N‐alkylated 3,5‐bis(arylidene)‐4‐piperidones. Synthetic approaches,X‐ray structure and anticancer activity

In a search for cytotoxic fluorescent materials a series of N‐alkylated and N,N‐dialkylated 3,5‐bis(arylidene)piperidones was synthesized. Alkylation of 3,5‐bis(arylidene)‐4‐piperidone afforded quaternary salts only while condensation of N‐alkyl‐4‐piperidones with substituted benzaldehydes was a convenient route to the corresponding N‐alkylated compounds. Compounds and their pharmaceutically acceptable salts demonstrated high activity against resistant human lung carcinoma cell line A549 with IC₅₀ values in the range of 0.3‐6.5 μM.     

Hydrogen adsorption in a highly stable porous rare-earth metal-organic framework: sorption properties and neutron diffraction studies

A highly stable porous lanthanide metal-organic framework, Y(BTC)(H2O).4.3H2O (BTC = 1,3,5-benzenetricarboxylate), with pore size of 5.8 A has been constructed and investigated for hydrogen storage. Gas sorption measurements show that this porous MOF exhibits highly selective sorption behaviors of hydrogen over nitrogen gas molecules and can take up hydrogen of about 2.1 wt % at 77 K and 10 bar. Difference Fourier analysis of neutron powder diffraction data revealed four distinct D2 sites that are progressively filled within the nanoporous framework. Interestingly, the strongest adsorption sites identified are associated with the aromatic organic linkers rather than the open metal sites, as occurred in previously reported MOFs. Our results provide for the first time direct structural evidence demonstrating that optimal pore size (around 6 A, twice the kinetic diameter of hydrogen) strengthens the interactions between H2 molecules and pore walls and increases the heat of adsorption, which thus allows for enhancing hydrogen adsorption from the interaction between hydrogen molecules with the pore walls rather than with the normally stronger adsorption sites (the open metal sites) within the framework. At high concentration H2 loadings (5.5 H2 molecules (3.7 wt %) per Y(BTC) formula), H2 molecules form highly symmetric novel nanoclusters with relatively short H2-H2 distances compared to solid H2. These observations are important and hold the key to optimizing this new class of rare metal-organic framework (RMOF) materials for practical hydrogen storage applications.     

Study the kinetics of thermolysis of textile materials modified by polyorganosiloxanes

Analysis of the parameters of thermal oxidative degradation of textile materials, modified commercial polyorganosiloxanes (DowCorning 3605, Silastic 9252/250 P) is performed. The influence of encapsulated adjuvants-refrigerant 23 (CHF₃) and ultrafine carbon-on the kinetic characteristics of thermolysis of cellulose fabrics is studied.     

Atomic force microscopy imaging of novel macromolecular species,nanosponges, and their clusters

Atactic polystyrene of M = 330,000 Da and M_w/M_n = 1.04 was subjected to a complete chloromethylation. By heating the chloromethyl polystyrene with SnCl₄ in a very dilute solution in ethylene dichloride, the polymeric coils were converted into intramolecularly hypercrosslinked macromolecules, called “nanosponges.” These species have a molecular weight of about 370,000 Da and a diameter of about 17 nm. When in solution, the nanosponges display a tendency to reversibly self‐assemble into regular clusters. Preparative size‐exclusion chromatography isolates a fraction consisting predominantly of spherical clusters that are composed of 13 subunits and acquire a molecular weight of approximately 5.0 × 10⁶ Da and a diameter of 45 nm. Scanning atomic force microscopy (AFM) provides images of individual nanosponges, N = 13 clusters, as well as higher spherical clusters. The regular spherical species most probably belong to the cluster series N = 1 + ∑(10n² + 2), where n is the number of shells around the central nanosponge. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 1451–1455, 1999     

Stereoselective Synthesis and X-Ray Structure Determination of Labeled [1, 2, 3-<Superscript>13</Superscript>C<Subscript>3</Subscript>]-1-(Phenylsulfinyl)-3-Benzyloxyacetone

[1,2,3-¹³C₃]-1-(Phenylsulfinyl)-3-benzyloxyacetone, C₁₆H₁₆O₃S, (3) has been synthesized and its crystal structure has been determined by a single-crystal X-ray diffraction analysis. The X-ray diffraction study revealed that compound 3 crystallizes in the monoclinic crystal system in the acentric space group Pc, with cell constants at T = 100 K: a = 16.073(5), b = 5.5079(16), c = 7.949(2) Å, β = 100.221(4)^°, V = 692.6(3) ų, Z = 2, d _calc = 1.383 g/cm³. Compound 3 contains the chiral tetravalent three-coordinated sulfur atom, which has a distorted tetrahedral configuration with a lone electron pair occupying one of the tetrahedron vertices. In the crystal, the molecules are packed in stacks along the b axis; the stacks consist of the molecules of the same chirality. Furthermore, the stacks of the molecules of the opposite chirality alternate along the c axis. The molecules in neighboring stacks are arranged by head-to-tail orientations. There are no short intermolecular contacts in the crystal of 3.     

The effect of schungite filler on the degree of crystallinity of polypropylene and polyethylene in ternary mixed composites

The effect of schungite filler with a carbon content of 39 wt % on the degree of crystallinity of polypropylene and polyethylene in mixed ternary composites is studied. The PP-to-PE volume ratios are 80: 20 and 50: 50. With an increase in the content of the schungite filler, the fraction of the crystalline phase in PP increases, although the degree of crystallinity of PE decreases; this behavior is related to the high affinity between polypropylene and schungite filler. The surface structure of the initial and schungite-loaded PP-PE materials of various compositions is studied via AFM. The surface structure of the above composites is shown to be different, and its specific features are dependent on the ratio between polymer components and on the order in which all components are introduced into the system.     

Insight into the structures of [M(C5H4I)(CO)3] and [M2(C12H8)(CO)6] (M = Mn and Re) containing strong I...O and π(CO)–π(CO) interactions

The compounds tricarbonyl(η⁵‐1‐iodocyclopentadienyl)manganese(I), [Mn(C₅H₄I)(CO)₃], (I), and tricarbonyl(η⁵‐1‐iodocyclopentadienyl)rhenium(I), [Re(C₅H₄I)(CO)₃], (III), are isostructural and isomorphous. The compounds [μ‐1,2(η⁵)‐acetylenedicyclopentadienyl]bis[tricarbonylmanganese(I)] or bis(cymantrenyl)acetylene, [Mn₂(C₁₂H₈)(CO)₆], (II), and [μ‐1,2(η⁵)‐acetylenedicyclopentadienyl]bis[tricarbonylrhenium(I)], [Re₂(C₁₂H₈)(CO)₆], (IV), are isostructural and isomorphous, and their molecules display inversion symmetry about the mid‐point of the ligand C[triple‐bond]C bond, with the (CO)₃M(C₅H₄) (M = Mn and Re) moieties adopting a transoid conformation. The molecules in all four compounds form zigzag chains due to the formation of strong attractive I...O [in (I) and (III)] or π(CO)–π(CO) [in (I) and (IV)] interactions along the crystallographic b axis. The zigzag chains are bound to each other by weak intermolecular C—H...O hydrogen bonds for (I) and (III), while for (II) and (IV) the chains are bound to each other by a combination of weak C—H...O hydrogen bonds and π(Csp²)–π(Csp²) stacking interactions between pairs of molecules. The π(CO)–π(CO) contacts in (II) and (IV) between carbonyl groups of neighboring molecules, forming pairwise interactions in a sheared antiparallel dimer motif, are encountered in only 35% of all carbonyl interactions for transition metal–carbonyl compounds.     

Tricarbonyl(η5‐formylcyclopentadienyl)manganese(I) and tricarbonyl(η5‐formylcyclopentadienyl)rhenium(I) containing short π(CO)...π(CO) and π(CO)...π interactions

The structures of tricarbonyl(formylcyclopentadienyl)manganese(I), [Mn(C₆H₅O)(CO)₃], (I), and tricarbonyl(formylcyclopentadienyl)rhenium(I), [Re(C₆H₅O)(CO)₃], (II), were determined at 100 K. Compounds (I) and (II) both possess a carbonyl group in a trans position relative to the substituted C atom of the cyclopentadienyl ring, while the other two carbonyl groups are in almost eclipsed positions relative to their attached C atoms. Analysis of the intermolecular contacts reveals that the molecules in both compounds form stacks due to short attractive π(CO)...π(CO) and π(CO)...π interactions, along the crystallographic c axis for (I) and along the [201] direction for (II). Symmetry‐related stacks are bound to each other by weak intermolecular C—H...O hydrogen bonds, leading to the formation of the three‐dimensional network.