Structural Investigation, UV–Vis Analysis and Crystal Packing of Spiro[chromeno[4,3-b]quinoline-6,1′-cycloalkan]-7-amine: Novel Tacrine Hybrids by Single Crystal X-Ray Diffraction

Abstract

The structure of four spiro[chromeno[4,3-b]quinoline-6,1′-cycloalkan]-7-amine (1–4) was determined by X-ray diffraction methods. The quinoline rings were obtained as almost planar structures, with an RMS deviation within a range of 0.0345–0.0641 A, while the chromene rings are not planar. Moreover, the cycloalkane rings are attached to the chromene in spiro form. Three of the four compounds crystallize as solvates—one with ethanol and the other two with water. The crystal packing for compounds 1–4 is discussed in terms of intermolecular interactions, and it is shown that the crystal packing of these heterocycles is governed by: strong O–H···N and N–H···O hydrogen bonds; weak C–H···O and C–H···N hydrogen bonds; and very weak C–H···Cl, C–H···Br, and C–H···π interactions. Also, π···π and lone pair···π interactions are present in the crystal packing of the heterocycles. These interactions lead to the formation of endless chains along a plane, as well as supramolecular dimers and the arrangement of molecules in layers. Additionally, UV–Vis absorption spectra properties are also discussed. The structure of four spiro[chromeno[4,3-b]quinoline-6,1’-cycloalkan]-7-amines are determined by single crystal X-ray diffraction. The crystal packing is discussed in terms of intermolecular interactions (strong O–H···N and N–H···O hydrogen bonds; weak C–H···O and C–H···N hydrogen bonds; and very weak C–H···Cl, C–H···Br, and C–H···π interactions). Also, π···π and lone pair π interactions are present in the crystal packing of the heterocycles.