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PubMed2006

Donor-acceptor-donor-type liquid crystal with a pyridazine core.

[structure: see text] A new liquid crystalline material having an ethylenedioxythiophene-pyridazine-ethylenedioxythiophene (EDOT-PDZ-EDOT) core with two peripheral long alkyl chains was prepared. The designated donor-acceptor-donor (D-A-D)-type core structure induced a distinct smectic liquid crystalline phase due to the strong intermolecular interaction. The photophysical property and the layer structure of the liquid crystal were investigated by differential scanning calorimetry, polarized light microscopy, X-ray diffraction, and cyclic voltammetry.

Journal Article↗

PubMed2004

Fused pyridazines: rigid multidentates for designing and fine-tuning the structure of hybrid organic/inorganic frameworks.

Fused pyridazines (1,2,3,6,7,8-hexahydro-cinnolino[5,4,3-cde]cinnoline, L and its 2,2,7,7-tetramethyl derivative, Me4L) are designed as rigid multidentate ligands for the construction of framework solids. In combination with copper(I) bromide (iodide) they provide excellent structural examples for predictive engineering and the possibilities for further fine-tuning of the framework architectures facilitated by the tetradentate function of the ligands and effective cooperation of organic and inorganic bridges. This study features control over helical structures for (CuX)n chains and homo/heterochiral combination of the helices in the lattice, the design of a range of channelled and tubular CuX networks and the structural significance of ligand shape complementarity. 3D tetragonal Cu2X2(L) frameworks exist either as chiral or achiral supramolecular isomers Cu2I2(Me4L) and Cu12I12[Cu(CH3CN)]3(L)(6-)Cu3I6.CH3CN illustrate 3D hexagonal channelled and tubular arrays; Cu2I2(Me4L)(CH3CN) and Cu4I4(L)(CH3CN)2 complexes are 1D polymers.

Journal Article↗

PubMed2005

Neutral Cu4N12 and Ag4N12 metallacycles with a para-cyclophane framework assembled from copper(I) and silver(I) pyrazolates and pyridazine.

Trinuclear copper(I) and silver(I) pyrazolates {[3,5-(CF3)2Pz]M}3 (M = Cu and Ag) react with pyridazine to give neutral, tetranuclear metallacycles with a para-cyclophane core whereas benzo[c]cinnoline fails to break the cyclic pyrazolate trimers under similar conditions, and affords a metalla-propellane featuring both two- and three-coordinate metal sites.

Journal Article↗

PubMed2006

Cadmium nitrate coordination polymers with substituted pyridazino[4,5-d]pyridazines.

catena-Poly[[aquabis(nitrato-kappa2O,O')cadmium(II)]-mu-1,2,3,6,7,8-hexahydrocinnolino[5,4,3-cde]cinnoline-kappaN1:kappaN6], [Cd(NO3)2(C12H12N4)(H2O)]n, (I), and catena-poly[[[bis(nitrato-kappa2O,O')cadmium(II)]-mu-2,2,7,7-tetramethyl-1,2,3,6,7,8-hexahydrocinnolino[5,4,3-cde]cinnoline-kappaN1:kappaN6] chloroform solvate], {[Cd(NO2)2(C12H12N4)].CHCl3}n, (II), are the first structurally examined cadmium-pyridazine coordination compounds. They possess one-dimensional polymeric structures supported by the bidentate bridging function of the cinnolino[5,4,3-cde]cinnoline ligands, which lie about inversion centres. The Cd atoms are seven-coordinated in (I) and six-coordinated in (II), involving two bidentate nitrate groups [Cd-O = 2.229 (2)-2.657 (2) A], two N atoms of the cinnoline ligands [Cd-N = 2.252 (2)-2.425 (2) A], and, additionally, a water O atom in (I) [Cd-O = 2.284 (2) A]. In (I), the coordinated organic and aqua ligands form an intramolecular O-H...N hydrogen bond [O...N = 2.730 (3) A].

Journal Article↗

PubMed2004

Pharmacological effects of ATI22-107 [2-(2-{2-[2-chloro-4-(6-oxo-1,4,5,6-tetrahydro-pyridazin-3-yl)-phenoxy]-acetylamino}-ethoxymethyl)-4-(2-chloro-phenyl)-6-methyl-1,4-dihydro-pyridine-3,5-dicarboxylic acid dimethyl ester)], a novel dual pharmacophore, on myocyte calcium cycling and contractility.

Historically, inhibitors of type III phosphodiesterases (PDE-III) have been effective inotropes in mammalian myocardium, but their clinical utility has been limited by adverse events, including arrhythmias that are considered to be due to Ca(2+) overload. ATI22-107 [2-(2-{2-[2-chloro-4-(6-oxo-1,4,5,6-tetrahydro-pyridazin-3-yl)-phenoxy]-acetylamino}-ethoxymethyl)-4-(2-chlorophenyl)-6-methyl-1,4-dihydro-pyridine-3,5-dicarboxylic acid dimethyl ester)], a novel, dual pharmacophore compound, was designed to simultaneously inhibit the cardiac phosphodiesterase (PDE-III) and produce inotropic effects, whereas inhibiting the L-type calcium channel (LTCC) was designed to minimize increases in diastolic Ca(2+). We compared the effects of ATI22-107 and enoximone, a pure PDE-III inhibitor, on the Fluo-3 calcium transient in normal feline ventricular myocytes and trabeculae. Enoximone-induced dose-dependent increases in peak [Ca(2+)](i), diastolic [Ca(2+)](i), T50, and T75. ATI22-107 demonstrated similar dose-dependent increases in peak [Ca(2+)](i) at 300 nM and 1.0 microM doses, with no further increases at higher doses. Throughout the dosing range, ATI22-107 induced much smaller, if any, increases in diastolic [Ca(2+)](i), T(25), and T(75). Current measurement of LTCC via patch-clamp techniques revealed dose-dependent decreases in LTCC current with an increasing dose of ATI22-107, thereby validating the dual functionality of the drug that has been proposed in this study. Studies in isolated trabeculae demonstrated that enoximone-induced a dose-dependent augmentation of the entire force-frequency relation in normal myocardium, whereas augmentation of contractility was only observed at lower stimulation frequencies with ATI22-107. These results demonstrate the effects of the LTCC-antagonizing moiety of ATI22-107 and suggest that the novel simultaneous combination of PDE-III and LTCC inhibition by one molecule may produce a favorable profile of limited inotropy without detrimental effects of increased diastolic [Ca(2+)](i).

3',5'-Cyclic-AMP Phosphodiesterases↗

PubMed1982

Cytotoxicity of a new uridine analog, 4-hydroxy-1-(beta-D-ribofuranosyl)-pyridazine-6-one, and its interaction with uridine kinase.

A new uridine analog, 4-hydroxy-1-(beta-D-ribonfuranosyl)-pyridazin-6-one (3-deaza-6-azaUrd), inhibited the growth of L1210 cells in culture, with a concentration to reduce growth rate to 50% of control of 7 X 10(-5) M. After treatment for 24 or 48 h with 5 X 10(-4) M 3-deaza-6-azaUrd, 80% of the cells were unable to resume growth when the analog was removed from the cultures; also, 99% of the cells were killed, as determined by colony formation in soft agar. Studies on the prevention of the cytotoxic effects of 5 X 10(-4) M 3-deaza-6-azaUrd showed that uridine or cytidine gave complete protection. 2'-Deoxycytidine also gave partial protection, but orotic acid or thymidine had no effect on the growth inhibition by 3-deaza-6-azaUrd. These results suggested that growth inhibition by 3-deaza-6-azaUrd might be due to interference in pyrimidine biosynthesis. Activation of 3-deaza-6-azaUrd to its 5'-phosphate derivative appeared to be catalyzed by uridine kinase. 3-Deaza-6-azaUrd was shown to complete with uridine for phosphorylation (Ki = 4.7 mM) and, therefore, to be a possible alternative substrate for uridine kinase from mouse kidney (Km for uridine = 82 microM). The enzyme was partially purified by streptomycin sulfate precipitation, ammonium sulfate fractionation, and gel filtration. This preparation was found to be free of pyrimidine nucleoside phosphorylase and uridine monophosphate kinase.

Animals↗

PubMed1963