Comparative phototransformation of environmental pollutants using metallophthalocyanines supported on electrospun polymer fibers
- Authors: Zugle, Ruphino , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/190509 , vital:45001 , xlink:href="https://doi.org/10.1002/app.38381"
- Description: The fluorescence and photoactivity of a series of Zn and Lu phthalocyanine complexes incorporated in various polymer fibers were investigated for the phototransformation of 4-chlorophenol, 4-nitrophenol, and methyl orange. The phthalocyanine complexes functionalized on polystyrene and polysulfone polymer fibers could be applied in the degradation of 4-chlorophenol, 4-nitrophenol, and methyl orange with 4-chlorophenol being much more susceptible to degradation while methyl orange was the least. Also polymer fibers of polystyrene were found to be reusable.
- Full Text:
- Date Issued: 2013
Zinc (II) 2, 9, 16, 23-tetrakis [4-(N-methylpyridyloxy)]-phthalocyanine anchored on an electrospun polysulfone polymer fiber: Application for photosensitized conversion of methyl orange
- Authors: Zugle, Ruphino , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/232741 , vital:50020 , xlink:href="https://doi.org/10.1016/j.molcata.2012.10.001"
- Description: In this work, a comparative study of photodegradation of methyl orange, an azo dye, in homogeneous aqueous solution of a quarternized cationic zinc phthalocyanine and a heterogeneous catalytic system based on the same phthalocyanine anchored on polysulfone polymer fiber is presented. In both cases, conversion involved the azo bond of the dye with no detectable opening up of the aromatic benzene rings. The reaction kinetics in both cases were consistent with first order with the conversion occurring in the homogeneous system being faster than when the functionalized polymer fiber was used. The reaction products consisted of a coupling product as well as a series of oligopolymeric products.
- Full Text:
- Date Issued: 2013
Electrospun polyacrylic acid polymer fibers functionalized with metallophthalocyanines for photosensitizing and gas sensing applications
- Authors: Zugle, Ruphino , Nyokong, Tebello
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/243543 , vital:51162 , xlink:href="https://doi.org/10.1080/10601325.2012.662006"
- Description: The photophysical and photochemical properties of tetraaminophthalocyanine complexes of lutetium and zinc covalently linked to polyacrylic acid were studied alongside those of unsubstituted zinc phthalocyanine within the same polymeric fiber matrix. All three phthalocyanines within the solid fiber matrices showed photoactivity by the generation of singlet oxygen as was observed in solution. The fluorescence behaviors of the composite fibers equally parallel those in solution. For the unsubstituted zinc phthalocyanine composite, the fiber showed fluorescence quenching on interaction with gaseous nitrogen dioxide similar to that in DMF and, thus could be a promising nanofabric material in developing optoelectronic devices that are responsive to the gas.
- Full Text:
- Date Issued: 2012
Photophysical characterization of dysprosium, erbium and lutetium phthalocyanines tetrasubstituted with phenoxy groups at non-peripheral positions
- Authors: Zugle, Ruphino , Litwinski, Christian , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247561 , vital:51595 , xlink:href="https://doi.org/10.1016/j.poly.2011.03.030"
- Description: Dysprosium bis-phthalocyanine and monomeric phthalocyanines of erbium and lutetium with non-peripheral phenoxy substituents have been synthesized using two different preparative routes. Photophysical studies on these phthalocyanines revealed that the triplet states of dysprosium and erbium are not populated while the monomeric phthalocyanine complex of lutetium is populated with a quantum yield of 0.83 and a lifetime of 25 μs in DMSO. It was further found that the phthalocyanine complex of lutetium was capable of photochemical generation of singlet state molecular oxygen with yield of 0.71 in THF, thus a promising photosensitizer. However, the three phthalocyanine molecules have very low fluorescence quantum yields of less than 0.01.
- Full Text:
- Date Issued: 2011
Physico-chemical properties of lutetium phthalocyanine complexes in solution and in solid polystyrene polymer fibers and their application in photoconversion of 4-nitrophenol
- 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
Photooxidation of 4-chlorophenol sensitized by lutetium tetraphenoxy phthalocyanine anchored on electrospun polystyrene polymer fiber
- Authors: Zugle, Ruphino , Antunes, Edith M , Khene, Samson M , Nyokong, Tebello
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/245787 , vital:51405 , xlink:href="https://doi.org/10.1016/j.poly.2011.11.005"
- Description: An electrospun polystyrene (PS) fiber incorporating tetraphenoxy phthalocyanine complex of lutetium (LuTPPc/PS) as a photosensitizer was applied for the degradation of 4-chlorophenol in aqueous solution in the presence of visible light. The photocatalytic activity of the LuTPPc in the fiber was compared to that of zinc phthalocyanine (ZnPc) incorporated into the PS fiber, and the former showed higher activity. UV–Vis spectral changes of sample solutions indicated transformation of the analyte with first order kinetics and half-lives that are within one and half hours for LuTPPc/PS. Products identified from the spectral changes and gas chromatography were benzoquinone, hydroquinone and 4,4′-dihydroxydiphenol suggesting that the photodegradation of 4-chlorophenol was through both Types I and II mechanisms.
- Full Text:
- Date Issued: 2012
Photophysical and photochemical behavior of electrospun fibers of a polyurethane polymer chemically linked to lutetium carboxyphenoxy phthalocyanine
- Authors: Zugle, Ruphino , Litwinski, Christian , Torto, Nelson , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/248428 , vital:51685 , xlink:href="https://doi.org/10.1039/C1NJ20126C"
- Description: A phthalocyanine complex of lutetium substituted with four peripherally substituted 4-carboxyphenoxy groups was synthesized using cyclotetramerisation reaction. Its structure was elucidated using conventional spectroscopic methods and elemental analysis. The spectral behavior of the complex was studied in DMF solution and in a solid polyurethane fiber matrix. The UV-Visible spectrum showed a red shift in its Q-band maximum absorption within the fiber as compared to that in solution. The triplet quantum yield in DMF was determined to be 0.51 with a lifetime of 2.7 μs and a singlet oxygen quantum yield of 0.33 with a lifetime of 19.85 μs in the same solvent. The functionalized phthalocyanine fiber could be a promising fabric material for applications such as self-disinfecting in wound dressing. A method based on the conversion of ADMA was used to estimate the singlet oxygen quantum yield of the Pc in the hybrid fiber. An estimated singlet oxygen quantum yield value of 0.11 in aqueous medium was obtained. The fluorescence quantum yield of the Pc was found to be 0.01 with a lifetime of 3.20 ns in DMF.
- Full Text:
- Date Issued: 2011
Nonlinear optical properties of natural laccaic acid dye studied using Z-scan technique
- Authors: Zongo, S , Sanusi, Kayode , Britton, Jonathan , Mthunzi, P , Nyokong, Tebello , Maaza, M , Sahraoui, B
- Date: 2015
- Language: English
- Type: Article
- Identifier: vital:7261 , http://hdl.handle.net/10962/d1020270
- Description: We have investigated the nonlinear optical properties, including the optical limiting behaviour for five different concentrations of laccaic acid dye in solution and a thin film obtained through doping in poly (methyl methacrylate) (PMMA) polymer. The experiments were performed by using single beam Z-scan technique at 532 nm with 10 ns, 10 Hz Nd:YAG laser pulses excitation. From the open-aperture Z-scan data, we derived that the laccaic dye samples exhibit strong two photon absorption (2PA). The nonlinear refractive index was determined through the closed aperture Z-scan data. The estimated absorption coefficient β2, nonlinear refractive index n2 and second order hyperpolarizability γ were found to be of the order of 10−10 m/W, 10−9 esu and 10−32 esu, respectively. The Z-scan study reveals that the natural laccaic acid dye emerges as a promising material for third order nonlinear optical devices application. , Original publication is available at http://dx.doi.org/10.1016/j.optmat.2015.04.031
- Full Text: false
- Date Issued: 2015
Structural modification of RhIIItriarylcorroles for enhanced electrocatalyzed hydrogen evolution reactions
- Authors: Zhu, Weihua , Li, Lihua , Wang, Yu , Mack, John , Dingiswayo, Somila , Nyokong, Tebello , Liang, Xu
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/229933 , vital:49724 , xlink:href="https://doi.org/10.1016/j.dyepig.2021.110046"
- Description: A series of A3 type RhIIItriarylcorroles 2a-c with different meso-substituents with differing electron-donating and withdrawing properties and two A2B type RhIIItriarylcorroles 4a-b with meso-methylthiophenyls at the B position have been prepared and characterized. An analysis of structure-property relationships of 2a-c and 4a-b has been carried out by comparing the optical spectroscopy and electrochemistry of the dyes to trends predicted in DFT and TD-DFT calculations. Rational structural modification strategies that enhance the suitability of 2a-c for use as highly efficient catalysts for hydrogen evolution reactions on glassy carbon electrodes coated with 2a-c/reduced graphene oxide composites and of 4a-b in surface-modified Au electrodes are explored.
- Full Text:
- Date Issued: 2022
Synthesis and properties of chiral amide-bonded porphyrin dimers with various functional bridging blocks
- Authors: Zhu, Weihua , Haider, Syed Najeeb-uz-Zaman , Zhang, Honglin , Attatsi, Isaac K , Mack, John , Dingiswayo, Somila , Nyokong, Tebello , Song, Yuting , Xu, Haijun , Liang, Xu
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186791 , vital:44534 , xlink:href="https://doi.org/10.1016/j.dyepig.2019.107740"
- Description: Eight porphyrin dimers with various functional bridging blocks and chiral amide-bonds were synthesized and characterized. An analysis of the spectroscopy and electrochemistry has been carried out to demonstrate that the chiral properties can be modified by changing the interchromophoric through-space coupling distance between the two porphyrin chromophores by introducing various bonding and bridging blocks.
- Full Text:
- Date Issued: 2019
Synthesis and photophysical properties of a covalently linked porphyrin-phthalocyanine conjugate
- Authors: Zhao, Zhixin , Ogunsipe, Abimbola O , Maree, M David , Nyokong, Tebello
- Date: 2005
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/300358 , vital:57922 , xlink:href="https://doi.org/10.1142/S1088424605000253"
- Description: The synthesis of a phthalocyanine-porphyrin heteropentamer (zinc(II) tetra(5-phenoxy-10,15,20-triphenylporphyrin)) zinc(II) phthalocyanine, (ZnPc-(ZnTPP)4), containing four units of zinc tetraphenylporphyrin linked to a central zinc phthalocyanine macrocycle via an ether linkage is reported. The photophysical parameters of the pentamer are reported in toluene and dimethyl sulfoxide (DMSO). The observed differences in the fluorescence behavior of the pentamer in the two solvents is explained in terms of emission from different states; charge transfer state in DMSO and locally excited state in toluene. The rate constants for fluorescence, intersystem crossing, internal conversion, and of charge and energy transfer are reported for the pentamer. Quantum yields for fluorescence, internal conversion, triplet state and of charge and energy transfer are also reported for the pentamer, ZnPc-(ZnTPP)4 and the mixture of ZnPc and ZnTPP. The latter two parameters are higher in the pentamer compared to a mixture containing ZnPc and ZnTPP.
- Full Text:
- Date Issued: 2005
Meso-and axially-modified IrIIItriarylcorroles with tunable electrocatalytic properties
- Authors: Zhang, Xifeng , Wang, Yu , Zhu, Weihua , Mack, John , Soy, Rodah C , Nyokong, Tebello , Liang, Xu
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/190851 , vital:45034 , xlink:href="https://doi.org/10.1016/j.molstruc.2015.02.040"
- Description: The synthesis of three A2B type Ir(III)triarylcorroles with meso-aryl substituents that provide electron donating (push) and withdrawing (pull) properties and three A3 type IrIIItriphenylcorroles with differing pyridine axial ligands is reported, along with their structural characterization. An analysis of the structure-property relationships in the optical and redox properties has been carried out by comparing their optical spectroscopy and electrochemistry to trends predicted in DFT and TD-DFT calculations. The results demonstrate that A2B type IrIIItriarylcorroles are highly efficient electrocatalyzed oxygen reduction reactions (ORRs) and that their reactivity can be modulated by modulating the electronic structure by changing the nature of the meso-substituent at the B-positions, and even axial pyridine ligands.
- Full Text:
- Date Issued: 2015
Aza boron-pyridyl-isoindoline analogues
- Authors: Zhang, Hui , Wu, Yanping , Fan, Minhui , Xiao, Xuqiong , Mack, John , Kubheka, Gugu , Nyokong, Tebello , Lu, Hua
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/232912 , vital:50037 , xlink:href="https://doi.org/10.1039/C7NJ00707H"
- Description: Several aza boron-pyridyl-isoindoline analogues are synthesized through a facile and scale-up two step reaction using 1,2-naphthalenedicarbonitrile as a starting material. These analogues show broad envelopes of intense vibrational bands in the absorption spectra with moderate fluorescence quantum yields in solution and the solid-state. An analysis of the structure–property relationships is described based on X-ray crystallography, optical spectroscopy, and theoretical calculations.
- Full Text:
- Date Issued: 2017
Metallophthalocyanine-based molecular materials as catalysts for electrochemical reactions
- Authors: Zagal, José H , Griveau, Sophie J , Silva, Francisco , Nyokong, Tebello , Bedioui, Fethi
- Date: 2010
- Language: English
- Type: text , Article
- Identifier: vital:7239 , http://hdl.handle.net/10962/d1019718
- Description: Metallophthalocyanines confined on the surface of electrodes are active catalysts for a large variety of electrochemical reactions and electrode surfaces modified by these complexes can be obtained by simple adsorption on graphite and carbon. However, more stable electrodes can be achieved by coating their surfaces with electropolymerized layers of the complexes, that show similar activity than their monomer counterparts. In all cases, fundamental studies carried out with adsorbed layers of these complexes have shown that the redox potential is a very good reactivity index for predicting the catalytic activity of the complexes. Volcano-shaped correlations have been found between the electrocatalytic activity (as log I at constant E) versus the Co(II)/(I) formal potential (E°′) of Co-macrocyclics for the oxidation of several thiols, hydrazine and glucose. For the electroreduction of O2 only linear correlations between the electrocatalytic activity versus the M(III)/M(II) formal potential have been found using Cr, Mn, Fe and Co phthalocyanines but it is likely that these correlations are “incomplete volcano” correlations. The volcano correlations strongly suggest that E°′, the formal potential of the complex needs to be in a rather narrow potential window for achieving maximum activity, probably corresponding to surface coverages of an M-molecule adduct equal to 0.5 and to standard free energies of adsorption of the reacting molecule on the complex active site equal to zero. These results indicate that the catalytic activity of metallophthalocyanines for the oxidation of several molecules can be “tuned” by manipulating the E°′ formal potential, using proper groups on the macrocyclic ligand. This review emphasizes once more that metallophthalocyanines are extremely versatile materials with many applications in electrocatalysis, electroanalysis, just to mention a few, and they provide very good models for testing their catalytic activity for several reactions. Even though the earlier applications of these complexes were focused on providing active materials for electroreduction of O2, for making active cathodes for fuel cells, the main trend in the literature nowadays is to use these complexes for making active electrodes for electrochemical sensors. , Original publication is available at http://dx.doi.org/10.1016/j.ccr.2010.05.001
- Full Text: false
- Date Issued: 2010
Core-modified rubyrins with phenanthrene-fused pyrrole rings
- Authors: Yuan, Xuemei , Li, Minzhi , Meng, Ting , Mack, John , Soy, Rodah C , Nyokong, Tebello , Zhu, Weihua , Xu, Haijun , Liang, Xu
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/234568 , vital:50209 , xlink:href="https://doi.org/10.1016/j.dyepig.2018.05.045"
- Description: Three fused-ring-expanded rubyrins with modified macrocyclic core have been synthesized and characterized. A series of spectroscopic, electrochemical measurements and a set of theoretical calculations demonstrate that the core-modification of the inner core of rubyrins has a large influence on the electronic structure. Colorimetric changes are observe that demonstrate that these core-modified rubyrins could be used as selective Hg2+ ion sensors. These properties can be fine-tuned by introducing lipophilic substituents on the meso-aryl rings.
- Full Text:
- Date Issued: 2018
Synthesis, photophysicochemical properties and TD-DFT calculations of tetrakis (2-benzoyl-4-chlorophenoxy) phthalocyanines
- Authors: Yilmaz, Yusuf , Mack, John , Sener, M Kasim , Sönmez, Mehmet , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241538 , vital:50948 , xlink:href="https://doi.org/10.1142/S1088424614500047"
- Description: The synthesis of metal free, magnesium and zinc tetrakis(2-benzoyl-4-chlorophenoxy) phthalocyanine derivatives (2–4) is described along with their characterization by elemental analysis, IR, UV-visible absorption, and 1H NMR spectroscopy and mass spectrometry. Trends observed in the fluorescence, triplet state, singlet oxygen and photodegradation quantum yields and the triplet state lifetimes are also analyzed. The compounds exhibit high solubility in a wide range of organic solvents and no evidence of aggregation was observed over a wide concentration range. The Zn(II) complex (4) was found to have a very high singlet oxygen quantum yield (ΦΔ = 0.78) in dimethylsulfoxide (DMSO) and a reasonably large triplet state quantum yield (ΦT = 0.82). The photophysical and photochemical properties clearly demonstrate that these compounds could prove useful in singlet oxygen applications such as photodynamic therapy (PDT). DFT and TD-DFT calculations were used to assess the impact of the positional isomerism of the 2-benzoyl-4-chlorophenoxy substituents on the electronic structures and optical spectroscopy.
- Full Text:
- Date Issued: 2014
Photophysicochemical properties and TD-DFT calculations of a novel terminal alkyne substituted metal free phthalocyanine
- Authors: Yilmaz, Yusuf , Mack, John , Sönmez, Mehmet , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241562 , vital:50950 , xlink:href="https://doi.org/10.1142/S1088424613501241"
- Description: The synthesis of a novel free base tetrakis(prop-2-ynyloxy)phthalocyanine (2) is described, along with its characterization by IR, UV-visible absorption, and 1H NMR spectroscopy and mass spectrometry. The compound exhibited good solubility in a wide range of organic solvents and no significant aggregation was observed over a wide concentration range. The values for the singlet oxygen (ΦΔ), photodegradation, fluorescence (ΦF) and triplet state quantum yields and the fluorescence and triplet state lifetimes are reported. A relatively high ΦΔ value of 0.46 was obtained in DMSO. The ability to carry out "click" chemistry at the ligand periphery enhances the potential utility of 2 for use in bioconjugates in photodynamic therapy (PDT). A moderately high ΦF value of 0.18 is observed for emission in the therapeutic window in the near-IR region, which suggests that it may also be possible to determine the level of localization of 2 in tumor cells through bioimaging.
- Full Text:
- Date Issued: 2014
Photophysical and photochemical properties of novel phthalocyanines bearing non-peripherally substituted mercaptoquinoline moiety
- Authors: Yaşa, Göknur , Erdoğmuş, Ali , Uğur, Ahmet Lütf , Şener, M Kasım , Avcıata, Ulvi , Nyokong, Tebello
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/244360 , vital:51250 , xlink:href="https://doi.org/10.1142/S1088424612500940"
- Description: The synthesis, photophysical and photochemical properties of nonperipherally (a) mercaptoquinoline substituted Zn(II), TiO(IV) and Mg(II) and quaternized Zn(II) phthalocyanines are described for the first time. These complexes (2 to 5) and their precursor are characterized by elemental analysis, FT-IR, 1 H NMR, electronic spectroscopy as well as mass spectroscopy. Complexes 2, 4 and 5 have good solubility in organic solvents such as CHCl3, DCM, DMSO, DMF, THF and toluene and are not aggregated in all solvents within a wide concentration range. Complex 3 showed very good solubility in water as well as DMSO and DMF. General trends are described for singlet oxygen, photodegradation and fluorescence quantum yields of these complexes in DMSO and DMF. While complex 2 has higher singlet oxygen and fluorescence quantum yields than 3, 4 and 5, complex 4 has higher fluorescence quantum yields in DMF and DMSO than 2, 3 and 5. The effect of the solvents and metal on the photophysical and photochemical parameters of the metallophthalocyanines are also reported.
- Full Text:
- Date Issued: 2012
Efficient energy transfer in ethynyl bridged corrole–BODIPY dyads
- Authors: Yan, Yu , Wu, Fan , Qin, Jiawei , Xu, Haijun , Shi, Maohu , Zhou, Jingfeng , Mack, John , Fomo, Gertrude , Nyokong, Tebello , Shen, Zhen
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/240899 , vital:50883 , xlink:href="https://doi.org/10.1039/C6RA12271J"
- Description: A series of new corrole–BODIPY dyads bridged by ethynyl linker moieties have been synthesized in high yields and fully characterized. The direction of energy transfer upon electronic excitation has been explored, and was found to be dependent on the number of corrole rings and their connection position on the BODIPY core. Intense bands in the absorption spectrum cover most of the visible region, which is potentially advantageous for capturing solar energy. Studies on the excitation spectra and lifetimes suggest that the energy transfer efficiency between the BODIPY and corrole moieties reaches almost 85%, which appears to be efficient in the context of energy transfer within the singlet manifold.
- Full Text:
- Date Issued: 2016
Synthesis, characterization and electrochemistry of rhodium (iii) complexes of meso-substituted [14] tribenzotriphyrin (2.1. 1)
- Authors: Xue, Zhaoli , Wang, Yemei , Mack, John , Mkhize, Scebi , Nyokong, Tebello , Fang, Yuanyuan , Ou, Zhongping , Kadish, Karl M
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241043 , vital:50899 , xlink:href="https://doi.org/10.1039/C6RA03028A"
- Description: A thermal reaction using a series of [14]tribenzotriphyrins(2.1.1) (TriPs, 1a–d) with Rh2(C8H12)Cl2 provides RhIII–TriP complexes (2a–d) in 40−52% yields. The complexes were characterized by mass spectrometry, UV-visible absorption and 1H NMR spectroscopy. Single crystal X-ray analysis reveals that 2b adopts a dome-shaped conformation. The rhodium(III) ion is coordinated by the three pyrrole nitrogen atoms, two chloride ions and the nitrogen atom of an acetonitrile (CH3CN) solvent molecule. The optical spectra can be assigned using Michl's perimeter model. The L and B bands of the 2a–d complexes lie at ca. 600 and 500 nm, respectively, and are markedly red shifted relative to those of 1a–d. A reversible one-electron oxidation and two reversible one-electron reductions are observed in the cyclic voltammograms of 2a–d in CH2Cl2. The redox potentials are consistent with the optical data and the relatively narrow HOMO–LUMO gaps that are predicted in DFT calculations. TD-DFT calculations have been used to assign a third intense spectral band at 375 nm to a higher energy π → π* transition of the [14]tribenzotriphyrin(2.1.1) π-system.
- Full Text:
- Date Issued: 2016