1:1 and 1:2 Inclusion Complexes of Di-tert-butyl l-tartrate with α-Cyclodextrin: A Diffusion Study

The diffusion properties at two overall compositions of a ternary aqueous system containing α-cyclodextrin and a double-functional guest molecule, namely di-tert-butyl l-tartrate, have been studied by means of the Gouy interferometry. The experimental data are interpreted in terms of two independent chemical equilibria involving inclusion compounds. The elements of the diffusion coefficient matrix have been expressed as functions of the two equilibrium constants as well as of the diffusivities of the actual species occurring in solution. The reliability of the diffusion coefficients obtained through the Fujita–Gosting–Revzin procedure is also discussed in terms of its dependence on the composition of solutions used in the Gouy experiments.     

LSb(μ‐I)2(μ‐S)SbL: a Neutral Triply Bridged Complex obtained from Sb Powder and Diiodine activated by Tetraphenyldithioimidodiphosphine (HL)

The synthesis of the complex LSb(μ‐I)₂(μ‐S)SbL ( 1 ) was accomplished by reacting antimony powder with diiodine activated by tetraphenyldithioimidodiphosphine (SPPh₂NHPPh₂S) (H L ). X‐ray diffraction (tetragonal, M = 1426.30, space group I 4₁/a (No. 88), Z = 8, a = 18.020(2) Å, c = 33.037(4) Å) shows that ( 1 ) is a dinuclear Sb^III complex, in which the two metal ions are bridged by one sulphide and two iodide anions. An anionic bidentate L ligand completes the coordination sphere of each metal with its two sulphur atoms, leading to a slightly distorted pyramidal coordination geometry, since each metal ion shows the presence of a sterically active lone‐pair in trans position to the bridging sulphide. ³¹P CP‐MAS NMR and IR spectroscopies are in accordance with the structural features of the complex.     

Evaluation by Fourier Transform Infrared Spectroscopy of the different crystalline forms in syndiotactic polystyrene samples

Fourier transform infrared (FTIR) spectra of syndiotactic polystyrene (s-PS) semicrystalline samples have been examined by using the spectral subtraction approach. For the crystalline forms including trans-planar chains (trigonal α and orthorhombic β) a number of conformational and structural order effects, not previously described in the literature, have been identified. A method based on the results of the spectral subtraction analysis has been developed for the determination of the crystallinity degree and compared with the standard method based on the wide-angle X-ray diffraction patterns. The spectral subtraction analysis on FTIR spectra allows also an easy evaluation of the amount of α and β crystalline phases (often simultaneously present in melt-crystallized samples) although both contain chains in a same conformation. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35 : 1055–1066, 1997     

Toward Multitasking Pharmacological COX-Targeting Agents: Non-Steroidal Anti-Inflammatory Prodrugs with Antiproliferative Effects

The antitumor activity of certain anti-inflammatory drugs is often attributed to an indirect effect based on the inhibition of COX enzymes. In the case of anti-inflammatory prodrugs, this property could be attributed to the parent molecules with mechanism other than COX inhibition, particularly through formulations capable of slowing down their metabolic conversion. In this work, a pilot docking study aimed at comparing the interaction of two prodrugs, nabumetone (NB) and its tricyclic analog 7-methoxy-2,3-dihydro-1H-cyclopenta[b]naphthalen-1-one (MC), and their common active metabolite 6-methoxy-2-naphthylacetic acid (MNA) with the COX binding site, was carried out. Cytotoxicity, cytofluorimetry, and protein expression assays on prodrugs were also performed to assess their potential as antiproliferative agents that could help hypothesize an effective use as anticancer therapeutics. Encouraging results suggest that the studied compounds could act not only as precursors of the anti-inflammatory metabolite, but also as direct antiproliferative agents.     

Spectroscopic studies and X-ray crystal structures of charge-transfer complexes of 1,4,7-trithiacyclononane with diiodine

1,4,7-Trithiacyclononane ([9]aneS₃) reacts with molecular diiodine in CH₂Cl₂ to form a 1:1 adduct. The formation constant and the thermodynamic parameters of this adduct have been determined by UV-visible spectra of several solutions at the temperatures of 15, 20, 25, 30, and 35°C. The ¹³C NMR spectra show that adducts with higher ligand/diiodine molar ratios are formed. Two neutral charge-transfer molecular compounds having formula 2[9]aneS₃ · 4I₂ ( I ) and [9]aneS₃ · 3I₂ · ( II ) have been obtained as crystals. The crystals of I are triclinic (a = 8.498(2) Å, b = 13.984(4) Å, c = 14.898(6) Å, α = 65.57(2)°, γ = 89.19(2)°, γ = 81.26(2)°, Z = 2, space group P1; R = 0.025) and contain units formed by two [9]aneS₃ molecules connected by a diiodine molecule; one [9]aneS₃ binds two other diiodine molecules, while the second binds only one other diiodine molecule. The crystals of II are monoclinic (a = 13.810(2) Å, b = 9.829(4) Å, c = 16.198(6) Å, β = 113.41(2)°, Z = 4, space group P2₁/c; R = 0.019) and contain molecules of [9]aneS₃ binding three diiodine molecules. FT-Raman spectra in the characteristic v(I–I) region, carried out on the solid adducts, are discussed in comparison with the structural parameters.     

Conformational analysis of highly extended poly(ethylene terephthalate) chains by Monte Carlo calculations

The conformational disorder compatible with the highly extended chains found in mesomorphic poly(ethylene terephthalate) has been studied by Monte Carlo calculations on model oligomers confined inside cylindrical tubes. The distribution of torsional angles for such extended chains is characterized by O C C O bonds being always in the trans domain, while the C O C C bonds show an approximately similar probability of being found in trans and gauche states, the probability maxima being centered at 90° and −90° in the latter cases. At variance with the torsional angles of the O C C O and the ester bonds, always very close to 180°, the distributions for all other torsional angles show flat and broad probability maxima, indicating the possibility of substantial deviations from the average value inside each domain. This is also true for the fictitious O C˙˙˙C O bonds across the phenylene rings, for which a nearly trans geometry is preferred in extended conformations.     

Functionalization of a polyaspartamide with glycidyl methacrylate: A useful method to prepare hydrogels through gamma irradiation

α,β-Poly(N-2-hydroxyethyl)-DL-aspartamide (PHEA) was derivatized with glycidyl methacrylate (GMA). Aqueous solutions of the obtained copolymer PHEA-GMA (PHG) were irradiated by gamma rays with a dose rate of 0.5 KGy/h and at zero°C in the presence or in the absence of N, N'-methylenebisacrylamide (BIS). New hydrogel systems were obtained and characterized by FT-IR analyses and swelling measurements in aqueous medium at different pH values.