José J. Campos-Gaxiola

Supramolecular networks in organic–inorganic hybrid materials from perchlorometalate(II) salts and 2,4,5-tri(4-pyridyl)imidazole

Three organic–inorganic hybrid compounds have been prepared by combination of the tripyridinium imidazole of cation [2,4,5-tri(4-pyridyl)imidazole] (L) and a series of perhalometallate anions to give, namely [H3L(CuCl4)]Cl (1), [(H3L)2(PdCl4)3]·4H2O (2) and [(H3L)2(PtCl4)3]·4H2O (3), which have been structurally characterized by single-crystal X-ray diffraction analysis, showing that the hydrogen bonding interactions of the resulting 1D, 2D, and 3D networks contain at least one of the following synthons: X–H⋯ClnM− [X = C, N, N+; n = 0,1,2; M = Cu(II), Pd(II), Pt(II)] The dimensions are enhanced further by strong X–H⋯Cl− (C, N+) and OH⋯ClnM− [n = 1,2; M = Pd(II), Pt(II)] hydrogen bonds. Additional weak C–H⋯O, π–π stacking and Cl⋯Cl interactions stabilize the crystal structures further.

Synthesis, structure, characterization and photophysical properties of copper(I) complexes containing polypyridyl ligands

Two novel photoluminescent copper(I) complexes having the compositions [CuI(L1)(PPh3)2]NO3·3CHCl3(1) and [CuI(L2)(PPh3)2]NO3·H2O(2) with PPh3 = triphenylphosphine, L1 = cis-(±)-2-(2,5-di(pyridin-2-yl)-4,5-dihydro-1H-imidazol-4-yl)pyridine and L2 = 2,4,6-tris(2-pyridyl)triazine have been successfully synthesized and characterized by IR and 1H-NMR spectroscopy, FAB+ mass spectrometry and single-crystal X-ray diffraction analysis. Both complexes showed interesting photophysical properties, which were studied experimentally in solution and in the solid state by UV-Vis and fluorescence spectroscopy and theoretically using TD-DFT calculations.

Selective and colorimetric detection of Ba2+ ions in aqueous solutions using 11-mercaptoundecylphosphonic acid functionalized gold nanoparticles

In this paper we describe a simple colorimetric method for the sensitive and selective detection of Ba2+ ions, using 11-mercaptoundecylphosphonic acid functionalized gold nanoparticles (AuNPs–MPA) in aqueous solution. With increasing concentration, Ba2+ ions induced aggregation of AuNPs–MPA, causing a change in color of the colloidal solution from pink to blue. The detection result was monitored using the naked eye and UV-Vis spectroscopy. The maximum absorption was located at 625 nm. The stability of AuNPs–MPA and detection of Ba2+ by AuNPs–MPA was investigated at different pH values (pH = 3, 4, 5, 6, 7, 8, 9, 10, 11, 12). Results indicated that AuNPs–MPA at pH 6 were the optimal choice for detecting Ba2+ ions. The detection limit for Ba2+ was found to be 43.27 μmol L−1 (R2 = 0.9901) within a range of 20–120 μmol L−1. In addition, the selectivity of this method was investigated using other metal ions. The AuNPs–MPA was selective for Ba2+ compared with other metal ions (Li+, Na+, K+, Mg2+, Ca2+, Sr2+, Ba2+, Mn2+, Fe2+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+, Hg2+, Sb3+, Bi3+) leading to a remarkable color change. Moreover, the developed cost-effective probe has been successfully applied to real drinking and tap water samples which demonstrated the potential for field applications.

Dichloridobis(methanol-κO)[cis-(±)-2,4,5-tris­(pyridin-2-yl)-2-imidazoline-κ3N2,N3,N4]ytterbium(III) chloride

In the crystal structure of the title complex, [YbCl2(C18H15N5)(CH3OH)2]Cl, the pseudo-pentagonal–bipyramidal coordination geometry of the YbIII cation is composed of three N atoms from one cis-(±)-2,4,5-tris(pyridin-2-yl)imidazoline (HL) ligand, two O atoms from two methanol molecules and two Cl− anions. Chains are formed along [010] through N—H⋯Cl, O—H⋯Cl and O—H⋯N hydrogen bonds.

Benzene-1,3,5-tri­carb­oxy­lic acid–pyridinium-2-olate (1/3)

The asymmetric unit of the title compound, C9H6O6·3C5H5NO, contains one benzene-1,3,5-tricarboxylic acid molecule (BTA) and three pyridin-2-ol molecules each present in the zwitterion form. In the crystal, these entities are linked through O—H⋯O− and N+—H⋯O− hydrogen bonds, forming sheets parallel to (10-1). These layers contain macrocyclic rings of composition [BTA]2[pyol]6 and with graph-set notation R 6 8(44), which are stacked along c through π–π interactions [inter-centroid distances = 3.536 (2)–3.948 (3) Å]. They are interconnected by N+—H⋯O− hydrogen-bonded chains of pyridin-2-ol molecules running parallel to c, forming a three-dimensional network. There are also C—H⋯O hydrogen bonds present which reinforce the three-dimensional structure.

2-(3-Amino-pyridinium-1-yl)-3-carb-oxy-propano-ate monohydrate.

The title compound, C9H10N2O4·H2O, was obtained as a zwitterion derived from the nucleophilic attack of 3-aminopyridine on the fumaric α,β-system. Within the molecule, the aminopyridine moiety and the carboxylate and carboxylic acid fragments form dihedral angles of 68.6 (2) and 62.8 (2)°, respectively. The geometry adopted by the molecule does not allow the formation of centrosymmetric dimeric hydrogen-bonded units; instead chains along the a axis are linked by COO—H⋯OOC motifs. These chains are interconnected by N—H⋯O and O—H⋯O hydrogen bonds involving the carboxylic acid and carboxylate units and the solvent water molecules.

Supramolecular networks in molecular complexes of pyridine boronic acids and polycarboxylic acids: synthesis, structural characterization and fluorescence properties

3- and 4-pyridineboronic acids have been combined with trimesic and pyromellitic acids to give three molecular complexes of compositions [(3PBAH+)(H2TMA−)] (1), [(3PBAH+)2(H2PMA2−)] (2), and [(4PBAH+)2(H2PMA2−)]·2H2O (3) (3PBA = 3-pyridineboronic acid, 4PBA = 4-pyridineboronic acid, H3TMA = trimesic acid, H4PMA = pyromellitic acid). The products have been characterized by elemental analysis, infrared spectroscopy, single-crystal X-ray diffraction analysis and luminescence spectroscopy. The structural analysis revealed that the hydrogen bonding interactions of the resulting 2D and 3D assemblies involve at least one of the following charge-assisted synthons: –B(OH)2⋯−OOCR, RCOOH⋯−OOCR or PyN+–H⋯−OOCR. The dimensions are enhanced by additional hydrogen bonds as well as π–π stacking interactions, which include B⋯π interactions in two crystal structures. Intermolecular close contacts have also been examined by Hirshfeld surface analysis, which by means of the associated 2D fingerprint plots enabled similarities and differences in the crystal structures to be revealed. Solid-state photoluminescence spectroscopy of compounds 1–3 revealed that variations of the π–π stacking in the molecular aggregates induced changes in the emission behavior.

Synthesis, crystal structure, DFT studies and photophysical properties of a copper(I)–tri­phenyl­phosphane complex based on trans-(±)-2,4,5-tris­(pyridin-2-yl)-2-imidazoline

The possibility of using less expensive and nontoxic metals, such as copper, as substitutes for more expensive heavy metals in the synthesis of new transition-metal complexes to be used as sensitizers in dye-sensitized solar cells (DSSCs) has stimulated research in this field. The novel photoluminescent copper(I) complex bis(triphenylphosphane-κP)[trans-(±)-2,4,5-tris(pyridin-2-yl)-2-imidazoline-κ2N2,N3]copper(I) hexafluorophosphate, [CuI(C18H15N5)(C18H15P)2]PF6, has been successfully synthesized and characterized by IR and 1H NMR spectroscopy, as well as by single-crystal X-ray diffraction and thermogravimetric analysis. The complex showed interesting photophysical properties, which were studied experimentally in solution and in the solid state by UV-Vis and fluorescence spectroscopy. Density functional theory (DFT) calculations with dichloromethane as solvent reproduced reasonably well the HOMO and LUMO orbitals of the title compound.

Two novel organic–inorganic hybrid materials from tetrachloridometallate(II) salts and 4‐[(E)‐2‐(pyridin‐1‐ium‐2‐yl)ethenyl]pyridinium

Two organic-inorganic hybrid compounds have been prepared by the combination of the 4-[(E)-2-(pyridin-1-ium-2-yl)ethenyl]pyridinium cation with perhalometallate anions to give 4-[(E)-2-(pyridin-1-ium-2-yl)ethenyl]pyridinium tetrachloridocobaltate(II), (C12H12N2)[CoCl4], (I), and 4-[(E)-2-(pyridin-1-ium-2-yl)ethenyl]pyridinium tetrachloridozincate(II), (C12H12N2)[ZnCl4], (II). The compounds have been structurally characterized by single-crystal X-ray diffraction analysis, showing the formation of a three-dimensional network through X-H...ClnM(-) (X = C, N(+); n = 1, 2; M = Co(II), Zn(II)) hydrogen-bonding interactions and π-π stacking interactions. The title compounds were also characterized by FT-IR spectroscopy and thermogravimetric analysis (TGA).

(1RS,2RS)-4,4'-(1-Aza-niumyl-2-hy-droxy-ethane-1,2-di-yl)dipyridinium tetra-chlorido-platinate(II) chloride.

The title compound, (C12H16N3O)[PtCl4]Cl, consists of a 4,4′-(1-azaniumyl-2-hydroxyethane-1,2-diyl)dipyridinium trication, a square-planar tetrachloridoplatinate(II) dianion and a chloride ion. In the cation, the pyridinium rings attached to the central 1-azaniumyl-2-hydroxyethane fragment have an anti conformation, as indicated by the central C—C—C—C torsion angle of −166.5 (6)°, and they are inclined to one another by 63.5 (4)°. In the crystal, the cations and anions are linked through N—H⋯Cl and O—H⋯Cl hydrogen bonds. There are also π–π contacts [centroid–centroid distances = 3.671 (4) and 3.851 (4) Å] and a number of C—H⋯Cl interactions present, consolidating the formation of a three-dimensional supramolecular structure.