Karl M. Kadish

University of Houston, Houston, Texas, United States

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Publications (560)2613.6 Total impact

  • Guifen Lu · Jing Li · Sen Yan · Cheng He · Mengying Shi · Weihua Zhu · Zhongping Ou · Karl M. Kadish
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    ABSTRACT: Two heteroleptic corrole–phthalocyanine europium triple-decker complexes were fabricated into organic nanostructures by the standard phase-transfer method. The investigated compounds are represented by Eu2(Pc)2[Cor(ClPh)3] (1) and Eu2[Pc(OC8H17)8]2[Cor(ClPh)3] (2), where Pc represents the dianion of phthalocyanine and Cor(ClPh)3 the trianion of 5,10,15-tri(4-chlorophenyl)corrole. Both compounds 1 and 2 show typical electronic absorption spectra for a non-aggregated molecular structure in chloroform or toluene. However, in methanol compound 1 self-assembled into belt-like nanostructures while compound 2, which possesses long OC8H17 alkoxy side chains, self-assembled into large scale sheet-like nanostructures. The third-order nonlinear optical properties of both triple-decker compounds were also investigated in toluene by the Z-scan technique and characterized as showing nonlinear reverse saturation absorption and self-defocusing behavior. A third-order nonlinear optical susceptibility, χ(3), of 3.18 × 10−10 and 3.35 × 10−10 esu was obtained for 1 and 2, respectively, thus indicating the potential application of these compounds in the field of optical devices.
    Dyes and Pigments 10/2015; 121. DOI:10.1016/j.dyepig.2015.05.008 · 3.97 Impact Factor
  • Guifen Lu · Jing Li · Xiaoqin Jiang · Zhongping Ou · Karl M Kadish
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    ABSTRACT: A series of europium triple-decker complexes containing phthalocyanine and nitrophenyl-corrole macrocycles were synthesized and characterized by spectroscopic and electrochemical methods in nonaqueous media. The examined compounds are represented as Eu2[Pc(OC4H9)8]2[Cor(Ph)n(NO2Ph)3-n], where n varies from 0 to 3, Pc(OC4H9)8 represents the phthalocyanine macrocycle, and Cor indicates the corrole macrocycle having phenyl (Ph) or nitrophenyl (NO2Ph) meso substituents. Three different methods were used for syntheses of the target complexes, two of which are reported here for the first time. Each examined compound undergoes five reversible one-electron oxidations and 3-5 one-electron reductions depending upon the number of NO2Ph substituents. The nitrophenyl groups on the meso positions of the corrole are highly electron-withdrawing, and this leads to a substantial positive shift in potential for the five oxidations and first reduction in CH2Cl2, PhCN, or pyridine as compared to the parent triple-decker compound with a triphenylcorrole macrocycle. The measured E1/2 values are linearly related to the number of NO2Ph groups on the corrole, and the relative magnitude of the shift in potential for each redox reaction was used in conjunction with the results from thin-layer spectro-electrochemistry to assign the initial site of oxidation or reduction on the molecule. The nitrophenyl substituents are also redox-active, and each is reduced to [C6H4NO2](-) in a separate one-electron transfer step at potentials between -1.12 and -1.42 V versus saturated calomel electrode.
    Inorganic Chemistry 09/2015; DOI:10.1021/acs.inorgchem.5b01713 · 4.76 Impact Factor
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    ABSTRACT: A silver β-octabromo-meso-triarylcorrole has been found to exhibit a strongly saddled geometry, providing the first instance of a strongly saddled corrole complex involving a metal other than copper. The Soret maxima of the Ag octabromocorroles also redshift markedly in response to increasingly electron-donating para substituents on the meso-aryl groups. In both these respects, the Ag octabromocorroles differ from simple Ag triarylcorrole derivatives, which exhibit only mild saddling and substituent-insensitive Soret maxima. These results have been rationalized in terms of an innocent M(III) -corrole(3-) description for the simple Ag corroles and a noninnocent M(II) -corrole(.2-) description for the Ag octabromocorroles. In contrast, all copper corroles are thought to be noninnocent, while all gold corroles are innocent. Uniquely among metallocorroles, silver corroles thus seem poised on a knife-edge, so to speak, between innocent and noninnocent electronic structures and may tip either way, depending on the exact nature of the corrole ligand.
    Chemistry - A European Journal 09/2015; DOI:10.1002/chem.201502150 · 5.73 Impact Factor
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    ABSTRACT: Four nitrated N-confused free-base tetraarylporphyrins were synthesized and characterized by electrochemistry and spectroelectrochemistry in nonaqueous media. The examined compounds are represented as NO2(Ar)4NcpH2, where NO2(Ar)4Ncp is the dianion of a tetraaryl N-confused porphyrin with an inner carbon bound NO2 group and Ar is a p-CH3OPh, p-CH3Ph, Ph or p-ClPh substituent on each meso-position of the macrocycle. UV/Vis spectra and NMR spectroscopy data indicate that the same form of the porphyrin exists in CH2Cl2 and DMF which is unlike the case of non-NO2 N-confused porphyrins. The Soret band of NO2(Ar)4NcpH2 exhibits a 30–36 nm red-shift in CH2Cl2 and DMF as compared to the spectrum of the non-NO2 N-confused porphyrins. The first two reductions and first oxidation of NO2(Ar)4NcpH2 are reversible in CH2Cl2 containing 0.1 M TBAP. The measured HOMO–LUMO gap averages 1.65 V in CH2Cl2 and 1.53 V in DMF, with both values being similar to those of the non-NO2 substituted compounds. The nitro group on the inverted pyrrole is itself not reduced within the negative potential limit of CH2Cl2 or DMF, but its presence significantly affects both the UV/Vis spectra and redox potentials.
    Chemistry - A European Journal 08/2015; 21(41). DOI:10.1002/chem.201501720 · 5.73 Impact Factor
  • Journal of Porphyrins and Phthalocyanines 08/2015; 19(08):903-919. DOI:10.1142/S1088424615500777 · 1.40 Impact Factor
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    ABSTRACT: Two-photon absorption and electrochemical properties of carbazole-linked porphyrin tweezers including a bisporphyrin dimer resulting from a Glaser homocoupling have been prepared and fully characterized by C. P. Gros, F. Bolze, K. M. Kadish, and co-workers. The dyads reported present a two-photon absorption maximum at 920 nm with two-photon absorption cross-section in the 1200 GM range. The comprehensive report can be found in the Full Paper on page 12018 ff.
    Chemistry - A European Journal 08/2015; 21(34):11910-11910. DOI:10.1002/chem.201590153 · 5.73 Impact Factor
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    ABSTRACT: Herein the synthesis, spectroscopic characterization, two-photon absorption and electrochemical properties of 3,6-disubstituted carbazole tweezers is reported. A dimer resulting from a Glaser homocoupling was isolated during a Sonogashira coupling reaction between a diethynyl-carbazole spacer and a 5-bromo-triarylporphyrin and the properties of this original compound were compared with the 3,6-disubstituted carbazole bisporphyrin tweezers. The dyads reported herein present a two-photon absorption maximum at 920 nm with two-photon absorption cross-section in the 1200 GM range. Despite a strong linear absorption in the Soret region and moderate fluorescence quantum yield, they both lead to a high brightness reaching 30 000 M(-1) cm(-1) . © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
    Chemistry - A European Journal 07/2015; 21(34). DOI:10.1002/chem.201501619 · 5.73 Impact Factor
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    ABSTRACT: Three meso-tetraaryl substituted N-5 sapphyrins were synthesized by a facile synthetic route from the corresponding open-chain pentapyrroles in high yield using acetic acid as the solvent and catalyst. Each compound was characterized by spectroscopic and electrochemical methods and the inverted pyrrole structure was confirmed in the solid state for the first time by single crystal X-ray analysis.
    Journal of Porphyrins and Phthalocyanines 06/2015; 19(06):1-9. DOI:10.1142/S1088424615500558 · 1.40 Impact Factor
  • Guifen Lu · Jing Li · Sen Yan · Weihua Zhu · Zhongping Ou · Karl M Kadish
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    ABSTRACT: We recently reported the first example of a europium triple-decker tetrapyrrole with mixed corrole and phthalocyanine macrocycles and have now extended the synthetic method to prepare a series of rare earth corrole-phthalocyanine heteroleptic triple-decker complexes, which are characterized by spectroscopic and electrochemical methods. The examined complexes are represented as M2[Pc(OC4H9)8]2[Cor(ClPh)3], where Pc = phthalocyanine, Cor = corrole, and M is Pr(III), Nd(III), Sm(III), Eu(III), Gd(III), or Tb(III). The Y(III) derivative with OC4H9 Pc substituents was obtained in too low a yield to characterize, but for the purpose of comparison, Y2[Pc(OC5H11)8]2[Cor(ClPh)3] was synthesized and characterized in a similar manner. The molecular structure of Eu2[Pc(OC4H9)8]2[Cor(ClPh)3] was determined by single-crystal X-ray diffraction and showed the corrole to be the central macrocycle of the triple-decker unit with a phthalocyanine on each end. Each triple-decker complex undergoes up to eight reversible or quasireversible one-electron oxidations and reductions with E1/2 values being linearly related to the ionic radius of the central ions. The energy (E) of the main Q-band is also linearly related to the radius of the metal. Comparisons are made between the physicochemical properties of the newly synthesized mixed corrole-phthalocyanine complexes and previously characterized double- and triple-decker derivatives with phthalocyanine and/or porphyrin macrocycles.
    Inorganic Chemistry 05/2015; 54(12). DOI:10.1021/acs.inorgchem.5b00477 · 4.76 Impact Factor
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    ABSTRACT: Two series of diphosphoryl-substituted porphyrins were synthesized and characterized by electrochemistry and spectroelectrochemistry in nonaqueous media containing 0.1 M tetra-n-butylammonium perchlorate (TBAP). The investigated compounds are 5,15-bis(diethoxyphosphoryl)-10,20-diphenylporphyrins (Ph)2(P(O)(OEt)2)2PorM and 5,15-bis(diethoxyphosphoryl)-10,20-di(para-carbomethoxyphenyl)porphyrins (PhCOOMe)2(P(O)(OEt)2)2PorM where M = 2H, Co(II), Ni(II), Cu(II), Zn(II), Cd(II), or Pd(II). The free-base and five metalated porphyrins with nonredox active centers undergo two ring-centered oxidations and two ring-centered reductions, the latter of which is followed by a chemical reaction of the porphyrin dianion to give an anionic phlorin product. The phlorin anion is electroactive and can be reoxidized by two electrons to give back the starting porphyrin, or it can be reversibly reduced by one electron at more negative potentials to give a phlorin dianion. The chemical conversion of the porphyrin dianion to a phlorin anion proceeds at a rate that varies with the nature of the central metal ion and the solvent. This rate is slowest in the basic solvent pyridine as compared to CH2Cl2 and PhCN, giving further evidence for the involvement of protons in the chemical reaction leading to phlorin formation. Calculations of the electronic structure were performed on the Ni(II) porphyrin dianion, and the most favorable atoms for electrophilic attack were determined to be the two phosphorylated carbon atoms. Phlorin formation was not observed after the two-electron reduction of the cobalt porphyrins due to the different oxidation state assignment of the doubly reduced species, a Co(I) π anion radical in one case and an M(II) dianion for all of the other derivatives. Each redox reaction was monitored by thin-layer UV-visible spectroelectrochemistry, and an overall mechanism for each electron transfer is proposed on the basis of these data.
    Inorganic Chemistry 03/2015; 54(7). DOI:10.1021/acs.inorgchem.5b00067 · 4.76 Impact Factor
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    ABSTRACT: Photoexcitation of dichloromethane solutions of an uranyl macrocyclic complex with cyclo[1]furan[1]pyridine[4]-pyrrole (1) at the near-infrared (NIR) band (1177 nm) in the presence of electron donors and acceptors resulted in NIR-induced electron transfer without producing singlet oxygen via energy transfer.
    Chemical Communications 03/2015; 51(31). DOI:10.1039/C5CC00903K · 6.83 Impact Factor
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    ABSTRACT: Bis-porphyrins containing a β,β′-fused pyrazino (Pz) linking group were examined by electrochemistry and thin-layer UV-visible spectroelectrochemistry in PhCN containing 0.1 M tetra-n-butylammonium perchlorate (TBAP) as supporting electrolyte. The investigated compounds are represented as M(TPP)-Pz-(TPP)M, where TPP is the dianion of tetraphenylporphyrin and M = Zn(II), Cu(II) or Ag(II). The effect of the linking Pz group on the redox potentials and UV-visible spectra of the neutral, electroreduced and electrooxidized bis-porphyrins is discussed and the data compared to what is observed for related monoporphyrins and earlier characterized bis-porphyrins containing a tetraazaanthracene (TA) linking group and the same central metal ions. The Cu(II) and Zn(II) Pz linked bis-porphyrins exhibit a relatively strong interaction between the two equivalent porphyrin macrocycles as evidenced by UV-visible spectra of the neutral compounds and characteristic splitting of redox processes for three of the four electron transfer reactions, the one exception being the first oxidation, where no splitting of potentials is observed in the formation of the bisporphyrin bis-cation radical, [M(TPP)-Pz-(TPP)M]2+. The first oxidation and first reduction of the bis-porphyrin with two Ag(II) central metal ions occurs via two overlapping one-electron transfer steps in each process indicating equivalent, but non-interacting redox centers. This difference in redox behavior is due to differences in the site of electron transfer, metal centered for the Ag(II) bisporphyrins, which undergo Ag(II)/Ag(III) and Ag(II)/Ag(I) processes as compared to only ring centered electron transfers for the Cu(II) and Zn(II) derivatives. The Pz-linked Zn(II) bis-porphyrins have a larger average HOMO–LUMO gap (2.01 V) as compared to related tetraazaanthracene linked bis-porphyrins (1.67 V), which were earlier characterized in the literature, but the gap is smaller than that for the mono-porphyrins with the same central metal ions (2.17 V). Each redox reaction of the investigated bisporphyrins was characterized by thin-layer spectroelectrochemistry.
    Journal of Porphyrins and Phthalocyanines 03/2015; 19(01n03):1-10. DOI:10.1142/S1088424615500224 · 1.40 Impact Factor
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    Guifen Lu · Sen Yan · Mengying Shi · Wenhan Yu · Jing Li · Weihua Zhu · Zhongping Ou · Karl M. Kadish
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    ABSTRACT: The first europium triple-decker tetrapyrrole with mixed corrole and phthalocyanine macrocycles was synthesized and characterized by spectroscopic and electrochemical methods. The molecular structure was characterized by single-crystal X-ray diffraction and showed the corrole to be in the middle of the sandwich with phthalocyanine macrocycles at each extreme.
    Chemical Communications 01/2015; 51(12). DOI:10.1039/C4CC09755F · 6.83 Impact Factor
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    ABSTRACT: The protonation and deprotonation reactions for a series N-confused meso-tetraaryl-substituted free-base porphyrins containing electron-donating or electron-withdrawing substituents was monitored in CHCl3 and DMF by UV-visible spectroscopy during titrations with trifluoroacetic acid or tetra-n-butylammonium hydroxide. The spectroscopic data was also used to calculate equilibrium constants for these reactions. The examined compounds are represented as (XPh)4NCPH2, where "NCP" represents the N-confused porphyrin π-conjugated macrocycle and X is a CH3O, CH3, H or Clpara-substituent on the four meso-phenyl rings (Ph) of the compound. The porphyrins can exist in two tautomeric forms depending upon the solvent and each tautomer undergoes two stepwise protonation reactions leading to formation of the mono- and bis-protonated porphyrins, [(XPh)4NCPH3]+ and [(XPh)4NCPH4]2+. A single step deprotonation is observed for the same compounds in DMF and the product is assigned as [(XPh)4NCPH]-. Comparisons are made between UV-visible spectra of the protonated, neutral and deprotonated forms of the porphyrin and the effect of the porphyrin ring substituents and tautomeric form of the neutral porphyrin on the UV-visible spectra and protonation constants is discussed along with data from DFT calculations.
    Journal of Porphyrins and Phthalocyanines 01/2015; 19(01n03):251-260. DOI:10.1142/S1088424614501132 · 1.40 Impact Factor
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    ABSTRACT: The synthesis of unsymmetrical push-pull benzoporphyrins has been realized. UV-Vis and fluorescence spectroscopy, cyclic voltammetry and DFT calculations reveal subtle substituent effects on the electronic and optical properties of these porphyrins.
    RSC Advances 01/2015; 5(64):51489-51492. DOI:10.1039/C5RA09179A · 3.84 Impact Factor
  • RSC Advances 01/2015; DOI:10.1039/C5RA15593B · 3.84 Impact Factor
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    ABSTRACT: A series of N-confused free-base meso-substituted tetraarylporphyrins was investigated by electrochemistry and spectroelectrochemistry in nonaqueous media containing 0.1 M tetra-n-butylammonium perchlorate (TBAP) and added acid or base. The investigated compounds are represented as (XPh)4NcpH2, in which “Ncp” is the N-confused porphyrin macrocycle and X is a OCH3, CH3, H, or Cl substituent on the para position of each meso-phenyl ring of the macrocycle. Two distinct types of UV/Vis spectra are initially observed depending upon solvent, one corresponding to an inner-2H form and the other to an inner-3H form of the porphyrin. Both forms have an inverted pyrrole with a carbon inside the cavity and a nitrogen on the periphery of the π-system. Each porphyrin undergoes multiple irreversible reductions and oxidations. The first one-electron addition and first one-electron abstraction are located on the porphyrin π-ring system to give π-anion and π-cation radicals with a potential separation of 1.52 to 1.65 V between the two processes, but both electrogenerated products are unstable and undergo a rapid chemical reaction to give new electroactive species, which were characterized in the present study. The effect of the solvent and protonation/deprotonation reactions on the UV/Vis spectra, redox potentials and reduction/oxidation mechanisms is discussed with comparisons made to data and mechanisms for the structurally related free-base corroles and porphyrins.
    Chemistry - A European Journal 12/2014; 21(6). DOI:10.1002/chem.201405570 · 5.73 Impact Factor
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    ABSTRACT: Two series of substituted manganese triarylcorroles were synthesized and characterized as to their electrochemical and spectroelectrochemical properties in CH2Cl2, CH3CN and pyridine. The investigated compounds are represented as (YPh)(3)CorMn(III) and (YPh)(3)CorMn(IV)Cl, where Cor is a trianion of the corrole and Y is a Cl, F, H or CH3 para-substituent on the three phenyl rings of the macrocycle. Each neutral Mn(III) corrole exists as a four-coordinate complex in CH2Cl2 and CH3CN and as a five-coordinate species in pyridine. (YPh)(3)CorMn(III) undergoes two oxidations to stepwise generate a Mn(IV) corrole and a Mn(IV) pi-cation radical. It also undergoes one reduction to generate a Mn(II) corrole in CH2Cl2 or CH3CN. In contrast, the reduction of (YPh)(3)CorMn(III) leads to a Mn(III) corrole pi-anion radical in pyridine. One oxidation is observed for (YPh)(3)CorMn(IV)Cl in CH2Cl2 and CH3CN to generate a Mn(IV) corrole pi-cation radical while Mn(III) and Mn(II) corroles are stepwise formed after reduction of the same compound. The second reduction of (YPh)(3)CorMn(IV)Cl in pyridine gives a Mn(III) pi-anion radical as opposed to a Mn(II) corrole with an unreduced pi-ring system. The neutral, reduced and oxidized forms of each corrole were characterized by electrochemistry and UV-visible spectroelectrochemistry and comparisons are made between the UV-visible spectra and redox potentials of the compounds in different central metal oxidation states. An overall reduction/oxidation mechanism in the three solvents is proposed.
    Journal of Porphyrins and Phthalocyanines 12/2014; 18(12):1131-1144. DOI:10.1142/S1088424614501119 · 1.40 Impact Factor
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    ABSTRACT: A cobalt(III) corrole, represented as (Cl2Ph)3CorCo(PPh3), where (Cl2Ph)3Cor is the trianion of 5,10,15-tri(2,4-dichlorophenyl)corrole, was synthesized and characterized as to its electrochemical and spectroelectrochemical properties. Single-crystal structure analysis showed the corrole to be monoclinic and have a space group P21/c with α = 13.441(3), b = 28.058(6), c = 27.584(6) Å, α = 90, β = 92.75(3), γ = 90°, Mr = 1144.38, V = 1039.1(4) Å3, Z = 8, Dc = 1.463 mg/cm3, μ = 0.816, F(000) = 4644, Rint = 0.0447, R(I > 4σ(I)) = 0.0769, wR(I > 4σ(I)) = 0.2104, R(all data) = 0.1214 and wR(all data) = 0.2705. The compound was also examined as a catalyst for the electroreduction of dioxygen when coated on an edge-plane pyrolytic graphite electrode in 1.0 M HClO4. Cyclic voltammetry and linear sweep voltammetry with a rotating disk electrode (RDE) or a rotating ring disk electrode (RRDE) were utilized to evaluate the catalytic activity of the corrole and elucidate the products of reduction, H2O or H2O2. Analysis of the data shows exclusively a two-electron transfer process to give 100% H2O2 as the product and no H2O was detectable.
    Journal of Porphyrins and Phthalocyanines 10/2014; 18(10n11):891-898. DOI:10.1142/S1088424614500734 · 1.40 Impact Factor
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    ABSTRACT: Electrochemical studies of the oxidation of dodecasubstituted and highly nonplanar nickel porphyrins in a noncoordinating solvent have previously revealed the first nickel(III) porphyrin dication. Herein, we investigate if these nonplanar porphyrins can also be used to detect the so far unobserved copper(III) porphyrin dication. Electrochemical studies of the oxidation of (DPP)Cu and (OETPP)Cu show three processes, the first two of which are macrocycle-centered to give the porphyrin dication followed by a Cu(II)/Cu(III) process at more positive potential. Support for the assignment of the Cu(II)/Cu(III) process comes from the linear relationships observed between E1/2 and the third ionization potential of the central metal ions for iron, cobalt, nickel, and copper complexes of (DPP)M and (OETPP)M. In addition, the oxidation behavior of additional nonplanar nickel porphyrins is investigated in a noncoordinating solvent, with nickel meso-tetraalkylporphyrins also being found to form nickel(III) porphyrin dications. Finally, examination of the nickel meso-tetraalkylporphyrins in a coordinating solvent (pyridine) reveals that the first oxidation becomes metal-centered under these conditions, as was previously noted for a range of nominally planar porphyrins.
    Inorganic Chemistry 09/2014; 53(19):10772–10778. DOI:10.1021/ic502162p · 4.76 Impact Factor

Publication Stats

11k Citations
2,613.60 Total Impact Points


  • 1979–2015
    • University of Houston
      • Department of Chemistry
      Houston, Texas, United States
  • 2010
    • Osaka University
      • Department of Materials Engineering Science
      Suika, Ōsaka, Japan
  • 2004–2007
    • Houston Baptist University
      Houston, Texas, United States
  • 2003–2007
    • University of Texas at Austin
      • • Department of Chemistry and Biochemistry
      • • Institute for Cellular and Molecular Biology
      Austin, Texas, United States
    • Sapienza University of Rome
      • Department of Chemistry
      Roma, Latium, Italy
  • 2006
    • Louisiana State University Health Sciences Center New Orleans
      New Orleans, Louisiana, United States
  • 2004–2006
    • University of Tsukuba
      • Graduate School of Pure and Applied Sciences
      Tsukuba, Ibaraki, Japan
  • 2005
    • Tokyo Gakugei University
      Koganei, Tōkyō, Japan
    • University of Sydney
      • School of Chemistry
      Sydney, New South Wales, Australia
  • 2003–2004
    • French National Centre for Scientific Research
      Lutetia Parisorum, Île-de-France, France
  • 1991–2004
    • University of Burgundy
      Dijon, Bourgogne, France
  • 1994–2003
    • University of Cologne
      • Institute of Organic Chemistry
      Köln, North Rhine-Westphalia, Germany
  • 2001
    • Roswell Park Cancer Institute
      Buffalo, New York, United States
  • 1993–1999
    • University of California, Davis
      • Department of Chemistry
      Davis, California, United States
    • University of Rome Tor Vergata
      Roma, Latium, Italy
  • 1996–1998
    • Wichita State University
      • Department of Chemistry
      Wichita, Kansas, United States
  • 1987–1989
    • Centre Hospitalier Universitaire de Dijon
      Dijon, Bourgogne, France
  • 1988
    • Princeton University
      • Department of Chemical and Biological Engineering
      Princeton, New Jersey, United States
  • 1987–1988
    • Mohammed V University of Rabat
      Rabat, Rabat-Salé-Zemmour-Zaër, Morocco
  • 1980–1982
    • Houston Zoo
      Houston, Texas, United States
    • Rice University
      Houston, Texas, United States