Molecular rearrangement of photoparthenin by BF3-etherate-acetic acid complex: X-ray crystal structure of a novel product

The structure of a novel compound,Iupac name: bicyclo [2.4.0]-octa-1,3-dimethyl-2,3-pentan-9-methylene-8, 10-butan-diolide, which resulted on treatment of photoparthenin with BF₃-etherate acetic acid, has been established uniquely by X-ray crystallography. C₁₅H₁₈O₄ is orthorhombic, space group P2₁2₁2₁, with the cell dimensionsa=8.444(1),b=9.964(2),c=16.239(2) Å,V=1366.3(2) ų,Z=4,M _r =262.3,D _o=1.29,D _x=1.28 g cm^–3, F(000)=560,T=293K,R=0.065 for 818 observed reflections. -lactone ring has a skew-boat, -lactone ring has an envelope, and the remaining six-membered ring has a distorted chair conformation. The four-membered ring is nonplanar. There are two intramolecular and one intermolecular short C-HO interactions 2.819, 2.834, and 3.259 Å, respectively, which stabilize the crystal structure.N.C.L. Communication No. 4583.     

Supramolecular Organization in Tetra Aqua (μ-8-Hydroxyquinoline-5-sulfonate) Barium (II) and Ag···I Interactions in a Pseudopolymorphic Form of (7-Iodo-8-hydroxyquinoline-5-sulfonate) Silver (I) Monohydrate

Abstract  

The complexes, Ba (HQS) (H₂O)₄ (HQS = 8-hydroxyquinoline-5-sulfonic acid) (1) and Ag (HIQS) (H₂O) (Ferron = 7-iodo-8-hydroxyquinoline-5-sulfonic acid) (2) have been synthesized and characterized by X-ray diffraction analysis and spectroscopic studies. In compound 1, Ba²⁺ ion has a nine-coordinate monocapped antiprismatic geometry. In compound 2, Ag⁺ has distorted tetrahedral coordination and Ag···I interactions generate the supramolecular architectures. The complexes have been characterized by FT-IR and UV–Visible measurements. In both the structures, the inversion-related organic ligands are stacked over one another leading to three-dimensional networks.     

Isoselenocyanates derived from Boc/Z-amino acids: synthesis, isolation, characterization, and application to the efficient synthesis of unsymmetrical selenoureas and selenoureidopeptidomimetics

Isoselenocyanates derived from Boc/Z-amino acids are prepared by the reaction of the corresponding isonitriles with selenium powder in presence of triethylamine at reflux. The utility of these new classes of isoselenocyanates in the preparation of selenoureidodipeptidomimetics possessing both amino as well as carboxy termini has been accomplished. The ¹H NMR analysis confirmed that the protocol involving the conversion of isonitriles to isoselenocyanates and their use as coupling agents in assembling selenoureido derivatives is free from racemization.     

An analysis of C—H⋯O and C—H⋯π interactions in three substituted 4‐ketotetra­hydro­indoles

The crystal and molecular structures of the three 4‐ketotetrahydro­indoles 2‐(4‐chloro­phenyl)‐1‐(4‐fluoro­phenyl)‐6,6‐dimethyl‐4,5,6,7‐tetra­hydro‐1H‐indol‐4‐one (C₂₂H₁₉ClFNO), (I), 1‐(4‐fluoro­phenyl)‐2‐(4‐methoxy­phenyl)‐6,6‐di­methyl‐4,5,6,7‐tetra­hydro‐1H‐indol‐4‐one (C₂₃H₂₂FNO₂), (II), and 6,6‐dimethyl‐1,2‐di­phenyl‐4,5,6,7‐tetra­hydro‐1H‐indol‐4‐one (C₂₂H₂₁NO), (III), have been determined via single‐crystal X‐ray diffraction in order to study the intermolecular interactions therein. All three structures are stabilized via intermolecular C—H⋯O and C—H⋯π interactions, generating different molecular motifs.     

A novel series of 2,5-disubstituted 1,3,4-thiadiazoles as potential anticonvulsant agent

<正>In pursuit for better antiepileptic drug and the importance of semicarbazones and 2,5-disubstituted 1,3,4-thiadiazoles as anticonvulsant pharmacophore,a series of novel N-({5-[(6-methyl-1-benzofuran-3-y1)methyl]-1,3,4-thiadiazol-2-yl}carbamothioyl) -2/3/4-substitutedbenzamide were designed,synthesized and evaluated for their anticonvulsant activity.The findings of the present studies confirmed that the pharmacophore model with four binding sites is crucial for anticonvulsant activity. Structure-activity relationships among synthesized compounds were also established.     

Weak interactions involving organic fluorine: a comparative study of the crystal packing in substituted isoquinolines

Weak interactions involving fluorine have been analyzed in the structure of 6-methoxy-1,2-diphenyl-1,2,3,4-tetrahydroisoquinoline with fluorine substitution at para-, meta- and ortho- positions, respectively, on the 1-phenyl ring. The packing modes in the crystalline lattice as determined by X-ray diffraction techniques generate motifs via F?F, C-H?F and C-F?π interactions. The three structures as compared to the parent compound depict conformational changes in the saturated tetrahydroisoquinoline moiety. The salient features of the four structures in terms of weak interactions involving fluorine suggest that organic fluorine does resemble the other halogens.     

Luminescence techniques and characterization of the morphology of polymer latices 2. Fluorescence lifetime, phosphorescence and fluorescence anisotropy studies

Five poly(n-butyl methacrylate), PBMA, latex dispersions have been prepared, each incorporating a different fluorescent label, via a two-stage seeded emulsion polymerization. The resultant latices contain ca. 35% by weight total solids and are of 80 (+/-10) nm diameter as determined by photon correlation spectrometry. Luminescence spectroscopic techniques, namely fluorescence (and phosphorescence) excited state lifetime measurements in addition to time-resolved anisotropy experiments have provided useful information regarding the morphology, microviscosity and water permeability of the resultant particles. A picture of the PBMA colloid emerges of an interior which is highly viscous and water impermeable in nature. Indeed, the environment is protective enough to sustain room temperature stabilized phosphorescence from both an acenaphthylene and 9-phenanthrylmethyl methacrylate labeled dispersion through simple nitrogen purging of the solutions. However, the current spectroscopic measurements should be viewed with the knowledge that each luminescent label may fashion its own distinctive microenvironment within the latex during polymerization.     

Julia Sets of Joukowski-Exponential Maps

Let $h$ be a transcendental entire function of finite type such that all the coefficients in its Taylor series about the origin are non-negative, $h(x)\! >\!0 \hbox { for } x \!<~0,\,h(0)\ge 1$ and each finite singular value of $h$ is either real or is with unit modulus. For $J(z) = z + (1/z)\hbox { and } n \in \mathbb {N}$ , we define $f_{\lambda }(z)=\lambda J^n(h(z))$ . It is proved that there exists a $\lambda ^{*}$ such that the Julia set of $f_\lambda $ is a nowhere dense subset of $\widehat{\mathbb {C}}\hbox { for }0< \lambda \le \lambda ^*$ whereas it becomes equal to $\widehat{\mathbb {C}}$ for $\lambda >\lambda ^*$ . A detailed study of the Julia sets of Joukowski-exponential maps $\lambda J( e^z+1)$ is undertaken when it is not equal to the whole sphere. Such a Julia set consists of a non-singleton, unbounded and forward invariant component, infinitely many non-singleton bounded components and singleton components. A bounded component of the Julia set eventually not mapped into the unbounded Julia component is singleton if and only if it is not expanding. The Julia set contains two topologically as well as dynamically distinct completely invariant subsets.