A series of tetrahydro-7H-indeno[2,1-c]quinoline derivatives 5a-e were efficiently obtained using a two-step synthetic pathway, based on the cationic Povarov reaction, with moderate and high global yields (36–88%). Considering the remarkable importance of the indeno[2,1-c]quinoline compounds as precursors of potential anticancer agents, the solid state forms of these structures were studied. In general, and despite the presence of methoxy and fluorine substituent groups in two compounds, the supramolecular assemblies are mainly directed by weak interactions. All molecules have isotropic crystal morphologies excepting 2-ethyl-5,6,6a,11b-tetrahydro-7H-indeno[2,1-c]quinoline (5c) with preference to grows along 〈211〉 directions, leaving a (020) preferred orientation in bulk samples as was confirmed by X-ray powder diffraction. Quinolone derivatives showed high thermal stabilities from TGA/DSC experiments, with fusion temperatures between 80 and 110 °C and decompositions around ~280 °C. Fusion and decomposition enthalpies were measured, having values between 19 and 20 kJ/mol and 67–80 kJ/mol, respectively. Total packing energies, determined by force-field-based intermolecular energy calculations, support the measured enthalpies and explain the weak intermolecular interactions along [010] direction that induces the (020) preferred orientation in 5c. The B3LYP calculated band gap diagrams show that electron-withdrawing groups (OCH3 and F) induce a softer character with decreasing energy of LUMO orbitals.
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