Synthesis and characterization of organic–inorganic macrocyclic molecular brushes with poly(ε-caprolactone) side chains

In this work, we reported the synthesis of a dodecahydroxyl-functionalized macrocyclic oligomeric silsesquioxane (MOSS). The novel 24-membered hydroxyl-functionalized MOSS was employed as a macroinitiator for the ring-opening polymerization of ε-caprolactone (CL) and the organic–inorganic macrocyclic molecular brushes with poly(ε-caprolactone) (PCL) side chains were successfully synthesized. The organic–inorganic macrocyclic molecular brushes were characterized by means of nuclear magnetic resonance spectroscopy (NMR) and gel permeation chromatography (GPC). The results of wide angle X-ray diffraction (XRD) indicate that the architecture of the organic–inorganic macrocyclic molecular brushes did not alter the structure of PCL crystals. Differential scanning calorimetry (DSC) shows that the architecture of organic–inorganic macrocyclic molecular brushes significantly affected the rearrangement of PCL crystals. Compared to linear PCL, the organic–inorganic macrocyclic molecular brushes possessed the improved thermal stability in terms of the temperatures at the maximum of degradation rate and the yields of degradation residues.     

Synthesis and properties of a luminescent organic material with triphenylamine and pentiptycene units

A donor–bridge–donor compound for blue light-emitting with triphenylamine as donor and pentiptycene derivative units as bridge was synthesized via Sonogashira reaction. The chemical structure was confirmed by NMR and MALDI-TOF MS. It emits blue light peaked at 442 nm with a FWHM of 59 nm in CH2Cl2. Fluorescent quantum efficiency in THF is 82% relative to 9,10- diphenylanthracene. A slight hypsochromic shift was found in its drop-cast film. Cyclic voltammetry revealed that it has high HOMO level corresponding to hole transporting character.     

Synthesis and properties of a star-shaped organic material with triphenylamine and N-vinyl carbazole units

A starburst triphenylamine cored N-vinyl carbazole (V-Cz) branched compound was designed and synthesized via optimized Heck reaction in a yield of 40-60%.Moderate yield came from decomposition of V-Cz and self-coupling of triiodo-triphenylamine. TCz-TPA adopts a highly twisted propeller conformation by molecular mechanical optimization.It is readily soluble for its highly twisted conformation.Transparent and pinhole free films could be easily fabricated by spin-coating for its starburst structure.It emits blue-greenish light in CH_2Cl_2 peaked at 460 nm with a narrow full-width at half-maximum (FWHM) of 65 nm.As compared, the absorption peaks of the spin-coated film blue shifted and emission peak red shifted to 510 nm with a FWHM of 96 nm.     

Synthesis of α-fluoro-β-hydroxy esters by an enantioselective Reformatsky-type reaction

The first enantioselective Reformatsky-type reaction of ethyl iodofluoroacetate has been accomplished with alkyl aryl ketones. High diastereoselectivities and excellent enantioselectivities for the major diastereomer (93-95% ee) were achieved with large alkyl groups. For smaller alkyl groups the diastereoselectivities were moderate, but excellent enantioselectivities were obtained for both diastereomers (79-94% ee).     

Synthesis of carba-β-d- and l-idopyranosides by rearrangement of unsaturated sugars

The triisobutylaluminium- (TIBAL) and titanium(IV)-promoted conversions of 6-deoxyhex-5-enopyranosides into highly functionalised cyclohexane derivatives provide intermediates for the synthesis of enantiomerically pure carba-sugars. The preparation of enantiomerically pure methyl carba-β-d-idopyranoside 1, methyl carba-β-l-idopyranoside 2 and 5′a-carbadisaccharide 3 is reported.     

Synthesis of conjugates of β-cyclodextrin with polyamidoamine dendrimers and their molecular inclusion interaction with levofloxacin lactate

Polyamidoamine (PAMAM) dendrimers of different generations (G2 and G4) conjugated with β-cyclodextrin (β-CD), PAMAM (G2, G4)-CD, were synthesized using substitution reaction from mono-6-iodine-β-cyclodextrin and PAMAM dendrimers. The resulting molecular structures were characterized by NMR, IR. The molecular interaction between various dendrimers and levofloxacin lactate (LFL) were investigated by monitoring the fluorescence of LFL in the presence of dendrimers in buffer solution (pH 7.4) at 25?°C. It was found that the PAMAM (G2, G4)-CD possesses higher sensitizing ability than that of the corresponding parent dendrimers and natural β-CD, and increases concomitantly with the increases of generation and content of β-CD, suggesting that the PAMAM (G2, G4)-CD possesses stronger inclusion ability with LFL. The possible interaction mechanism between PAMAM-CD and LFL was proposed by ¹H NMR analysis and theoretical calculation. The results show that the LFL molecule is located at the amine end of dendrimer molecule and along the side of cyclodextrin cavities to form supramolecular complexes. Furthermore, results indicate that the main driving force of the complex could be attributed to the electrostatic interactions and hydrogen bonding between LFL and PAMAM-CD, as well as the synergistic effect of intermolecular forces.     

Green and efficient oxidation of benzylic alcohols with hydrogen peroxide catalyzed by an inorganic–organic hybrid catalyst

Inorganic–organic hybrid catalysts 1-POM(M) were prepared by electrostatic interaction between transition metal-substituted polyoxometalates, {[PW₁₁MO₃₉]^4? [M?=?Cr(III), Fe(III)], [PW₁₁MO₃₉]^5?, [M?=?Mn(II), Co(II), Ni(II), Cu(II), Zn(II)], [PW₁₁VO₄₀]^4?}, and branched organic polyammonium, (tris[2-(dimethylammonium)ethyl]-1,3,5-benzenetricarboxylate), and characterized by elemental analyses, UV–vis and FT IR spectroscopic techniques, XRD, SEM, and Thermogravimetric-Differential thermogravimetric analyses. The hybrid material 1-POM(Zn) was an efficient and selective heterogeneous catalyst in the oxidation of benzylic alcohols to their corresponding carbonyl compounds with hydrogen peroxide. The catalyst was reused several times without significant loss of catalytic activity.     

Synthesis of pyrazolines by the reactions ofα,β-enones with diazomethane and hydrazines (review)

The first representatives of pyrazolines were synthesized in the last century. These nitrogen-containing heterocyclic compounds became important in the development of different bioactive substances. For this reason, various procedures have been worked out for their synthesis. In the present article we summarize those synthetic methods providing 1- or 2-pyrazolines by the reactions of ,-unsaturated ketones with diazomethane or hydrazine derivatives.Department of Organic Chemistry, Kossuth Lajos University, Egyetem ter I, H 4010 Debrecen, Hungary. Published in Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 747–759, June, 1997.     

Volatile complexes of Pd(II) with methoxy-β-iminoketones: Synthesis,properties, and crystal and molecular structure

This paper describes a procedure for the synthesis of two new volatile complexes, Pd(L¹)₂ and Pd(L²)₂, from sterically hindered methoxy-β-iminoketones, where HL¹ = C(CH₃)₂(OCH₃)-C(NH)-CH₂-C(O)-C(CH₃)₃; HL² = C(CH₃)₂(OCH₃)-C(NH)-CH₂-C(O)-CH(CH₃)₂. Element analysis and IR spectral data are given. The results of full X-ray crystal structure analysis of the complexes are reported. The compounds have molecular structures; the crystals of the complexes have different symmetry groups and unit cell dimensions. The Pd(L¹)₂ complex molecule has a nonplanar structure; the Pd(L²)₂ complex has a cis-structure. The geometrical characteristics obtained for the coordination units are as follows: the Pd-O and Pd-N bond lengths and N-Pd-O chelate angles were estimated at 1.960 Å, 93.7° for Pd(L¹)₂, and 1.984 Å, 1.976 Å, 92.4° for Pd(L²)₂.     

Synthesis,molecular structure and reactivity of new π-conjugated diyne with ferrocenyl and phenyl units

New π-conjugated butadiynyl ligand FcC(CH₃)₂Fc′–CC–CC–Ph (L₁) has been synthesized and its reaction with Co₂(CO)₈ has been studied. New clusters [FcC(CH₃)₂Fc′–CC–CC–Ph][Co₂(CO)₆]_n [(1): n = 1; (2): n = 2] and [Fc–CC–CC–Ph][Co₂(CO)₆]_n [(3): n =  1; (4): n = 2] were obtained by the reaction of ligands FcC(CH₃)₂Fc′–CC–CC–Ph (L₁) and Fc–CC–CC–Ph (L₂) with Co₂(CO)₈ respectively and the composition and structure of the clusters and ligands have been characterized by elemental analysis, FTIR, ¹H and ¹³C NMR and MS. The crystal structures of compounds L₁, L₂, 2 and 4 have been determined by X-ray single crystal analysis.     

Synthesis of α-trifluoromethyl-β-keto phosphonates by electrophilic trifluoromethylation with Togni reagent

A new synthetic method of trifluoromethylated phosphonates was developed via electrophilic trifluoromethylation with Togni reagent. A variety of β-keto phosphonates were converted into the corresponding α-trifluoromethyl-β-keto phosphonates in moderate to good yields. This protocol could also be extended to other fluoroalkylation reactions, such as pentafluoroethylation.     

Synthesis and characterization of hydroxyapatite obtained from different organic precursors by sol–gel method

The synthesis of four types of hydroxyapatite synthesized from calcium chloride and four different organic phosphites is presented. The method of synthesis chosen is the sol–gel route, which has a number of advantages compared to other methods, like the intimate contact between reactants and the milder synthesis conditions. The samples were thermally treated, the TG/DTG/DTA curves being obtained at four heating rates, namely: 7, 10, 12 and 15 °C min⁻¹. The samples were characterized before and after the thermal treatment using FT-IR analysis. The FT-IR spectra certified that the formed compounds represent hydroxyapatite. Based on the information from the TG curves and IR spectra interpretation, a reaction mechanism was proposed.     

Synthesis and characterization of manganese–zinc ferrite obtained by thermal decomposition from organic precursors

Mn–Zn ferrites were obtained by the sol–gel autocombustion methods. The effect of the precursor used in the sol–gel autocombustion synthesis on the ferrite’s microstructure was examined. The as-obtained powders were characterized by XRD, FTIR, SEM, and TG/DTA. All ferrite powders obtained from different organic precursors, after gel autocombustion, were pure spinel phase, without secondary phases. The average crystallite size, estimated from Scherrer equation, was the smallest for ferrite obtained from a mixture of fuels/precursors (citric acid and EDTA). This ferrite powder has sponge-like microstructure with large pores, but it is less agglomerated than the material obtained from glycine as the fuel.     

Synthesis and characterization of push–pull organic semiconductors with various acceptors for solution-processed small molecule organic solar cells

New efficient push–pull organic semiconductors comprising of the bis(9,9-dimethyl-9H-fluoren-2-yl)aniline (bisDMFA) donor and the various acceptors such as NO₂, DCBP, and TCF, which were linked with bithiophene or vinyl bithiophene π-conjugation bridges, were synthesized, and their photovoltaic characteristics were investigated in solution-processed small molecule organic solar cells (SMOSCs). The intramolecular charge transfers of these materials were effectively appeared in between bisDMFA donor and acceptors, depending on the electron-withdrawing strength of acceptors. The organic semiconductors having NO₂ and DCBP acceptors exhibited the most efficient photovoltaic performance, showing power conversion efficiency (PCE) of 1.98% (±0.17) and 2.01% (±0.21), respectively. When the TiO_x thin layer was treated on photoactive layer, the organic semiconductor having NO₂ showed the best PCE of 2.70% with short circuit current of 8.19 mA/cm², fill factor of 0.40, and open circuit voltage of 0.83 V in SMOSC devices.     

Synthesis of water-soluble cystine C60 derivative with catalyst and its active oxygen radical scavenging ability

A novel water-soluble cystine C_(60)derivative was synthesized in the presence of the catalyst,tetrabutylammonium hydroxide (TBAH).The product was characterized by FT-IR,UV,~1H NMR,~(13)C NMR,MS and elemental analysis.Furthermore,the scavenging ability to superoxygen anion radical O_2~(·-)and hydroxyl radical ~·OH was studied by chemiluminescence.It was found that cystine C_(60)derivative showed an excellent efficiency in eliminating superoxygen anion radical and hydroxyl radical.The 50% inhibition concentration(IC_(50))for superoxygen anion radical and hydroxyl radical were 0.167 and 0.008 mg/mL,respectively.     

Preparation and characterization of the inclusion complex of baicalein with γ-cyclodextrin: an antioxidant ability study

The formation of the complex of Baicalein with γ-cyclodextrin (γ-CD) was studied by UV–Vis absorption spectroscopy, fluorescence spectra and nuclear magnetic resonance spectroscopy (NMR) in solution. The solid inclusion complex of Baicalein with γ-CD was synthesized by the co-precipitation method. The characterization of the solid inclusion complexes have been proved by infrared spectra. The formation constant (K) of complex was determined by fluorescence method. The results suggested that in different pH solutions, γ-CD has different inclusive capacity to different forms of Baicalein. γ-CD was most suitable for inclusion in neutral media. In addition, the experimental resulted confirmed the existence of 1:1 inclusion complex of Baicalein with γ-CD. Kinetic studies of DPPH? with Baicalein and γ-CD complex were done. The results obtained indicated that the Baicalein/γ-CD complex was the most reactive form. Special configuration of complex has been proposed on NMR technique.     

Synthesis and Antitumor Activity of an Analog of Phthalascidin

Ecteinascidin 743 (Et-743) is an exceedingly potent antitumor agent isolated from the extracts of the marine tunicate Ecteinascidia turbinate1 that is currently undergoing phase Ⅱ/Ⅲ clinical trials in Europe and the United States2. As the result of its …     

Synthesis and luminescence behavior of inorganic–organic hybrid materials covalently bound with pyran-containing dyes

A DCM derivative, namely 4-Dicyanomethylene-2-methyl-6-{[4′-(N-hydroxyethyl-N-methyl)amino]styryl}-4H-pyran (DCMH), has been synthesized and covalently incorporated into the inorganic silica network as pendants via a sol–gel process. Molecular structures of the resultants are confirmed by elemental analysis, ¹H NMR, DSC, TGA, FTIR and UV–Vis spectroscopy. Photoluminescence (PL) spectra shows that the emission of DCMH peaked at 625 nm is almost completely quenched in DMF solution with a concentration of 1 × 10⁻⁴ mol/L, however, in hybrid films, the PL intensity enhances obviously with increasing DCMH concentration even at the high loading content of 40 mol%. All the hybrid films exhibit PL emission around 646–650 nm and the peak position reveal little dependence on the concentration of dye, suggesting they can be used as red emissive materials in light-emitting diodes. The relationship between fluorescence lifetime and dye concentration is also investigated by time-resolved PL measurements.     

Synthesis ofD-apio-β-D-furanosyl maleimide, an analogue of showdomycin with transposed hydroxymethyl group

Summary Apioshowdomycin (3-(D-apio--D-furanosyl)-1H-pyrrole-2,5-dione,2) has been prepared as an analogue of the C-nucleoside showdomycin (1) in eight steps and with 5% overall yield, starting from 2,3-O-isopropylidene-D-apio--D-furanose (3).

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Synthese vonD-Apio--D-furanosyl-maleinsäureimid, einem Showdomycinanalogen mit verschobener Hydroxymethylgruppe

Zusammenfassung Ausgehend von 2,3-O-Isopropyliden-D-apio--D-furanose (3) wurde in acht Stufen und 5% Gesamtausbeute Apioshowdomycin (3-(D-Apio--D-furanosyl)-1H-pyrrol-2,5-dion,2), ein Analoges des C-Nucleosids Showdomycin (1), hergestellt.