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Synthesis, Photophysical and Photochemical Properties of Poly (oxyethylene)‐Substituted Phthalocyaninato Oxotitanium (IV) Complexes

  • Authors: Atilla, Devrim , Durmus, Mahmut , Yılmaz, Özgür , Gürek, Ayşe Gül , Ahsen, Vefa , Nyokong, Tebello
  • Date: 2007
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/271263 , vital:54526 , xlink:href="https://doi.org/10.1002/ejic.200700057"
  • Description: The synthesis, photophysical and photochemical properties of tetra- and chlorotetrapoly(oxyethylene)-substituted oxotitanium(IV) phthalocyanines are reported for the first time. The new compounds were characterized by elemental analysis, IR, 1H and 13C NMR spectroscopy, electronic spectroscopy and mass spectra. These complexes showed monomeric behaviour in solution. General trends are described for photodegredation, singlet oxygen, triplet state and fluorescence quantum yields, and triplet and fluorescence lifetimes of these compounds in dimethyl sulfoxide (DMSO). Photophysical and photochemical properties of phthalocyanine complexes are very useful for PDT applications. The complexes showed high triplet quantum yields and triplet lifetimes in DMSO. The singlet oxygen quantum yields (ΦΔ), which give an indication of the potential of the complexes as photosensitizers in applications where singlet oxygen is required (Type II mechanism), were 0.72 and 0.78 for 3a and 5a, respectively. Thus, these complexes show potential as Type II photosensitizers. These complexes were also quenched by benzoquinone for fluorescence quenching studies.
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  • Date Issued: 2007

Comparative efficiency of immobilized non-transition metal phthalocyanine photosensitizers for the visible light transformation of chlorophenols

  • Authors: Agboola, Bolade , Ozoemena, Kenneth I , Nyokong, Tebello
  • Date: 2006
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/286043 , vital:56233 , xlink:href="https://doi.org/10.1016/j.molcata.2005.12.009"
  • Description: Photolysis of aqueous solutions of chlorophenols (4-chlorophenol, 2,4-dichlorophenol, 2,4,5-trichlorophenol and pentachlorophenol) in the presence of immobilized non-transition metal phthalocyanine photosensitizers onto Amberlite® is presented. The photosensitizers studied are: Al (AlOCPc) and Zn (ZnOCPc) octacarboxyphthalocyanines; Al (AlPcS4) and Zn (ZnPcS4) tetrasulfophthalocyanines; sulfonated phthalocyanine complexes (containing mixtures of differently substituted derivatives) of Al (AlPcSmix), Zn (ZnPcSmix), Ge (GePcSmix), Si (SiPcSmix) and Sn (SnPcSmix). Photolysis of the chlorophenols resulted mainly in the formation of chlorobenzoquinone derivatives. The complexes showed order of activity towards the transformation of pentachlorophenol as follows: ZnOCPc > SiPcSmix > SnPcSmix > ZnPcSmix > GePcSmix > ZnPcS4 > AlPcSmix > AlOCPc > AlPcS4. The generation of singlet oxygen (1O2) by these immobilized MPc photosensitizers was found to play a major role in their photoactivities towards the transformation of these chlorophenols. Langmuir–Hinshelwood (L–H) kinetic model studies showed that the ZnOCPc, GePcSmix and ZnPcSmix photocatalysis occurred on the catalysts surface. © 2005 Elsevier B.V. All rights reserved.
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  • Date Issued: 2006

Comparative electrochemistry and electrocatalytic activities of cobalt, iron and manganese phthalocyanine complexes axially co-ordinated to mercaptopyridine self-assembled monolayer at gold electrodes

  • Authors: Ozoemena, Kenneth I , Nyokong, Tebello
  • Date: 2006
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/286054 , vital:56234 , xlink:href="https://doi.org/10.1016/j.electacta.2005.08.007"
  • Description: Comparative surface electrochemistry and electrocatalytic properties of solid ultrathin monolayer films of metallophthalocyanine (MPc) complexes of cobalt (CoPc), iron (FePc) and manganese (MnPc) self-immobilised, via axial ligation reaction, onto preformed 4-mercaptopyridine self-assembled monolayers (SAMs) on gold electrodes have been described. Surface electrochemical parameters of the modified electrodes showed that these MPc-SAMs are densely packed with flat orientations. The electrochemical, electrocatalytic and stability properties of these MPc complexes follow this order: FePc > MnPc > CoPc. This finding is remarkable as it suggests that the success of using this method of self-assembling of MPc onto gold electrode is largely dependent on the bond distance between the pyridine linker and the central metal of the MPc; the shorter the distance, the faster the co-ordination and the better the electrocatalytic properties towards L-cysteine and thiocyanate. Thus, the superiority of FePc-based SAM over those of the MnPc and CoPc, has been proposed to be the result of the more favorable axial co-ordination properties of FePc with pyridine (i.e. shorter Fe–N(pyridine) bond length.
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  • Date Issued: 2006

Synthesis and electrochemical characterisation of α-and β-tetra-substituted oxo (phthalocyaninato) titanium (IV) complexes

  • Authors: Tau, Prudence , Nyokong, Tebello
  • Date: 2006
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/283869 , vital:55998 , xlink:href="https://doi.org/10.1016/j.poly.2005.11.025"
  • Description: The synthesis, spectroscopic and electrochemical characterisation of the following oxotitanium tetra-substituted phthalocyanines are reported: 1,(4)-(tetraphenoxyphthalocyaninato)titanium(IV) oxide (5a); 1,(4)-(tetra-tert-butylphenoxyphthalocyaninato)titanium(IV) oxide (5b); 2,(3)-(tetraphenoxyphthalocyaninato)titanium(IV) oxide (6a) and 2,(3)-(tetra-tert-butylphenoxyphthalocyaninato)titanium(IV) oxide (6b). Complexes 5a and 5b are substituted at the non-peripheral (α) positions, whereas complexes 6a and 6b are substituted at the peripheral (β) positions. Cyclic voltammograms of all four complexes are similar, with three reversible reduction couples and three quasi-reversible to irreversible oxidations. The first two reductions are two-electron processes, confirmed by spectroelectrochemistry to be due to TiIVPc−2/TiIIPc−3 and TiIIPc−2/TiIPc−3 redox processes. Spectroelectrochemistry showed that upon oxidation, the molecule decomposes. Oxidation is expected to occur at the ring. Chronocoulometry confirmed two electron transfer at the first and second reduction steps; and a one electron transfer at the third reduction.
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  • Date Issued: 2006

Photophysical properties of a water-soluble adjacently substituted bisnaphthalophthalocyanine

  • Authors: Seotsanyana-Mokhosi, Itumeleng , Nyokong, Tebello
  • Date: 2005
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/286091 , vital:56237 , xlink:href="https://doi.org/10.1142/S1088424605000599"
  • Description: Spectral properties of a water soluble metal free tetracarboxyphenoxy bisnaphthalo-phthalocyanine (3) were studied in water and organic solvents. It was found that in protic solvents, complex 3 was highly aggregated. The surfactant, Triton X100, and bovineserum albumin (BSA) do not effect disaggregation while cetyl trimethylammonium chloride (CTAC) caused the molecule to disaggregate. The fluorescence quantum yields were higher in the presence of CTAC. Studying the interaction of BSA with complex 3 using fluorometry revealed that BSA is highly quenched by the latter. A 1:1 stoichiometric binding ratio between BSA and the Pc was found. Triplet quantum yields in water containing CTAC were higher than in organic solvents.
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  • Date Issued: 2005

Electrochemical and catalytic properties of chromium tetraaminophthalocyanine

  • Authors: Obirai, Joe , Nyokong, Tebello
  • Date: 2004
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/300310 , vital:57915 , xlink:href="https://doi.org/10.1016/j.jelechem.2004.06.026"
  • Description: Chromium tetraaminophthalocyanine (CrIIITAPc) has been synthesized and its electrochemical and spectroelectrochemical properties reported. The first reduction and oxidation in this complex occur at the central metal, giving CrIITAPc and CrIVTAPc complexes, respectively, the latter having been observed for the first time. The CrIIITAPc species was polymerized onto glassy carbon (GCE) or indium tin oxide (ITO) electrodes and the polymer evolution confirmed by UV/Visible spectroscopy and by scanning electron microscopy. The polymers were employed for the catalytic oxidation of nitrite or nitric oxide, and the catalysis involved the CrIVTAPc−1 species.
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  • Date Issued: 2004

Synthesis and photochemical studies of substituted adjacent binaphthalophthalocyanines

  • Authors: Seotsanyana-Mokhosi, Itumeleng , Nyokong, Tebello
  • Date: 2004
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/289883 , vital:56689 , xlink:href="https://doi.org/10.1142/S1088424604000568"
  • Description: Adjacent phthalocyanines with a binaphthalo backbone and phenoxy substituents were synthesized and their photochemical properties were investigated. The adjacent phthalocyanines are the binaphthalophthalocyanines, with the phenoxy, 4-tert-butylphenoxy and the sulfophenoxy substituents, respectively and bis-binaphthalophthalocyanine which has an extended π conjugation system and larger singlet oxygen quantum yield compared to the other compounds. The presence of the phenoxy substituents as well as the binaphthalo bridge does not cause a marked difference on the fluorescing properties of these complexes when compared to zinc phthalocyanine. The binaphthalo backbone allowed the molecules to photoswitch during photolysis affording them very high photostability.
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  • Date Issued: 2004

The renaissance in optical spectroscopy of phthalocyanines and other tetraazaporphyrins

  • Authors: Nyokong, Tebello , Isago, Hiroaki
  • Date: 2004
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/289388 , vital:56628 , xlink:href="https://doi.org/10.1142/S1088424604000453"
  • Description: Spectral properties of metallophthalocyanines and other tetraazaporphyrins are governed mainly by the Q band which originates from the π-π* transitions within the ring. The position and intensity of the Q band is important in tailoring new phthalocyanine derivatives for particular applications. Aggregation, the nature of the central metal, π conjugation, symmetry of the molecules, and axial, peripheral or non-peripheral substitutions affect the spectra and hence the properties of the phthalocyanine molecule. This review gives a brief outline on how optical spectroscopy provides useful informations on molecular and electronic structures, chemistry and physics of phthalocyanines and other tetraazaporphyrins.
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  • Date Issued: 2004

Indomethacin reduces lipid peroxidation in rat brain homogenate by binding Fe2+

  • Authors: Anoopkumar-Dukie, Shailendra , Lack, Barbara , McPhail, Kerry L , Nyokong, Tebello , Lambat, Zaynab , Maharaj, Deepat , Daya, Santy
  • Date: 2003
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/304763 , vital:58487 , xlink:href="https://doi.org/10.1023/A:1021958016928"
  • Description: One of the hallmarks of Alzheimer's disease (AD) is the progressive degeneration of cholinergic neurons in the cerebral cortex and hippocampus. It is generally accepted that this neuronal degeneration is due to free-radical-induced damage. These free radicals attack vital structural components of the neurons. This implies that agents that reduce free radical generation could potentially delay the progression of AD. Free radical generation in the brain is assisted by the presence of iron, required by the Fenton reaction. Thus, agents that reduce iron availability for this reaction could potentially reduce free radical formation. Since non steroidal anti-inflammatory drugs (NSAIDS) have been shown to reduce the severity of AD, we investigated the possible mechanism by which indomethacin could afford neuroprotection. Our results show that indomethacin (1 mM) is able to reduce the iron-induced rise in lipid peroxidation in rat brain homogenates. In addition, our NMR data indicate that indomethacin binds the Fe2+/Fe3+ ion. This was confirmed by a study using UV/Vis spectrophotometry. The results imply that indomethacin provides a neuroprotective effect by binding to iron and thus making it unavailable for free radical production.
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  • Date Issued: 2003

Influence of cyclodextrins on the fluorescence, photostability and singlet oxygen quantum yields of zinc phthalocyanine and naphthalocyanine complexes

  • Authors: Tau, Prudence , Ogunsipe, Abimbola O , Maree, Suzanne , Maree, M David , Nyokong, Tebello
  • Date: 2003
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/304775 , vital:58488 , xlink:href="https://doi.org/10.1142/S1088424603000562"
  • Description: The effects of formation of cyclodextrin inclusion complexes on the photochemical and photophysical properties of zinc phthalocyanine (ZnPc) and various peripherally substituted zinc phthalocyanines as well as zinc naphthalocyanine (ZnNPc) are investigated. The cyclodextrins employed were the hydroxypropyl-γ-cyclodextrin and unsubstituted β-cyclodextrin. Job's plots were employed to confirm the stoichiometry of the inclusion complexes and showed 2:1 and 4:1 (cyclodextrin:phthalocyanine) inclusion behavior. The phthalocyanine inclusion complexes showed larger singlet oxygen quantum yield (ϕΔ) values when compared to the free phthalocyanines before inclusion, for complexes 1 (zinc naphthalocyanine), 2 (zinc tetranitrophthalocyanine) and 4 (zinc tetra-tert-butylphenoxyphthalocyanine). The fluorescence quantum yields generally remained unchanged following inclusion.
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  • Date Issued: 2003

Phthalocyanines and related complexes as electrocatalysts for the detection of nitric oxide

  • Authors: Nyokong, Tebello , Vilakazi, Sibulelo
  • Date: 2003
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/290346 , vital:56741 , xlink:href="https://doi.org/10.1016/S0039-9140(03)00356-4"
  • Description: Metallophthalocyanine (MPc) and metalloporphyrin complexes as well as some metalloproteins including myoglobin, hemoglobin, cyanocobalamin and cytochrome c catalyse the detection of nitric oxide (NO). The catalytic process often involve changes in the oxidation state of the catalyst. These complexes catalyse both the reduction and oxidation of NO. MPc complexes containing electroactive central metals such as CoPc and FePc generally show better catalytic activity towards the detection of NO than complexes containing electroinacive central metals. However, the involvement of ring based redox processes was confirmed for the homogenous NO catalysis using CoPc.
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  • Date Issued: 2003

Self-Assembled Monolayers of Cobalt and Iron Phthalocyanine Complexes on Gold Electrodes

  • Authors: Ozoemena, Kenneth I , Nyokong, Tebello , Westbroek, Philippe
  • Date: 2003
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/290363 , vital:56743 , xlink:href="https://doi.org/10.1002/elan.200302753"
  • Description: The self-assembling of the octa(hydroxyethylthio)-metallophthalocyanine {MOHETPc (M=Co and Fe)} complexes and their similar analogues, octabutylthiometallophthalocyanine {MOBTPc (M=Co and Fe)} complexes on gold electrodes are investigated. Comparative surface voltammetric insights into their distinct self-assembling properties with respect to the passivation of Faradaic processes and surface coverages, including their solution electrochemistry, suggest different orientations and non-cleavage of their CS bonds. In the pH 2−9 range, the reversible [M(III)Pc(−2)]+ / [M(II)Pc(−2)] redox couples show potential shifts close to −59 mV / pH. The gold electrodes modified with the SAMs of these species show electrocatalytic activity towards the oxidation of thiols (L-cysteine, homocysteine and penicillamine) and thiocyanate in acidic media with detection limits in the region of 10−7–10−6 mol dm−3. These monolayers are stable and easily reproducible.
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  • Date Issued: 2003

Spectrophotometric and electrochemical studies of the interaction between iron (II) tetrasulfophthalocyanine and histamine

  • Authors: Oni, Joshua , Nyokong, Tebello
  • Date: 2002
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/289629 , vital:56657 , xlink:href="https://doi.org/10.1142/S1088424602000233"
  • Description: The interaction between iron(II) tetrasulfophthalocyanine ([FeIITSPc]4+) and histamine results in the oxidation of the central metal by oxygen in the former, with the formation of a complex denoted as [(His)FeIIITSPc]3− (where His = histamine). The rate constant for the formation of the complex is kf = 2.41 × 10−2dm3.mol−1.s−1 and an equilibrium constant of 6.3 dm3.mol-1 was obtained. The oxidation state of the central metal of [FeIITSPc]4− before and after the coordination of histamine is confirmed by spectroelectrochemistry. Further electrochemical oxidation of this [(His)FeIIITsPc]3− derivative results in a metal-based process proposed to involve an FeIV phthalocyanine species.
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  • Date Issued: 2002

Voltammetric characterization of the self-assembled monolayer (SAM) of octabutylthiophthalocyaninatoiron (II)

  • Authors: Ozoemena,Kenneth , Nyokong, Tebello
  • Date: 2002
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/290419 , vital:56748 , xlink:href="https://doi.org/10.1016/S0013-4686(02)00362-6"
  • Description: The fabrication of a self-assembled monolayer (SAM) of 2,3,9,10,16,17,23,24-octa (butylthio)-phthalocyaninatoiron(II) [FePc(SBu)8] on gold electrode is described. The integrity of the SAM, with respect to its ability to block certain Faradaic processes, is interrogated using cyclic voltammetric experiments in aqueous solutions. The experiments show that this SAM provide an excellent blocking capability to the Faradaic processes emanating from gold surface oxidation, underpotential deposition (UPD) of copper and redox chemistry of Fe(NH4)(SO4)2 in HClO4. It is revealed by cyclic voltammetry that an ill-defined reversible couple of the SAM of FePc(SBu)8 can be greatly improved by a simple repetitive cycling of the modified electrode in a DMF solution containing TBAP within a short space of time (ca. 2 min). This ‘activation’ process provides good information concerning the surface coverage and orientation of the monolayer. The reversible redox wave shows a potential shift of about −57 mV per pH in the pH range of 2–9. A preliminary investigation indicates that FePc(SBu)8-SAM modified gold electrode shows electrocatalytic activity toward the oxidation of L-cysteine in acidic medium. The monolayer is stable and easily reproducible. However, due to its susceptibility to destruction via oxidative and reductive desorptions, its potential application as an electrochemical sensor would be much better in acidic and neutral than alkaline environments.
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  • Date Issued: 2002

Electrooxidation of cresols on carbon electrodes modified with phthalocyaninato and octabutoxyphthalocyaninato cobalt (II) complexes

  • Authors: Grootboom, Natasha , Nyokong, Tebello
  • Date: 2001
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/293207 , vital:57065 , xlink:href="https://doi.org/10.1016/S0003-2670(00)01351-9"
  • Description: Glassy carbon electrodes (GCE) modified with cobalt(II) phthalocyanine (CoPc-GCE) and cobalt(II) octabutoxyphthalocyanine (CoOBuPc-GCE) were employed for the electrochemical analysis of ortho-, meta-, and para-cresols. The oxidation potential of p-cresol was shifted towards less positive values to a larger extent, when compared to m- and o-cresols, on CoOBuPc-GCE. However, the GCE was less stable when modified with CoOBuPc than with CoPc. This is explained using the possible differences in the orientation of the adsorbed phthalocyanine molecules on the electrode. Bulk electrolysis of p-cresol at anodic potentials (1.0 V versus Ag|AgCl) on carbon electrodes modified with CoPc resulted in the formation of radicals which coupled to form trimeric products. On unmodified carbon electrodes, coupling of the radicals resulted in dimeric products following bulk electrolysis. The products formed following bulk electrolysis were characterized by liquid chromatography coupled with mass spectrometry.
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  • Date Issued: 2001

Silicon octaphenoxyphthalocyanines

  • Authors: Maree, M David , Kuznetsova, Nina , Nyokong, Tebello
  • Date: 2001
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/291591 , vital:56890 , xlink:href="https://doi.org/10.1016/S1010-6030(01)00409-9"
  • Description: Photochemical properties of series of axially substituted silicon octaphenoxyphthalocyanines with aryloxy, siloxy, aminoalkoxy, esters of carboxylic acids and sulphonic acid esters residues as axial ligands were studied in dimethylsulfoxide (DMSO) solution. It was found, that under Q-band excitation axial ligands in compounds studied have the propensity to be changed by hydroxyl groups with quantum yields in the range 10−5 to 10−2 depending on the nature of the axial ligand. Axial substituent phototransformation was followed by slow photobleaching of dihydroxysilicon octaphenoxyphthalocyanine (photoproduct) in self-sensitized singlet oxygen mediated oxidation of the macrocycle. Singlet oxygen quantum yields were found to be in the range 0.15–0.20 for majority of the phthalocyanines (Pc) studied.
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  • Date Issued: 2001

Electrocatalytic properties of vitamin B12 towards oxidation and reduction of nitric oxide

  • Authors: Vilakazi, Sibulelo Lea , Nyokong, Tebello
  • Date: 2000
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/293196 , vital:57064 , xlink:href="https://doi.org/10.1016/S0013-4686(00)00628-9"
  • Description: This paper reports on the catalytic behaviour of cyanocobalamin (VB12) towards the reduction and oxidation of nitric oxide. When VB12 is adsorbed on glassy carbon electrodes, it catalyses the reduction of nitric oxide (NO) in pH 4 and 9 buffers. In the absence of NO, cyclic voltammetry shows that VB12 is reduced by a one-step two-electron reduction from CoIII to the CoI species. Addition of NO at pH 9 to solutions of VB12 resulted in the splitting of the cyclic voltammetry peaks as a result of a consecutive one-electron reduction of the central CoIII metal in VB12 to CoII and finally to CoI. The catalytic peak for oxidation of NO on a glassy carbon electrode modified with VB12 was observed at 1.21 V versus Ag∣AgCl, at pH 9. The products of the catalytic reduction of nitric oxide include ammonia and hydroxylamine.
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  • Date Issued: 2000

Integrating the development of academic literacy into mainstream teaching and learning

  • Authors: Amos, Trevor L
  • Date: 1999
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/270891 , vital:54489 , xlink:href="https://hdl.handle.net/10520/AJA10113487_947"
  • Description: Higher education is challenged to develop effective and independent learners of students who experience learning difficulties. These students are however, (potentially) able to engage in and do not necessarily lack the the inherent bstract cognitive capability necessary for academic success. The aim of this article is to be done in practice to integrate the development of academic literacy into mainstream teaching and learning.
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  • Date Issued: 1999

Interaction of nitric oxide with cobalt (II) phthalocyanine

  • Authors: Vilakazi, Sibulelo L , Nyokong, Tebello
  • Date: 1998
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/293579 , vital:57100 , xlink:href="https://doi.org/10.1016/S0277-5387(98)00244-7"
  • Description: The coordination of nitric oxide (NO) to cobalt(II) phthalocyanine (CoPc) in dimethyl sulphoxide (DMSO) has been studied. CoPc coordinates with NO in a 1:1 ratio, forming a CoPc(NO) species. The IR band observed at 1680 cm−1 is assigned to the coordinated NO. In the presence of excess NO, pseudo first order kinetics were followed. The observed rate constant, kf, was determined to be 15.0±0.3 dm−3 mol−1 s−1 and the equilibrium constant was K=5.4±0.4×104dm3 mol−1. Solution or adsorbed CoPc catalyses the reduction of NO. The products of reduction include NH3 and NH2OH.
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  • Date Issued: 1998

Photoassisted reduction of thionyl chloride by neodymium, europium, thulium and lutetium diphthalocyanines

  • Authors: Nensala, Ngudiankama , Nyokong, Tebello
  • Date: 1998
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/293590 , vital:57101 , xlink:href="https://doi.org/10.1016/S0277-5387(98)00133-8"
  • Description: Diphthalocyanine complexes of Nd III, EuIII, TmIII and LuIII ( [Pc (−2) Nd IIIPc (−2) ] −, [Pc (−2) EuIIIPc (−2) ] −, [Pc (−2) TmIIIPc (−2) ] − and [Pc (−2) LuIIIPc (−2) ] −, respectively) , undergo one or two-electron oxidation in the presence of thionyl chloride. The oxidation products depend on the concentration of the thionyl chloride. At low concentrations of SOCl2 (larger than 10−4 mol dm−3) one-electron oxidation occurs only upon photolysis, giving the neutral lanthanide diphthalocyanine, Pc (−2) LnPc (−1) , complexes. The Pc (−2) LnPc (−1) species undergo one-electron photooxidation to the [Pc (−1) LnPc (−1) ] + in dichloromethane and in the presence of SOCl2. At large concentrations of SOCl2 (>10−2 mol dm−3) , two electron oxidation of the [Pc (−2) LnPc (−2) ] − species directly to [Pc (−1) LnPc (−1) ] + occurs.
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  • Date Issued: 1998
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