- Lausanne, Vaud, Switzerland
Peter PECHY
Ecole Polytechnique Federale de Lausanne, SB ISIC LPI, Faculty Member
- Genealogy, Medieval Hungary, Zapolya/Szapolyai/Zapolsky Family, Medieval History, Medieval Studies, History, and 17 moreRoman Archaeology, Ethnobotany, Political History, Church History, Biography, Roman Art, Archaeobotany, History of Hungary, Late Roman Archaeology, Croatian History, Archaeology of Roman Pannonia, Migration Period Archaeology, Jagiellonians, late Roman silver, Late Medieval Transylvania, Roman Silver, and Seuso Treasureedit
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ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full... more
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
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The adsorption on a titanium dioxide substrate of organic monolayers used in the nanocrystalline dye sensitized solar cells was investigated by Raman spectroscopy, owing to the high resonance effect in these molecules. During the... more
The adsorption on a titanium dioxide substrate of organic monolayers used in the nanocrystalline dye sensitized solar cells was investigated by Raman spectroscopy, owing to the high resonance effect in these molecules. During the polarization of TiO2 modified by Ru-bi or ter pyridinium compounds in a photoelectrochemical cell, an enhancement affect appeared, allowing us to scrutinize the part of the complex which is in contact with the substrate. This affect remains to a large extent unexplained; it could be attributed to SERRS (surface enhanced Raman resonance). Noticeable differences appeared in the function of the nature of the pyridil ligands. In the case of bipy, in addition to the `normal' (ground state) Raman bands, a new series of bands appeared which correspond to the particular ligand exchanging electrons with the substrate titanium atoms. The Raman intensity of these new peaks is directly related to the electric field (i.e., to the potential magnitude independently of its cathodic or anodic nature). In the case of terpy, the enhancement mechanism seems different. The similarity of the molecular configuration created by the adsorption with the radical anion formed by the excitation of the metal ligand charge transfer complex has to be emphasized. Very interesting prospects for the understanding of the adsorption mechanisms are therefore opened.
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Patent number: 81-2147-25912 Reference LPI-PATENT-1983-003Search for this record at the European Patent Office Record created on 2006-02-21, modified on 2017-05-12
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Reference LPI-CONF-1997-009View record in Web of Science Record created on 2006-02-21, modified on 2017-05-12
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The 17O NMR signal of formaldehyde was measured and the literature values of the 13C and 1H signals are discussed. They are compared with values obtained by other spectroscopic methods and by ab initio calculation.
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The 17O NMR shift values δo of 20 sulfinylamines R–NSO 2 and of 14 sulfines RR′CSO 3(R and R′ mostly arene groups) were compared with those of the isoelectronic SO21. They show δo at much lower field than practically all other classes of... more
The 17O NMR shift values δo of 20 sulfinylamines R–NSO 2 and of 14 sulfines RR′CSO 3(R and R′ mostly arene groups) were compared with those of the isoelectronic SO21. They show δo at much lower field than practically all other classes of S–O compounds; at the same time they exhibit the high substituent sensitivity which is typical for true πp bond systems, and absent in S+–O– compounds. The difference is discussed in terms of bond order and electronic excitation energy. Comparison of the E- and Z isomers of O-methyldiaryl sulfines yields the conformation of these compounds: one arene ring is (nearly) coplanar with the CSO group and the other (nearly) perpendicular to it. This demonstration for the molecules in solution is supported by an X-Ray structure determination.
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The "naked sugar" (+)-(1R,2S,4R)-2-cyano-7-oxa-bicyclo[2.2.1]hept-5-en-2-yl (1S)-camphanate [(+)-3] (Diels-Alder adduct of furan with 1-cyanovinyl (1S)-camphanate) was converted into... more
The "naked sugar" (+)-(1R,2S,4R)-2-cyano-7-oxa-bicyclo[2.2.1]hept-5-en-2-yl (1S)-camphanate [(+)-3] (Diels-Alder adduct of furan with 1-cyanovinyl (1S)-camphanate) was converted into (1R)-1-C-(6-amino-7H-purin-8-yl)-1,4-anhydro-2,3-dideoxy-3-fluoro-D-eryt hro-pentitol [(+)-2] in nine synthetic steps and 12% overall yield
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High-efficiency flexible dye-sensitized solar cells were fabricated with a Ti-metal foil substrate for photo anode and using a Pt-electrodeposited counter electrode on ITO/polyethylene naphthalate (ITO/PEN); these devices were... more
High-efficiency flexible dye-sensitized solar cells were fabricated with a Ti-metal foil substrate for photo anode and using a Pt-electrodeposited counter electrode on ITO/polyethylene naphthalate (ITO/PEN); these devices were characterized by incident photon-to-current efficiency (IPCE), optical transmittance and electrical impedance spectroscopy.
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The benzoyl derivatives of SeR, TeR and I show lower field 17O NMR signals than those of the lighter elements in the same group of the Periodic Table, whereas ArCOGeR3 is as low-field as ArCOSiR3. The δo values of 14 types of benzoyl... more
The benzoyl derivatives of SeR, TeR and I show lower field 17O NMR signals than those of the lighter elements in the same group of the Periodic Table, whereas ArCOGeR3 is as low-field as ArCOSiR3. The δo values of 14 types of benzoyl compounds ArCOX are discussed in terms of π-bond order (obtained from arene substituent sensitivities using the ‘tool of increasing electron demand’) and of electronic excitation energy (obtained from UV spectra). It is concluded that, for 17O NMR, the terms ΔE–1 and ΣQ of the Karplus–Pople equation are, at least to a certain degree, independent of one another.
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Patent number: 2000-EP11510-2002040073 Reference LPI-PATENT-2002-006Search for this record at the European Patent Office Record created on 2006-02-21, modified on 2017-05-12
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Herein we report the synthesis, characterizations and photovoltaic performance of a series of indacenodithiophene (IDT)-based D-π-A organic dyes with varying electron-accepting units. Via control of the electron affinity, we achieved... more
Herein we report the synthesis, characterizations and photovoltaic performance of a series of indacenodithiophene (IDT)-based D-π-A organic dyes with varying electron-accepting units. Via control of the electron affinity, we achieved perfectly matching energy levels with a copper(I/II) based redox electrolyte, reaching high open-circuit voltage (>1.1 V) while harvesting a large fraction of solar photons at the same time. Besides achieving high power conversion efficiencies (PCEs) for dye-sensitized solar cells (DSCs), i.e. 11.8% under standard AM 1.5 G sunlight, and 28.4% under 1000 lux fluorescent light tube, our work provides a possible methodology for systematically design and fabrication of low-cost highly efficient DSCs.
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ABSTRACT To anchor transition-metal compounds onto metal oxide surfaces 2,2′:6′,2″-terpyridine-4′-phosphonic acid (4′-PO3H2-terpy) is synthesized; strong surface adhesion as well as efficient charge-transfer sensitization of... more
ABSTRACT To anchor transition-metal compounds onto metal oxide surfaces 2,2′:6′,2″-terpyridine-4′-phosphonic acid (4′-PO3H2-terpy) is synthesized; strong surface adhesion as well as efficient charge-transfer sensitization of nanocrystalline TiO2 films has been observed with a ruthenium complex involving this ligand.
ABSTRACT Linear heteronuclear π-systems of sp character, when compared with corresponding sp2 systems, show increased shift to higher field for all atoms concerned (O, C, N); acetylene compared with ethylene is a model case. In 17O NMR,... more
ABSTRACT Linear heteronuclear π-systems of sp character, when compared with corresponding sp2 systems, show increased shift to higher field for all atoms concerned (O, C, N); acetylene compared with ethylene is a model case. In 17O NMR, the molecules NO+, PhCO+, RCNO, NξCξO−, RNξCξO and NO2+ were examined (in addition to known CO, CO2, COS and N2O). For these molecules, 13C and 15N shieldings were also analysed. As had been shown before for 13C and 15N, the increase in shielding of 17O in linear molecules is mainly attributable to the vanishing of the deshielding component along the linear axis of the molecule (manifest also in the increase in the anisotropy of shielding Δσ). Abinitio IGLO calculations were executed to evaluate Δσ ( = σ‖-σ⊥). For each of the atoms concerned, the resulting calculated average values agreed well with the experimental values of isotropic shielding, σiso. As in the case of C and N, the values of σ‖ of 17O in linear compounds are close to that of the diamagnetic shielding of the isolated O atom, σd (atom). The particular case of organic isocyanates, RNCO, which, although not completely linear, show related behaviour, is discussed.
ABSTRACT On the scale of carbonyl electrophilicities, measured by 17O NMR spectroscopy, carbonyl groups in aroyl (1), acetyl (2) and ethoxycarbonyl (3) phosphonium ylides are similar to those of amide groups, showing a considerable effect... more
ABSTRACT On the scale of carbonyl electrophilicities, measured by 17O NMR spectroscopy, carbonyl groups in aroyl (1), acetyl (2) and ethoxycarbonyl (3) phosphonium ylides are similar to those of amide groups, showing a considerable effect of resonance donation. The relative weight of the limiting formulae in the resonance in 1 and 3 is found to be close to earlier estimations which were based upon 1H and 13C NMR shift values. For comparison, a series of phenacyl compounds PhCOCH2X have been investigated; they show a very small effect of X on δo The δo values of aroyl (4) and ethoxycarbonyl (5) diazoalkanes are found to be less shielded than those of the corresponding ylides, demonstrating the importance of long-wave electronic transitions observable in the UV–VIS spectrum. However, the substituent sensitivity coefficient ρ+ of aroyldiazoalkanes 4 is similar to those of esters and amides.
An indoline dye (D205), the synthesis method of which is disclosed in this report, gave high-efficiency organic dye-sensitized solar cells (9.52%) using an anti-aggregation reagent (chenodeoxycholic acid).
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ABSTRACT Oxygen-17 NMR spectra of 45 substituted methyl benzoates in acetonitrile were measured at natural abundance. The substituent-induced chemical shifts (SCS) of the carbonyl oxygen correlate well with the σm and σ substituent... more
ABSTRACT Oxygen-17 NMR spectra of 45 substituted methyl benzoates in acetonitrile were measured at natural abundance. The substituent-induced chemical shifts (SCS) of the carbonyl oxygen correlate well with the σm and σ substituent constants in two separate correlations for meta and para derivatives; principal component analysis (PCA) is only slightly better [particularly for the N(CH3)2 substituent]. The 17O SCS generally depend on the same factors as the 13C SCS of the β-carbon of alkenes, provided comparison is made between compounds of similar polarity. SCS of the methoxyl oxygen depend less precisely on σm or σp, with some unexplained deviations.
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R. Battersby, R. Bmks, RJ Francis, DJ McCaldm, F d H. Ramuz, J. Chem. SOC., 3800 (1964);(c) DH R. Barton, GW Kirby, W. Steglich, GM Thomas, AR Battersby, TA Dobson, and H. Ramuz, ibid., 2423 (1965);(d) AR Battersby, DM Foulkes, and R.... more
R. Battersby, R. Bmks, RJ Francis, DJ McCaldm, F d H. Ramuz, J. Chem. SOC., 3800 (1964);(c) DH R. Barton, GW Kirby, W. Steglich, GM Thomas, AR Battersby, TA Dobson, and H. Ramuz, ibid., 2423 (1965);(d) AR Battersby, DM Foulkes, and R. Binks, ibid., 3323 ( ...
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ABSTRACT Linear heteronuclear π-systems of sp character, when compared with corresponding sp2 systems, show increased shift to higher field for all atoms concerned (O, C, N); acetylene compared with ethylene is a model case. In 17O NMR,... more
ABSTRACT Linear heteronuclear π-systems of sp character, when compared with corresponding sp2 systems, show increased shift to higher field for all atoms concerned (O, C, N); acetylene compared with ethylene is a model case. In 17O NMR, the molecules NO+, PhCO+, RCNO, NξCξO−, RNξCξO and NO2+ were examined (in addition to known CO, CO2, COS and N2O). For these molecules, 13C and 15N shieldings were also analysed. As had been shown before for 13C and 15N, the increase in shielding of 17O in linear molecules is mainly attributable to the vanishing of the deshielding component along the linear axis of the molecule (manifest also in the increase in the anisotropy of shielding Δσ). Abinitio IGLO calculations were executed to evaluate Δσ ( = σ‖-σ⊥). For each of the atoms concerned, the resulting calculated average values agreed well with the experimental values of isotropic shielding, σiso. As in the case of C and N, the values of σ‖ of 17O in linear compounds are close to that of the diamagnetic shielding of the isolated O atom, σd (atom). The particular case of organic isocyanates, RNCO, which, although not completely linear, show related behaviour, is discussed.
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The present concepts evolved in the context of research and development of artificial photosynthetic systems. Our biosphere depends totally on the action of a porphyrin dye, chlorophyll, for its continued existance, since all food... more
The present concepts evolved in the context of research and development of artificial photosynthetic systems. Our biosphere depends totally on the action of a porphyrin dye, chlorophyll, for its continued existance, since all food resources find their origin in photosynthesis. Equally, for much of our energy resources we rely on the same process, present or past, as stored in fossil fuels. Naturally, therefore, when it comes to the molecular design of dyes for solar photochemical applications the reference to the porphyrins and similar organometallic complexes based on nitrogen ring structures as prototypes is obvious. However, although nature confines itself to magnesium and iron for its principal pigments, chlorophyll and haemoglobin respectively, the synthetic chemist can access the whole range of metallic elements. The use of ruthenium pyridyl complexes has almost thirty years of development history, and although other compounds have been assessed, such as zinc porphyrins and even prussian-blue analogues, the most suitable dyes today are still modifications of the ruthenium-based pyridyl complexes. The molecular engineering of dyes extends the visible spectrum response, enhances stability and promotes chemisorption to oxide semiconductor substrates while maintaining the energetics and kinetics for efficient charge transfer to function in sensitised electrochemical photovoltaic devices. There is also an overview of the present status of the technology, the materials incorporated in current devices, and their reliability in practical applications especially in situations of thermal stress. The conclusion will present the case for ongoing development of dye-sensitised systems in photovoltaic technology.
Research Interests: Kinetics, Magnesium, Fossil Fuels, Thermal Stress, Nitrogen, and 4 moreZinc, Iron, Prussian Blue, and Spectrum
ABSTRACT On the scale of carbonyl electrophilicities, measured by 17O NMR spectroscopy, carbonyl groups in aroyl (1), acetyl (2) and ethoxycarbonyl (3) phosphonium ylides are similar to those of amide groups, showing a considerable effect... more
ABSTRACT On the scale of carbonyl electrophilicities, measured by 17O NMR spectroscopy, carbonyl groups in aroyl (1), acetyl (2) and ethoxycarbonyl (3) phosphonium ylides are similar to those of amide groups, showing a considerable effect of resonance donation. The relative weight of the limiting formulae in the resonance in 1 and 3 is found to be close to earlier estimations which were based upon 1H and 13C NMR shift values. For comparison, a series of phenacyl compounds PhCOCH2X have been investigated; they show a very small effect of X on δo The δo values of aroyl (4) and ethoxycarbonyl (5) diazoalkanes are found to be less shielded than those of the corresponding ylides, demonstrating the importance of long-wave electronic transitions observable in the UV–VIS spectrum. However, the substituent sensitivity coefficient ρ+ of aroyldiazoalkanes 4 is similar to those of esters and amides.
The adsorption on a titanium dioxide substrate of organic monolayers used in the nanocrystalline dye sensitized solar cells was investigated by Raman spectroscopy, owing to the high resonance effect in these molecules. During the... more
The adsorption on a titanium dioxide substrate of organic monolayers used in the nanocrystalline dye sensitized solar cells was investigated by Raman spectroscopy, owing to the high resonance effect in these molecules. During the polarization of TiO2 modified by Ru-bi or ter pyridinium compounds in a photoelectrochemical cell, an enhancement affect appeared, allowing us to scrutinize the part of the complex which is in contact with the substrate. This affect remains to a large extent unexplained; it could be attributed to SERRS (surface enhanced Raman resonance). Noticeable differences appeared in the function of the nature of the pyridil ligands. In the case of bipy, in addition to the `normal' (ground state) Raman bands, a new series of bands appeared which correspond to the particular ligand exchanging electrons with the substrate titanium atoms. The Raman intensity of these new peaks is directly related to the electric field (i.e., to the potential magnitude independently of...
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Lead tetraacetate (LTA) oxidation of different monoor non-phenolic tetrahydrobenzylisoquinolines containing secondary amino group leads to dibenzopyrrocoline derivative or oxoaporphine, respectively. The substrate selectivity of LTA has... more
Lead tetraacetate (LTA) oxidation of different monoor non-phenolic tetrahydrobenzylisoquinolines containing secondary amino group leads to dibenzopyrrocoline derivative or oxoaporphine, respectively. The substrate selectivity of LTA has been discussed.