2,4,5-Tris(pyridin-4-yl)-4,5-dihydro-1,3-oxazole

In the title compound, C18H14N4O, the mol­ecules are disordered about a crystallographic twofold axis, leading to 50:50 disorder of the O- and N-atom sites within the oxazole ring. As a consequence, symmetry-related oxazole C—N and C—O bonds are averaged. The oxazole ring makes a dihedral angle of 6.920 (1)° with the pyridyl ring in the 2-position and 60.960 (2)° with the pyridyl rings in the 4- and 5-positions

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 R68(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

2,6-Dihydroxy-4-oxo-2-(pyridin-1-ium-3-yl)-4H-1,3,2-benzodioxaborinin-2-ide 0.67-hydrate

The asymmetric unit of the title compound, C12H10BNO5·0.67H2O, contains three independent pyridinylboronic acid esters adopting zwitterionic forms and two water molecules. The six-membered heterocyclic rings in the boronic esters have half-chair conformations and the deviations of the B atoms from the boronate mean planes range from 0.456 (3) to 0.657 (3) Å. All of the B atoms have tetrahedral coordination environments, with B—O and B—C bond lengths of 1.446 (4)–1.539 (3) and 1.590 (5)–1.609 (5) Å, respectively. In the crystal, the ester and water molecules are linked into a three-dimensional network by a large number of O—H...O, N—H...O and C—H...O hydrogen bonds. The crystal packing is further accomplished by π–π interactions, with centroid–centroid distances of 3.621 (4)–3.787 (4) Å

Crystal structure and Hirshfeld surface analysis of 3-cyanophenylboronic acid

In the title compound, C7H6BNO2, the mean plane of the –B(OH)2 group is twisted by 21.28 (6)° relative to the cyanophenyl ring mean plane. In the crystal, molecules are linked by O—H...O and O—H...N hydrogen bonds, forming chains propagating along the [101] direction. Offset π–π and B...π stacking interactions link the chains, forming a three-dimensional network. Hirshfeld surface analysis shows that van der Waals interactions constitute a further major contribution to the intermolecular interactions, with H...H contacts accounting for 25.8% of the surface

Synthesis, Crystal Structure, DFT Studies and Optical/Electrochemical Properties of Two Novel Heteroleptic Copper(I) Complexes and Application in DSSC

New copper(I) compounds of compositions [Cu(HL)(PPh3)2]·H2O (1) and [Cu(HL)POP]·CH2Cl2 (2), where HL = monoanion of pyridine-2,5-dicarboxylic acid, PPh3 = triphenylphosphine and POP = bis [2-(diphenylphosphine)phenyl]ether), are documented. The complexes were characterized by elemental analysis, spectroscopic techniques (IR, 1H/31P RMN and UV–VIS), cyclic voltammetry, and thermogravimetric analysis. Single-crystals for 1 and 2 enabled X-ray diffraction analysis, revealing distorted tetrahedral geometries for Cu(I) centers embedded in NOP2 environments. The crystal structures are stabilized by O−H∙∙∙O, C−H∙∙∙O, C−H∙∙∙π and π∙∙∙π interactions that were analyzed by inspection of the Hirshfeld surfaces and fingerprint plots. Compounds 1 and 2 show interesting optical/electrochemical properties, which were studied experimentally in solution by UV–Vis spectroscopy and cyclic voltammetry, as well as theoretically using Time-Dependent Density Functional Theory (TD-DFT). Additionally, in combination with the ruthenium complex N719, their efficiency as co-sensitizers in dye-sensitized solar cells (DSSCs) was assessed, showing good activity