Bis(2-, 3-, 4-carboxyethylpyridinium) hexafluorosilicates as potential caries prophylactic agents.

Interaction of 2-, 3-, 4-carboxyethylpyridines (L1, L2, L3) with fluorosilicic acid results in the corresponding bis(pyridinium) hexafluorosilicates I-III, characterized by elemental analysis, IR, 1 H, 19 F nuclear magnetic resonance (NMR), and mass spectrometry, solubility data, and X-ray crystallography. Crystallographic data: Fdd2, Z = 8, a = 28.610(2) Å, b = 18.8378(14) Å, c = 7.3236(5) Å (I); P-1, Z = 1, a = 6.2712(4) Å, b = 7.1706(5) Å, c = 10.9721(7) Å, α = 102.514(6)°, ß = 97.037(5)°, γ = 93.640(6)° (II); P21 /c, Z = 2, a = 10.0345(6) Å, b = 9.8734(5) Å, c = 9.4704(6) Å, ß = 94.347(6)° (III). The dominant intermolecular contacts from the Hirshfeld surface analysis are H… F/F… H, H… H, and H… O/O… H with percentages of 33.3%-34.5%, 26.4%-30.0%, and 16.0%-21.8%. The infrared spectra for I-III exhibit stretching vibrations ν(N+ H) at 3300-3050 cm-1 ; stretching and deformation vibrations ν(SiF) and δ(SiF2 ) for [SiF6 ]2- anions are registered near 740 cm-1 and in the range of 480-440 cm-1 . In the 19 F NMR spectra of aqueous solutions of I-III, strong singlet signals of the [SiF6 ]2- anion were registered at δ(F) = -133.35 ppm (I), -131.43 ppm (II), -129.02 ppm (III) with two satellites due to the spin-spin interaction 29 Si-19 F (J(29 Si-19 F) = 107.5 Hz (II), 107.6 Hz (III)). I-III reveal high solubility in water and dimethyl sulfoxide and very poor solubility in methanol and ethanol. All compounds demonstrate noticeable anticaries activity and absence of hepatotoxic effects, and bis(3-carboxyethylpyridinium) hexafluorosilicate II displays the highest caries-preventive efficacy, which significantly exceeds values for the reference preparations, NaF and (NH4 )2 [SiF6 ].

From 1D to 2D Cd(II) and Zn(II) Coordination Networks by Replacing Monocarboxylate with Dicarboxylates in Partnership with Azine Ligands: Synthesis, Crystal Structures, Inclusion, and Emission Properties.

Eight mixed-ligand coordination networks, [Cd(2-aba)(NO3)(4-bphz)3/2]n·n(dmf) (1), [Cd(2-aba)2(4-bphz)]n·0.75n(dmf) (2), [Cd(seb)(4-bphz)]n·n(H2O) (3), [Cd(seb)(4-bpmhz)]n·n(H2O) (4), [Cd(hpa)(3-bphz)]n (5), [Zn(1,3-bdc)(3-bpmhz)]n·n(MeOH) (6), [Cd(1,3-bdc)(3-bpmhz)]n ·0.5n(H2O)·0.5n(EtOH) (7), and [Cd(NO3)2(3-bphz)(bpe)]n·n(3-bphz) (8) were obtained by interplay of cadmium nitrate tetrahydrate or zinc nitrate hexahydrate with 2-aminobenzenecarboxylic acid (H(2-aba)), three dicarboxylic acids, sebacic (decanedioic acid, H2seb), homophthalic (2-(carboxymethyl)benzoic acid, H2hpa), isophthalic (1,3-benzenedicarboxylic acid, H2(1,3-bdc)) acids, bis(4-pyridyl)ethane (bpe) and with four azine ligands, 1,2-bis(pyridin-4-ylmethylene)hydrazine (4-bphz), 1,2-bis(1-(pyridin-4-yl)ethylidene) hydrazine (4-bpmhz), 1,2-bis(pyridin-3-ylmethylene)hydrazine (3-bphz), and 1,2-bis(1-(pyridin-3-yl) ethylidene)hydrazine (3-bpmhz). Compounds 1 and 2 are 1D coordination polymers, while compounds 3-8 are 2D coordination polymers. All compounds were characterized by spectroscopic and X-ray diffraction methods of analysis. The solvent uptakes and stabilities to the guest evacuation were studied and compared for 1D and 2D coordination networks. The de-solvated forms revealed a significant increase of emission in comparison with the as-synthesized crystals.

Partial in Situ Reduction of Copper(II) Resulting in One-Pot Formation of 2D Neutral and 3D Cationic Copper(I) Iodide-Pyrazine Coordination Polymers: Structure and Emissive Properties.

On the way to copper(I) iodide coordination polymers with specific luminescent properties, the in situ reduction of Cu(II) in the presence of KI and bidentate N-heteroatomic ligand, either pyrazine (pyz) or 4,4'-bipyridine (bpy), resulted in one two-dimensional and two three-dimensional new coordination networks. Starting from Cu(NO3)2·3H2O in the presence of pyz, successive precipitation of known yellow [(CuII)2(pyz)]n, new orange [CuII(pyz)]n, and new dark blue {[CuI(pyz)2]·I5}n polymeric solids was observed. Starting from the same salt in the presence of bpy resulted in the successive precipitation of known yellow [(CuII)2(bpy)]n and new brown {[CuII(NO3)(bpy)2]·I3·(dmf·H2O)}n coordination polymers. By using either Cu(CH3COO)2·H2O or Cu(BF4)2 as starting materials, both known forms, yellow [(CuII)2(bpy)]n and orange [CuII(bpy)]n, precipitated successively. The new solids were characterized by IR spectroscopy and X-ray analysis. [CuII(pyz)]n represents the missing member in the row of two-dimensional coordination networks with general formula [CuIX(pyz)]n (X = Cl, Br, I). Its steady state and time-resolved characterization together with DFT and TDDFT calculations revealed that the emission at room temperature is mainly delayed fluorescence originating from mixed singlet metal-to-ligand charge transfer and halide-to-ligand charge transfer states, while that at 77 K is phosphorescence, associated with the small singlet-triplet energy differences (ΔE = 70 meV).

A 1:1 flavone cocrystal with cyclic trimeric perfluoro-o-phenyl-enemercury.

The title compound, systematic name tris-(µ2-perfluoro-o-phenyl-ene)(µ2-3-phenyl-4H-chromen-4-one)-triangulo-trimercury, [Hg3(C6F4)3(C15H10O2)], crystallizes in the monoclinic P21/n space group with one flavone (FLA) and one cyclic trimeric perfluoro-o-phenyl-enemercury (TPPM) mol-ecule per asymmetric unit. The FLA mol-ecule is located on one face of the TPPM acceptor and is linked in an asymmetric coordination of its carbonyl oxygen atom with two Hg centers of the TPPM macrocycle. The angular-shaped complexes pack in zigzag chains where they stack via two alternating TPPM-TPPM and FLA-FLA stacking patterns. The distance between the mean planes of the neighboring TPPM macrocycles in the stack is 3.445 (2) Å, and that between the benzo-γ-pyrone moieties of FLA is 3.328 (2) Å. The neighboring stacks are inter-digitated through the shortened F⋯F, CH⋯F and CH⋯π contacts, forming a dense crystal structure.

Crystal structure and characterization of a new one-dimensional copper(II) coordination polymer containing a 4-amino-benzoic acid ligand.

A CuII coordination polymer, catena-poly[[[aqua-copper(II)]-bis-(µ-4-amino-benz-o-ato)-κ2 N:O;κ2 O:N] monohydrate], {[Cu(pABA)2(H2O)]·H2O}n (pABA = p-amino-benzoate, C7H4NO2 -), was synthesized and characterized. It exhibits a one-dimensional chain structure extended into a three-dimensional supra-molecular assembly through hydrogen bonds and π-π inter-actions. While the twinned crystal shows a metrically ortho-rhom-bic lattice and an apparent space group Pbcm, the true symmetry is monoclinic (space group P2/c), with disordered Cu atoms and mixed roles of water mol-ecules (aqua ligand/crystallization water). The luminescence spectrum of the complex shows an emission at 345 nm, cf. 349 nm for pABAH.

Synthesis, biological evaluation, X-ray molecular structure and molecular docking studies of RGD mimetics containing 6-amino-2,3-dihydroisoindolin-1-one fragment as ligands of integrin αIIbß3.

A series of novel RGD mimetics containing phthalimidine fragment was designed and synthesized. Their antiaggregative activity determined by Born's method was shown to be due to inhibition of fibrinogen binding to αIIbß3. Molecular docking of RGD mimetics to αIIbß3 receptor showed the key interactions in this complex, and also some correlations have been observed between values of biological activity and docking scores. The single crystal X-ray data were obtained for five mimetics.

Di-aqua-bis-(pyridine-2-carboxyl-ato-κ(2) N,O)zinc di-methyl-formamide hemisolvate.

In the title compound, [Zn(C6H4NO2)2(H2O)2]·0.5C3H7NO, the Zn(II) ion is coordinated in a distorted octa-hedral N2O4 environment by two N,O-chelating pyridine-2-carboxyl-ate ligands and two cis water mol-ecules. The chelating pyridine-2-carboxyl-ate ligands create two five-membered Zn/N/C/C/O rings, which form a dihedral angle of 86.4 (2)°. In the crystal, O-H⋯O hydrogen bonds link the complex mol-ecules into a two-dimensional network parallel to (100). The di-methyl-formamide solvent mol-ecule is disordered about a twofold rotation axis.

Pyridine-4-carbaldehyde-fumaric acid (2/1).

In the title co-crystal, 2C6H5NO·C4H4O4, two crystallographically different hydrogen-bonded trimers are formed, one in which the components occupy general positions, and one generated by an inversion centre. This results in the uncommon situation of Z = 3 for a triclinic crystal. In the formula units, mol-ecules are linked by O-H⋯N hydrogen bonds.

Pyrimidine-2,4-diamine acetone monosolvate.

In the title compound, C(4)H(6)N(4)·C(3)H(6)O, the pyrimidine-2,4-diamine mol-ecule is nearly planar (r.m.s. deviation = 0.005 Å), with the endocyclic angles covering the range 114.36 (10)-126.31 (10)°. In the crystal, N-H⋯N and N-H⋯O hydrogen bonds link the mol-ecules into ribbons along [101], and weak C-H⋯π inter-actions consolidate further the crystal packing.

Pyridine-2,5-diamine.

In the title mol-ecule, C5H7N3, intra-cyclic angles cover the range 117.15 (10)-124.03 (11)°. The N atoms of the amino groups have trigonal-pyramidal configurations deviating slightly from the pyridine plane by 0.106 (2) and -0.042 (2) Å. In the crystal, the pyridine N atom serves as an acceptor of an N-H⋯N hydrogen bond which links two mol-ecules into a centrosymmetric dimer. Inter-molecular N-H⋯N hydrogen bonds between the amino groups further consolidate the crystal packing, forming a three-dimensional network.

Extrinsic Heavy Metal Atom Effect on the Solid-State Room Temperature Phosphorescence of Cyclic Triimidazole.

Four coordination compounds [Zn3 (CH3 COO)6 (H2 O)2 ](TT)2 [Cd(H2 O)6 ](ClO4 )2 (TT)2 , [Cd(H2 O)6 ](BF4 )2 (TT)2 , [Zn(H2 O)6 ](BF4 )2 (TT)2 (1-4) accommodating the crystallization induced emissive triimidazo[1,2-a:1',2'-c:1'',2''-e][1,3,5]triazine (TT) as a guest in their crystal lattice are isolated and fully photophysically and structurally characterized. Their emission properties are compared with those of afterglow TT and interpreted taking into account the heavy atom effect and crystal packing similarities and differences. In the case of 1, due to the closeness of the TT H-aggregates arrangement with that of the phosphor's pure phase, the observed intensification of the phosphorescent emission at the expense of the prompt one is attributed to the extrinsic heavy atom effect of Zn. In 2 and 3, the heavier Cd atom is responsible for a decrease in the lifetimes of the afterglow emission, despite the presence of tightly overlapped H-dimers in the crystal structure. Finally, for 4, isostructural with 3, the Zn atom reveals in RTUP lifetime comparable with that of 1.

Crystal structure of poly[bis-(ammonium) [bis-(µ4-benzene-1,3,5-tri-carboxyl-ato)dizincate] 1-methyl-pyrrolidin-2-one disolvate].

The title three-dimensional metal-organic framework (MOF) compound, {(NH4)2[Zn2(C9H3O6)2]·2C5H9NO} n , features an anionic framework constructed from Zn(2+) cations and benzene-1,3,5-tri-carboxyl-ate (BTC) organic anions. Charge balance is achieved by outer sphere ammonium cations formed by degradation of di-n-butyl-amine in the solvothermal synthesis of the compound. Binuclear {Zn2(COO)2} entities act as the framework's secondary building units. Each Zn(II) atom has a tetrahedral coordination environment with an O4 set of donor atoms. The three-dimensional framework adopts a rutile-type topology and channels are filled in an alternating fashion with ordered and disordered 1-methyl-pyrrolidin-2-one solvent mol-ecules and ammonium cations. The latter are held in the channels via four N-H⋯O hydrogen bonds, including three with the benzene-1,3,5-tri-carboxyl-ate ligands of the anionic framework and one with a 1-methyl-pyrrolidin-2-one solvent mol-ecule.

Crystal structure of a polymeric calcium levulinate dihydrate: catena-poly[[di-aqua-calcium]-bis-(µ2-4-oxo-butano-ato)].

In the title calcium levulinate complex, [Ca(C5H7O3)2(H2O)2] n , the Ca(2+) ion lies on a twofold rotation axis and is octa-coordinated by two aqua ligands and six O atoms from four symmetry-related carboxyl-ate ligands, giving a distorted square-anti-prismatic coordination stereochemistry [Ca-O bond-length range = 2.355 (1)-2.599 (1) Å]. The levulinate ligands act both in a bidentate carboxyl O,O'-chelate mode and in a bridging mode through one carboxyl O atom with an inversion-related Ca(2+) atom, giving a Ca⋯Ca separation of 4.0326 (7) Å. A coordination polymeric chain structure is generated, extending along the c-axial direction. The coordinating water mol-ecules act as double donors and participate in intra-chain O-H⋯O hydrogen bonds with carboxyl O atoms, and in inter-chain O-H⋯O hydrogen bonds with carbonyl O atoms, thus forming an overall three-dimensional structure.

A one-dimensional coordination polymer based on Cu3-oximato metallacrowns bridged by benzene-1,4-dicarboxylato ligands: structure and magnetic properties.

A one-dimensional linear coordination polymer {[Cu3(µ3-OH)(2-pyao)3(bdc)]·6(H2O)}n () composed of trinuclear [Cu3(µ3-OH)(2-pyao)3](2+) metallacrown cores bridged by bis-carboxylato linkers has been obtained by treatment of copper(ii) fluoride with pyridine-2-aldoxime (2-pyaoH) ligand and benzene-1,4-dicarboxylic acid (H2bdc). Magnetic susceptibility measurements show strong antiferromagnetic interactions between Cu(ii) centers within the trinuclear metallacrown core with J = -430 cm(-1).

Halogen impact into new oxonium benzo-crown ether complexes with tetrachloro- and tetrabromoaurates(III).

Five oxonium tetrahalogenaurate(III) (Hal = Cl, Br) benzo-crown ether (BCE) complexes are prepared and reported. The new compounds are [(H3O)(B18C6)(0.58)(4'-Cl-B18C6)0.42][AuCl4] 1, [(H3O)(B18C6)][AuCl4] 2, [(H3O)(4'-Br-B18C6)][AuCl4] 3, [(H3O)(4'-Br-B18C6)][AuBr4] 4, and [(H3O)(B18C6)][AuBr4] 5. The reaction medium, distinctive from the previously used aqua regia, allowed avoiding the unwanted nitration of initial macrocycles. The compositions and structures for 1, 3, 4, and 5 were proved by single crystal X-ray crystallography. The complete conversion of tetrachloroaurate(III) to the tetrabromoaurate(III) salts resulted in complex 4 isomorphous and isostructural to 3. All compounds form the laminated structures with alternation of cationic and anionic layers. The robustness of the anionic sheets is sustained by the halogen-halogen interactions and makes crucial impact on extraction of stoichiometric products in the case of tetrabromoaurate(III) salts.

Two new "onium" fluorosilicates, the products of interaction of fluorosilicic acid with 12-membered macrocycles: structures and spectroscopic properties.

Two novel compounds, (L(1)H)(2)[SiF(6)] x 2H(2)O (1) and (L(2)H)(2)[SiF(5)(H(2)O)](2) x 3H(2)O (2), resulting from the reactions of H(2)SiF(6) with 4'-aminobenzo-12-crown-4 (L(1)) and monoaza-12-crown-4 (L(2)), respectively, were studied by X-ray diffraction and characterised by IR and (19)F NMR spectroscopic methods. Both complexes have ionic structures due to the proton transfer from the fluorosilicic acid to the primary amine group in L(1) and secondary amine group incorporated into the macrocycle L(2). The structure of 1 is composed of [SiF(6)](2-) centrosymmetric anions, N-protonated cations (L(1)H)(+), and two water molecules, all components being bound in the layer through a system of NH[...]F, NH[...]O and OH[...]F hydrogen bonds. The [SiF(6)](2-) anions and water molecules are assembled into inorganic negatively-charged layers via OH[dot dot dot]F hydrogen bonds. The structure of 2 is a rare example of stabilisation of the complex anion [SiF(5)(H(2)O)](-), the labile product of hydrolytic transformations of the [SiF(6)](2-) anion in an aqueous solution. The components of 2, i.e., [SiF(5)(H(2)O)](-), (L(2)H)(+), and water molecules, are linked by a system of NH[...]F, NH[...]O, OH[...]F, OH[dot dot dot]O hydrogen bonds. In a way similar to 1, the [SiF(5)(H(2)O)](-) anions and water molecules in 2 are combined into an inorganic negatively-charged layer through OH[...]F and OH[...]O interactions.

Hierarchy of hydrogen bonding in bis(1,4,7-trioxa-10-azoniacyclododecane) bis(4-aminobenzoate) trihydrate.

In the title compound, 2C8H18NO3+.2C7H6NO2-.3H2O, proton transfer occurs from the carboxylic acid group of the 4-aminobenzoic acid (PABA) molecule to the amine group of the macrocycle, resulting in the formation of a salt-like adduct. The anions are combined into helical chains which are further bound by the water molecules into sheets. The macrocyclic cations are situated between these layers and are bound to the anions both directly and via bridging water molecules. The structure exhibits a diverse system of hydrogen bonding.

1,4,7,10-tetraoxacyclododecane-triphenylmethanethiol (1/2).

In the centrosymmetric formula unit of the title complex, C8H16O4.2C18H16S, the 1,4,7,10-tetraoxacyclododecane molecule adopts the biangular [66] conformation, and the triphenylmethanethiol molecules are linked to the macrocycle via a long S-H...O hydrogen bond [S...O = 3.460 (2) A and S-H...O = 161 (2) degrees]. Attractive interactions of phenyl groups in edge-to-face conformations combine inversion-related formula units into chains running along the [111] direction in the crystal structure. Association of the chains into sheets is achieved via C-H...pi interactions.

2,4-dithiouracil: the reproducible H-bonded structural motifs in the complexes with 18-membered crown ethers.

2,4-dithiouracil (DTU) forms in the crystals the H-bonded monohydrates of a 1:1:1 ratio with 18-crown-6 (18C6) 1, cis,syn,cis-isomer of dicyclohexano-18-crown-6 (DCH6A) 2, and benzo-18-crown-6 (B18C6) 3, while the anhydrous adduct with cis,anti,cis-isomer of dicyclohexano-18-crown-6 (DCH6B) 4 is of a 2:1 ratio. In 1-3 the components reproducibly alternate in the chains, while in 4 the chains are built of the alternative centrosymmetric dimers of 2,4-dithiouracil and the molecules of the cis,anti,cis-isomer of dicyclohexano-18-crown-6.

A new phase of 7,16-dibenzyl-1,4,10,13-tetraoxa-7,16-diazacyclooctadecane, and 7,16-dibenzyl-1,4,10,13-tetraoxa-7,16-diazoniacyclooctadecane bis(tetrafluoroborate) monohydrate, both determined at 123 K.

7,16-Dibenzyl-1,4,10,13-tetraoxa-7,16-diazacyclooctadecane, C26H38N2O4, (I), crystallizes in space group P2(1)/c, with two independent molecules adopting different conformations. The 'free' crowns adopt a typical 'arallelogram' shape, in which two methylene groups are turned inward toward the center of the ring and the benzyl groups splay out from the ring. In 7,16-dibenzyl-1,4,10,13-tetraoxa-7,16-diazoniacyclooctadecane bis(tetrafluoroborate) monohydrate, C26H40N2O4(2+).2BF4-.H2O, (II), the macrocycle is centrosymmetric, and the protonated N atoms adopt an endo-endo orientation that is stabilized by a bifurcated N-H...O hydrogen bond, where the O atoms of the macrocycle act as hydrogen-bond acceptors. The phenyl groups of the benzyl side arms are turned above and below the macrocycle; C-H...pi interactions between the phenyl substituents and two macrocyclic methylene H atoms govern the overall conformation of the macrocycle. Bridging tetrafluoroborate anions link the macrocyclic cations via weak C-H...F hydrogen bonds into channels running along [100], which are filled by the weakly hydrogen-bonded water molecules.