Synthesis of ß-carboline-benzimidazole conjugates using lanthanum nitrate as a catalyst and their biological evaluation.

A series of ß-carboline-benzimidazole conjugates bearing a substituted benzimidazole and an aryl ring at C3 and C1 respectively were designed and synthesized. The key step of their preparation was determined to involve condensation of substituted o-phenylenediamines with 1-(substituted phenyl)-9H-pyrido[3,4-b]indole-3-carbaldehyde using La(NO3)3·6H2O as a catalyst and their cytotoxic potential was evaluated. Conjugates 5a, 5d, 5h and 5r showed enhanced cytotoxic activity (GI50 values range from 0.3 to 7.1 µM in most of the human cancer cell lines) in comparison to some of the previously reported ß-carboline derivatives. To substantiate the cytotoxic activity and to understand the nature of interaction of these conjugates with DNA, spectroscopy, DNA photocleavage and DNA topoisomerase I inhibition (topo-I) studies were performed. These conjugates (5a, 5d and 5r) effectively cleave pBR322 plasmid DNA in the presence of UV light. In addition, the effect of these conjugates on DNA Topo I inhibition was studied. The mode of binding of these new conjugates with DNA was also examined by using both biophysical as well as molecular docking studies, which supported their multiple modes of interaction with DNA. Moreover, an in silico study of these ß-carboline-benzimidazole conjugates reveals that they possess drug-like properties.

Syntheses and structural characterization of new mixed-valent tellurium oxides, a4[te5(6+)te(3)4+]o23 (a=rb and k).

Two new isostructural mixed-valent tellurium oxides, A4[Te(5)6+Te3(4+)]O23 [A=Rb and K], have been synthesized by solid-state reactions and characterized by X-ray diffraction and infrared spectroscopy. Compound could be prepared by hydrothermal reaction as well. These compounds, as determined from the single-crystal X-ray structure of, consist of corrugated [Te6O23] layers, built from corner-connected TeO6 octahedra and TeO5 square pyramids. These layers are connected to one another by tetravalent telluriums, having square-pyramidal and disphenoid geometries. Both compounds crystallize in the orthorhombic space group Pna2(1) (33) with Z=4 and have the following unit cell parameters: For 1, a=19.793(4), b=14.664(4), and c=7.292(4) A. For 2, a=19.573(3), b=14.448(2), and c=7.273(8) A.

Hydrothermal synthesis and characterization of new pillared layered ethylenediphosphonates of molybdenum(VI), A2[Mo2O5(O3PCH2CH2PO3)] (A = NH4, Tl, Cs, Rb) and K(H3O)[Mo2O5(O3PCH2CH2PO3)].

New ethylenediphosphonates of molybdenum, A[Mo2O5(O3PCH2CH2PO3)] (A = NH4 (1), Tl (2), Cs (3), Rb (4)), and K(H3O)[Mo2O5(O3PCH2CH2PO3)] (5), have been synthesized by a hydrothermal method and structurally characterized by X-ray diffraction, spectroscopic, and thermal studies. These compounds consist of pillared anionic layers [Mo2O5(O3PCH2CH2PO3)]2-, with A+, K+, and H3O+ ions in the interlayer region as well as in the cavities within the anionic layers. Single-crystal X-ray structures of compounds 1 and 5 have been determined. They crystallize in the orthorhombic space group Cmca with Z = 8 and have the following unit cell parameters. For 1, a = 25.60(1), b = 10.016(4), and c = 9.635(3) angstroms and for 5, a = 25.63(1), b = 10.007(2), and c = 9.512(1) angstroms.

Solid-state synthesis and characterization of novel aluminophosphates, A3Al2P3O12 (A = Na, K, Rb, Tl): influence of A+ ions on the coordination of aluminum.

Four aluminophosphates, A3Al2P3O12 (A = Na, K (1), Rb (2), Tl (3)), have been synthesized by solid-state reactions and characterized by X-ray diffraction and NMR and IR spectroscopic techniques. Aluminum has trigonal bipyramidal coordination in the thallium compound and tetrahedral coordination in the others. Potassium, rubidium and thallium analogues have been structurally characterized by single-crystal X-ray diffraction and found to possess three-dimensional (Al2P3O12)3- anionic frameworks with channels occupied by A+ countercations. These frameworks are built from corner connections of PO4 tetrahedra with AlO4 tetrahedra in 1 and 2 and with AlO5 trigonal bipyramids in 3. Pertinent crystal data are as follows: for 1, orthorhombic space group Pna2(1), a = 8.685(2) A, b = 16.947(2) A, c = 8.458(3) A, Z = 4; for 2, orthorhombic space group Cmc2(1), a = 17.164(2) A, b = 8.6270(6) A, c = 8.8140(14) A, Z = 4; for 3, orthorhombic space group Pna2(1), a = 6.1478(15) A, b = 10.396(3) A, c = 17.787(5) A, Z = 4. Compound 3 is a rare example of an oxide possessing aluminum exclusively in trigonal bipyramidal coordination.

Hydrothermal Synthesis and Characterization of a Novel Two-Dimensional Tellurite of Molybdenum(VI), (NH(4))(6)Mo(8)Te(8)O(43).H(2)O.

A novel, two-dimensional tellurite of molybdenum(VI), (NH(4))(6)Mo(8)Te(8)O(43).H(2)O, has been isolated as single crystals in a hydrothermal reaction and characterized by single-crystal X-ray diffraction, infrared spectroscopy, and thermal analysis. Pertinent crystal data are as follows: trigonal space group P&thremacr;, a = 12.124(4) Å, c = 8.130(3) Å, Z = 1. Its strucrure consists of (Mo(8)Te(8)O(43))(6)(-) layers interleaved with ammonium ions. The novel feature of the anionic layer is that it contains two anions, discrete [Mo(2)O(7)](2)(-) anions residing in an extended framework of (Mo(6)Te(8)O(36))(4)(-) anions made by corner connection of edge-shared bi-octahedral Mo(2)O(10) units, TeO(3) pyramids, and TeO(4) units with SF(4) geometry. Its decomposition temperature is 371 degrees C.

Low-Temperature Syntheses and Characterization of Novel Layered Tellurites, A(2)Mo(3)TeO(12) (A = NH(4), Cs), and "Zero-Dimensional" Tellurites, A(4)Mo(6)Te(2)O(24).6H(2)O (A = Rb, K).

Hydrothermal synthetic investigations to prepare new A(2)Mo(3)TeO(12) (A = NH(4), Cs, Rb, K) compounds are described. Novel noncentrosymmetric layered tellurites, (NH(4))(2)Mo(3)TeO(12) (1) and Cs(2)Mo(3)TeO(12) (2), have been synthesized by hydrothermal methods. Their structures contain two-dimensional hexagonal tungsten oxide related (Mo(3)TeO(12))(2)(-) anionic layers interleaved with NH(4)(+)/Cs(+) ions. New "zero-dimensional" tellurites, Rb(4)Mo(6)Te(2)O(24).6H(2)O (3) and K(4)Mo(6)Te(2)O(24).6H(2)O (4), containing discrete centrosymmetric (Mo(6)Te(2)O(24))(4)(-) anionic aggregates and alkali metal ions have been synthesized by simple refluxing of stoichiometric reactants in water. In this hexamolybdoditellurite anion, the Mo(6)O(24) flat hexagonal ring, formed from edge sharing of six MoO(6) octahedra, is capped by tellurium on both sides. The two types of anions have the same empirical formula. Cs(2)Mo(3)TeO(12) (2) could be prepared by a solid state reaction as well. All four new tellurites have been structurally characterized by single-crystal X-ray diffraction studies. Pertinent crystal, data are as follows: for 1, hexagonal space group P6(3), a = 7.332(2) Å, c = 12.028(4) Å, Z = 2; for 2, hexagonal space group P6(3), a = 7.3956(10) Å, c = 12.186(2) Å, Z = 2; for 3, monoclinic space group P2(1)/c, a = 10.0564(14) Å, b = 9.877(8) Å, c = 15.724(3) Å, beta = 109.988(11) degrees, Z = 2; for 4, monoclinic space group P2(1)/c, a = 9.878(3) Å, b = 9.724(4) Å, c = 15.301(3) Å, beta = 108.57(2) degrees, Z = 2. Low-temperature syntheses, structure, and powder X-ray diffraction, spectroscopic, and thermal studies of compounds 1-4 are described.