| 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. |
- Qian, Deping, et al.
(author)
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Design rules for minimizing voltage losses in high-efficiency organic solar cells
- 2018
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In: Nature Materials. - : NATURE PUBLISHING GROUP. - 1476-1122 .- 1476-4660. ; 17:8, s. 703-
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Journal article (peer-reviewed)abstract
- The open-circuit voltage of organic solar cells is usually lower than the values achieved in inorganic or perovskite photovoltaic devices with comparable bandgaps. Energy losses during charge separation at the donor-acceptor interface and non-radiative recombination are among the main causes of such voltage losses. Here we combine spectroscopic and quantum-chemistry approaches to identify key rules for minimizing voltage losses: (1) a low energy offset between donor and acceptor molecular states and (2) high photoluminescence yield of the low-gap material in the blend. Following these rules, we present a range of existing and new donor-acceptor systems that combine efficient photocurrent generation with electroluminescence yield up to 0.03%, leading to non-radiative voltage losses as small as 0.21 V. This study provides a rationale to explain and further improve the performance of recently demonstrated high-open-circuit-voltage organic solar cells.
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| 3. |
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| 4. |
- Abelev, Betty, et al.
(author)
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Measurement of prompt J/psi and beauty hadron production cross sections at mid-rapidity in pp collisions at root s=7 TeV
- 2012
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In: Journal of High Energy Physics. - 1029-8479. ; :11
-
Journal article (peer-reviewed)abstract
- The ALICE experiment at the LHC has studied J/psi production at mid-rapidity in pp collisions at root s = 7 TeV through its electron pair decay on a data sample corresponding to an integrated luminosity L-int = 5.6 nb(-1). The fraction of J/psi from the decay of long-lived beauty hadrons was determined for J/psi candidates with transverse momentum p(t) > 1,3 GeV/c and rapidity vertical bar y vertical bar < 0.9. The cross section for prompt J/psi mesons, i.e. directly produced J/psi and prompt decays of heavier charmonium states such as the psi(2S) and chi(c) resonances, is sigma(prompt J/psi) (p(t) > 1.3 GeV/c, vertical bar y vertical bar < 0.9) = 8.3 +/- 0.8(stat.) +/- 1.1 (syst.)(-1.4)(+1.5) (syst. pol.) mu b. The cross section for the production of b-hadrons decaying to J/psi with p(t) > 1.3 GeV/c and vertical bar y vertical bar < 0.9 is a sigma(J/psi <- hB) (p(t) > 1.3 GeV/c, vertical bar y vertical bar < 0.9) = 1.46 +/- 0.38 (stat.)(-0.32)(+0.26) (syst.) mu b. The results are compared to QCD model predictions. The shape of the p(t) and y distributions of b-quarks predicted by perturbative QCD model calculations are used to extrapolate the measured cross section to derive the b (b) over bar pair total cross section and d sigma/dy at mid-rapidity.
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| 5. |
- Blanton, Michael R., et al.
(author)
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Sloan Digital Sky Survey IV : Mapping the Milky Way, Nearby Galaxies, and the Distant Universe
- 2017
-
In: Astronomical Journal. - : IOP Publishing Ltd. - 0004-6256 .- 1538-3881. ; 154:1
-
Journal article (peer-reviewed)abstract
- We describe the Sloan Digital Sky Survey IV (SDSS-IV), a project encompassing three major spectroscopic programs. The Apache Point Observatory Galactic Evolution Experiment 2 (APOGEE-2) is observing hundreds of thousands of Milky Way stars at high resolution and. high signal-to-noise ratios in the near-infrared. The Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey is obtaining spatially resolved spectroscopy for thousands of nearby galaxies (median z similar to 0.03). The extended Baryon Oscillation Spectroscopic Survey (eBOSS) is mapping the galaxy, quasar, and neutral gas distributions between z similar to 0.6 and 3.5 to constrain cosmology using baryon acoustic oscillations, redshift space distortions, and the shape of the power spectrum. Within eBOSS, we are conducting two major subprograms: the SPectroscopic IDentification of eROSITA Sources (SPIDERS), investigating X-ray AGNs. and galaxies in X-ray clusters, and the Time Domain Spectroscopic Survey (TDSS), obtaining spectra of variable sources. All programs use the 2.5 m Sloan Foundation Telescope at the. Apache Point Observatory; observations there began in Summer 2014. APOGEE-2 also operates a second near-infrared spectrograph at the 2.5 m du Pont Telescope at Las Campanas Observatory, with observations beginning in early 2017. Observations at both facilities are scheduled to continue through 2020. In keeping with previous SDSS policy, SDSS-IV provides regularly scheduled public data releases; the first one, Data Release 13, was made available in 2016 July.
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| 6. |
- Chen, Jie, et al.
(author)
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Bidirectional Mendelian Randomisation Analysis Provides Evidence for the Causal Involvement of Dysregulation of CXCL9, CCL11 and CASP8 in the Pathogenesis of Ulcerative Colitis
- 2023
-
In: Journal of Crohn's & Colitis. - : Oxford University Press. - 1873-9946 .- 1876-4479. ; 17:5, s. 777-785
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Journal article (peer-reviewed)abstract
- Background and Aims Systemic inflammation is well recognised to be associated with ulcerative colitis [UC], but whether these effects are causal or consequential remains unclear. We aimed to define potential causal relationship of cytokine dysregulation with different tiers of evidence. Methods We first synthesised serum proteomic profiling data from two multicentred observational studies, in which a panel of systemic inflammatory proteins was analysed to examine their associations with UC risk. To further dissect observed associations, we then performed a bidirectional two-sample Mendelian randomisation [TSMR] analysis from both forward and reverse directions using five genome-wide association study [GWAS] summary level data for serum proteomic profiles and the largest GWAS of 28 738 European-ancestry individuals for UC risk. Results Pooled analysis of serum proteomic data identified 14 proteins to be associated with the risk of UC. Forward MR analysis using only cis-acting protein quantitative trait loci [cis-pQTLs] or trans-pQTLs further validated causal associations of two chemokines and the increased risk of UC: C-X-C motif chemokine ligand 9 [CXCL9] [OR 1.45, 95% CI 1.08, 1.95, p = 0.012] and C-C motif chemokine ligand 11 [CCL11] [OR 1.14, 95% CI 1.09, 1.18, p = 3.89 x 10(-10)]. Using both cis- and trans-acting pQTLs, an association of caspase-8 [CASP8] [OR 1.04, 95% CI 1.03, 1.05, p = 7.63 x 10(-19)] was additionally identified. Reverse MR did not find any influence of genetic predisposition to UC on any of these three inflammation proteins. Conclusion Pre-existing elevated levels of CXCL9, CCL11 and CASP8 may play a role in the pathogenesis of UC.
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| 7. |
- Ding, Xin, et al.
(author)
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Artificial photosynthesis : A two-electrode photoelectrochemical cell for light driven water oxidation with molecular components
- 2014
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In: Electrochimica Acta. - : Elsevier BV. - 0013-4686 .- 1873-3859. ; 149, s. 337-340
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Journal article (peer-reviewed)abstract
- An efficient two-electrode molecular PEC was assembled, in which a photoanode was constructed using a co-adsorbed method with a molecular photosensitizer (PS) 1 and a molecular catalyst 2 on TiO2-sintered FTO electrode (TiO2(1 + 2)). Without applied bias against a reference electrode, the system achieves remarkable photocurrent densities and carries out light driven water oxidation as evidenced by Clark electrode measurements in solution. A photocurrent density of 70 mA/cm(2) has been obtained within 10 s illumination time, and a TON of about 220 was obtained with a maximum turnover frequency (TOF) of ca. 4 min(-1) within the initial 5 minutes illumination duration.
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| 8. |
- Ding, Xin, et al.
(author)
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Visible Light-Driven Water Splitting in Photoelectrochemical Cells with Supramolecular Catalysts on Photoanodes
- 2014
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In: ACS Catalysis. - : American Chemical Society (ACS). - 2155-5435. ; 4:7, s. 2347-2350
-
Journal article (peer-reviewed)abstract
- By using a supramolecular self-assembly method, a functional water splitting device based on a photoactive anode TiO2(1+2) has been successfully assembled with a molecular photosensitizer 1 and a molecular catalyst 2 connected by coordination of 1 and 2 with Zr4+ ions on the surface of nanostructured TiO2. On the basis of this photoanode in a three-electrode photoelectrochemical cell, a maximal incident photon to current conversion efficiency of 4.1% at similar to 450 nm and a photocurrent density of similar to 0.48 mA cm(-2) were successfully obtained.
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| 9. |
- 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
-
In: Comptes rendus. Chimie. - : Elsevier BV. - 1631-0748 .- 1878-1543. ; 11:8, s. 915-921
-
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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| 10. |
- Gao, Weiming, et al.
(author)
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Bidentate phosphine ligand based Fe2S2-containing macromolecules : Synthesis, characterization, and catalytic electrochemical hydrogen production
- 2006
-
In: Inorganic Chemistry. - : American Chemical Society (ACS). - 0020-1669 .- 1520-510X. ; 45:23, s. 9169-9171
-
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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| 11. |
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| 12. |
- 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
-
In: Inorganic Chemistry. - : American Chemical Society (ACS). - 0020-1669 .- 1520-510X. ; 46:6, s. 1981-1991
-
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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| 13. |
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| 14. |
- 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
-
In: Journal of Organometallic Chemistry. - : Elsevier BV. - 0022-328X .- 1872-8561. ; 692:7, s. 1579-1583
-
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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| 15. |
- 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
-
In: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 131:25, s. 8726-
-
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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| 16. |
- 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
-
In: Tetrahedron. - : Elsevier BV. - 0040-4020 .- 1464-5416. ; 63:9, s. 1987-1994
-
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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| 17. |
- 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
-
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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| 18. |
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| 19. |
- Gao, Yan, et al.
(author)
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Visible Light Driven Water Splitting in a Molecular Device with Unprecedentedly High Photocurrent Density
- 2013
-
In: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 135:11, s. 4219-4222
-
Journal article (peer-reviewed)abstract
- A molecular water oxidation catalyst (2) has been synthesized and immobilized together with a molecular photosensitizer (1) on nanostructured TiO2 particles on FTO conducting glass, forming a photoactive anode (TiO2(1+2)). By using the TiO2(1+2) as working electrode in a three-electrode photoelectrochemical cell (PEC), visible light driven water splitting has been successfully demonstrated in a phosphate buffer solution (pH 6.8), with oxygen and hydrogen bubbles evolved respectively from the working electrode and counter electrode. By applying 0.2 V external bias vs NHE, a high photocurrent density of more than 1.7 rnA.cm(-2) has been achieved. This value is higher than any PEC devices with molecular components reported in literature.
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| 20. |
- 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
-
In: Dalton Transactions. - : Royal Society of Chemistry (RSC). - 1477-9226 .- 1477-9234. ; :8, s. 896-902
-
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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| 21. |
- 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
-
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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| 22. |
- Li, Guoqiang, et al.
(author)
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Differential ice volume and orbital modulation of Quaternary moisture patterns between Central and East Asia
- 2020
-
In: Earth and Planetary Science Letters. - : Elsevier. - 0012-821X .- 1385-013X. ; 530
-
Journal article (peer-reviewed)abstract
- Desertification is of pressing environmental concern in large parts of Asia and directly affects millions of people. Arid Central Asia (ACA) in particular is highly sensitive to desertification and environmental change. Climate change in ACA may be driven by westerly circulation or monsoon variation. However, no consensus exists over their relative importance during the Quaternary and this greatly restricts our understanding of how this region may be affected by future climate change. Here we use the most detailed luminescence dating age model yet produced for ACA for three loess records in the Tianshan Mountains spanning the past 250 ka to show a sharp dichotomy in moisture variation between lowland and high mountain areas. The lowland areas of ACA are subjected to persistent aridity during past 250 ka, while highland areas clearly show dry-glacial and moist-interglacial changes, synchronous to moisture variability in monsoonal East Asia, and both co-varying with global ice volume and greenhouse gas (GHG) variation. In contrast, moisture variability across ACA within interglacials varies inversely with insolation-driven precessional changes. This is directly out of phase with the moisture changes of East Asia, which co-vary with precessional insolation changes, and indicates the influence of Westerly circulation in ACA. Our Flexible Global Ocean-Atmosphere-Land System model simulations further reveal that coupled ice volume and GHG variations dominated climatic variability in both ACA and East Asia over glacial-interglacial cycles. However, the out of phase relationship between the intensity of the Westerly and East Asian monsoon systems during interglacial periods indicates that precessional forcing is responsible for differences in moisture patterns between ACA and East Asia. These observations indicate that moisture levels will not increase even in high altitude regions of ACA over the next several millennia; rather desertification is likely to worsen resulting from stabilization of the Westerlies as a result of low summer insolation.
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| 23. |
- 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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| 24. |
- 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
-
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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| 25. |
- Li, Xiane, et al.
(author)
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Mapping the energy level alignment at donor/acceptor interfaces in non-fullerene organic solar cells
- 2022
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In: Nature Communications. - : Nature Portfolio. - 2041-1723. ; 13:1
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Journal article (peer-reviewed)abstract
- Energy level alignment (ELA) at donor-acceptor heterojunctions is of vital importance yet largely undetermined in organic solar cells. Here, authors determine the heterojunction ELA with (mono) layer-by-layer precision to understand the co-existence of efficient charge. Energy level alignment (ELA) at donor (D) -acceptor (A) heterojunctions is essential for understanding the charge generation and recombination process in organic photovoltaic devices. However, the ELA at the D-A interfaces is largely underdetermined, resulting in debates on the fundamental operating mechanisms of high-efficiency non-fullerene organic solar cells. Here, we systematically investigate ELA and its depth-dependent variation of a range of donor/non-fullerene-acceptor interfaces by fabricating and characterizing D-A quasi bilayers and planar bilayers. In contrast to previous assumptions, we observe significant vacuum level (VL) shifts existing at the D-A interfaces, which are demonstrated to be abrupt, extending over only 1-2 layers at the heterojunctions, and are attributed to interface dipoles induced by D-A electrostatic potential differences. The VL shifts result in reduced interfacial energetic offsets and increased charge transfer (CT) state energies which reconcile the conflicting observations of large energy level offsets inferred from neat films and large CT energies of donor - non-fullerene-acceptor systems.
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| 26. |
- 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
-
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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| 27. |
- Liu, Guofeng, et al.
(author)
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Helicity Inversion of Supramolecular Hydrogels Induced by Achiral Substituents
- 2017
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In: ACS Nano. - : American Chemical Society (ACS). - 1936-0851 .- 1936-086X. ; 11:12, s. 11880-11889
-
Journal article (peer-reviewed)abstract
- Probing the supramolecular chirality of assemblies and controlling their handedness are closely related to the origin of chirality at the supramolecular level and the development of smart materials with desired handedness. However, it remains unclear how achiral residues covalently bonded to chiral amino acids can function in the chirality inversion of supramolecular assemblies. Herein, we report macroscopic chirality and dynamic manipulation of chiroptical activity of hydrogels self-assembled from phenylalanine derivatives, together with the inversion of their handedness achieved solely by exchanging achiral substituents between oligo(ethylene glycol) and carboxylic acid groups. This helicity inversion is mainly induced by distinct stacking mode of the self-assembled building blocks, as collectively confirmed by scanning electron microscopy, circular dichroism, crystallography, and molecular dynamics calculations. Through this straightforward approach, we were able to invert the handedness of helical assemblies by merely exchanging achiral substituents at the terminal of chiral gelators. This work not only presents a feasible strategy to achieve the handedness inversion of helical nanostructures for better understanding of chiral self-assembly process in supramolecular chemistry but also facilities the development of smart materials with controllable handedness in materials science.
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| 28. |
- Liu, Xintao, et al.
(author)
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Analysis of urban agglomeration structure through spatial network and mobile phone data
- 2021
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In: Transactions in GIS. - : Wiley. - 1361-1682 .- 1467-9671. ; 25:4, s. 1949-1969
-
Journal article (peer-reviewed)abstract
- Urban agglomeration is an important strategy used to promote economic development and urbanization in China. Understanding the structure of urban agglomeration is therefore essential for policy-makers and planners. In this study, the Beijing–Tianjin–Hebei urban agglomeration (BTHUG) is explored through a proposed spatial network analytical framework and a large mobile phone data set (over 20 million users). We first construct a weight-directed spatial interaction network based on an origin–destination matrix derived from the data set. Several network metrics (i.e., degree, strength, the rich-club coefficient, and the assortativity coefficient) and three selected community detection algorithms (i.e., Infomap, Louvain, and Regionalization) are applied and compared to reveal the structure of the BTHUG. A four-level hierarchical structure is defined and observed: one global center, two local centers, major cities that have low mobility flow but strong linkages with the three centers, and peripheral cities that have low mobility flow and weak linkages with the three centers. In particular, the results imply that the spatial structure of the BTHUG is over-dependent on the global center (i.e., Beijing and northern Langfang). Further, ignoring spatial interaction patterns in top-down administrative planning for urban agglomeration may lead to ineffective integrated development. The implications for BTHUG planning are discussed.
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| 29. |
- Liu, Xiang, et al.
(author)
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N-Acetyl peak in MR spectra of intracranial metastatic mucinous adenocarcinomas.
- 2010
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In: Magnetic resonance imaging. - : Elsevier BV. - 1873-5894 .- 0730-725X. ; 28:9, s. 1390-4
-
Journal article (peer-reviewed)abstract
- Absence of N-acetylaspartate (NAA) is one important diagnostic criterion of MR spectroscopy (MRS) that may suggest that an intracranial mass lesion is a metastasis. We report two cases of histopathology-confirmed intracranial metastatic mucinous adenocarcinoma, which predominantly showed a large metabolite peak at 2.0 ppm, mimicking an NAA peak of normal brain tissue. This finding could be of help in the interpretation of MRS in cases of intracranial enhancing mass lesions, metastases or gliomas.
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| 30. |
- Luo, Xuhao, et al.
(author)
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Intrinsic polarization-sensitive organic photodetector with self-assembled all-polymer heterojunction
- 2022
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In: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 121:23
-
Journal article (peer-reviewed)abstract
- Intrinsic polarization-sensitive photodetectors (IPPDs) have attracted considerable attention in recent years due to their simplicity in configuration, making them ideal candidates for compact and integrated polarization-sensitive sensing and imaging systems. Photoactive films with intrinsic optical anisotropy are necessary for IPPDs. This study reports an achievement of photoactive films based on all-polymer heterojunction films with in-plane optical anisotropy using a simple bottom-up self-assembly method. Both the donor (TQ1) and acceptor (N2200) polymers have the same spatial orientation with distinct anisotropy, approaching a dichroic ratio (DR) of 8. Polarization-sensitive light absorption is due to the uniaxially oriented polymer chains, which are dominated by lamellar packing with edge-on orientation. For IPPDs based on this anisotropic all-polymer heterojunction film, a photocurrent anisotropy was found with a polarized photocurrent ratio of 2.6. The detectivity of these IPPDs was found to be 1.9 × 1011 Jones (@ ∼600 nm, 0 V bias). Our work shows that oriented polymer donor-acceptor films fabricated using bottom-up self-assembly have great potential in applications, such as polarization detection.
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| 31. |
- Nie, Jintao, et al.
(author)
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SignFind: A Synchronized Sign Language and Chinese Character Teaching Game for Chinese Deaf Children Using Gesture Recognition
- 2022
-
In: CHI EA '22: Extended Abstracts of the 2022 CHI Conference on Human Factors in Computing Systems. - New York, NY, USA : Association for Computing Machinery (ACM). - 9781450391566 ; , s. 1-7
-
Conference paper (peer-reviewed)abstract
- This paper presents a targeted system to help Chinese deaf children learn both sign language and Chinese characters in early language learning. The system combines sign recognition and in-air writing techniques with games so that children can practice sign language and Chinese character writing at the same time. Sign recognition is used to assess the accuracy of sign language and in-air writing records the process of writing Chinese characters. In addition, the game adds to the learning fun and makes children more willing to complete learning tasks. We have developed a prototype to evaluate the effectiveness of a simultaneous Chinese sign language and Chinese character teaching system based on gesture recognition and in-air writing. We expect that this system will increase children's willingness and efficiency to learn sign language and Chinese characters, and eventually be used to assist in early language education for deaf children in the Chinese region.
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| 32. |
- Pan, Y. -Z, et al.
(author)
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2-(5-Bromothiophen-2-yl)-5-[5-(10-ethyl-phenothia-zin-3-yl)thiophen-2-yl] -1,3,4-oxadiazole
- 2012
-
In: Acta Crystallographica Section E. - 1600-5368. ; 68:5, s. o1383-o1384
-
Journal article (peer-reviewed)abstract
- The molecule of the title compound, C 24H 16BrN 3OS 3, contains three approximately planar fragments, viz. an oxadiazole ring plus two adjacent thiophene groups, and two phenothia-zine benzene rings, with largest deviations from the least-squares planes of 0.051 (3), 0.019 (4) and 0.014 (3) Å, respectively. The phenothia-zine unit adopts a butterfly conformation, with a dihedral angle of 38.06 (15)°between the terminal benzene rings. The dihedral angle between the 2,5-bis-(thiophen-2- yl)oxadiazole unit and the attached benzene ring is 15.35 (11)°. In the crystal, molecules form stacks along the b-axis direction; neighboring molecules within the stack are related by inversion centers, with shortest inter-centroid separations of 3.741 (2) and 3.767 (2) Å.
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| 33. |
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| 34. |
- 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
-
In: Inorganic Chemistry. - : American Chemical Society (ACS). - 0020-1669 .- 1520-510X. ; 46:17, s. 7075-7086
-
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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| 35. |
- Shi, Yu, et al.
(author)
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A Suzuki-type cross-coupling reaction of arylacetylene halides with arylboronic acids
- 2011
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In: Applied organometallic chemistry. - : Wiley. - 0268-2605 .- 1099-0739. ; 25:7, s. 514-520
-
Journal article (peer-reviewed)abstract
- A PdCl(2)-catalyzed direct alkynylation of arylboronic acids to give diarylacetylenes is described. The optimal conditions using PdCl(2) as catalyst, MeOH-PhMe-H(2)O as solvent and K(2)CO(3) as base effectively suppressed the formation of homo-coupling product and afforded moderate to good yield of the desired unsymmetrical coupling product. This reaction represents a Suzuki-type sp(2)(C-B)-sp(C-X) cross-coupling.
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| 36. |
- Shi, Yu, et al.
(author)
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PdCl2-catalyzed cross-coupling reaction of arylacetylene iodides with arylboronic acids to diarylacetylenes
- 2010
-
In: Tetrahedron Letters. - : Elsevier BV. - 0040-4039 .- 1359-8562. ; 51:28, s. 3626-3628
-
Journal article (peer-reviewed)abstract
- Anew Suzuki-type cross-coupling reaction between 1-iodo-2-arylalkynes and arylboronic acids to afford a wide variety of functionalized diarylacetylenes in a mild reaction condition was developed. The reaction was catalyzed by a small amount of a structurally simple, commercially available, and stable PdCl2. This unique sp-sp(2) carbon-carbon bond formation provides a new protocol for the synthesis of diarylacetylenes, which is a new addition to the Suzuki cross-coupling reaction. (C) 2010 Elsevier Ltd. All rights reserved.
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| 37. |
- Wang, Lei, et al.
(author)
-
Toward Controlling Water Oxidation Catalysis : Tunable Activity of Ruthenium Complexes with Axial Imidazole/DMSO Ligands
- 2012
-
In: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 134:45, s. 18868-18880
-
Journal article (peer-reviewed)abstract
- Using the combinations of imidazole and dimethyl :sulfoxide (DMSO) as axial ligands and 2,2'-bipyridine-6,6'-dicarboxylate (bda) as the equatorial ligand, we have synthesized six novel ruthenium complexes with noticeably different activity as water oxidation catalysts (WOCs). In four C-s symmetric Ru-II(kappa(3)-bda)(DMSO)L-2 complexes L = imidazole (1), N-methylimidazole (2), 5-methylimidazole (3), and 5-bromo-N-methylimidazole (4). Additionally, in two C-2v symmetric Ru-II(kappa(4)-bda)L-2 complexes L = 5-nitroimidazole (5) and 5-bromo-N-methylimidazole (6), that is, fully equivalent axial imidazoles. A detailed characterization of all complexes and the mechanistic investigation of the catalytic water oxidation have been carried out with a number of experimental techniques, that is, kinetics, electrochemistry and high resolution mass spectrometry (HR-MS), and density functional theory (DFT) calculations. We have observed the in situ formation: of a Ru-II-complex with the accessible seventh coordination position. The measured catalytic activities and kinetics of complex 1-6 revealed details about an important structure activity relation: the connection between the nature of axial ligands in the combination and either the increase or decrease of the catalytic activity. In particular, an axial DMSO group substantially increases the turnover frequency of WOCs reported in article, with the ruthenium-complex having one axial 5-bromo-N-methylimidazole and one axial DMSO: (4), we have obtained a high initial turnover frequency of similar to 180 s(-1). DFT modeling Of the binuclear reaction pathway of the O-O bond formation in catalytic Water oxidation further corroborated the concept of the mechanistic significance of the axial ligands and rationalized the experimentally observed difference in the activity of complexes with imidazole/DMSO and imidazole/imidazole combinations of axial ligands.
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| 38. |
- Wang, Zhen, et al.
(author)
-
Diiron azadithiolates with hydrophilic phosphatriazaadamantane ligand as iron-only hydrogenase active site models : Synthesis, structure, and electrochemical study
- 2007
-
In: Inorganica Chimica Acta. - : Elsevier BV. - 0020-1693 .- 1873-3255. ; 360:7, s. 2411-2419
-
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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| 39. |
- 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
-
In: Journal of Organometallic Chemistry. - : Elsevier BV. - 0022-328X .- 1872-8561. ; 693:17, s. 2828-2834
-
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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| 40. |
- Xia, Ming, et al.
(author)
-
Synthesis and photophysical and electrochemical study of tyrosine covalently linked to high-valent copper(III) and manganese(IV) complexes
- 2007
-
In: Helvetica Chimica Acta. - : Wiley. - 0018-019X .- 1522-2675. ; 90:3, s. 553-561
-
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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| 41. |
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| 42. |
- Zhang, Wei, et al.
(author)
-
Practical synthesis of new beta-diketone-connected bipyridine and its conversion to pyrazole-centered bipyridine ligand
- 2007
-
In: Synthetic Communications. - : Informa UK Limited. - 0039-7911 .- 1532-2432. ; 37:19-21, s. 3393-3402
-
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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| 43. |
- 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
-
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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