Poly[tetra­kis­(dimethyl­formamide)tris(μ₄-terephthalato)trimagnesium]

The title framework compound, [Mg₃(C₈H₄O₄)₃(C₃H₇NO)₄]_n or [Mg₃(bdc)₃(DMF)₄]_n, was obtained as a side product of the solvothermal reaction of magnesium nitrate, terephthalic acid (bdcH₂), and 1,3-bis­(4-pyrid­yl)propane in a 1:2:1 ratio in dimethyl­formamide (DMF). The asymmetric unit consists of three Mg^II cations, three terephthalate anions, and four coordinating DMF mol­ecules. One of the four DMF mol­ecules was refined as disordered over two mutually exclusive positions, with an occupancy rate for the major moiety of 0.923 (4). The three Mg^II cations possess distorted octa­hedral coordination geometries that form linear Mg trimers. Of the three Mg^II cations, the central Mg^II is octa­hedrally coordinated by six different carboxyl­ate O atoms. The terminal Mg^II cations are bonded to four O atoms of three bdc linkers and to two O atoms of coordinating DMF mol­ecules. The compound has a two-dimensional 3⁶-network structure parallel to (001) that is formed by connection of the Mg trimers as distorted octa­hedral nodes to the bdc ligands as linkers.

4,4′-Bipyridine–terephthalic acid (1/1)

The asymmetric unit of the title compound, C₁₀H₈N₂·C₈H₆O₄, consists of one half-mol­ecule of each moiety, 4,4′-bipyridine (bpy) and terephthalic acid (bdc), both being located on crystallographic inversion centers. They are linked together via strong inter­molecular O—H...N hydrogen bonds, forming infinite chains propagating along [1-21]. The chains are further connected through C—H...O inter­actions giving sheets in (012). The sheets are linked via π–π inter­actions between the bpy rings and the bdc–bpy rings [centroid–centroid distances = 3.690 (2) and 3.869 (2) Å], resulting in the formation of a three-dimensional supra­molecular layer-like structure.

Dimethyl­ammonium 3-carb­oxy­benzoate

The asymmetric unit of the title organic salt, C₂H₈N⁺·C₈H₅O₄⁻, consists of two dimethyl­ammonium cations and two 3-carb­oxy­benzoate anions. The 3-carb­oxy­benzoate anions are linked via strong inter­molecular and nearly symmetrical O—H...O hydrogen bonds forming infinite chains parallel to [111]. Neighbouring chains are further connected by the dimethyl­ammonium cations via N—H...O bonds, resulting in a double-chain-like structure. The dihedral angles of all carboxylate groups with respect to the phenylene rings are in the range 7.9 (1)–20.48 (9)°.