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| 2. |
- Arkhypchuk, Anna I., et al.
(författare)
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Cascade Reactions Forming Highly Substituted, Conjugated Phospholes and 1,2-Oxaphospholes
- 2012
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Ingår i: Angewandte Chemie International Edition. - : Wiley. - 1433-7851 .- 1521-3773. ; 51:31, s. 7776-7780
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Tidskriftsartikel (refereegranskat)abstract
- The reaction of a phospha-Wittig–Horner reagent with diacetylenic ketones (see scheme) results in a cascade of reactions that can lead to both an oxaphosphole-terminated cumulene system and an alkene-bridged bis-phosphole. The reaction outcome is determined by the nature of the acetylene termini, with phenyl groups stabilizing a carbene intermediate that dimerizes to give the bis-phosphole product.
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| 3. |
- Arkhypchuk, Anna I., et al.
(författare)
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Revisiting the Phospha-Wittig - Horner Reaction
- 2012
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Ingår i: Organometallics. - : American Chemical Society (ACS). - 0276-7333 .- 1520-6041. ; 31:3, s. 1118-1126
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Tidskriftsartikel (refereegranskat)abstract
- P,P-Dichlorophosphines 2a-c (RPCl2, R = Ph (a), t-Bu (b), 2,4,6-Me3Ph (c)) and P,P-dibromophosphines 4d,e (RPBr2, R = (i-Pr)(3)SiC C (d) and H2C=CH (e)) react with triethylphosphite under Michaelis-Arbuzov conditions to give phosphinodiphosphonates 3a-e in quantitative yields. After complexation to W(CO)(5) and treatment with CH3ONa, phospha-Wittig-Horner reagents 9a,b are obtained on a multigram scale in good overall yield. Phospha-Wittig-Horner reagents with unsaturated, substituents at P-III (10d,e) can be prepared in analogous procedures; however, their prevail in an unusual ylide form that allows conjugation between the lone pair and the acetylene and vinyl pi-systems, respectively. Phosphinophosphonate 9a has been characterized by X-ray crystallography and is shown to react smoothly with acetone within minutes. The resulting W(CO)(5)-coordinated phosphaalkene is shown to dimerize to a 1,2-diphosphitane or to undergo a 1,3-proton shift depending on the reaction conditions. In addition, a one-pot synthetic sequence starting from W(CO)(5)-coordinated phosphinodiphosphonates 5d,e has been developed to engage compounds with vinyl and acetylene substituents in phospha-Wittig-Horner reactions.
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| 4. |
- Beyler, Maryline, et al.
(författare)
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Pentacoordinate iron complexes as functional models of the distal iron in [FeFe] hydrogenases
- 2011
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Ingår i: Chemical Communications. - : Royal Society of Chemistry (RSC). - 1359-7345 .- 1364-548X. ; 47:42, s. 11662-11664
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Tidskriftsartikel (refereegranskat)abstract
- Mononuclear pentacoordinate iron complexes with a free coordination site were prepared as mimics of the distal Fe (Fe(d)) in the active site of [FeFe] hydrogenases. The complexes catalyze the electrochemical reduction of protons at mild overpotential.
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| 5. |
- Delices, Annette, et al.
(författare)
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Experimental and theoretical study of organic sensitizers for solid-state dye-sensitized solar cells (s-DSSCs)
- 2022
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Ingår i: Journal of Photochemistry and Photobiology A. - : Elsevier. - 1010-6030 .- 1873-2666. ; 428
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Tidskriftsartikel (refereegranskat)abstract
- The effect of a series of triarylamine based D-pi-A organic dyes, namely RK1, BA504, BA741 and the simple L1 reference dye on solid-state dye sensitized solar cells (s-DSSCs) performances was studied. The solid hole transporting material (HTM) was obtained by in-situ photoelectrochemical polymerization (in-situ PEP) process applied in two different media (water and acetonitrile) to produce the poly-3,4 ethylenedioxythiophene (PEDOT) conducting polymer (CP). A joint experimental and theoretical (density functional theory and time-dependent density functional theory) study is conducted to correlate the dye molecular structure containing different donor, pi-bridge or acceptor with several physicochemical characteristics such as optical (absorption and emission), electronic and redox properties of dyes in organic and aqueous medium; in-situ PEP process and charge transfer kinetics at the DSSC interfaces (Dye/TiO2 and Dye/HTM) through the alignment of the different energy levels of the dyes and electrodes. These properties are considered since they govern the performance of s-DSSCs denoted by the short-circuit current (J(sc)), open circuit cell potential (V-oc) and fill factor (FF). Among the four studied dyes, the s-DSSCs based on RK1, shows the best power conversion efficiency of 1.75% resulting from highest FF (0.57), V-oc (550 mV) and J(sc) (5.6 mA/cm(2)). The large differences in experimental photovoltaic performances of the obtained s-DSSCs have been well outlined and provide the guidelines for future development of more efficient solar-cell sensitizers.
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| 6. |
- Delices, Annette, et al.
(författare)
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New covalently bonded dye/hole transporting material for better charge transfer in solid-state dye-sensitized solar cells
- 2018
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Ingår i: Electrochimica Acta. - : Elsevier BV. - 0013-4686 .- 1873-3859. ; 269, s. 163-171
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Tidskriftsartikel (refereegranskat)abstract
- A novel metal-free organic dye based on triarylamine functionalized by a carbazole unit is synthesized and used in solid state dye sensitized solar cells (sDSC). The carbazole is co-polymerized with bis-EDOT by in-situ photo-electrochemical polymerization leading to a hole transporting polymer material covalently bonded to the light active centre. These first photovoltaic performances results are promising in sDSCs applications.
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| 7. |
- Karnahl, Michael, et al.
(författare)
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Mixed-valence [(FeFeII)-Fe-I] hydrogenase active site model complexes stabilized by a bidentate carborane bis-phosphine ligand
- 2012
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Ingår i: Dalton Transactions. - : Royal Society of Chemistry (RSC). - 1477-9226 .- 1477-9234. ; 41:40, s. 12468-12477
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Tidskriftsartikel (refereegranskat)abstract
- A series of [FeFe]-hydrogenase active site analogues, with the general formula [Fe-2(dt)(CO)(4)(BC)] 1-3 (dt = dithiolate, pdt = propyl-1,3-dt (1), bdt = benzene-1,2-dt (2), edt = ethyl-1,2-dt (3); BC = 1,2-bisdiphenylphosphine-1,2-o-carborane), has been prepared and structurally characterized. While the electrochemical reductions of 1-3 are largely invariant to the different nature of their dt bridges, the oxidations differ by more than 120 mV in between the series. Remarkably, all three compounds are reversibly oxidized, with complex 1 that contains the most electron-donating pdt ligand at the mildest potential of -0.09 V vs. Fc/Fc(+). The one-electron oxidized state 1(ox) is stable for several minutes and was spectroscopically characterized by FTIR and EPR. EPR spectroscopy provided evidence that in the mixed-valence [(FeFeII)-Fe-I] state most of the spin density is located on the iron with the BC-ligand. This is monitored through the strong P-31 hyperfine coupling of the phenyl groups of the BC ligand, while further delocalization into the o-carborane unit is negligible.
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| 8. |
- Lissau, Jonas Sandby, et al.
(författare)
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Anchoring Energy Acceptors to Nanostructured ZrO2 Enhances Photon Upconversion by Sensitized Triplet-Triplet Annihilation Under Simulated Solar Flux
- 2013
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Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 117:28, s. 14493-14501
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Tidskriftsartikel (refereegranskat)abstract
- Photon upconversion by sensitized triplet-triplet annihilation (UC-STTA) is a promising strategy for boosting the theoretical maximum efficiency of single threshold solar cells, in particular, dye-sensitized solar cells (DSSCs). Here, we report a substantial increase in the efficiency of UC-STTA on a nanostructured surface, using noncoherent excitation light with intensities as low as 0.5 mW cm(-2), easily achieved under sun illumination. The studied surface was a mesoporous ZrO2 film working as a proxy system for the study of photophysics relevant to DSSCs. A well-known UC-STTA "emitter" dye, 9,10-diphenylanthracene (DPA), was chemically modified to yield methyl 4-(10-p-tolylanthracen-9-yl)benzoate (MTAB), which was chemisorbed onto ZrO2. The "sensitizer" dye, platinum(II) octaethylporphyrin (PtOEP), was free in butyronitrile (BuN) solution surrounding the ZrO2 nanostructure. A rigorous oxygen removal minimized photodegradation of the dyes and enhanced triplet-triplet annihilation efficiency. The system already approaches the so-called "strong annihilation limit" at light intensities below 8 mW cm(-2). Highly efficient triplet-triplet annihilation is a requisite for the use of UC-STTA in DSSCs. Time-resolved data show that the limiting process in the UC-STTA mechanism of the present system is the dynamic triplet energy transfer step from PtOEP in solution to MTAB on the surface of ZrO2. This result can guide the way toward a better understanding and further efficiency improvement of UC-STTA on nanocrystalline metal oxides.
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| 9. |
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| 10. |
- Lissau, Jonas Sandby, et al.
(författare)
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Photon Upconversion from Chemically Bound Triplet Sensitizers and Emitters on Mesoporous ZrO2 : Implications for Solar Energy Conversion
- 2015
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Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 119:46, s. 25792-25806
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Tidskriftsartikel (refereegranskat)abstract
- Photon upconversion by sensitized triplet-triplet annihilation (UC-STTA) is studied in systems with triplet sensitizers and emitter molecules cochemisorbed onto nanostructured ZrO2 films. UC-STTA is a promising strategy to overcome the Shockley-Queisser efficiency limit of single-threshold solar cells. The dye-loaded mesoporous ZrO2 films studied herein allow high molecular densities and are good proxy systems for the study of photophysics relevant to dye-sensitized solar cells. Two sensitizer/emitter dye pairs are studied: platinum(II) deuteroporphyrin IX dicarboxylic acid/4,4'-(10-(anthracene-9,10-diyl)dibenzoic acid and platinum(II) deuteroporphyrin IX dimethyl ester/methyl 4-(10-(p-tolyl)anthracen-9-yl)benzoate. Both dye pairs are closely related to the standard UC-STTA molecular pair platinum(II) octaethylporphyrin (PtOEP)/9,10-diphenylanthracene (DPA). By chemically anchoring the upconverting dye pairs onto ZrO2 films a significant improvement in UC-STTA efficiency is achieved with respect to previously studied cophysisorbed PtOEP/DPA. Controlled variation of the sensitizer/emitter dye ratios onto the surface shows that new energy loss mechanisms appear at high sensitizer surface coverage. Spectral signatures of porphyrin aggregates suggest separate sensitizer domains form, which limits the triplet sensitization of emitter molecules. The nanosecond time scale rise and decay of the observed UC emission are likely linked to the sample stability over time; UC emission is observed 1 year after sample preparation. These are promising properties for the application of this type of system for solar energy conversion.
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