Studies concerning the effect of 2-alkyl pyridine N-oxides with different substituents on electron transfer, phosphorylation, and light-dependent proton transport in photosynthesizing membranes of chloroplasts were conducted. It is determined that 2-alkyl pyridine N-oxides with short alkyl chains stimulate the Hill reaction and light-dependent proton transport inside chloroplasts. Compounds having alkyl residues with 6-10 carbon atoms in the chain inhibit electron transport, ADP phosphorylation, and reduction of ferrocyanide in thylakoids. A conclusion is drawn on the presence of the hydrophobic “pocket,” which is of importance for organization of the electron-transport chain of chloroplasts, near photosystem II. 相似文献
We present a new method for describing photokinetics in the liquid crystalline or amorphous glassy state of polymers. A stochastic model has been developed in order to simulate the ordering process in azo side chain polymers which is induced by photoselective isomerization cycles. The dependence of the reorientation process on photochemical and thermal transition rate constants as well as the influence of matrix rigidity and cooperative interactions between the side chains is explained. With additional information about the molecular polarizabilities, the optical properties of the system, e.g. the evolution of birefringence, can be evaluated directly by this method. 相似文献
The Pariser-Parr-Pople approximation was used to predict the properties of compounds I, 3-oxo-2H-1,2,3-triazolo[3,4-a]pyridine, and II, 3-oxoisoxazolo[2,3-a]pyridine, originated by joining a pyridine ring to two sydnone-like heterocyclic systems not yet reported in the literature. A parallel computation was carried out for two known compounds of similar structure, to give the predictions a better reliability through the comparison with observed spectral data and chemical behaviour. Compound I is expected to be stable, with an absorption spectrum similar to III, 2-oxo-1,3,4-oxadiazolo[4,5-a]pyridine, and chemical properties analogous to IV, 1-methyl-3-oxo-1,2,4-triazolo-[4,3-a]pyridine. A reaction path is suggested for obtaining from I the unknown isomeric structure V, 3-oxo-1H-1,2,3-triazolo[3,4-a]pyridine. Compound II is predicted as an unstable orange-red substance which should be handled and kept at low temperatures. 相似文献
Novel polymers containing pyridine moieties in main chains have been prepared by facile oxidative-coupling co-polymerization of pyridine N-oxide with N-alkyl carbazole and fluorene as the precursor polymers, which were reduced to the pyridine-containing polymers respectively. The polymers were characterized by FT-IR, 1H NMR, UV-Vis, X-ray, thermo-gravimetric analysis, and fluorescence spectroscopy. The pyridine-containing polymers good solubility in convenient organic solvents, high thermal stability with the onset decomposition temperature above 310 °C. The electrochemical behaviors of the polymers were investigated by cyclic voltammetry; the HOMO and LUMO energy level of the polymers were estimated from the electrochemistry and UV-Vis spectroscopy. The fluorescence spectra of the pyridine-containing polymers display blue light emitting properties in both solution and solid-state film. 相似文献
Ethynylpyridine polymers and oligomers consisting of 4‐substituted pyridine rings linked by acetylene bonds at the 2‐ and 6‐positions have been investigated. Ethynylpyridine oligomers covalently linked with a glycosyl chiral template form chiral helical complexes by intramolecular hydrogen bonding, in which the chirality of the template is translated to the helix. With a view to fixation of the chiral architecture, D /L ‐galactosyl‐ and D /L ‐mannosyl‐linked ethynylpyridine oligomers have been developed with 4‐(3‐butenyloxy)pyridine units having alkene side chains. The helical structures are successfully stapled by alkene metathesis of the side chains. Subsequent removal of the chiral templates by acidolysis produces template‐free stapled oligomers. The chiral, template‐free, stapled oligomers show chiral helicity, which is resistant to polar solvents and heating. 相似文献
Alkylating agents are simple and reactive molecules that are commonly used in many and diverse fields such as organic synthesis, medicine, and agriculture. Some highly reactive alkylating species are also being used as blister chemical‐warfare agents. The detection and identification of alkylating agents is not a trivial issue because of their high reactivity and simple structure. Herein, we report on a new multispot luminescence‐based approach to the detection and identification of alkylating agents. In order to demonstrate the potential of the approach, seven π‐conjugated oligomers and polymers bearing nucleophilic pyridine groups, 1 – 7 , were adsorbed onto a solid support and exposed to vapors of alkylators 8 – 15 . The alkylation‐induced color‐shift patterns of the seven‐spot array allow clear discrimination of the different alkylators. The spots are sensitive to minute concentrations of alkylators and, because the detection is based on the formation of new covalent bonds, these spots saturate at about 50 ppb. 相似文献
The direct polymerization of an unsymmetrical kink non-coplanar heterocyclic diamine (1) with various aromatic bis(trimellitimide)s (2a-e) using triphenyl phosphite and pyridine as condensing agents could generate a series of new aromatic poly(amide imide)s (3a-e) containing the kink non-coplanar phthalazinone heterocyclic units in the polymer main chains with inherent viscosities of 0.58-0.66 dL/g. The polymers are readily soluble in a variety of solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, N-methyl-2-pyrrolidinone, pyridine and m-cresol and can be cast to form flexible and tough films. The glass transition temperatures of polymers (T8) are in the range of 301-327℃, and the temperatures for 5% weight loss in nitrogen are in the range of 498-521℃. 相似文献
The first and second generations of dendronized polyprolines P3G1 , P3G2, and P4G1 are prepared via the “grafting to” route, and their thermoresponsive properties and helical conformations investigated. High molar masses of polyproline main chains carrying azido groups are achieved first by polycondensation of peptide precursors through activated ester strategy. Oligoethylene glycol dendrons cored with alkyne are then attached onto the main chains through click reaction. These polymers are found to be thermoresponsive. Circular dichroism spectroscopy investigation indicates, in contrast to P3G2 and P4G1 which adopt the expected PPII conformation in aqueous conditions, P3G1 prefers to adopt PPI helical conformation, and this conformation is stable within the measured time period and temperature range.
A novel aromatic diamine,2-(5-(3,5-diaminophenyl)-l,3,4-oxadiazole-2-yl)pyridine(POBD),containing a pyridine ring and a 1,3,4-oxadiazole moiety,was synthesized.It was used in a polycondensation with various aromatic and aliphatic diacid chlorides to generate a series of new aromatic polyamides with pendant 1,3,4-oxadiazole groups.The prepared polyamides were characterized by IR,elemental analysis and through the synthesis of model compounds.Thermophysical properties of the synthesized polyamides have been studied by DSC,TGA and inherent viscosity measurements. Relatively high inherent viscosity values(0.76-1.62 dL/g,in 0.125%H2SO4 at 25℃) were observed for these compounds. Number average molecular weight(Mn) of the polymers was measured by vapor phase osmometry(VPO).The introduction of bulky side chains in the structure of aromatic polyamides led to increased solubility of these polymers in common polar and aprotic solvents,such as DMF,DMSO,NMP and DMAc,which allowed thin films to be cast from polymer solutions. The highest molecular weight(Mn = 51190) was observed for polymer(DC),which was prepared from pyridine-2,6-dichlorocarbonyl. 相似文献
<正>Five new optically active polyamides(PAs) 6a-6e were prepared by direct polycondensation reaction of 2-(1,3- isoindolinedione-2-yl)-glutaric acid 4 as a new chiral diacid with various aromatic diamines 5a-5e in a medium consisting of triphenyl phosphite(TPP),calcium chloride,pyridine(Py) and N-methyl-2-pyrrolidone(NMP).The polycondensation reaction produced a series of polyamids 6a-6e in quantitative yields with inherent viscosities of 0.26-0.39 dL/g.The resulting polymers were fully characterized by means of ~1H-NMR,FT-IR spectroscopy,elemental analysis,inherent viscosity and specific rotation.Thermal properties of these polymers were investigated using thermal gravimetric analysis (TGA) and differential thermal gravimetry(DTG).Phthalimide rings as a bulky pendent group in the polymer chains disturb the interchain and intrachain interactions and make these PAs readily soluble in polar,aprotic solvents such as N,N-dimethyl acetamide(DMAc),N,N-dimethyl formamide(DMF),dimethyl sulfoxide(DMSO),N-methyl-2-pyrrolidone(NMP) and sulfuric acid. 相似文献
A chiral, nonracemic pentadentate pyridine bis(oxazoline) ligand forms unprecedented P-helical inorganic-organic hybrid polymers with cadmium halides. The one-dimensional chains consist of Lambda2-configured pentagonal-bipyramidal cadmium complexes with metal-centered chirality bridged by [CdX4]2- tetrahedra via shared halide atoms. In the solid state, the overall helicity exhibits strongly directed orientation parallel to the crystallographic axis a. 相似文献
Four simple agarose derivatives have been synthesized: 3-(Z-pyridylsulfido)-2-hydroxypropyl- 3-(2-pyridyloxy)-2-hydroxypropyl- 3-(phenylsulfido)-2-hydroxypropyl-, and 3-(phenyloxy)-2-hydroxypropylagarose. Their affinities for serum proteins have been studied in the presence and absence of water-structuring salt. About 50% of the proteins, among them immunoglobulins and α2-macroglobulin, but not albumin, were non-covalently adsorbed to the PyS-gel in buffer containing 0.5 M K2SO4. These proteins are the same as those adsorbed to the so-called thiophilic gel, T-gel (5), but there are some additional proteins found in the adsorbate that strongly indicate a specific influence on the protein adsorption exerted by the π-electron system of the pyridine residue. The thio-ether sulfur appears to be a necessary structural requirement for the characteristic adsorption behaviour. Thiophilic vs. hydrophobic ligand-protein interaction is discussed. 相似文献
The formation of stable multilayer films by using as constituents sodium poly(4-styrene sulfonate) (PSS) and poly(4-vinyl pyridine) (PVP) was studied by electrooptics. A strong increase in basicity of the pyridine rings in the electrical field of the oppositely charged PSS chains was suggested to be the driving force for multilayer film formation. A linear increase in the film thickness was registered after deposition of the first three layers, with no dependence on the polyelectrolyte molecular weight. The electrooptical effect was found to increase with increasing area of each next layer, but depended on the molecular weights of both polymers. Polarization of "condensed" counterions along the chains of the last-adsorbed layer was suggested to explain this dependence. Following the counterion dynamics, we come to the conclusion that the electrical properties of the top layer govern the electrooptical behavior of the PSS/PVP film. 相似文献