scholarly journals 1,2,3-Triazoles as leaving groups in SNAr–Arbuzov reactions: synthesis of C6-phosphonated purine derivatives

2021 ◽  
Vol 17 ◽  
pp. 193-202 ◽  
Author(s):  
Kārlis-Ēriks Kriķis ◽  
Irina Novosjolova ◽  
Anatoly Mishnev ◽  
Māris Turks
Keyword(s):  
New Method ◽  
Arbuzov Reaction ◽  
Purine Derivatives ◽  
X Ray ◽  
Bond Forming ◽  
Leaving Groups ◽  
First Time

A new method for C–N bond transformations into C–P bonds was developed using 1,2,3-triazoles as leaving groups in SNAr–Arbuzov reactions. A series of C6-phosphonated 2-triazolylpurine derivatives was synthesized for the first time, with the isolated yields reaching up to 82% in the C–P-bond-forming event. The SNAr–Arbuzov reaction of 2,6-bistriazolylpurines follows the general regioselectivity pattern of the C6-position being more reactive towards substitution, which was unambiguously proved by X-ray analysis of diethyl (9-heptyl-2-(4-phenyl-1H-1,2,3-triazol-1-yl)-9H-purin-6-yl)phosphonate.

Studies of Dye-Titania Interactions in Dye-sensitised Solar Cells

2021 ◽  
Author(s):  
◽  
Christopher P. Kershaw
Keyword(s):  
Solar Cell ◽  
Thin Layer ◽  
Computer Modelling ◽  
New Method ◽  
Device Performance ◽  
X Ray ◽  
Dye Sensitized ◽  
Titania Surface ◽  
One Step ◽  
First Time

This work details the synthesis of several bespoke materials to derivatise the surface of titania (TiO2) in order to obtain greater understanding of the sensitisation process in dye-sensitised solar cells and how this can influence device performance. In particular, this work has combined synthetic (dye synthesis), experimental (AR-XPS) and theoretical experiments (computer modelling) in order to investigate the self-assembly of organic dyes onto titania surfaces in dye-sensitised solar cell (DSC) devices. To test the dyes and other materials in this thesis both liquid and solid-state dye-sensitised solar devices were made. The standard liquid DSC device utilised TEC 8 glass (3 cm x 1.5 cm) for both the photo and counter electrode. On the photoelectrode a mesoporous TiO2 layer is deposited and sensitised with N719 dye. The counter electrode is coated with a thin layer of platinum PT-1 paste (GreatCellsolar). The two electrodes are bound together by melting 20 µm surlyn and a standard triiodide electrolyte is injected to the cell and the cell sealed. With this method we have managed to achieve 6.5 % using N719 dye. Solid-state dye-sensitised solar cell (ssDSC) devices we made using TEC 7 glass (2.8 cm2). Onto the glass a compact layer of TiO2 has been deposited via spray coating, thereafter a thin layer of mesoporous TiO2 is spin coated and sensitised overnight in a dye bath. After which, a thin layer of Spiro-OMeTAD is deposited via spin coating, after which Au is deposited under vacuum. With this method 4.0 % has been achieved using LEG4 dye. This thesis reports the first synthesis of ten novel half-squaraine (HfSQ) dyes, five containing a benzothiazole backbone and another five identical dyes with a dimethyl-derivatised carbon. These new dyes have been purified using various preparative (column and flash) chromatography. Once purified the dyes have been analysed using nuclear magnetic resonance (NMR), attenuated total reflectance infra-red (ATR-IR), ultraviolet-visible spectroscopy (UV-Vis) and mass spectrometry. These novel dye materials have then been used to derivatise the titania surface in DSC devices. The dyes have been designed so that a sulphur heteroatom can be used as an atomic probe of the dye-TiO2 interface in order to study surface coverage, dye orientation and dye-electrolyte interactions in dye-sensitized solar cell (DSC) devices. X-ray single crystal structural and opto-electronic data have also been correlated with density functional theory/computer modelling to better understand the widely reported but poorly understood influence of S heteroatoms on dye photochemistry, DSC device performance and lifetime. To the best of our knowledge, for the first time, the S heteroatom in the dyes has been used as a molecular probe along with angle-resolved X-ray photoelectron (ARXPS) data to study how the dye-TiO2 orientation varies with the position of the carboxylate linker on the dye periphery. In further work, a one-step synthesis has been used to link two dye-sensitized solar cell (DSC) dyes together through an anhydride moiety. The dyes we have attempted to combine are triphenylamine dye “Yellow dye” to another Yellow dye and squaraine dye SQ2 to other moieties such as Chenodeoxycholic acid and stearic acid. To the best of our knowledge, this is also the first time this has been attempted in DSC dyes. The resulting anhydride precursor has been used to self-assemble the two dyes onto TiO2 surfaces in a controlled manner. Hence, this represents a brand-new method of sensitising two dyes, in a single sorption process; providing a new method to control dye-sorption kinetics, dye loading and surface organisation. When two dyes are introduced to the titania surface at the same time it is possible to control the positions of the two dyes without the need of bulky co-sorbents (e.g. CDCA) to supress dye aggregation. This one-step synthesis method was applied to combine two different dye materials into one anhydride moiety. Attempts have been made to combine SQ2 dye to co-adsorbent CDCA and SQ2 dye to stearic acid. The photo-physical properties of the anhydride and its precursor dyes have been studied (via UV-Vis, ATR-IR NMR and tested in ssDSC devices) and compared highlighting the potential of this new method for co-sensitisation.

New Method of Preparation of Superionic BaSnF4

2002 ◽  
Vol 755 ◽  
Author(s):  
Georges Dénès ◽  
Abdualhafed Muntasar ◽  
Tony Retrif
Keyword(s):  
Mössbauer Spectroscopy ◽  
High Temperature ◽  
Powder Diffraction ◽  
Mossbauer Spectroscopy ◽  
New Method ◽  
Direct Reaction ◽  
X Ray ◽  
Mößbauer Spectroscopy ◽  
First Time

ABSTRACTThe first preparation of superionic BaSnF4, BaSnF4(ssr), was carried out in 1975 by direct reaction at high temperature between appropriate amounts of BaF2 and SnF2 under inert conditions in sealed copper tubes. In the present work, BaSnF4(aq2) was synthesized for the first time by the wet method. X-ray powder diffraction and Mössbauer spectroscopy were used to characterize the products, and show that BaSnF4(aq2) and BaSnF4(ssr) are the same material.

An oxidative carbon–carbon bond-forming reaction proceeds via an isolable iminium ion

2011 ◽  
Vol 83 (3) ◽  
pp. 655-665 ◽  
Author(s):  
Althea S.-K. Tsang ◽  
Paul Jensen ◽  
James M. Hook ◽  
A. Stephen K. Hashmi ◽  
Matthew H. Todd
Keyword(s):  
Solid State ◽  
Solid State Nmr ◽  
One Pot ◽  
X Ray ◽  
Bond Forming ◽  
X Ray Crystallography ◽  
Carbon Carbon Bond ◽  
Iminium Ion ◽  
Reaction Proceeds ◽  
First Time

The mechanism of our previously reported DDQ-mediated oxidative C–C bond-forming reaction is investigated. We are able to trap and characterize an iminium ion intermediate with X-ray crystallography, elemental analysis, and solid-state NMR spectroscopy; to our knowledge this is the first time this putative intermediate ion has been directly observed in such cross-dehydrogenative couplings (CDCs). The intermediate can be reacted with a range of nucleo-philes, including a malonate that is not amenable to a one-pot reaction protocol.

Mapping of accumulation of SeNPs in developing zebrafish embryos and larvae: a new method using SEM with energy dispersive X‐ray spectrometer

2017 ◽  
Vol 12 (7) ◽  
pp. 497-499
Author(s):  
Kalimuthu Kalishwaralal ◽  
Subhaschandrabose Jeyabharathi ◽  
Krishnan Sundar ◽  
Azhaguchamy Muthukumaran
Keyword(s):  
Energy Dispersive ◽  
New Method ◽  
Zebrafish Embryos ◽  
X Ray

X-ray standing waves—a new method of studying the structure of crystals

1986 ◽  
Vol 149 (05) ◽  
pp. 69-103 ◽  
Author(s):  
M.V. Koval'chuk ◽  
V.G. Kohn
Keyword(s):  
Standing Waves ◽  
New Method ◽  
X Ray

Diphosphinoazine Rhodium(I) and Iridium(I) Complexes

2006 ◽  
Vol 71 (2) ◽  
pp. 197-206 ◽  
Author(s):  
Martin Pošta ◽  
Jan Čermák ◽  
Pavel Vojtíšek ◽  
Ivana Císařová
Keyword(s):  
Rhodium Complexes ◽  
Iridium Complexes ◽  
X Ray ◽  
First Time

The first rhodium complexes of diphosphinoazines [{RhCl(1,2-η:5,6-η-CH=CHCH2CH2CH=CHCH2CH2)}2 {μ-R2PCH2C(But)=NN=C(But)CH2PR2] (R = Ph, Cy, Pri) were prepared by cleavage of the bridge in chloro(cycloocta-1,5-diene)rhodium(I) dimer, the analogous iridium(I) complexes were also prepared for the first time. The X-ray structures of isostructural rhodium and iridium complexes with bis(dicyclohexylphosphino)pinacoloneazine were determined. Diphosphinoazine ligands in the complexes remained in (Z,Z) configuration bridging two RhCl(C8H12) units.

A new method for the identification and quantification of magnetite–maghemite mixture using conventional X-ray diffraction technique

Talanta ◽  
2012 ◽  
Vol 94 ◽  
pp. 348-352 ◽  
Author(s):  
Wonbaek Kim ◽  
Chang-Yul Suh ◽  
Sung-Wook Cho ◽  
Ki-Min Roh ◽  
Hanjung Kwon ◽  
...  
Keyword(s):  
New Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
Identification And Quantification

scholarly journals Quartz Crystallite Size and Moganite Content as Indicators of the Mineralogical Maturity of the Carboniferous Chert: The Case of Cherts from Eastern Asturias (Spain)

Minerals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 611
Author(s):  
Celia Marcos ◽  
María de Uribe-Zorita ◽  
Pedro Álvarez-Lloret ◽  
Alaa Adawy ◽  
Patricia Fernández ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Crystallite Size ◽  
Archaeological Sites ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Infrared And Raman Spectroscopy ◽  
First Time ◽  
Geological Formations

Chert samples from different coastal and inland outcrops in the Eastern Asturias (Spain) were mineralogically investigated for the first time for archaeological purposes. X-ray diffraction, X-ray fluorescence, transmission electron microscopy, infrared and Raman spectroscopy and total organic carbon techniques were used. The low content of moganite, since its detection by X-ray diffraction is practically imperceptible, and the crystallite size (over 1000 Å) of the quartz in these cherts would be indicative of its maturity and could potentially be used for dating chert-tools recovered from archaeological sites. Also, this information can constitute essential data to differentiate the cherts and compare them with those used in archaeological tools. However, neither composition nor crystallite size would allow distinguishing between coastal and inland chert outcrops belonging to the same geological formations.

scholarly journals First Report on the Geologic Occurrence of Natural Na–A Zeolite and Associated Minerals in Cretaceous Mudstones of the Paja Formation of Vélez (Santander), Colombia

Crystals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 218
Author(s):  
Carlos Alberto Ríos-Reyes ◽  
German Alfonso Reyes-Mendoza ◽  
José Antonio Henao-Martínez ◽  
Craig Williams ◽  
Alan Dyer
Keyword(s):  
Natural Zeolite ◽  
Scanning Electron Micrographs ◽  
Total Sulfur ◽  
Zeolite A ◽  
X Ray Diffraction ◽  
X Ray ◽  
Mineral Phases ◽  
The World ◽  
Porosity And Permeability ◽  
First Time

This study reports for the first time the geologic occurrence of natural zeolite A and associated minerals in mudstones from the Cretaceous Paja Formation in the urban area of the municipality of Vélez (Santander), Colombia. These rocks are mainly composed of quartz, muscovite, pyrophyllite, kaolinite and chlorite group minerals, framboidal and cubic pyrite, as well as marcasite, with minor feldspar, sulphates, and phosphates. Total organic carbon (TOC), total sulfur (TS), and millimeter fragments of algae are high, whereas few centimeters and not biodiverse small ammonite fossils, and other allochemical components are subordinated. Na–A zeolite and associated mineral phases as sodalite occur just beside the interparticle micropores (honeycomb from framboidal, cube molds, and amorphous cavities). It is facilitated by petrophysical properties alterations, due to processes of high diagenesis, temperatures up to 80–100 °C, with weathering contributions, which increase the porosity and permeability, as well as the transmissivity (fluid flow), allowing the geochemistry remobilization and/or recrystallization of pre-existing silica, muscovite, kaolinite minerals group, salts, carbonates, oxides and peroxides. X-ray diffraction analyses reveal the mineral composition of the mudstones and scanning electron micrographs show the typical cubic morphology of Na–A zeolite of approximately 0.45 mμ in particle size. Our data show that the sequence of the transformation of phases is: Poorly crystalline aluminosilicate → sodalite → Na–A zeolite. A literature review shows that this is an unusual example of the occurrence of natural zeolites in sedimentary marine rocks recognized around the world.

scholarly journals The Effect of Surfactant-Modified Montmorillonite on the Cross-Linking Efficiency of Polysiloxanes

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2623
Author(s):  
Monika Wójcik-Bania ◽  
Jakub Matusik
Keyword(s):  
Total Pore Volume ◽  
Cross Linking ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
The Cross ◽  
Chain Lengths ◽  
First Time ◽  
Substituent Influence ◽  
Benzyl Substituent

Polymer–clay mineral composites are an important class of materials with various applications in the industry. Despite interesting properties of polysiloxanes, such matrices were rarely used in combination with clay minerals. Thus, for the first time, a systematic study was designed to investigate the cross-linking efficiency of polysiloxane networks in the presence of 2 wt % of organo-montmorillonite. Montmorillonite (Mt) was intercalated with six quaternary ammonium salts of the cation structure [(CH3)2R’NR]+, where R = C12, C14, C16, and R’ = methyl or benzyl substituent. The intercalation efficiency was examined by X-ray diffraction, CHN elemental analysis, and Fourier transform infrared (FTIR) spectroscopy. Textural studies have shown that the application of freezing in liquid nitrogen and freeze-drying after the intercalation increases the specific surface area and the total pore volume of organo-Mt. The polymer matrix was a poly(methylhydrosiloxane) cross-linked with two linear vinylsiloxanes of different siloxane chain lengths between end functional groups. X-ray diffraction and transmission electron microscopy studies have shown that the increase in d-spacing of organo-Mt and the benzyl substituent influence the degree of nanofillers’ exfoliation in the nanocomposites. The increase in the degree of organo-Mt exfoliation reduces the efficiency of hydrosilylation reaction monitored by FTIR. This was due to physical hindrance induced by exfoliated Mt particles.

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