Lan-Ping Xu

Bis(dimethyl-ammonium) 2,2'-(1,3,6,8-tetra-oxo-2,7-diaza-pyrene-2,7-di-yl)diacetate.

The asymmetric unit of title compound, 2C2H8N+·C18H8N2O8 2−, comprises one crystallographically independent dimethylammonium cation and half of a 2,2′-(1,3,6,8-tetraoxo-2,7-diazapyrene-2,7-diyl)diacetate dianion. The anion lies on an inversion centre and the two carboxylate groups are in trans positions based on the naphthaleneteracarboxylic diimide group. The crystal packing is stabilized by N—H⋯O hydrogen bonds between cations and anions, as well as by π–π interactions between the naphthaleneteracarboxylic diimide groups [centroid–centroid distance = 4.812 (3) Å].

Bis(dimethyl­ammonium) 3,3′-dicarb­oxy-5,5′-(5,7,12,14-tetra­oxo-6,13-diaza­tetra­cyclo­[6.6.2.04,16.011,15]hexa­deca-1,3,8,10,15-penta­ene-6,13-di­yl)dibenzoate dihydrate

The title compound, 2C2H8N+·C30H12N2O12 2−·2H2O, comprises dimethylammonium cations, 3,3′-dicarboxy-5,5′-(5,7,12,14-tetraoxo-6,13-diazatetracyclo[6.6.2.04,16.011,15]hexadeca-1,3,8,10,15-pentaene-6,13-diyl)dibenzoate dianions and water molecules. The dianion is situated on a crystallographic inversion centre. Two very strong symmetry-restricted O⋯H⋯O hydrogen bonds are present which are situated about the crystallographic inversion centres. In one of these hydrogen bonds, the H atom is situated at its centre, while in the other one the H atom is disordered about its centre. Both H atoms are involved in the chain-like C 2 2(16) motif, and not in a more common motif R 2 2(8) that is composed of a pair of hydrogen carboxylates with the H atoms situated about the centre between the pair of O atoms. In the crystal, interaction of these hydrogen bonds results in formation of anionic layers of dianions parallel to (-111). The water molecules donate their H atoms to one of two of the carboxylate O atoms, forming strong hydrogen bonds. The dimethylammonium donates a bifurcated hydrogen bond to an oxo group of the dianion, forming weak hydrogen bonds. All the hydrogen bonds form a three-dimensional hydrogen-bonded network.

catena-Poly[[[tetra­aqua­copper(II)]-μ-4,4′-bipyridyl-κ2N:N′] tetra­fluorido­succinate tetra­hydrate]

In the title compound, {[Cu(C10H8N2)(H2O)4](C4F4O4)·4H2O}n, the CuII atom adopts an elongated octahedral geometry because of the Jahn–Teller effect. Both cation and anion have crystallographic twofold rotation symmetry with the twofold axes passing through the Cu and N atoms and through the midpoint of the central C—C bond. The 4,4′-bipyridyl ligand links the CuII atoms into a linear chain along the b axis. O—H⋯O hydrogen-bonding interactions between the cationic chains and the tetrafluoridosuccinate anions and the free water molecules generate a three-dimensional supramolecular network.

4,4'-Bipyrid-yl-4,4'-(hy-droxy-methyl-ene)dibenzoic acid (1/1).

In the title 1:1 co-crystal, C10H8N2·C15H12O5, strong intermolecular O—H⋯N hydrogen bonds link alternating molecules of 4,4′-(hydroxymethylene)dibenzoic acid and 4,4′-bipyridyl into zigzag chains in [501]. The crystal packing also exhibits π–π interactions between the 4,4′-bipyridyl rings of neighbouring chains [centroid–centroid distance = 3.608 (3) Å] and weak C—H⋯O hydrogen bonds.