| 1. |
- Liu, Xien, et al.
(author)
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Synthesis, electrochemical, and photophysical studies of multicomponent systems based on porphyrin and ruthenium(II) polypyridine complexes
- 2007
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In: Tetrahedron. - : Elsevier BV. - 0040-4020 .- 1464-5416. ; 63:37, s. 9195-9205
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Journal article (peer-reviewed)abstract
- Two ruthenium tris-bipyridine functionalized porphyrins 4, 8 and their Zn derivatives 4-Zn, 8-Zn were designed, synthesized, and characterized. The redox potentials of these complexes as well as their corresponding monomeric reference porphyrin and ruthenium bipyridine complexes were also measured for comparison. Primary dynamic studies on the electron injection and backing recombination between these complexes and TiO2 nanoparticles were carried out by means of transient absorption spectroscopy. The results indicate that a long-lived charge separation state was obtained in these assemblies.
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| 2. |
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| 3. |
- Gao, Weiming, et al.
(author)
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An azadithiolate bridged Fe2S2 complex as active site model of FeFe-hydrogenase covalently linked to a Re(CO)(3)(bpy)(py) photosensitizer aiming for light-driven hydrogen production
- 2008
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In: Comptes rendus. Chimie. - : Elsevier BV. - 1631-0748 .- 1878-1543. ; 11:8, s. 915-921
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Journal article (peer-reviewed)abstract
- In order to create photoactive catalysts for hydrogen production, a novel trimetallic Re-Fe2S2 complex 4 was synthesized by the coordination of the free -PPh2 group of the ligand of the rhenium photosensitizer 6 to an azadithiolate (ADT)-bridged diiron complex 8 with the assistance of the decarbonylation reagent Me3NO. Complex 4 was characterized by H-1, C-13, P-31 NMR and HRMS spectra. The IR, UV-vis and electrochemical data indicate some interactions between Re and Fe2S2 moieties, and the photo-induced electron transfer from the excited state of the Re moiety to the Fe2S2 catalyst is thermodynamically feasible.
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| 4. |
- Gao, Weiming, et al.
(author)
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Bidentate phosphine ligand based Fe2S2-containing macromolecules : Synthesis, characterization, and catalytic electrochemical hydrogen production
- 2006
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In: Inorganic Chemistry. - : American Chemical Society (ACS). - 0020-1669 .- 1520-510X. ; 45:23, s. 9169-9171
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Journal article (peer-reviewed)abstract
- The reaction of [Fe-2(CO)(6)(mu-SCH2)(2)NCH2CH2N(mu-SCH2)(2)Fe-2(CO)(6)] (1) with 1,2-bis(diphenylphosphino) ethane in the presence of Me3NO, 2H(2)O affords two structurally different metallomacromolecules: a dimer of the type [{Fe-2(CO)(5)(mu-SCH2)(2)NCH2CH2N(mu-SCH2) Fe-2(2)(CO)(5)}(Ph2PCH2)(2)] (2) and a tetramer species containing eight iron centers with an overall formula of [{Fe-2(CO)(6)(mu-SCH2)(2)NCH2CH2N( mu-SCH2)(2)Fe-2(CO)(5)}(2)(Ph2PCH2)(2)] (3). Their structures have been determined by X-ray crystallography, showing one macrocyclic complex (2) and one linear complex (3). Electrochemical hydrogen evolution catalyzed by these two complexes with ca. 80-90 single-run turnovers is observed, indicating good potential as catalysts for future applications.
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| 5. |
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| 6. |
- Gao, Weiming, et al.
(author)
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Binuclear iron-sulfur complexes with bidentate phosphine ligands as active site models of Fe-hydrogenase and their catalytic proton reduction
- 2007
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In: Inorganic Chemistry. - : American Chemical Society (ACS). - 0020-1669 .- 1520-510X. ; 46:6, s. 1981-1991
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Journal article (peer-reviewed)abstract
- The displacement of CO in a few simple Fe(I)-Fe(I) hydrogenase model complexes by bisphosphine ligands Ph2P-(CH2)(n)-PPh2 [with n = 1 (dppm) or n = 2 (dppe)] is described. The reaction of [{mu-(SCH2)(2)CH2}Fe-2(CO)(6)] (1) and [{mu-(SCH2)(2)N(CH2CH2CH3)}Fe-2(CO)(6)] (2) with dppe gave double butterfly complexes [{mu-(SCH2)(2)CH2}Fe-2(CO)(5)(Ph2PCH2)](2) (3) and [{mu-(SCH2)(2)N(CH2CH2CH3)}Fe-2(CO)(5)(Ph2PCH2)](2) (4), where two Fe2S2 units are linked by the bisphosphine. In addition, an unexpected byproduct, [{mu-(SCH2)(2)N(CH2CH2CH3)}Fe-2(CO)(5){Ph2PCH2CH2(Ph2PS)}] (5), was isolated when 2 was used as a substrate, where only one phosphorus atom of dppe is coordinated, while the other has been converted to PS, presumably by nucleophilic attack on bridging sulfur. By contrast, the reaction of 1 and 2 with dppm under mild conditions gave only complexes [{mu-(SCH2)(2)CH2}Fe-2(CO)(5)(Ph2PCH2PPh2)] (6) and [{mu-(SCH2)(2)N(CH2CH2CH3)}Fe-2(CO)(5)(Ph2PCH2PPh2)] (8), where one ligand coordinated in a monodentate fashion to one Fe2S2 unit. Furthermore, under forcing conditions, the complexes [{mu-(SCH2)(2)CH2}Fe-2(CO)(4){mu-(Ph2P)(2)CH2}] (7) and [{mu-(SCH2)(2)N(CH2CH2CH3)}Fe-2(CO)(4){mu-(Ph2P)(2)CH2}] (9) were formed, where the phosphine acts as a bidentate ligand, binding to both the iron atoms in the same molecular unit. Electrochemical studies show that the complexes 3, 4, and 9 catalyze the reduction of protons to molecular hydrogen, with 4 electrolyzed already at -1.40 V versus Ag/AgNO3 (-1.0 V vs NHE).
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| 7. |
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| 8. |
- Gao, Weiming, et al.
(author)
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Facile and highly efficient light-induced PR3/CO ligand exchange : A novel approach to the synthesis of (mu-(SCH2NPrCH2S)-Pr-n)Fe-2(CO)(4)(PR3)(2)
- 2007
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In: Journal of Organometallic Chemistry. - : Elsevier BV. - 0022-328X .- 1872-8561. ; 692:7, s. 1579-1583
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Journal article (peer-reviewed)abstract
- A straightforward and efficient transformation of the Fe-S complex [(mu-SCH2NPrCH2S)Fe-2(CO)(6)] to its double phosphine coordinated analogues [(mu-(SCH2NPrCH2S)-Pr-n)Fe-2(CO)(4)(PR3)(2)] (R = Ph, Me) is described. The single crystal structure of the PPh3-disubstituted Complex [(mu-(SCH2NPrCH2S)-Pr-n)Fe-2(CO)(4)(Ph3P)(2)] (3) showed that both of the phosphine ligands take an apical/apical instead of a basal/ basal or an apical/basal configuration.
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| 9. |
- Gao, Yan, et al.
(author)
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Nucleophilic Attack of Hydroxide on a Mn-V Oxo Complex : A Model of the O-O Bond Formation in the Oxygen Evolving Complex of Photosystem II
- 2009
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In: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 131:25, s. 8726-
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Journal article (peer-reviewed)abstract
- A manganese(III) corrole complex, 1, has been synthesized and used to study a potential mechanism for oxidation of water to molecular oxygen. Oxidation by t-BuOOH gave the Mn-V=O complex 2. Addition of hydroxide Led to release of oxygen via the Mn-IV complex 4 and regeneration of complex 1. It could be shown that the oxygen from O-18-labeted water was incorporated in both the formed molecular oxygen and the peroxy intermediate 4.
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| 10. |
- Gao, Yan, et al.
(author)
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Synthesis and characterization of manganese and copper corrole xanthene complexes as catalysts for water oxidation
- 2007
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In: Tetrahedron. - : Elsevier BV. - 0040-4020 .- 1464-5416. ; 63:9, s. 1987-1994
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Journal article (peer-reviewed)abstract
- Two corrole xanthene ligands and four corresponding Mn-IV and Cu-III complexes have been synthesized and spectroscopically characterized. This kind of complexes, comprising of xanthene and corrole linked by an amide bond, were designed as bio-inspired models for the oxygen evolving complex (OEC) in Photosystem II. We find that both manganese complexes 4a and 5a have efficiency on catalyzing oxygen evolution at low potential (about 0.80 V) by electrochemical method, which is a significant progress in the study of dioxygen formation.
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| 11. |
- Gao, Yan, et al.
(author)
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Synthesis and photophysical and electrochemical properties of a binuclear Ru(bpy)(3)-Cu(III) corrole complex
- 2007
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In: Journal of Porphyrins and Phthalocyanines. - 1088-4246 .- 1099-1409. ; 11:06-maj, s. 463-469
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Journal article (peer-reviewed)abstract
- A novel binuclear Ru-Cu complex, composed of a copper(III)-corrole and a ruthenium(II) tris(bipyridine) moicty linked by an amide bond, has been synthesized and characterized by H-1 NMR, UV-vis and mass spectrometry. The steady-state emission and the electrochemical properties were investigated. Compared to the parent [Ru(bpy)(3)](2+), the emission-of the desired complex was substantially quenched when the MLCT of [Ru(bpy)(3)](2+) was selectively photoexcited.
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| 12. |
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| 13. |
- Jiang, Shi, et al.
(author)
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Fe-S complexes containing five-membered heterocycles : novel models for the active site of hydrogenases with unusual low reduction potential
- 2007
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In: Dalton Transactions. - : Royal Society of Chemistry (RSC). - 1477-9226 .- 1477-9234. ; :8, s. 896-902
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Journal article (peer-reviewed)abstract
- Three biomimetic 2Fe2S complexes [{(mu-SCH2)(2)NCH2(2-C4H3O)}](Fe-2(CO)(6)) (6a), [{(mu-SCH2)(2) NCH2(2-C4H3S)}](Fe-2(CO)(6)) (6b) and [{(mu-SCH2)(2)NCH2(5-Br-2-C4H2S)}Fe-2(CO)(6)] (6c) were prepared as models for the active site of Fe-only hydrogenase by the convergent process from [(mu-S-2)Fe-2(CO)(6)] and N,N-bis(hydromethyl)-2-furan and thiophene. The structures of these complexes were identified spectroscopically and crystallographically. The electrochemical behavior of the complexes 6a and 6c was unique as they showed catalytic proton reduction with a low reduction potential at -1.13 and -1.09 V vs Fc/Fc(+), respectively, in the presence of HClO4.
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| 14. |
- Jiang, Shi, et al.
(author)
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Preparation, characteristics and crystal structures of novel N-heterocyclic carbene substituted furan- and pyridine-containing azadithiolate Fe-S complexes
- 2007
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In: Polyhedron. - : Elsevier BV. - 0277-5387 .- 1873-3719. ; 26:7, s. 1499-1504
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Journal article (peer-reviewed)abstract
- Two novel N-heterocyclic carbene disubstituted furan- and pyridine-containing azadithiolate Fe-only hydrogenase models (2 and 4) have been synthesized, and characterized by IR and H-1 NMR spectra and X-ray single crystal diffraction. Cyclic voltammetry (CV) experiments indicate that they show more negative reductive potentials at -2.53 V and -2.49 V, respectively versus the ferrocene/ferrocenium couple (Fc/Fc(+)) and are easier to capture proton attributing to the strong electron-donating ligand NHC. After the protonation under F3CCO2H the reductive potentials of 2 and 4 have 1.02 V and 0.77 V shifts, indicating the formation of Fe-H-Fe bond. The results also are confirmed by the data changes in IR spectra and the negative H signals are detected by 1H NMR spectra at -27 ppm and -55 ppm.
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| 15. |
- Li, Minna, et al.
(author)
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Aryl-diamide bridged binuclear ruthenium(II) tris(bipyridine) complexes : Synthesis, photophysical, electrochemical and electrochemiluminescence properties
- 2006
-
In: Journal of Organometallic Chemistry. - : Elsevier BV. - 0022-328X .- 1872-8561. ; 691:20, s. 4189-4195
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Journal article (peer-reviewed)abstract
- Several new symmetrical aromatic hydrocarbon bridged bipyridine ligands and their binuclear Ru (II) complexes have been designed, synthesized and characterized on the basis of H-1 NMR, MS and HRMS. Their absorption and emission properties, electrochemical behaviors and electrochemical luminescence were investigated. All ruthenium complexes show characteristic MLCT absorption and similar redox potential. Among the three complexes reported, 4c has the best electrochemical luminescence property.
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| 16. |
- Li, Minna, et al.
(author)
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Oligo thiophene-2-yl-vinyl bridged mono- and binuclear ruthenium(II) tris-bipyridine complexes : Synthesis, photophysics, electrochemistry and electrogenerated chemiluminescence
- 2008
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In: Journal of Organometallic Chemistry. - : Elsevier BV. - 0022-328X .- 1872-8561. ; 693:1, s. 46-56
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Journal article (peer-reviewed)abstract
- A series of mono- and binuclear ruthenium(II) tris-bipyridine complexes tethered to oligothienylenevinyleries have been synthesized and characterized by H-1 NMR, C-13 NMR and TOF-MS spectrometry. Photophysics, electrochemistry and electrogenerated chemiluminescence (ECL) properties of these complexes are investigated. The electronic absorption spectra of the mononuclear ruthenium complexes show a significant red shift both at MLCT (metal-to-ligand charge transfer) and pi-pi* transitions of oligothienylenevinylenes with increase in the number of thiophenyl-2-yl-vinyl unit. For the binuclear complexes these two absorption bands are overlapped.) All the metal complexes have very weak emission compared to that of the reference complex Ru(bpy)(3)(2+). The first reduction potentials of all mononuclear ruthenium complexes are less negative than that of Ru(bpy)(3)(2+), due to the moderate electron-withdrawing effect of oligothienylenevinylenes. For binuclear ruthenium complexes, only one Ru(II/III) oxidation peak (E-1/2=0.96V vs. Ag/Ag+) was observed, suggesting a weak interaction between two metal centers. Three successive reduction processes of bipyridine ligands are similar among all ruthenium complexes except for RuTRu, which has a very sharp peak owing to the accumulation of neutral product oil the electrode surface. All these ruthenium complexes exhibited different ECL property in CH3CN solution without any additional reductant or oxidant. For three mononuclear ruthenium complexes, the ECL intensity strengthens with increase in the number of thiophene-2-yl-vinyl unit. However, the ECL efficiency dramatically decreased in the binuclear ruthenium complexes. The ECL efficiencies of all the)2+, reported complexes do not exceed that of Ru(bpy 3 where the ECL efficiency decreases in the order of RuTRu > Ru3T > Ru2T > RuT > Ru2TRu (RuT, bis-2,2'-bipyridyl-(4-metliyl-4'-(2-thienylethenyl)-2,2'-bipyridine) ruthenium dihexafluorophosphate; Ru2T, bis-2,2'-bipyridyl-(4-methyl-4'-{(E) -2-[5-((E) -2-thienylethenyl)-thienylethenyl])-2,2'-bipyridine)ruthenium dihexafluorophosphate; Ru3T, bis-2,2'-bipyridyl-(4-methyl-4'-[(E)-2-{(E)-2-[5-((E)-2-thienylethenyl)- thienylethenyl])}-2,2'-bipyridine) ruthenium dihexafluorophosphate; RuTRu, bis-2,2'-bipyridyl-ruthenium-bis-[2-((E)-4'-methyl-2,2'-bipyridinyl-4)-e thenyl]-thienyl-bis-2,2'-bipyridyl-ruthenium tetrahexafluorophosphate; Ru2TRu, bis-2,2'-bipyridyl-ruthenium-(E)-1,2-bis-{2-[2-((E)-4'-methyl-2,2'-bipyr idinyl-4)-ethenyl]-thienyl}ethenyl-bis-2,2'-bipyridyl-ruthenium tetrahexafluorophosphate).
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| 17. |
- Li, Xueqiang, et al.
(author)
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Noncovalent assembly of a metalloporphyrin and an iron hydrogenase active-site model : Photo-induced electron transfer and hydrogen generation
- 2008
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In: Journal of Physical Chemistry B. - : American Chemical Society (ACS). - 1520-6106 .- 1520-5207 .- 1089-5647. ; 112:27, s. 8198-8202
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Journal article (peer-reviewed)abstract
- A noncovalent assembly of a pyridyl-functionalized hydrogenase active-site model complex and zinc tetraphenylporphyrin has been obtained and characterized. Upon light irradiation, fluorescence quenching by electron transfer was observed from the singlet excited state of the porphyrin to the diiron center, and the mechanism was verified by fluorescence lifetime and transient absorption spectroscopic measurements. In contrast to molecular dyads linked by covalent bonds, the assembled system was designed to avoid charge recombination via complex dissociation after photo-induced electron transfer. Visible light-driven hydrogen generation was observed from this self-assembled system. The assembling strategy employed in this study has the potential to be used for any other hydrogenase models in the future.
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| 18. |
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| 19. |
- Privalov, Timofei, et al.
(author)
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A computational study of O-O bond formation catalyzed by monoand Bis-Mn-IV-Corrole complexes
- 2007
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In: Inorganic Chemistry. - : American Chemical Society (ACS). - 0020-1669 .- 1520-510X. ; 46:17, s. 7075-7086
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Journal article (peer-reviewed)abstract
- A detailed computational study of O-O bond formation, catalyzed by monomeric and dimeric Mn-corrole complexes, is reported. The model explicitly takes into account the solvent, with respect to the first and second coordination spheres, while the bulk solvent is described by the polarizable continuum model. Two reaction mechanisms are proposed and computationally characterized: the concerted and the two-step mechanisms. The concerted mechanism is based on a OH--(MnO)-O-IV interaction via the outer-sphere pathway involving the bridging solvent molecules in the first coordinating sphere. The two-step mechanism is proposed to operate via the coordination of a hydroxide to the Mn-Iv ion, forming a MnO(OH)(-)-corrole complex with a strongly nonplanar corrole ligand. Comparison of the proposed mechanisms with available experimental data. is performed.
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| 20. |
- Wang, Zhen, et al.
(author)
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Diiron azadithiolates with hydrophilic phosphatriazaadamantane ligand as iron-only hydrogenase active site models : Synthesis, structure, and electrochemical study
- 2007
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In: Inorganica Chimica Acta. - : Elsevier BV. - 0020-1693 .- 1873-3255. ; 360:7, s. 2411-2419
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Journal article (peer-reviewed)abstract
- Three novel complexes (mu-adt)[Fe-2(CO)(5)PTA] (2-PTA), (mu-adt)[Fe-2(CO)(4)PTA(2)](2-PTA(2)) and (mu-adt)[Fe-2(CO)(5)DAPTA] (2-DAPTA), where adt is SCH2N(CH2CH2CH3)CH2S, PTA stands for 1,3,5-triaza-7-phosphaadamantane and DAPTA is 3,7-diacetyl-1,3,7-triaza-5-phosphabicyclo[3.3.1]nonane, were prepared as the models of the iron hydrogenase active site through controlled CO displacement of (mu-adt)[Fe-2(CO)(6)] with PTA and DAPTA. The coordination configurations of 2-PTA and 2-PTA(2) were characterized by X-ray crystallography. The disubstituted diiron complex 2-PTA(2) features a basal/apical coordination mode, instead of the typical transoid basal/basal configuration. Protonation of three complexes only occurred at the bridging-N atom, rather than at the tertiary nitrogen atom on the PTA or DAPTA ligands. Electrochemical properties of the complexes were studied in acetonitrile or a mixture of acetonitrile and water in the presence of acetic acid, by cyclic voltammetry. The current sensitivity of the reduced species to acid concentration in the presence of H2O is greater than in the pure CH3CN solution.
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| 21. |
- Wang, Zhen, et al.
(author)
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Pendant bases as proton transfer relays in diiron dithiolate complexes inspired by Fe-Fe hydrogenase active site
- 2008
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In: Journal of Organometallic Chemistry. - : Elsevier BV. - 0022-328X .- 1872-8561. ; 693:17, s. 2828-2834
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Journal article (peer-reviewed)abstract
- Three dinuclear iron complexes containing pendant nitrogen bases in phosphine ligands with general formular ( l- pdt) [ Fe2( CO) 5L] ( where pdt is SCH2CH2CH2S, L = PPh2NH( CH2) 2N( CH3) 2 ( 5), PPh2NH( 2- NH2C6H4) ( 6), PPh2[ 2- N( CH3) 2CH2C6H4] ( 7)), were prepared as the models of the [ Fe - Fe] hydrogenase active site. The molecular structures of 5 - 7 were characterized by X- ray crystallography. The secondary amine in 6 has weak intramolecular hydrogen bonding with both the terminal nitrogen and sulfur atom, which may suggest a proton transfer pathway from amine in phosphine ligand to the sulfur atom of active site. Protonation of complexes 5 and 6 only occurred at the terminal nitrogen atom. Electrochemical properties of the complexes were studied in the presence of tri. ic acid by cyclic voltammetry.
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| 22. |
- Xia, Ming, et al.
(author)
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Synthesis and photophysical and electrochemical study of tyrosine covalently linked to high-valent copper(III) and manganese(IV) complexes
- 2007
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In: Helvetica Chimica Acta. - : Wiley. - 0018-019X .- 1522-2675. ; 90:3, s. 553-561
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Journal article (peer-reviewed)abstract
- As bio-inspired chemical model of the oxygen-evolving complex (OEC) in photosystem II, a new tyrosine-modified corrole ligand 3 and its high-valent copper and manganese complexes 3a and 3b were synthesized and characterized. The copper complexes 1a and 2a of corrole 1 and 2 were also prepared for comparison. The emission property indicates that the emission of ligands 2 and 3 is located at 670 nm, but no emission is observed for their metal complexes due to its suppression by the metal center. The electrochemical study shows that 3a might dimerize at the first two reversible oxidations, a behavior which was not observed in the case of In and 2a. ne corrolato manganese(IV) complex 3b shows one reversible reduction and one quasireversible oxidation at -0.17 and 0.77 V vs. Ag/Ag+, respectively.
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| 23. |
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| 24. |
- Zhang, Wei, et al.
(author)
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Practical synthesis of new beta-diketone-connected bipyridine and its conversion to pyrazole-centered bipyridine ligand
- 2007
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In: Synthetic Communications. - : Informa UK Limited. - 0039-7911 .- 1532-2432. ; 37:19-21, s. 3393-3402
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Journal article (peer-reviewed)abstract
- Two new polydentate ligands, 1-(6-hydroxymethyl-2-pyridyl)-3-(2-pyridyl)-propane-1,3-dione (6) and 1,3-bis(6-hydroxymethyl-2-pyridyl)-propane-1, 3-dione (8), have been synthesized starting from 2,6-pyridinedicarboxylic acid by conventional esterification, reduction, and condensation reactions. They were further converted to two new polydentate ligands, 3-(6-hydroxymethyl-2-pyridyl)-5-(2-pyridyl)-1H-pyrazole (7) and 3,5-bis(6-hydroxymethyl-2-pyridyl)-1H-pyrazole (9), by reaction with hydrazine hydrate. These four compounds were characterized by proton nuclear magnetic resonance (H-1 NMR), electrospray ionization-mass spectrum (ESI-MS), infrared spectrum (IR), and elemental analyses. The structure of 9 was also determined by X-ray diffraction.
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| 25. |
- Zhang, Wei, et al.
(author)
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Synthesis of some new 4-substituted-3,5-bis(2-pyridyl)-1H-pyrazole
- 2006
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In: Journal of Heterocyclic Chemistry. - : Wiley. - 0022-152X .- 1943-5193. ; 43:6, s. 1669-1672
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Journal article (peer-reviewed)abstract
- Several 4-substituted-3, 5-bis(2-pyridyl)-1H-pyrazoles, where the substituent is chloro, bromo, iodo, nitro, diazo, were synthesized under mild reaction conditions in high yields. The structures of the products were characterized by H-1 NMR, C-13 NMR, ESI-MS, IR and elemental analyses.
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