title: A monoclinic modification of propane-1,3-diyl bis-(pyridine-3-carboxyl-ate).
abstract: In the title compound, C(15)H(14)N(2)O(4), (I), the mol-ecule lies on a twofold rotation axis which passes through the central C atom of the aliphatic chain, giving one half-mol-ecule per asymmetric unit. The structure is a monoclinic polymorph of the triclinic structure previously reported [Brito, Vallejos, Bolte & López-Rodríguez (2010). Acta Cryst. E66, o792], (II). The most obvious difference between them is the O/C/C/C-O/C/C/C torsion angle [58.2 (7)° in (I) and 173.4 (3)/70.2 (3)° in (II) for GG and TG conformations, respectively]. Another important difference is observed in the dihedral angle between the planes of the aromatic rings [86.49 (7)° for (I) and 76.4 (3)° for (II)]. The crystal structure features a weak π-π inter-action [centroid-centroid distance = 4.1397 (10)Å]; this latter kind of inter-action is not evident in the triclinic polymorph.
authors.forename: Iván
authors.initials: I
authors.lastname: Brito
authors.forename: Javier
authors.initials: J
authors.lastname: Vallejos
authors.forename: Alejandro
authors.initials: A
authors.lastname: Cárdenas
authors.forename: Matías
authors.initials: M
authors.lastname: López-Rodríguez
authors.forename: Michael
authors.initials: M
authors.lastname: Bolte