Search results for "Conjugate"
showing 10 items of 644 documents
A Fully Conjugated TTF-π-TCAQ System: Synthesis, Structure, and Electronic Properties
2011
The synthesis of the first fully conjugated tetrathiafulvalene-tetracyano-p-quinodimethane ((TTF)-TCNQ)-type system has been carried out by means of a Julia-Kocienski olefination reaction. In particular, a tetracyanoanthraquinodimethane (TCAQ) formyl derivative and two new sulfonylmethyl-exTTFs (exTTF = 2-[9-(1,3-dithiol-2-ylidene)anthracen-10(9H)-ylidene]-1,3-dithiole)--prepared as new building blocks--were linked. A variety of experimental conditions reveal that the use of sodium hexamethyldisilazane (NaHMDS) as base in THF afforded the E olefins with excellent stereoselectivity. Theoretical calculations at the B3LYP/6-31G** level point to highly distorted exTTF and TCAQ that form an almo…
Tetrasubstituted Thieno[3,2- b]thiophenes as Hole-Transporting Materials for Perovskite Solar Cells
2019
Three hole-transporting materials (HTMs) were prepared following a straightforward synthetic route by cross-linking arylamine-based ligands with a simple thieno[3,2-b]thiophene (TbT) core. The novel HTMs were fully characterized with standard techniques to gain insight into their optical and electrochemical properties and were incorporated in solution-processed mesoporous (FAPbI3)0.85(MAPbBr3)0.15 perovskite-based solar cells. The similar molecular structure of the synthesized HTMs was leveraged to investigate the role that the bridging units between the conjugated TbT core and the peripheral arylamine units plays on their properties and thereby on the photovoltaic response. A remarkable po…
Versatile behavior of conjugated diynes with zirconocene reactive species
2008
Thermal decomposition of Cp2ZrPh2 in the presence of the buta-1,3-diynes RC≡CC≡CR (R = Ph, SiMe3) can lead to seven- or five-membered metallacycles. In both cases a stable benzo-fused seven-membered zirconacyclocumulene arising from a 2-fold insertion of the triple bonds of the dialkyne in the in situ generated zirconocene benzyne is formed. In the case of Me3SiC≡CC≡CSiMe3 a second minor complex is isolated: a 3-alkynyl-substituted zirconaindene arising from a β monoinsertion of one acetylenic function of the conjugated diyne in the zirconocene benzyne. No stable 2-alkynyl-substituted zirconacycle was isolated. This α monoinsertion complex is an intermediate in the exchange of the metalated…
Reversible Covalent and Supramolecular Functionalization of Water-Soluble Gold(I) Complexes.
2017
The ligation of gold(I) metalloamphiphiles with biomolecules is reported, using water-soluble AuI -N-alkynyl substituted maleimide complexes. For this purpose, two different polar ligands were applied: 1) a neutral, dendritic tetraethylene glycol-functionalized phosphane and 2) a charged, sulfonated N-heterocyclic carbene (NHC). The retro Diels-Alder reaction of a furan-protected maleimide gold(I) complex, followed by cycloaddition with a diene-functionalized biotin under mild conditions leads to a novel gold(I) metalloamphiphile. The strong streptavidin-biotin binding affinity in buffered aqueous solution of the resulting biotin alkynyl gold(I) phosphane conjugate remains intact. The cytot…
Total Synthesis of (-)-Oxycodone via Anodic Aryl-Aryl Coupling.
2019
A fully regio- and diastereoselective electrochemical 4a–2′-coupling of a 3′,4′,5′-trioxygenated laudanosine derivative enables the synthesis of the corresponding morphinandienone. This key intermediate is further transformed into (−)-oxycodone through conjugate nucleophilic substitution for E-ring closure and [4 + 2] cycloaddition with photogenerated singlet oxygen to accomplish diastereoselective hydroxylation at C-14. The anodic transformation provides high yields and can be performed under constant current conditions both in a simple undivided cell or in continuous flow.
Further synthetic and structural investigations of new pre-organized picket porphyrins
2005
The straightforward synthesis of three new picket porphyrins with a restrained conformation is described. These porphyrins have an unusual behavior due to the conjugated but still flexible nature of their pickets. The crystal structure of their common precusor is also reported and confirms the presumed geometry of this type of picket. Indeed, the latter one is formally obtained by the conjugation of two aromatic rings through an amide bond. Although the specific shape of the picket is expected to overcrowd the center of the porphyrin, it is shown that different types of nucleophilic reagents can add easily on these pickets.
Zipper junctions: A new approach to the intersections of conjugate strike-slip faults
2016
Intersecting pairs of simultaneously active faults with opposing slip sense present geometrical and kinematic problems. Such faults rarely offset each other but usually merge into a single fault, even when they have displacements of many kilometers. The space problems involved are solved by lengthening the merged fault (zippering up the conjugate faults) or splitting it (unzippering). This process can operate in thrust, normal, and strike-slip fault settings. Examples of conjugate pairs of large-scale strike-slip faults that may have zippered up include the Garlock and San Andreas faults in California (USA), the North and East Anatolian faults (Turkey), the Karakoram and Altyn Tagh faults (…
Purification, characterization and influence on membrane properties of the plant-specific sphingolipids GIPC
2020
AbstractThe plant plasma membrane (PM) is an essential barrier between the cell and the external environment. The PM is crucial for signal perception and transmission. It consists of an asymmetrical lipid bilayer made up of three different lipid classes: sphingolipids, sterols and phospholipids. The most abundant sphingolipids in the plant PM are the Glycosyl Inositol Phosphoryl Ceramides (GIPCs), representing up to 40% of total sphingolipids, assumed to be almost exclusively in the outer leaflet of the PM. In this study, we investigated the structure of GIPCs and their role in membrane organization. Since GIPCs are not commercially available, we developed a protocol to extract and isolate …
Differential Effect of Plant Lipids on Membrane Organization
2015
SPE IPM; International audience; The high diversity of the plant lipid mixture raises the question of their respective involvement in the definition of membrane organization. This is particularly the case for plant plasma membrane, which is enriched in specific lipids, such as free and conjugated forms of phytosterols and typical phytosphingolipids, such as glycosylinositolphosphoceramides. This question was here addressed extensively by characterizing the order level of membrane from vesicles prepared using various plant lipid mixtures and labeled with an environment-sensitive probe. Fluorescence spectroscopy experiments showed that among major phytosterols, campesterol exhibits a stronger…
An annotated checklist and bibliography of the diaptomidae (copepoda, calanoida) of Italy, Corsica, and the maltese islands
2021
Calanoids of the family Diaptomidae are the most widespread copepods in the lentic inland waters of the Palearctic region. In Italy, studies on the family date back to the end of 19th century. Since then, several papers contributed to increasing the knowledge on their presence, distribution, and ecological preferences. Nevertheless, new records for the area and the discovery of putative new species stress that the current knowledge on these inland water crustaceans is still far from being exhaustive. This paper presents an updated and annotated checklist and bibliography of the Diaptomidae of the Italian peninsula and surrounding islands, including Corsica and the Maltese islands, compiled …