Aida I. Samigullina

Crystal structure of chiral ortho-alkyl phenyl ethers of glycerol: true racemic compound, normal, false and anomalous conglomerates within the single five-membered family

For a family of chiral terminal ortho-alkylphenyl glycerol ethers [alkyl = Me (1), Et (2), n-Pr (3), i-Pr (4), t-Bu (5)] nine different crystalline modifications have been obtained and investigated by X-ray analysis. All possible types for chiral compound crystallization, including a very rare type of false conglomerate (polymorph of rac-4.1) and extremely rare case of anomalous conglomerate (metastable form of rac-5) have been found within this set. Three tested substances crystallize as normal conglomerates, while two are capable of forming normal racemic compounds. Centrosymmetrical dimers of enantiomers, which are typical for most racemates, are absent in all the investigated crystals. The samples of the enantiopure compound 2 and 3 form stable supramolecular gels in hydrocarbon solvents. Some assumptions have been made linking the features of the molecular and crystal structures in the investigated series.

Molecular Oxygen as Mediator in the Metal Nanoparticles’ Electrosynthesis in N,N -Dimethylformamide

Ultra-fine gold (<2 nm), silver (5 ± 2 nm), and palladium (<1–2 nm) nanoparticles stabilized in polyvinylpyrrolidone shell were synthesized in N,N-dimethylformamide, using molecular oxygen dissolved in the electrolyte as mediator, by the reduction of the metals’ ions and complexes at the controlled potential of the oxygen reduction to its radical-anion. Pd-nanoparticles showed high catalytic activity in the reactions of p-nitrophenol reduction and Suzuki cross-coupling. Long-term ageing of spherical Ag-nanoparticles for 60 days in the post- electrolysis solution resulted in their consolidation (up to 17 ± 5 nm; the average size of crystallites 7.5 (3) nm). Upon similar exposure of Au-nanoparticles for 15 days, V-shaped nanoparticles were formed (length 112 ± 53 nm, width 58 ± 22 nm, crystallites 20(2)–31(1) nm); upon the isolation, dispersing into ethanol, and exposure for 48 h, hexagonal nanoparticles (105 ± 29 nm) and polygons (56 ± 25 nm, crystallites 24(2)–51(1) nm; upon dispersing into water and exposure for 8 h, spherical nanoparticles (13 ± 8 nm, crystallites 7(1)–13.4(5) nm). Thus obtained nanoparticles are characterized by methods of cyclic voltammetry, dynamic light scattering, scanning and high resolution transmission electron microscopy, and X-ray powder diffraction.

Highly active Pd–Ni nanocatalysts supported on multicharged polymer matrix

In this article, we report the synthesis of mono- and bimetallic Pd–Ni nanocomposites supported on a multicharged polymeric matrix for catalytic applications. The morphology and catalytic properties of the composites depend on the Pd–Ni ratio. In the Suzuki–Miyaura coupling reaction, the composite with an equal amount of palladium and nickel is the most active and the reaction occurs within six hours in water at room temperature.

Application of ferrocene-resorcinarene in silver nanoparticle synthesis

An amphiphilic resorcinarene with ferrocene groups at the lower rim has been applied as both reductant and stabilizer in the synthesis of colloidal silver nanoparticles. The structure of the nanocomposite obtained was investigated by transmission electron microscopy, atomic force microscopy, X-ray powder diffraction, dynamic light scattering, and UV and IR spectroscopy. In the nanocomposite, the silver nanoparticles are stabilized by the multi-layers formed by ferrocene-resorcinarene. The diameter of the nanoparticles is 20–30 nm while the size of the nanocomposite is about 45 nm. The nanoparticles demonstrate good catalytic activity for p-nitrophenol reduction. 40 nanomoles of the silver nanoparticles is sufficient to complete the reduction of p-nitrophenol over ten minutes.

Transformations of anilides of 3-aryl-2,3-epoxypropionic acids when exposed to acidic agents

Anilides of 3-aryl-2,3-epoxypropionic acids on treatment with aqueous HBr gave 3-aryl-3-bromo-2-hydroxypropionic acid anilides and (in some cases) 2-bromo-3-hydroxy regioisomers. Cyclization of these products into 3-arylquinolin-2(1H)-ones was studied.

Electrochemical synthesis of metal nanoparticles using a polymeric mediator, whose reduced form is adsorbed (deposited) on an electrode

Efficient mediated electrosynthesis of nanocomposite Au@р(MVCA8+-co-St) (~6 nm), in which ultrasmall Au nanoparticles (Au-NP) were bound in nanocapsules of water-soluble nanoparticles of соpolymer р(MVCA8+-co-St) of tetraviologen calix[4]resorcinol (MVCA8+) with styrene (St), was accomplished by the reduction of AuI in aqueous medium. The quanti- tative reduction of AuI was carried out using the theoretically necessary amount of electricity and was not accompanied by the deposition of metal on the electrode. Radical cations of viologen units MV•+ of the molecule р(MVCA4•+-co-St) adsorbed on the electrode and π-dimers MV•+···MV•+ of π-polymers [р(MVCA4•+-co-St)]n deposited on the electrode act- ed as the reducing agents with respect to AuI. During electrolysis, the nanoparticles agglo- merated to 37—50 nm. The nanocomposite particles dispersed in ethanol had sizes of 72±16 nm and also contained Au-NP with sizes of 51±8 and 19±3 nm. The catalytic activity of the nanocomposite in the reduction of p-nitrophenol with sodium borohydride was demon- strated. A similar reduction of AgCl nanoparticles (~250 nm) led to the formation of silver nanoparticles with crystallite sizes in the range of 7—11 nm, the process was inefficient, however, even when using 250% of electricity, an incomplete reduction of AgCl was still observed.

“Doubly enantiophobic” behavior during crystallization of racemic 1,5-dihydro-2H-pyrrol-2-one thioether

The titled compound 7 demonstrates unusual “doubly enantiophobic” behavior during crystallization. Namely, the mentioned substance forms two polymorphic modifications 7a and 7b that appear to be racemic conglomerates in the space groups P21 and P65 (or P61), respectively. Both 7a and 7b are thermodynamically stable at certain temperature ranges. Hence, γ-lactam 7 is prone to spontaneous resolution of the racemate into the enantiomers in two different ways, which is an exceptional phenomenon. Phase behavior and structure of the crystalline modifications of 7 were investigated by means of single crystal and powder X-ray diffraction, differential scanning calorimetry, temperature-resolved vibration spectroscopy, and hot-stage microscopy.

Influence of the nature of the substituent on the supramolecular synthon in crystals of benzo[b][1,4]diazepine derivatives

New benzo[b][1,4]diazepine derivatives, which differ only by the substituents in the positions 2 and 4 of the diazepine ring, were synthesized and studied by physicochemical methods. According to the X-ray diffraction data, the benzodiazepine moiety adopts a boat conformation in the crystal. The influence of the nature of the substituents on the type of the resulting supramolecular synthons was investigated.