Some symmetry aspects of layered-clathrate structures formed by Ni (NCS)2 (4-methylpuridine)4

The crystal structures of layered clathrate inclusion compounds of Ni(CNS)₂ (4-methylpyridine)₄ with 1-bromonaphthalene (I) and azulene (II) were analyzed by x-ray single-crystal diffractometry [crystal data: I–C₄₆H₄₂N₆S₂Br₂Ni; a=11.88(1), b=11.82(1), c=32.79(3), =102.0(1), Z=4, P2₁/c; II–C₄₆H₄₄N₆S₂Ni; a=11.51(2), b=11.64(1), c=32.98(2), =103.4, Z=4, P2₁/n]. Disordering of guest molecules in I is concluded, based on x-ray study, and positions of the guest (each of the two symmetry independent molecules disordered over two orientations) have been refined. In II disoder of guest-azulene is also observed but only one from the two symmetrically independent guest molecules could be located from the x-ray data. The empirical force field calculations were performed for I and II. The results were used for location of the second azulene molecule and for discussion of the disorder mole (short or long-range).     

On the clathratogenic properties of the Ni (NCS)2 (4-Vinylpyridine)4 host

The crystal structure of the non-clathrated -Ni(NCS)₂ (4-Vinylpyridine)₄ complex was solved and refined to R=0.056 (crystal data: a=11.27(3), b=16.86(1), c=32.06(1) Z=8, V=6092 ų;Pbca; d_x=1.30 g. cm^–3). The complex molecule adopts an asymmetric, windmill conformation of the four pyridine ligands. The -phase was used as a solid substrate for clathration of liquid o-, m- and p-xylene, at 25°C. The composition of the products, the enthalpies of clathration and kinetic course of the processes were investigated. The clathration enthalpies, per mole of the host, are equal to 17.07, 14.1 and 21.77 kJ and correspond to the 1.05, 1.11 and 1.30 guest/host molar ratios for, respectively, ortho, meta and para-xylene. The clathration rates follow the order para>ortho>meta. The results are discussed from the structural point of view.     

The role of template in the synthesis of meso-hexamethyl-meso-hexaphenyl-calix[6]pyrrole: trihalogenated compounds as templates for the assembly of a host with a trigonal cavity

Trihalogenated compounds act as effective and selective templates in the template-assisted synthesis of meso-hexaphenyl-calix[6]pyrrole.     

IntelliDrug Implant for Medicine Delivery in Alzheimer's Disease Treatment

Summary : IntelliDrug it is a denture implant containing a reservoir with drug and making enable a galantamine transport via buccal mucosa by means of iontophoresis. The in vitro experimental studies on drug passive and iontophoretic transport through porcine buccal mucosa were carrying out in horizontal two-chamber permeation cell with silver electrodes. The drug mass flux was investigated. The influences of initial drug concentration and current density for transport velocity were defined.     

Stereoselective syntheses of pinane-based 1,3-diamines and their application as chiral ligands in the enantioselective addition of diethylzinc to benzaldehyde

A library of 1,3-difunctionalized pinane derivatives was synthesized and applied as chiral catalysts in the addition of diethylzinc to benzaldehyde. The key intermediate β-lactam 2 was prepared regio- and stereoselectively from (?)-apopinene 1. The treatment of 2 with di-tert-butyl dicarbonate afforded N-Boc β-lactam 3, while acid-catalyzed ring opening of 2 resulted in amino acid 4. Nucleophilic ring opening of 3 with dimethylamine, followed by deprotection and benzylation, furnished β-amino amides 5, 8, and 11, which were transformed in two steps into the corresponding N-tosyldiamines 7, 10, and 13, respectively. Since the use of other amines, such as diethylamine, to study the influence of dialkyl substitution was unsuccessful, an alternative synthetic route was applied. Amidation of tosylated β-amino acid 14 furnished amides 15–25. Reduction of 15, 16, 19, 20, and 24 resulted in N-tosyl diamines 26–30. The β-amino amides and N-tosylated diamines were used as chiral ligands in the enantioselective alkylation of benzaldehyde with diethylzinc, resulting in (R)- and (S)-1-phenyl-1-propanol. The (R)-enantiomer was predominant except when 17, 22, 23, and 25 were used as ligands, in which case the opposite stereochemistry was observed. The best ee values (up to 83%) were obtained when 17, 20, 23, and 25 were used as catalysts.     

Ring-Opening Polymerization of Lactones Initiated with Metal Hydroxide-Activated Macrocyclic Ligands: Determination of Mechanism and Structure of Polymers

Anhydrous alkali metal hydroxide (KOH, NaOH, and LiOH)-activated macrocyclic ligand complexing metal cations, i.e., coronands 12C4, 15C5, 18C6, DCH24C8, and cryptand C222, were selected for initiation of β-butyrolactone (β-BL) and ε-caprolactone (ε-CL) polymerization. It was found that β-BL polymerizes in the presence of KOH/18C6, KOH/C222, and NaOH/C222 systems. The real initiators in this case are two salts, potassium 3-hydroxybutyrate and potassium trans-crotonate, which are responsible for the formation of two fractions of the obtained polymer. ε-CL underwent polymerization with KOH or NaOH activated by all ligands used or without the ligand but with LiOH/12C4. Using KOH-activated strong ligands, i.e., 15C5, 18C6, or C222, two polymer fractions were generated containing linear and, unexpectedly, also cyclic macromolecules. The mechanism of the studied processes is discussed.     

Derivatives of benzo[b]furan. Part I. Conformational studies of khellinone and visnaginone

Structural Chemistry - The structural analysis of khellinone and visnaginone indicated the planarity of the benzo[b]furan ring system. The oxygen or carbon atoms of the substituents, –OH,...     

Effects of low-dose ionizing radiation on α,β-globulins solutions studied by DSC

An attempt has been made to detect the effect of a small dose of ionizing radiation on the course of α,β-globulin thermal denaturation in aqueous solutions. Doses of 0.1 and 1.8 Gy have been delivered using γ-rays emitted by ⁶⁰Co isotope while doses of 10 and 100 Gy have been supplied by X-rays produced by linear accelerator. The highest dose has visibly changed DSC curve of protein solution while the changes due to lower doses are hardly detectable. Although very weak, the irradiation effect found has been dose dependent. The results suggest that the influence of ionizing radiation on globulins solution is bigger when the dose rate is lower at given dose. The opposite direction of differences between irradiated and control samples for fresh and stored protein solutions suggests various characters of changes in initial and later period of sample aging. This may be an important reason for difficulties in an investigation of the effect of ionizing radiation on protein solution, especially for low doses delivered very slowly.     

Novel 3-Acetyl-2,5-disubstituted-1,3,4-oxadiazolines: Synthesis and Biological Activity

The aim of our study was the two-stage synthesis of 1,3,4-oxadiazole derivatives. The first step was the synthesis of hydrazide–hydrazones from 3-methyl-4-nitrobenzhydrazide and the corresponding substituted aromatic aldehydes. Then, the synthesized hydrazide–hydrazones were cyclized with acetic anhydride to obtain new 3-acetyl-2,3-disubstituted-1,3,4-oxadiazolines. All of obtained compounds were tested in in vitro assays to establish their potential antimicrobial activity and cytotoxicity. Our results indicated that few of the newly synthesized compounds had some antimicrobial activity, mainly compounds 20 and 37 towards all used reference bacterial strains (except Klebsiella pneumoniae, Proteus mirabilis, and Pseudomonas aeruginosa) and fungi. These substances showed a strong or powerful bactericidal effect, especially against Staphylococcus spp. belonging to Gram-positive bacteria. Compound 37 was active against Staphylococcus epidermidis at minimal inhibitory concentration (MIC) = 0.48 µg/mL and was characterized by low cytotoxicity. This compound possessed quinolin-4-yl substituent in the second position of 1,3,4-oxadiazole ring and 3-methyl-4-nitrophenyl in position 5. High effectiveness and safety of these derivatives make them promising candidates as antimicrobial agents. Whereas the compound 20 with the 5-iodofurane substituent in position 2 of the 1,3,4-oxadiazole ring showed the greatest activity against S. epidermidis at MIC = 1.95 µg/mL.