Search results for "Mono"
showing 10 items of 6843 documents
In-situ synthesis of thiophene-based multifunctional polymeric networks with tunable conductivity and high photolithographic performance
2017
Abstract Design of novel multifunctional polymeric materials combining electrically conducting properties with patterning capability is a significant challenge in materials science. Herein, we report on the synthesis of multifunctional interpenetrating polymer networks (IPN) by the in-situ oxidative polymerization of thiophene-based monomers with Cu(ClO 4 ) 2 inside a novolac-based photoresist. The resulting IPNs show conductivities up to 20 S/cm depending on the monomer properties. Among them, 3,3‴-Dihexyl-2,2’:5′,2’’:5″,2‴-quaterthiophene (DH4T) is chosen because it has the largest conjugation length and excellent solubility in organic solvents. Moreover, it renders a low percolation thre…
Long-term cropping systems and tillage management effects on soil organic carbon stocks and steady state level of C sequestration rates in a semiarid…
2010
A calcareous and clayey xeric Chromic Haploxerept of a long-term experimental site in Sicily (Italy) was sampled (0–15 cm depth) under different land use management and cropping systems (CSs) to study their effect on soil aggregate stability and organic carbon (SOC). The experimental site had three tillage managements (no till [NT], dual-layer [DL] and conventional tillage [CT]) and two CSs (durum wheat monocropping [W] and durum wheat/faba bean rotation [WB]). The annually sequestered SOC with W was 2·75-times higher than with WB. SOC concentrations were also higher. Both NT and CT management systems were the most effective in SOC sequestration whereas with DL system no C was sequestered. …
Copper(II) complexes of 3-aminopropanols. Synthesis and structure of (3-aminopropanolato)formatocopper(II)
1987
Abstract The crystal and molecular structure of the title compound has been determined from single-crystal X-ray data and refined to a final R value of 0.030 for 971 reflections. The compound crystallizes in the monoclinic space group P21/c with two dimeric molecules in a cell of dimensions a=856.9(1), b= 887.7(1), c=837.0(1) pm and β=99.55(1)°. The blue crystals of Cu(ap)(HCOO) (ap=3-aminopropanolato ion) are made of centrosymmetric dialkoxy bridged dimers (Cu…Cu 296.4(1) pm). The dimers are polymerized along the c axis into chains via two NHO hydrogen bonds (Cu…Cu 547.9(1) pm). These chains are joined together along the b axis by CuOCOCu bridges and NHO hydrogen bonds (Cu…Cu 462.2(1) pm…
Hybrid Organic/Inorganic Molecular Materials Formed by Tetrathiafulvalene Radicals and Magnetic Trimeric Clusters of Dimetallic Oxalate‐Bridged Compl…
2003
The first examples of trimeric, dimetallic, pure oxalate-bridged complexes [ox = (C2O4)2−] have been synthesized and characterized structurally and magnetically for the two new series of crystalline molecular assemblies formulated as (TTF)4{MII(H2O)2[MIII(ox)3]2}·nH2O [for MIII = Cr; MII = Mn (1), Fe (2), Co (3), Ni (4), Cu (5) and Zn (6); for MIII = Fe; MII = Mn (7), Fe (8), Co (9), Ni (10) and Zn (11)]. Both series (Cr2M and Fe2M) are isostructural. The crystal structure of (TTF)4{Mn(H2O)2[Cr(ox)3]2}⋅14H2O (1) [monoclinic, space group C2/c (no. 15), a = 13.240(5) A, b = 19.450(5) A, c = 27.690(5) A, β = 97.63(5)°, V = 7068(3) A3 and Z = 4] shows alternating layers of the organic radical T…
Cation and Anion Coordination Chemistry of Palladium(II) with Polyazacycloalkanes. Thermodynamic and Structural Studies
1992
The interaction of PdCI2 4 - with the macrocyclic ligands of the series [3k]aneNk has been studied both in solution and in the solid state. [18]aneN6 and [21]aneN7 form both mono- and binuclear Pd2+ complexes, whose stability constants have been determined in 0.5 mol dm-3 NaCI at 298.15 K. [21]aneN7 also forms, in solution, a trinuclear species in which an amino group deprotonates to bridge two Pd2+ ions, as observed in the solid state. The crystal structure of the complexes [Pd2([18]aneN6)Cl2][CIO4]2 and [Pd3[21]aneN7)CI3][CIO4]2 ⋅ H2O have been solved by single crystal X-ray analysis. C12H30N6CI4O8Pd2: monoclinic, space group C2/m, a = 10.876(2), b = 18.117(2), c = 7.043(2) A, s = 113.78(…
Langmuir-Blodgett Mono- and Multilayer Assemblies of Amphiphilic Liquid- Crystalline n-Alkyl-4′-n-alkoxybiphenyl-4-carboxylates. I
1991
Five n-Alkyl-4′-Alkoxy-biphenyl-4-carboxylates were investigated as Langmuir monolayers at the air/ water interface and as Langmuir-Blodgett (LB) films on solid supports. All five compounds form stable monolayers at the air/water interface and can be transferred onto solid supports yielding LB-films, whose structures and kinetic behavior strongly depend on the headgroup. The structures of the LB-films were investigated by means of optical textures and X-ray diffraction and compared with the structures of the corresponding bulk phases which were investigated by means of Differential Scanning Calorimetry and X-ray powder diffraction. The LB-films of the acid and the two methyl esters exhibit …
Ring opening polymerization of $\varepsilon$-caprolactone in the presence of wet $\beta$-cyclodextrin: Effect of the operative pressure and of water …
2016
International audience; The ring opening polymerization (ROP) of $\varepsilon$-caprolactone (CL) in the presence of $\beta$-cyclodextrin ($\beta$-CD) wasperformed in batch reactors both at room pressure and with the reaction system pressurized with CO$_2$, N$_2$ orAr. Significant enhancements of the polymerization rate was observed when the ROP was carried out withwet $\beta$-CD under pressure. For example, after 24 hours at 120° C with a $\beta$-CD/CL molar ratio of about1/100, the monomer conversion increased from 4 to 98–99% when the pressure was changed from 0.1to 12.5–13.0 MPa independent of the nature of the compressing gas. MALDI-TOF analyses indicated thata major fraction of polymer…
Cyclic fatty acid monomers : synthesis and characterization of methyl w-(2-alkylcyclopentyl) alkenoates and alkanoates
1988
Abstract Some 1,2-disubstituted cyclopentanes were synthesized. These were methyl 9-(2-butyl-cyclopentyl)-8-nonenoate, methyl 7-(2-hexyl-cyclopentyl)-6-heptenoate and methyl 5-(2-octyl-cyclopentyl)-4-pentenoate and their corresponding alkanoates. The synthesis involved a Michael addition of alkylmagnesium bromide to an unsaturated cyclic ester. The resulting cis and trans ethyl 2-alkylcyclopentane carboxylate were further converted to the alcohols then to the aldehydes. The aldehydes were condensed with the ylide derived from the (ω-carboxyalkyl)-triphenylphosphonium bromide and methylsulfinylmethide in DMSO to give unsaturated C18 cyclic fatty acid monomers. These cyclic fatty acids were f…
Homochiral self-assembly of biocoordination polymers: anion-triggered helicity and absolute configuration inversion
2015
The different natures of the weakly coordinating anions – triflate or perchlorate – in the Cu2+-mediated self-assembly of cytidine monophosphate nucleotide play a fundamental role in the homochiral resolution process, yielding one-dimensional copper(II) coordination polymers of opposite helicity that can be easily inverted, in a reversible way, by changing the nature of the anion as revealed by circular dichroism experiments both in solution and in the solid state.
Significance of various enzymes in the control of reactive metabolites
1987
Most chemical carcinogens are relatively inert and need metabolic activation to the ultimately carcinogenic species. The concentration of such species is controlled by several different enzymes. Especially well studied is the important group of enzymes responsible for the control of reactive epoxides. Many natural, as well as man-made foreign compounds, including pharmaceuticals, possess olefinic or aromatic double bonds. Such compounds can be transformed to epoxides by microsomal monooxygenases present in many mammalian organs. By virtue of their electrophilic reactivity, such epoxides may spontaneously react with nucleophilic centres in the cell and thus covalently bind to DNA, RNA and pr…