d-Xylose-based surfactants: Synthesis,characterization and molecular modeling studies

Pentose-derived surfactants were easily synthesized and fully characterized through classical analytical methods. The interfacial behaviors revealed the importance of both the length of the hydrophobic chain and the nature of the anomeric form. Finally, the spatial conformation of four xylosides was obtained by molecular modeling with software Hyperchem^® 4 using the semi-empirical method PM3, which demonstrated the role of hydrophobic interactions in the stability of the compounds.     

Synthesis, properties, and molecular structure of nitro-substituted N-methyl-N-nitroanilines

Ten mono-, di-, and trinitro derivatives of N-methyl-N-nitroaniline were synthesized and studied by spectral, electrooptical, and quantum-chemical methods. Three of these derivatives, N-methyl-N,2,3-trinitroaniline, N-methyl-N,2,5-trinitroaniline, N-methyl-N,3,5-trinitroaniline, were also examined by the X-ray diffraction method. The N-nitroamino group in their molecules is almost planar, the N⁷-N⁸ bond is shortened, and the N⁸ atom is characterized by a strong deficit of electron density. The dihedral angle between the planes of the N-nitroamino group and the benzene ring is 56°–92°, which makes conjugation between these fragments impossible. The N-nitroamino group in the examined compounds acts as a weak electron donor with respect to the nitro groups in the aromatic ring; the mechanism of this effect is inductive.     

Al柱层状钛铌酸盐的制备

本文采用分步交换法,首次将[Al~1~3O~4(OH)~2~4(H~2O)~1~2]^7^+Keggin离子交换进入到层状金属钛铌酸盐(KTiNbO~5)的层间.通过焙烧,制备了以Al~2O~3 为柱的层状金属化合物.该化合物具有较高的热稳定性(>500℃)和比较大的层间距(d=1.34nm,500℃)     

Synthesis and molecular structure of a perfluorinated pyridyl carbanion

Reaction of pentafluoropyridine with sodium nitromethanide allowed the isolation and characterisation of the first perfluorinated pyridyl carbanion system, sodium nitrobis(perfluoropyridin-4-yl)methanide, by X-ray crystallography.     

Synthesis and structure of a triptycene-based nanosized molecular cage

A triptycene-based nanosized molecular cage was designed and efficiently synthesized by Eglington-Glaser coupling reaction, and its structure was determined by NMR, MS spectrometry and X-ray analysis. Moreover, it was found that the cage molecules could pack into a microporous structure in the solid state and 1,3,5-trimethylbenzene molecules were located in the channels.     

Synthesis,properties and molecular modeling of functional hyperbranched polymers and dendrimers

The design, synthesis, properties and molecular modeling of fully conjugated dendritic molecules and conjugated hyperbranched polymers are described. It has been shown that conjugated hyperbranched molecules are much more soluble than their linear analogues while maintaining all the properties characteristic of conjugated polymers. It was found that the use of polymeric solid support in hyperbranched polymerization allows to control molecular weight and degree of branching (DB). The molecular modeling of hyperbranched conjugated molecules reveals that hyperbranched structure of conjugated molecules affects significantly neither their stability nor the conjugation. On the other hand the terminal groups affect appreciably the electronic structure of conjugated hyperbranched molecules.     

Synthesis of polyaluminoorganosiloxanes with a cycloreticular molecular structure

Summary The polycondensation of ,-dihydroxypolydimethylsiloxane with aluminum butoxide was investigated. When the molar ratio of the reactants is 3: 1 terfunctional branched oligomers are formed in the first stage of the reaction, and these condense further with formation of polymers having a cycloreticular structure.     

Synthesis and molecular structure of o-isopropylchloro-formiminodiphenylphosphinate

Conclusions Diphenylphosphine reacts with two equivalents of 1,1-dichloro-1-nitrosoisobutane to give O-isopropylchloroformiminodiphenylphosphinate. The molecular structure of this product was determined by x-ray diffraction structural analysis.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2595–2597, November, 1987.     

Synthesis, structural characterization, and molecular modeling of dodecaniobate keggin chain materials

Four new isostructural one-dimensional dodecaniobate Keggin materials, Na12[Ti2O2][TNb12O40] x xH2O and Na10[Nb2O2][TNb12O40] x xH2O with T = (Si or Ge), have been synthesized hydrothermally using a Lindqvist-ion salt, Na7[Nb6O19H] x 15H2O, as the precursor. Their structure, consisting of chains of Keggin ions [TNb12O40]16- linked by [Ti2O2]4+ or [Nb2O2]6+ bridges, was solved ab initio from powder diffraction data. The location of the charge-balancing sodium atoms and the water molecules was further investigated by molecular simulations. These compounds were also characterized by IR and solid-state 1H, 29Si, and 23Na MAS NMR spectroscopies. The structural relationships between these and related phases based on similar Keggin ion building units are discussed.     

Synthesis,structure, and host-guest chemistry of a pair of isomeric selenanthrene-bridged molecular cages

A pair of selenanthrene-bridged molecular cages have been constructed through a one-step cyclization reaction of a tetrakis(iodo) crown ether with selenium powder. The tubular belt-shaped cage has an intrinsic cavity which can adaptively transform to accommodate electron-deficient guests forming [2]pseudorotaxane complexes. The other product was determined to be an isomeric cage featuring a Möbius strip structure, which exhibits slower twist-migration dynamics than its thianthrene counterpart. The success of using selenanthrene as joints enables an alternative way to structural design and property regulation of molecular cages.     

Synthesis,molecular structure and reactivity of new biferrocenylpropane derivatives

New biferrocenylpropane derivatives FcC(CH₃)₂Fc′-C≡C–R [Fc?=?C₅H₅FeC₅H₄; Fc′?=?C₅H₅FeC₅H₃, R?=?C₆H₅ (L ₁ ), Fc (L ₂ )] and their complexes [FcC(CH₃)₂Fc′-C≡C–R][Co₂(CO)₆] [R?=?C₆H₅ (1); R?=?Fc (2)] have been synthesized by the Castro-Stephens coupling reaction and the reactions of ligands L ₁ , L ₂ with Co₂(CO)₈. Compounds L ₁ , L ₂ , 1 and 2 were characterized by elemental analysis, IR, ¹H (¹³C) NMR and MS, and the molecular structures of ligands L ₁ , L ₂ were determined by X-ray single crystal analysis. The electrochemical properties of L ₁ , L ₂ , 1 and 2 demonstrate two or three resolved one-electron redox processes.     

Synthesis, molecular structure, and reactivity of the isolable silylenoid with a tricoordinate silicon

The first tricoordinate fluorosilylenoid, (t-Bu2MeSi)2SiFLi.3THF (1), was synthesized, and its X-ray molecular structure was determined. 1 was synthesized in 40% yield by a bromine-lithium exchange reaction in THF of the corresponding fluorobromosilane with t-Bu2MeSiLi. 1 is best described as an R2SiF- anion attracted to a (Li.3THF)+ cation with a small contribution of resonance structure that consists of a silylene fragment and FLi.3THF. 1 reacts as a nucleophile with MeCl, PhH2SiCl, H2O, and MeOH, as an electrophile with MeLi, and as a silylene with Li (or t-BuLi) and Na, yielding alpha-lithium and alpha-sodium silyl radicals, respectively. Either photolysis or thermolysis of 1 yields the corresponding disilene R2Si=SiR2 (R = t-Bu2MeSi), probably via dimerization of R2Si:.     

Synthesis and molecular structure of a novel barium arylspiroboronate ester

The compound barium bis{bis-(4,6-di-tert-butyl[1,2-benzenediolato(2-)-O,O′]borate)} has been prepared by the addition of 3,5-di-tert-butylcatechol to a solution of boric acid and Ba(OH)₂ and characterized by a single crystal X-ray diffraction study. The title compound crystallized in the triclinic space group P-1, with cell parameters a = 13.280(2) Å, b = 15.755(3) Å, and c = 16.980(3) Å, α = 71.691(2)o, β = 79.528(3)o, γ = 80.741(3)o, Z = 1, and V = 3296.1(10) ų. The structure was solved by direct methods and refined to a final R = 0.0459 for 14370 reflections with I > 2σ(I). One of the arylspiroboronate ester counterions is bound to the barium atom in a rare example of the η1 bonding mode via a single oxygen of one of the catecholato groups. The coordination sphere around the barium is complemented by four molecules of water, one molecule of acetone and two bridging water molecules, connecting to an adjacent barium atom.     

New potential DNA intercalators of the carbazole series from indole-2,3-quinodimethanes: Synthesis,crystal structure,and molecular modeling with a watson-crick mini-helix

Summary 1-Alkylpyrano[3,4-b]indol-3-ones3 react via a Diels-Alder step with an aryne or N-phenylmaleimide to furnish the new [b]annellated carbazoles4–10 in a one-pot process. In an analogous procedure, the in situ generated N-benzoylindole-2,3-quinodimethane (13) reacted with quinones to furnish the dioxocarbazoles14–16. Compounds4–8 and14–16 with a coplanar skeleton are members of a class of potential DNA intercalators, as has been shown for5 and8 by X-ray structural analysis. On the basis of the geometries determined by X-ray crystallography, the intercalative binding of these molecules with a Watson-Crick mini-helix was predicted by molecular modeling methods.

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Neue potentielle DNA-Interkalatoren der Carbazol-Reihe aus Indol-2,3-chinodimethanen: Synthese, Kristallstruktur und Molecular Modeling mit einer Watson-Crick Minihelix

Zusammenfassung 1-Alkylpyrano[3,4-b]indol-3-one3 reagieren über einen Diels-Alder-Schritt mit Arin oder N-Phenylmaleinimid zu [b]annellierten Carbazolen4–10 in einer Einstufenreaktion. In analoger Weise reagiert ein in situ erzeugtes N-Benzoylindol-2,3-chinodimethan13 mit Chinonen zu den Dioxocarbazolen14–16. Die Verbindungen4–8 und14–16 gehören infolge ihrer coplanaren Struktur zur Klasse potentieller DNA-Interkalatoren. Auf der Basis von Röntgenstrukturanalysen von5 und8 wird die interkalative Bindung mit einer Watson-Crick Minihelix durch Molecular Modeling vorhergesagt.

     

Synthesis and molecular structure of gold triarylcorroles

A number of third-row transition-metal corroles have remained elusive as synthetic targets until now, notably osmium, platinum, and gold corroles. Against this backdrop, we present a simple and general synthesis of β-unsubstituted gold(III) triarylcorroles and the first X-ray crystal structure of such a complex. Comparison with analogous copper and silver corrole structures, supplemented by extensive scalar-relativistic, dispersion-corrected density functional theory calculations, suggests that "inherent saddling" may occur for of all coinage metal corroles. The degree of saddling, however, varies considerably among the three metals, decreasing conspicuously along the series Cu > Ag > Au. The structural differences reflect significant differences in metal-corrole bonding, which are also reflected in the electrochemistry and electronic absorption spectra of the complexes. From Cu to Au, the electronic structure changes from noninnocent metal(II)-corrole(?2-) to relatively innocent metal(III)-corrole(3-).     

Synthesis,molecular and crystal structure of new 9,10-substituted deazaflavins

Cyclocondensation of 6-N-(3-hydroxypropyl)aminouracyl with 2-fluoro- or 2,3-dimethoxy-substituted benzaldehydes provided the corresponding 9,10-substituted 5-deazaflavins {pyrimido[4,5-b]quinoline-2,4-(3H,10H)diones}. X-ray diffraction analysis was carried out for 9-methoxy-10-(3-hydroxy-propyl)-substituted 5-deazaflavin derivative.     

Synthesis, characterization, molecular structure and theoretical studies of axially fluoro-substituted subazaporphyrins

A new and general synthetic method for the preparation of fluoro-substituted subazaporphyrins is reported that involves the treatment of the corresponding chloro- or aryloxy-substituted subazaporphyrins (SubAPs) with BF(3).OEt(2). The strategy has been applied to both subphthalocyanines (SubPcs) and subporphyrazines (SubPzs). The yields were high for the latter, although low yields were obtained for the benzo derivatives. In contrast to the corresponding chloro derivatives, fluorosubazaporphyrins are quite robust towards hydrolysis. All of the new compounds were characterized by several spectroscopic techniques, which included (1)H, (13)C, (19)F, (15)N, and (11)B NMR spectroscopy, IR spectroscopy, UV/Vis spectrophotometry, and mass spectrometry (both high and low resolution). In addition, DFT calculations provided theoretical NMR spectroscopy values that are in good agreement with the experimental ones. The high dipole moments exhibited by the fluorosubazaporphyrins as a result of the presence of a fluorine atom in an axial position are responsible for the spontaneous and singular supramolecular aggregation of the macrocycles in the crystalline state. The molecular and crystal structures of two one-dimensional fluorine SubAPs, namely, a SubPc and a SubPz, are discussed. Molecules of the same class stack in alternating configurations along the c axis, which gives rise to columns that contain large numbers of monomers. SubPz 3 c forms aggregates with the macrocycles arranged in a parallel fashion with the B-F bonds perfectly aligned within a column, whereas with SubPc 3 b the neighboring columns cause a commensurate sinusoidal distortion along the columns in the c direction, which prevents the alignment of the B-F bonds. However, the most remarkable feature, common to both crystalline architectures, is the extremely short and unusual intermolecular F...N distances of the contiguous molecules, which are shorter than the sum of the corresponding van der Waals radii. Theoretical calculations have shown that these short distances can be explained by the existence of a cooperativity effect as the number of monomers included in the cluster increases.     

Acylated benzothiazinesulfoneamides: Synthesis and molecular structure

1,2,3,4,4a,10b-Hexahydro-1,4-methano-6H-dibenzo[c,e]-5,6-thiazine-5,5-dioxide has been converted into the corresponding N-acyl derivatives via the reaction with acid chlorides and anhydrides. X-Ray diffraction data have revealed the presence of an intramolecular С–H···O=S hydrogen bond in the molecules of the obtained compounds.     

Ferrocenyl anthracenes: Synthesis and molecular structure

The synthesis of a series of ferrocenylanthracene derivatives is described, utilising the palladium catalysed coupling reaction of 1,1′-bis(chlorozincio)ferrocene with halo-anthracenes. Bis-1,1′-(9-anthracenyl)ferrocene (1) was characterised by single crystal X-ray diffraction and shows an eclipsed ferrocenyl geometry. X-ray crystallographic studies indicate that there are no clear stacking interactions of either an intra- or intermolecular nature between the anthracenyl rings in the structure. A series of 9- and 10-disubstituted ferrocenylanthracene derivatives has also been prepared. In each case the palladium catalyst (Pd(dppf)Cl₂) is recovered in a modified form, e.g. as the [(dppf)PdBr(9-anthracenyl)] complex in the synthesis of bis-1,1′-(9-anthracenyl)ferrocene. The single crystal X-ray structure of one such palladium complex [(dppf)PdBr-9-(10-chloroanthracenyl)] (15a) has been determined in a case where chloride/bromide exchange had occurred in the palladium complex intermediate. The potential application of compound 1 as synthon for the construction of a molecular sensing device is discussed. Cyclic voltammetry and fluorescence studies have been carried out for selected derivatives.