Bis(9-amino-acridinium) bis-(pyridine-2,6-dicarboxyl-ato-κO,N,O)nickelate(II) trihydrate.

The title compound, (C(13)H(11)N(2))(2)[Ni(C(7)H(3)NO(4))(2)]·3H(2)O, consists of a mononuclear anionic complex, two 9-amino-acridinium cations and three uncoordinated water mol-ecules. Two pyridine-2,6-dicarboxyl-ate (pydc) ligands are bound to the Ni(II) ion, giving an NiN(2)O(4) bonded set. The coordination geometry around the Ni(II) atom is distorted octa-hedral. There are two types of robust O-H⋯O hydrogen-bond synthons, namely R(6) (6)(24) and R(2) (4)(8), which link the complex anions and water mol-ecules to each other. N-H⋯O hydrogen bonds connect the stacks of anions and cations in the structure. Other inter-molecular inter-actions, including weak C-H⋯O hydrogen bonds, π-π [shortest centroid-centroid distance = 3.336 (7) Å] and C-O⋯π [O⋯centroid distance = 3.562 (10) Å] inter-actions, connect the various components

Bis(2,9-dimethyl-1,10-phenanthrolin-1-ium) hydrogen (S,S)-tartrate nona­hydrate

The asymmetric unit of the title compound, 2C14H13N2 +·2C4H5O6 −·9H2O, contains two cations and two anions in addition to nine mol­ecules of water. Each of the hydrogen tartrate anions is hydrogen bonded to itself by translation along [100] in a head-to-tail fashion via a short hydrogen bond with donor–acceptor distances of 2.473 (4) and 2.496 (4) Å. A large number of inter­molecular O–H⋯O, N—H⋯O and C–H⋯O hydrogen-bonding inter­actions, as well as π–π stacking [centroid–centroid distances in the range 3.642 (3) to 3.866 (3) Å], play an important role in the crystal structure

Acridinium 3,5-dicarboxy­benzoate monohydrate

The title compound, C13H10N+·C9H5O6 −·H2O, exhibits a wide range of non-covalent inter­actions, such as O—H⋯O and N—H⋯O hydrogen bonds, π–π stacking [centroid-centroid distances = 3.562 (8) and 3.872 (8) Å] and ion pairing, connecting the various components into a supra­molecular structure

Acridinium 6-carb­oxy­pyridine-2-carboxyl­ate monohydrate

The title compound, C13H10N+·C7H4NO4 −·H2O or (acrH)+(pydcH)−·H2O, is a monohydrate of acridinium cations and a mono-deprotonated pyridine-2,6-dicarb­oxy­lic acid. The structure contains a range of non-covalent inter­actions, such as O—H⋯O, O—H⋯N and N—H⋯O hydrogen bonds, as well as π–π stacking [range of centroid–centroid distances = 3.4783 (5)–3.8059 (5) Å]. The N—H⋯O hydrogen bond between the donor acridinium cation and the carboxyl­ate acceptor is particularly strong. The average separation between the π-stacked acridinium planes is 3.42 (3) Å

Poly[μ2-aqua-aqua-μ4-pyridine-2,4-dicarboxyl­ato-strontium]

In the title polymeric complex, [Sr(C7H3NO4)(H2O)2]n, the SrII atom is eight-coordinated by four O atoms and one N atom of four pyridine-2,4-dicarboxyl­ate (py-2,4-dc) ligands and three O atoms of three coordinated water mol­ecules in a dodeca­hedral geometry. These units are connected via the carboxyl­ate O atoms and water mol­ecules, building polymeric layers parallel to (100). In the crystal structure, non-covalent inter­actions consisting of O—H⋯O hydrogen bonds and π–π stacking inter­actions [centroid–centroid distances = 3.862 (17) and 3.749 (17) Å] connect the various components, forming a three-dimensional structure

Poly[piperazinediium [aqua­bis(μ-pyridine-2,5-dicarboxyl­ato)zincate] dihydrate]

The polymeric title compound, {(C4H12N2)[Zn(C7H3NO4)2(H2O)]·2H2O}n, was obtained by the reaction of zinc(II) nitrate hexa­hydrate with the proton-transfer compound (pipzH2)(py-2,5-dc) (where pipz is piperazine and py-2,5-dcH2 is pyridine-2,5-dicarboxylic acid) in aqueous solution. Each ZnII atom is coordinated in a distorted octa­hedral geometry by four O atoms and two N atoms from one water mol­ecule and two (py-2,5-dc)2– ligands, which also act as bridging ligands between ZnII atoms. π–π Stacking inter­actions between two aromatic rings of (py-2,5-dc)2– fragments, with centroid–centroid distances of 3.4747 (7) and 3.7081 (7) Å are observed. The crystal structure is stabilized by O—H⋯O and N—H⋯O hydrogen bonds

Acridinium 3-carb­oxy­pyrazine-2-carboxyl­ate

The title ion pair, C13H10N+·C6H3N2O4 −, contains a protonated acridine cation and a 3-carb­oxy­pyrazine-2-carboxyl­ate monoanion, which are linked together through O—H⋯O, N—H⋯O and weak C—H⋯O hydrogen bonds. These hydrogen bonds generate a C(10) chain graph-set motif. The crystal structure is further stabilized by extensive π–π stacking inter­actions between nearly parallel [dihedral angle = 1.21(2)°] acridine systems. The shortest distance between the centroids of the six-membered rings within the cations is 3.6315 (8) Å. In addition, C—H⋯π edge-to-face inter­actions are present

Bis(9-amino­acridinium) bis­(pyridine-2,6-dicarboxyl­ato)cuprate(II) trihydrate

The asymmetric unit of the title compound, (C13H11N2)2[Cu(C7H3NO4)2]·3H2O, consists of one [Cu(pydc)2]2− dianion (pydc is pyridine-2,6-dicarboxyl­ate), two 9-amino­acridinum monocations and three uncoordinated water mol­ecules. The CuII atom is coordinated by two pydc dianions acting as tridentate ligands, and forming five-membered chelate rings with copper(II) as the central atom. The CuII atom is surrounded by four O atoms in the equatorial plane and two pyridine N atoms in axial positions, resulting in a distorted octa­hedral coordination geometry. In the crystal, there are two types of O—H⋯O and N—H⋯O hydrogen-bonding synthons linking the anionic and cationic fragments and the water mol­ecules, namely R 4 4(16), and R 4 2(8). There are also weak C—H⋯O hydrogen bonds, π–π stacking inter­actions [the shortest centroid–centroid distance is 3.350 (2) Å], and a C—O⋯π inter­action [O⋯centroid distance = 3.564 (2) Å], which connect the various components into a three-dimensional network

Bis(guanidinium) tris­(pyridine-2,6-dicarboxyl­ato-κ3 O 2,N,O 6)zirconate(II) tetra­hydrate

In the title complex, (CH6N3)2[Zr(C7H3NO4)3]·4H2O, the ZrIV ion lies on a twofold rotation axes and is coordinated by six O and three N atoms of three tridentate pyridine-2,6-dicarboxyl­ate ligands, forming a slightly distorted tricapped trigonal–prismatic geometry. In the crystal, O—H⋯O and N—H⋯O hydrogen bonds link the components into a three-dimensional network

2,6-Diamino­pyridinium bis­(4-hydroxy­pyridine-2,6-dicarboxyl­ato-κ3 O 2,N,O 6)ferrate(III) dihydrate

The reaction of iron(II) sulfate hepta­hydrate with the proton-transfer compound (pydaH)(hypydcH) (pyda = pyridine-2,6-diamine; hypydcH2 = 4-hydroxy­pyridine-2,6-dicarboxylic acid) in an aqueous solution led to the formation of the title compound, (C5H8N3)[Fe(C7H3NO5)2]·2H2O. The anion is a six-coordinated complex with a distorted octa­hedral geometry around the FeIII atom. Extensive inter­molecular O—H⋯O, N—H⋯O and C—H⋯O hydrogen bonds, involving the complex anion, (pydaH)+ counter-ion and two uncoordinated water mol­ecules, and π–π [centroid-to-centroid distance 3.323 (11) Å] and C—O⋯π [O–centroid distance 3.150 (15) Å] inter­actions connect the various components into a supra­molecular structure