Adriana Cruz-Enríquez

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.

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.

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.

(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.

Bis{2-[2,5-bis­(pyridin-2-yl)-1H-imidazol-4-yl]pyridinium} tetra­cyanidoplatinate(II) tetra­hydrate

The asymmetric unit of the title hydrated complex salt, (C18H14N5)2[Pt(CN)4]·4H2O, consists of one 2-[2,5-bis(pyridin-2-yl)-1H-imidazol-4-yl]pyridinium cation, half a tetracyanidoplatinate(II) dianion, which is located about a crystallographic inversion center, and two water molecules of crystallization. The PtII atom has a square-planar coordination environment, with Pt—CCN distances of 1.992 (4) and 2.000 (4) Å. In the cation, there is an N—H⋯N hydrogen bond linking adjacent pyridinium and pyridine rings in positions 4 and 5. Despite this, the organic component is non-planar, as shown by the dihedral angles of 10.3 (2), 6.60 (19) and 15.66 (18)° between the planes of the central imidazole ring and the pyridine/pyridinium substituents in the 2-, 4- and 5-positions. In the crystal, cations and anions are linked via O—H⋯O, O—H⋯N and N—H⋯O hydrogen bonds, forming a three-dimensional network. Additional π–π, C—H⋯O and C—H⋯N contacts provide stabilization to the crystal lattice.

Bis[(1RS,2RS)-4,4′-(1-aza­niumyl-2-hy­droxy­ethane-1,2-di­yl)dipyridinium] tris­[tetra­chloridopalladate(II)]

The asymmetric unit of the title compound, (C12H16N3O)2[PdCl4]3, consists of a 4,4′-(1-azaniumyl-2-hydroxyethane-1,2-diyl)dipyridinium dication and one and a half tetrachloridopalladate(II) anions; the latter has inversion symmetry. In the cation, the pyridinium rings attached to the central 1-azaniumyl-2-hydroxyethane fragment show an anti conformation, as indicated by the central C—C—C—C torsion angle of −178.1 (4)°, and they are inclined to one another by 25.7 (2)°. 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 distance = 3.788 (3) Å] and a number of C—H⋯O and C—H⋯Cl interactions are present, consolidating the formation of a three-dimensional structure.

4-[(E)-2-(Pyridin-2-yl)ethen-yl]pyridine-terephthalic acid (2/1).

The title 2:1 co-crystal, 2C12H10N2·C8H6O4, crystallizes with one molecule of 4-[(E)-2-(pyridin-2-yl)ethenyl]pyridine (A) and one half-molecule of terephthalic acid (B) in the asymmetric unit. In the crystal, the components are linked through heterodimeric COOH⋯Npyridine synthons, forming linear aggregates of composition –A–B–A–B–. Further linkage through weak C—H⋯O and C—H⋯π interactions gives two-dimensional hydrogen-bonded undulating sheets propagating in the [100] and [010] directions. These layers are connected through additional weak C—H⋯O contacts, forming a three-dimensional structure.

Tetra­kis(μ-acetato-κ2O:O′)-bis­[(3-pyridine­carboxaldehyde-κN′)]dicopper(II)(Cu—Cu)

The binuclear title compound, [Cu2(CH3CO2)4(C6H5NO)], is located about a center of inversion. The CuII atoms are connected [Cu—Cu = 2.6134 (5) Å] and bridged by four acetate ligands. Their distorted octahedral coordination geometry is completed by a terminal pyridine N atom of a 3-pyridincarboxaldehyde ligand. In the crystal, the complex molecules are linked by C—H⋯O hydrogen bonds, forming two-dimensional networks lying parallel to the ab plane. These networks are linked via C—H⋯O hydrogen bonds involving inversion-related 3-pyridinecarboxaldehyde ligands, forming a three dimensional supramolecular architecture.