Abstract

Six new compounds of the homologous series of N,N'-bis(2-quinolinecarboxamide) alkane (4a-c) and N,N'-bis(6-quinolinecarboxamide) alkane (5a-c) derivatives having two, four and six carbon atoms in the alkyl spacer were synthesized and their crystal structures were determined by single crystal X-ray diffraction. These solid-state structures have been analyzed finding that the two series exhibit interesting differences between them. The remarkable preference of the bis(6-quinolinecarboxamide) alkanes to form one-or two-dimensional networks via N-H center dot center dot center dot O intermolecular hydrogen bonds appears total or partially disrupted by the intramolecular N-H center dot center dot center dot N-quinoline hydrogen bond in bis(2-quinolinecarboxamide) alkanes. These interactions, theoretically sorted as a 'very weak and purely electrostatic', seems to play a fundamental role in the crystal packing of bis(2-quinolinecarboxamide) derivatives. On the other hand, the rationalization of the bis(6-quinolinecarboxamide) structures are completely in agreement with the statement that the amide-to-amide hydrogen bond formation and network (beta-sheets or 4,4-network), in these systems, depends on the interplanar angle between the amide group and the heterocyclic ring.