GROWTH AND MORPHOLOGY OF POLYMER-ACTIN COMPLEXES

F-actins are semi-flexible polyelectrolytes and can be assembled into large polymer-actin complex with polymorphism through electrostatic interaction with polycations. This study investigates the structural phase behavior and the growth of polymer-actin complexes in terms of its longitudinal and lateral sizes. Our results show that formation of polymer-actin complexes is cooperative, and morphology and growth of polymer-actin complexes depend on polycation species and concentrations of polycation and salt in a constant actin concentration. We found that the longitudinal growth and lateral growth of polymer-actin complexes are dominated by different factors. This induces the structural polymorphism of polymer-actin complexes. Major factors to influence the polymorphism of polymer-actin complexes in polyelectrolyte system have been discussed. Our results indicate that the semi-flexible polyelectrolyte nature of F-actins is important for controlling the morphology and growth of actin architectures in cell.     

SYNTHESIS OF ONE-AND TWO-DIMENSIONAL ZINC AND CADMIUM COMPLEXES WITH 4, 4′-BIPY

Abstract

The zinc(II) and cadmium(II) complexes [Zn(4, 4′-bipy)(SCN)₂]_∞ 1 and [Cd(4, 4′-bipy)-(SCN)₂]_n 2 have been synthesized and their crystal structures determined by X-ray crystallography. Complex 1 is monoclinic, space group C2/c, with a = 18.076(5), b = 5.190(1), c = 17.315(4)Å; β = 115.54(2), V = 1465.8(8)ų, calculated density 1.530gcm^?3, Z = 4. In this compound, the rod-like ligand 4, 4′-bipy bridges Zn(II) centres, and the NCS groups are terminally coordinated. (N-Zn-N) is 108.5°, resulting in the formation of a zigzag Zn-bipy-Zn chain. These chains are arranged in parallel fashion. The 4, 4′-bipy ligands of adjacent layers are separated by 3.95 (Å). Complex 2 is monoclinic, space group C2/c, a = 11.902(2), b = 11.745(2), c = 10.500(2)Å; β = 109.71(3), V = 1381.8(4)ų calculated density 1.849gcm^?3, Z = 4. In this structure, the cadmium(II) ion is slightly distorted octahedral and the SCN groups act as doubly bridging ligands connecting cadmium atoms to form zigzag chains, separated by 4, 4′-bipy to create two-dimensional planes.     

SYNTHESES AND SPECTRA OF HETEROPOLY BLUES OF DOUBLE 2:17 MOLYBDOPHOSPHATES LANTHANIDE COMPLEXES

The present paper reports eight heteropoty blues of double 2:17 motybdophosphates tanthanide comptexes with tacunary Dawson structure, i.e., K_(17)H_2[Ln(P_2Mo_2~ⅤMo_(15)~ⅥO_(16))_2], nH_2O and K_(17)H_4 [Ln(P_2Mo~Ⅴ_4Mo_(13)~ⅥO_(61))_2], nH_2O(Ln=La, Pr, Sm, Yb). They were characterized by etementat anatyses, potentiometric titration, IR, UV, potarography, cyclic vottammetry, X-ray photoelectron spectra, X-ray powder diffraction, thermat analyses and ESR. The results show that the properties of these heteropoty btues are different from those of heteropoty blues with saturated Dawson structure and other tacunary series. They are more stabte than their parent heteropoty acids in aqueous sotution and have the abitity of anti-base decomposition.     

SYNTHESIS AND CHARACTERIZATION OF DINUCLEAR,BRIDGED COMPLEXES OF THE TYPE LxM(NCSe)2M′(SCN)2L′2

Abstract

L _x M(NCSe)₂ M′(SCN)₂(PPh₃)₂ [M=Co(II), Ni(II); M′=Hg(II), Cd(II), Zn(II); L=pyridine (py), 2,2′-bipyridyl (bipy); x=4, 2] have been synthesized. Elemental analysis, magnetic moment, electronic and infrared spectral and thermogravimetric studies indicate that these complexes are dinuclear. The total softness of M and M′ in the complexed state have also been calculated to derive certain conclusions.     

INVESTIGATION OF THE SOLUTION STRUCTURE OF Cu(II) MIXED-LIGAND COMPLEXES OF ADENOSINE 5′-MONOPHOSPHATE AND CYTIDINE 5′-MONOPHOSPHATE AND POLYAMINES

Abstract

The coordination mode of complexes formed in the systems Cu(II)/NMP/PA; (NMP =adenosine 5′-monophosphate, cytidine 5′-monophosphate; PA = 1,4-diaminopropane (putrescine, Put), 1,7-diamino-4-azaheptane (3,3-tri) and 1,11-diamino-4,8-diazaundekane (3,3,3-tet)) was determined on the basis of the equilibrium and spectroscopic studies. The presence of the following mixed complexes was established: Cu(CMP)H(Put), Cu(AMP)H₂(3,3-tri) and Cu(CMP)H₂(3,3-tri), Cu(CMP)H₄(3,3-tri) and coordination compounds of MLL′ type-Cu(CMP)(3,3,3-tet), Cu(AMP)(3,3,3-tet). A significant influence of the polyamine length on the solution structure of the complexes was observed. In mixed-ligand complexes Cu(NMP)(3,3,3-tet) a {N4, O} chromophore is formed, and metallation involves all nitrogen atoms from 3,3,3-tet. In the analogous system with 3,3-tri, protonated complexes occur. Non-covalent intramolecular interaction between the protonated amine groups and donor atoms from the purine ring from the nucleotide results in an increase of complex stability.     

FUSED PHOSPHONO SUBSTITUTED O-, AND N-HETEROCYCLES via CONDENSATIVE CYCLISATION REACTIONS OF α-PHOSPHONYL CARBANIONS WITH 4-THIAZOLIDINONES

Phosphono substituted-thiazolones 5a, b together with fused phosphono-pyran-5-ones 9a, b and the diolefins 8a–d were regioselectively prepared in reasonable yields from the reactions of 5-arylidene-4-thiazolidinones 1a, b with phosphonoacetates 2a, b. Conversely, Michael addition products 11a, b (～30%) along with the phosphono substituted-thiazole derivatives 12a, b (～33%) were obtained from treating 1a, b with cyanomethylenephosphonates (2c). The reactions of 1a, b with vinylphosphonate 2d proceeded with phase-transfer catalysis, yielding the corresponding 2-thioalkyl-derivatives 14a, b and phosphonates 13a, b.     

SYNTHESIS AND CHARACTERIZATION OF POLYMER DERIVATIVES OF cis-PLATINUM COMPLEXES

Cis-platinum complexes used as antitumor drugs were attached onto preformed polymers toreduce the toxicity. Either alternating copolymer of styrene and maleic anhydride (CPSMA) orpolyacrylic acid (PAA) is readily dissolved in alkaline solution. The cis-platinum complexes areeasily converted into water soluble species when treated by silver nitrate in water. The expectedproducts could be obtained when the two aqueous solutions were brought together. The productswere characterized by elementary analysis, IR and XPS. The polymer derivatives could exchangeligands with nucleophilic groups in biological environment and also exhibit antineoplastic activity.     

THERMAL AND PHOTOCHEMICAL REACTIONS BETWEEN α, α′-DIBROMOKETONES AND FIVE-MEMBERED HETEROCYCLES IN THE PRESENCE OF IRON NONACARBONYL

Abstract

[3 + 4] Cycloaddition reactions of 2-oxyallilic cations to furan¹ to form seven-membered oxobicyclic compounds have been known for some time. The purpose of this paper has been to try to extend the reaction to five-membered heterocycles with more aromatic character than furan. An analogy has been found between the behavior of thiophene, selenophene and tellurophene in these reactions and in oxetane-forming reactions. The higher the aromaticity of the heterocycle, the more difficult it is to achieve the formation of the seven-membered ring. Contrary to what is observed in oxetane-forming reactions, where it is not possible to isolate a stable tellurium compound, the tellurabicyclic compound was isolated and identified by spectroscopic methods in the present investigation.     

SYNTHESIS AND PROPERTIES OF NEW INTERPOLYMERIC COMPLEXES

β-(2-imidazolinyl)-ethyl methyl diethoxy silane quarternary halides and its condensed polymers with bisphenol A were synthesized and characterized. The polycation-polyanion complexes were prepared by the condensed polymers and poly (styrene sulfonate). The solubility and thermal stability of interpolymeric complexes were investigated.     

SYNTHESIS AND CHARACTERIZATION OF ZEROVALENT PALLADIUM COMPLEXES

A series of nine Pd(0)complexes(L)Pd(L')[L=bis(diphenylphosphino)methane(dppm),1,2-bis(diphenylphosphino)ethane(dppe),and 1,1'-bis(diphenyl-phosphino)ferrocene(dppf),respectively;L=dibenzylideneacetone(dba),2,3,5,6-tetrachloro-1.4-benzoquinone(q)and 2,3-dichloro-1,4-naphthoquinone(nq)]were synthesized and characterized by means of elemental analyses,IR,UV,1~H-NMR and~(31)P-NMR spectra.The redox wave peak potentials of the ferrocenylgroup of complexes with dppf were measured by using CV method.Results showedthat all the diphosphorus ligands behaved as chelating bidentate ligand anddba,q,nq were coordinated to the Pd(0)atom through their C=C moieties,nottheir carbonyl ones.Analytical data also showed that there were interactionsbetween the two different ligands in each complex.     

SYNTHESIS AND CHARACTERIZATION OF DVE-CO-MA DERIVATIVES OF CIS- PLATINUM COMPLEXES

Copolymer of divinyl ether and maleic anhydride (DVE-co-MA) derivatives of cis-platinum complexes were synthesized and characterized by elementary analysis, IR and XPS ( X-ray photoelectron spectroscopy). The behavior of the products in biological environment was also studied. UV-visible and fluorescence spectra show that these polymer derivatives are able to exchange ligands with selected nucleophilic groups in biological environment.     

NBS AND NCS APPLIED TO THIOCYANATION OF AROMATIC RINGS

Instead of Br_2 and Cl_2,NBS and NCS are applicable tothe thiocyanation of o-nitroaniline and carbendazim.The resultsshow that NBS and NCS are superior to Br_2 and Cl_2 due to theireasier operation.     

SYNTHESIS, SPECTRA AND ELECTROCHEMICAL PROPERTIES OF OXYGEN ADDUCTS OF TETRAKIS(2-ANILINOPYRIDINATO) DIRHODIUM COMPLEXES

Two oxygen adducts of different geometric isomers of the tetrakis(μ-2-anilinopyridinato) dirhodium unit, Rh_2(ap)_4~+, have been synthesized and characterized. Rh_2(ap)_4O_2(4,0) is the oxygen adduct 1 of 4, 0 isomer; and Rh_2(ap)_4O_2(2, 2) is the oxygen adduct 2 of 2, 2 isomer. The ESR spectra of both oxygen adducts show that there is a characteristic signal of a superoxide ion, g=2.03. The 4, 0 isomer with different axial ligands gives the order of A_Ⅱ values; O_2~-≈ClO_4~-相似文献   

MOLECULAR DESIGN OF NEW KINDS OF AUXETIC POLYMERS AND NETWORKS

Three new kinds of molecular networks are designed and predicted to exhibit negative Poisson ratios. Molecular mechanics calculations on these networks show that the magnitude of Poisson ratios depends on the relative flexibility of beam and arm structures. Several new kinds of auxetic polymers, whose successful synthesis should be easier than that of the corresponding auxetic networks, are then proposed. It is found that the kabob-like polymers with auxegens lying vertically on the main chain can acquire auxeticity while those with auxegens lying horizontally on the main chain cannot. Besides, a half kabob-like or pseudo-ladder polymer with auxegens linked at the intersection of the beam and the arm does show auxeticity when adopting constrictive conformers. It is, however, worthwhile noting that the origins of auxeticity still await and strongly deserve further experimental and theoretical investigations.     

THERMAL DECOMPOSITION OF METAL COMPLEXES. MIXED COMPLEXES OF DIVALENT TRANSITION METALS WITH α-NITROKETONES

Abstract

The thermal behaviour of mixed complexes containing transition metals, α-nitroketones and pyridine or ethanol was investigated by thermogravimetric analysis (TG), differential thermal analysis (DTA) and differential scanning calorimetry (DSC). The values of the activation energies and the enthalpies for the dissociation processes have been calculated in high vacuum and isothermal conditions. Comments are made on the obtained heats and correlations with structural characteristics are looked for.     

DICATIONICALLY LIVING CHAINS: COPOLYMERIZATION OF TETRAHYDROFURAN WITH PROPYLENE OXIDE AND SYNTHESIS OF THE TELECHELIC OLIGOMERS

The living chains were obtained in the bulk copolymerization of tetrahydrofuran (THF) withpropylene oxide (PO) (10--20 wt.%) initiated by adipoyl chloride (AC)AgC10_4 ([ACl0,=0.02-0.09 mo1.1~(-1)) catalyst at-10--0℃without chain termination and transfer reactions. The estimationof reactivity ratios gave values of 0.8±0.2 and 0.08±0.03 for THF and PO, respectively. The func-tionality of living chains with 10% PO in the feed is close to 2. Four different telechelic THF-PO co-polymers with amine or hydroxyl end-groups [P(THF-co-PO)R, where R=-NHBu,-NHPh,-NEt_2 or--OH were synthesized.     

CORRELATION BETWEEN GLASS TRANSITION OF POLYMERS AND ENERGY OF ROTATIONAL ISOMERIZATION OF MOLECULAR CHAINS

It has been shown that the free volume fraction at T_g is not a universal parameter for linear polymers of different molecular structure. The reason is that the volume expansion at T_g is partially contributed from the change of the numbers of conformations of isolated molecular chains due to internal rotation. In this paper, glassy transformation was connected with internal rotation of isolated molecular chains, and the relationship between free volume fraction of polymers at T_g and energy e of rotational isomerization of isolated molecular chains was formulated, e=-k·T_g·In (△α·T_g/1-△α. T_g). The values of calculated from the above formula are in good agreement with those published in the literatures. Thus, the method described in this paper can be used to estimate a parameter for the flexibility of isolated molecular chains.7     

CRYSTAL STRUCTURE OF LITHIUM,POTASSIUM, AND CALCIUM COMPLEXES WITH β-CYCLODEXTRINE

Journal of Structural Chemistry - Three new coordination compounds are obtained in the reaction of aqueous solutions of lithium and potassium hydroxides or calcium chloride with...     

SYNTHESIS AND CHARACTERIZATION OF THE COMPLEXES OF β－ALKOXYCARBONYLETHYLTIN TRICHLORIDES WITHDBSO AND HMPA

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SYNTHESES AND SPECTROSCOPIC PROPERTIES OF PORPHYRIN-PHTHALOCYANINE MITH FLEXIBLE POLYATONIC CHAINS

The syntheses of porphyrin-phthalocyanine heterodimers with flexible polyatomic chains especially designed for the studies of intramolecular photoinduced processes are presented along with the effect of mutual orientation of the chromophore subunits on intramolecular energy transfer efficiency.