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Aromatic Derivatives (aromatic + derivative)
Selected AbstractsHydrogen-bonding versus,,, stacking interactions in dipyrido[f,h]quinoxaline-6,7-dicarbonitrile and 6,7-dicyanodipyrido[f,h]quinoxalin-1-ium chloride dihydrateACTA CRYSTALLOGRAPHICA SECTION C, Issue 9 2008Leonid Kozlov The solvent-free title compound, C16H6N6, is an aromatic derivative of phenanthroline with an extended , system. It exhibits a remarkable ,,, columnar stacking in the crystal structure, with interplanar distances of 3.229,(3) and 3.380,(3),Å, the shorter spacing being between the two molecules within the asymmetric unit. Adjacent units along the stacked arrays are rotated in-plane with respect to one another by approximately 120°. The hydrochloride derivative, C16H7N6+·Cl,·2H2O, in which one of the phenanthroline N atoms has been protonated, crystallized as a dihydrate. The supramolecular organization in this compound is characterized by continuous hydrogen bonding between the component species, yielding two-dimensional hydrogen-bonded networks. This study demonstrates the high significance of the ,,, stacking interactions in the solvent-free aromatic system and how they can be undermined by introducing hydrogen-bonding capacity into the ligand. [source] Ab Initio Structure/Reactivity Investigations of Illudin-Based Antitumor Agents: A Model for Reaction in vivoHELVETICA CHIMICA ACTA, Issue 12 2003Laura (Hydroxymethyl)acylfulvene (HMAF, irofulven; 4), a third-generation derivative of a natural product extracted from the mushroom Omphalotus illudens, is selectively toxic towards certain forms of malignant tumors. Conversion of HMAF and cognates to stable aromatic derivatives is triggered by thiol attack in vitro and in vivo. Quantum-chemical methods predict well the structure for several functionalized derivatives of irofulven as compared to known X-ray crystallographic structures. Computational reaction profiles for thiol attack and aromatic rearrangement of irofulven and illudin S, a toxin from which irofulven is derived, provide insight into HMAF's selectivity and toxicity. Methods used include hybrid density-functional theory (HDFT), HartreeFock (HF), and MøllerPlesset second-order perturbation theory (MP2). Solvent effects have been explored by means of the new continuum-solvation method, COSab, presented in an accompanying paper. [source] Photophysical Properties of Terbium Molecular-based Hybrids Assembled with Novel Ureasil LinkagesPHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 4 2007Bing Yan Three silica-based organic,inorganic hybrid systems composed of hydroxyl aromatic derivatives (2-acetylphenol [HAP], 2-hydroxy-3-methylbenzoic acid [HMBA], 3-hydroxy-meta-phthalic acid [HMPHTH] complexes) were prepared via a sol,gel process. The active hydroxyl groups of the three ligands grafted by 3-(triethoxysilyl)-propyl isocyanate (TESPIC) through hydrogen transfer addition reaction were used as multi-functional bridge components, which can coordinate to Tb3+ with carbonyl groups, strongly absorb ultraviolet light and effectively transfer energy to Tb3+ through their triplet excited state, as well as undergo polymerization or crosslinking reactions with tetraethoxysilane (TEOS), for anchoring terbium ions to silica backbone. NMR, FT-IR, UV,vis absorption, luminescence spectroscopy was used to investigate the obtained hybrid material. UV excitation in the organic component resulted in strong green emission from Tb3+ ions due to an efficient ligand-to-metal energy transfer mechanism. [source] Antimicrotubular and cytotoxic activity of geiparvarin analogues, alone and in combination with paclitaxelCELL BIOCHEMISTRY AND FUNCTION, Issue 3 2001Antonella Miglietta Abstract Geiparvarin is an antiproliferative compound isolated from the leaves of Geijera parviflora, and may represent a new drug which targets tubulin. To better explore the potential use of this agent, we investigated the antimicrotubular and cytotoxic effects of new synthetic aromatic derivatives of geiparvarin. These drugs inhibited polymerization of microtubular protein, particularly when the assembly was induced by paclitaxel. The microtubular network organization of fibroblasts was altered more effectively by some drugs. Normal microtubule architecture completely disappeared when the cells were treated simultaneously with drugs and paclitaxel: microtubules depolymerized or were reorganized into bundles, in a similar but more disarrayed fashion than that observed after treatment with paclitaxel alone. Cytotoxicity studies showed a dose-dependent effect, whereas combined administration of drugs and paclitaxel increased cytotoxicity, more effectively in paclitaxel versus derivatives administration alone. Copyright © 2001 John Wiley & Sons, Ltd. [source] Carbonic Anhydrase Inhibitors: Inhibition of Cytosolic Carbonic Anhydrase Isozymes II and VII with Simple Aromatic Sulfonamides and Some Azo DyesCHEMICAL BIOLOGY & DRUG DESIGN, Issue 2 2009Fabrizio Carta Several substituted benzenesulfonamides were synthesized by various pathways starting from sulfanilamide. The sulfanilamide diazonium salt was reacted with copper (I) halides, potassium iodide and/or aromatic derivatives, leading to 4-halogeno-, and 4-hydroxy-benzenesulfonamides as well as diazo dyes incorporating sulfamoyl moieties. These sulfonamides were assayed as inhibitors of two physiologically relevant isoforms of the zinc enzyme carbonic anhydrase (CA, EC 4.2.1.1), i.e., the cytosolic CA II (ubiquitous), and CA VII (brain-specific enzyme). Good CA inhibitory activity was detected for some of these derivatives, with inhibition constants (Ki) in the range of 17.5,863 nm against CA II; and 30,4200 nm against CA VII. [source] | |||||||||||||