplet state. All complexes showed reasonably long triplet lifetimes with τT 510, 310, 910 and 350 μs in DMSO, respectively.
- Full Text:
- Date Issued: 2012
Unquenched fluorescence lifetime for β-phenylthio substituted zinc phthalocyanine upon conjugation to gold nanoparticles
- Forteath, Shaun, Antunes, Edith M, Chidawanyika, Wadzanai J U, Nyokong, Tebello
- Authors: Forteath, Shaun , Antunes, Edith M , Chidawanyika, Wadzanai J U , Nyokong, Tebello
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/245774 , vital:51404 , xlink:href="https://doi.org/10.1016/j.poly.2011.12.015"
- Description: Photoinduced processes in phthalocyanine-functionalized gold nanoparticles have been investigated by spectroscopic measurements. The zinc phthalocyanine used contained four phenylthio peripheral substituents (ZnPc(SPh)4). The conjugates formed are represented as ZnPc(SPh)4–AuNP. The absorption spectrum of the ZnPc(SPh)4–AuNP shows a broadening of the phthalocyanine Q-band absorption, probably due to a tight packing of the phthalocyanines on the gold nanoparticle surface. For the attached phthalocyanines, the two fluorescence lifetimes obtained by time-correlated single photon counting (TCSPC) were determined to be both longer and shorter than that of the free Pc. The fluorescence lifetimes were resolved using time resolved fluorescence spectroscopy (TRES).
- Full Text:
- Date Issued: 2012
- Authors: Forteath, Shaun , Antunes, Edith M , Chidawanyika, Wadzanai J U , Nyokong, Tebello
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/245774 , vital:51404 , xlink:href="https://doi.org/10.1016/j.poly.2011.12.015"
- Description: Photoinduced processes in phthalocyanine-functionalized gold nanoparticles have been investigated by spectroscopic measurements. The zinc phthalocyanine used contained four phenylthio peripheral substituents (ZnPc(SPh)4). The conjugates formed are represented as ZnPc(SPh)4–AuNP. The absorption spectrum of the ZnPc(SPh)4–AuNP shows a broadening of the phthalocyanine Q-band absorption, probably due to a tight packing of the phthalocyanines on the gold nanoparticle surface. For the attached phthalocyanines, the two fluorescence lifetimes obtained by time-correlated single photon counting (TCSPC) were determined to be both longer and shorter than that of the free Pc. The fluorescence lifetimes were resolved using time resolved fluorescence spectroscopy (TRES).
- Full Text:
- Date Issued: 2012
Comparative behavior of conjugates of tantalum phthalocyanines with gold nanoparticles or single walled carbon nanotubes towards bisphenol A electrocatalysis
- Chauke, Vongani P, Antunes, Edith M, Nyokong, Tebello
- Authors: Chauke, Vongani P , Antunes, Edith M , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247152 , vital:51551 , xlink:href="https://doi.org/10.1016/j.jelechem.2011.06.019"
- Description: The characterization of tantalum phthalocyanine conjugates with gold nanoparticles and single wall carbon nanotubes as well as their electrocatalytic oxidation of bisphenol A is hereby presented. The formation of the conjugates was confirmed by X-ray diffraction and transmission electron microscope techniques. Single walled carbon nanotube conjugates of TaPc complexes showed the best catalysis as well as less passivation for bisphenol A detection and significant recovery of ∼98% compared to gold nanoparticle conjugates.
- Full Text:
- Date Issued: 2011
- Authors: Chauke, Vongani P , Antunes, Edith M , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247152 , vital:51551 , xlink:href="https://doi.org/10.1016/j.jelechem.2011.06.019"
- Description: The characterization of tantalum phthalocyanine conjugates with gold nanoparticles and single wall carbon nanotubes as well as their electrocatalytic oxidation of bisphenol A is hereby presented. The formation of the conjugates was confirmed by X-ray diffraction and transmission electron microscope techniques. Single walled carbon nanotube conjugates of TaPc complexes showed the best catalysis as well as less passivation for bisphenol A detection and significant recovery of ∼98% compared to gold nanoparticle conjugates.
- Full Text:
- Date Issued: 2011
Conjugates of low-symmetry Ge, Sn and Ti carboxy phthalocyanines with glutathione caped gold nanoparticles
- Masilela, Nkosiphile, Nyokong, Tebello
- Authors: Masilela, Nkosiphile , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247003 , vital:51536 , xlink:href="https://doi.org/10.1016/j.jphotochem.2011.08.009"
- Description: This work reports on conjugation of low symmetry Ge (GeMCPc), Ti (TiMCPc) and Sn (SnMCPc) carboxy phthalocyanines with glutathione capped gold nanoparticles (GSH-AuNPs). The photophysical behaviour of the novel phthalocyanines–GSH-AuNPs conjugate was investigated and compared to the monocarboxy Pcs and to the mixture of Pc with GSH-AuNPs without a chemical bond. Blue shifting of Q band of the phthalocyanines was observed on linking to GSH-AuNPs. An improvement in triplet lifetimes was obtained for all the MPcs–GSH-AuNPs-linked conjugates compared to the MPcs alone. The highest triplet quantum yield of 0.75 and the longest triplet lifetime of 130 μs were obtained for the GeMCPc–GSH-AuNPs-linked conjugate. Fluorescence quantum yields and lifetimes were low for the conjugates due to quenching by the nanoparticles.
- Full Text:
- Date Issued: 2011
- Authors: Masilela, Nkosiphile , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247003 , vital:51536 , xlink:href="https://doi.org/10.1016/j.jphotochem.2011.08.009"
- Description: This work reports on conjugation of low symmetry Ge (GeMCPc), Ti (TiMCPc) and Sn (SnMCPc) carboxy phthalocyanines with glutathione capped gold nanoparticles (GSH-AuNPs). The photophysical behaviour of the novel phthalocyanines–GSH-AuNPs conjugate was investigated and compared to the monocarboxy Pcs and to the mixture of Pc with GSH-AuNPs without a chemical bond. Blue shifting of Q band of the phthalocyanines was observed on linking to GSH-AuNPs. An improvement in triplet lifetimes was obtained for all the MPcs–GSH-AuNPs-linked conjugates compared to the MPcs alone. The highest triplet quantum yield of 0.75 and the longest triplet lifetime of 130 μs were obtained for the GeMCPc–GSH-AuNPs-linked conjugate. Fluorescence quantum yields and lifetimes were low for the conjugates due to quenching by the nanoparticles.
- Full Text:
- Date Issued: 2011
Cyclic voltammetry and spectroelectrochemistry of a novel manganese phthalocyanine substituted with hexynyl groups
- Quinton, Damien, Antunes, Edith M, Griveau, Sophie, Nyokong, Tebello, Bedioui, Fethi
- Authors: Quinton, Damien , Antunes, Edith M , Griveau, Sophie , Nyokong, Tebello , Bedioui, Fethi
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/248450 , vital:51687 , xlink:href="https://doi.org/10.1016/j.inoche.2010.11.029"
- Description: We report here on the synthesis of a new manganese phthalocyanine complex, namely Mn tetrakis(5-hexyn-oxy) phthalocyanine (3), specifically designed to possess an alkyne moiety for its potential use in controlled immobilization on electrodes via the so called “click” chemistry reaction. The electrochemical activity of complex 3 was investigated by cyclic voltammetry and the nature of the observed redox couples was elucidated by spectroelectrochemistry. This work has also shown that the reduction of Mn(III)Pc complex to Mn(II)Pc is accompanied by the formation of MnPc μ-oxo species. Further reduction results in the formation of Mn(II)Pc(− 3) rather than Mn(I)Pc(− 2).
- Full Text:
- Date Issued: 2011
- Authors: Quinton, Damien , Antunes, Edith M , Griveau, Sophie , Nyokong, Tebello , Bedioui, Fethi
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/248450 , vital:51687 , xlink:href="https://doi.org/10.1016/j.inoche.2010.11.029"
- Description: We report here on the synthesis of a new manganese phthalocyanine complex, namely Mn tetrakis(5-hexyn-oxy) phthalocyanine (3), specifically designed to possess an alkyne moiety for its potential use in controlled immobilization on electrodes via the so called “click” chemistry reaction. The electrochemical activity of complex 3 was investigated by cyclic voltammetry and the nature of the observed redox couples was elucidated by spectroelectrochemistry. This work has also shown that the reduction of Mn(III)Pc complex to Mn(II)Pc is accompanied by the formation of MnPc μ-oxo species. Further reduction results in the formation of Mn(II)Pc(− 3) rather than Mn(I)Pc(− 2).
- Full Text:
- Date Issued: 2011
Electrochemical behavior of phthalocyanines containing high oxidation state central metals
- Chauke, Vongani, Arslanoglu, Yasin, Nyokong, Tebello
- Authors: Chauke, Vongani , Arslanoglu, Yasin , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247111 , vital:51547 , xlink:href="https://doi.org/10.1016/j.poly.2011.05.028"
- Description: The syntheses of 2,(3)-(peripheral) and 1,(4)-(non-peripheral) (2-mercaptopyridine)phthalocyanine complexes of titanium(IV) oxide (5a and 6a, respectively), vanadium(IV) oxide (7a and 8a, respectively) and tantalum(V) hydroxide (9a, peripheral only) and their electrochemical characterization are presented in this report. Their electrochemistry is compared to that of thiophenyl and thiobenzyl substituted derivatives. The non-peripherally substituted complexes are more difficult to reduce than peripherally substituted derivatives. In addition, the mercaptopyridine substituted derivatives are more difficult to reduce compared to benzylmercapto and phenylmercapto derivatives, and aryl easier reduce than alkyl substitution. Spectroelectrochemistry of the complexes confirmed metal and ring redox processes for TaPc and TiPc derivatives and ring based processes only for VPc complexes.
- Full Text:
- Date Issued: 2011
- Authors: Chauke, Vongani , Arslanoglu, Yasin , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247111 , vital:51547 , xlink:href="https://doi.org/10.1016/j.poly.2011.05.028"
- Description: The syntheses of 2,(3)-(peripheral) and 1,(4)-(non-peripheral) (2-mercaptopyridine)phthalocyanine complexes of titanium(IV) oxide (5a and 6a, respectively), vanadium(IV) oxide (7a and 8a, respectively) and tantalum(V) hydroxide (9a, peripheral only) and their electrochemical characterization are presented in this report. Their electrochemistry is compared to that of thiophenyl and thiobenzyl substituted derivatives. The non-peripherally substituted complexes are more difficult to reduce than peripherally substituted derivatives. In addition, the mercaptopyridine substituted derivatives are more difficult to reduce compared to benzylmercapto and phenylmercapto derivatives, and aryl easier reduce than alkyl substitution. Spectroelectrochemistry of the complexes confirmed metal and ring redox processes for TaPc and TiPc derivatives and ring based processes only for VPc complexes.
- Full Text:
- Date Issued: 2011