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A new series of amino acid derivatives of quinolines was synthesized through the hydrolysis of amino acid methyl esters of quinoline carboxamides with alkali hydroxide. The compounds were purified on silica gel by column chromatography and further characterized by TLC, NMR and ESI-TOF mass spectrometry. All compounds were screened for in vitro antimicrobial activity against different bacterial strains using the microdilution method. Most of the synthesized amino acid-quinolines show more potent or equipotent inhibitory action against the tested bacteria than their correspond esters. In addition, many of them exhibit fluorescent properties and could possibly be utilized as fluorophores. Molecular docking and simulation studies of the compounds at putative bacterial target enzymes suggest that the antimicrobial potency of these synthesized analogues could be due to enzyme inhibition via their favorable binding at the fluoroquinolone binding site at the GyrA subunit of DNA gyrase and/or the ParC subunit of topoisomerase-IV.

Due to the ever‐increasing antimicrobial resistance there is an urgent need to continuously design and develop novel antimicrobial agents. Inspired by the broad antibacterial activities of various heterocyclic compounds such as 2‐quinolone derivatives, we designed and synthesized new methyl‐(2‐oxo‐1,2‐dihydroquinolin‐4‐yl)‐L‐alaninate‐1,2,3‐triazole derivatives via 1,3‐dipolar cycloaddition reaction of 1‐propargyl‐2‐quinolone‐L‐alaninate with appropriate azide groups. The synthesized compounds were obtained in good yield ranging from 75 to 80 %. The chemical structures of these novel hybrid molecules were determined by spectroscopic methods and the antimicrobial activity of the compounds was investigated against both bacterial and fungal strains. The tested compounds showed significant antimicrobial activity and weak to moderate antifungal activity. Despite the evident similarity of the quinolone moiety of our compounds with fluoroquinolones, our compounds do not function by inhibiting DNA gyrase. Computational characterization of the compounds shows that they have attractive physicochemical and pharmacokinetic properties and could serve as templates for developing potential antimicrobial agents for clinical use.

The substituted cyclopentadienyl ring in the title molecule, [Fe(C5H5)(C18H13ClN)], is nearly coplanar with the phenyl-1-(4-chlorophenyl)methanimine substituent, with dihedral angles between the planes of the phenylene ring and the Cp and 4-(chlorophenyl)methanimine units of 7.87 (19) and 9.23 (10)°, respectively. The unsubstituted cyclopentadienyl ring is rotationally disordered, the occupancy ratio for the two orientations refined to a 0.666 (7)/0.334 (7) ratio. In the crystal, the molecules pack in `bilayers' parallel to the ab plane with the ferrocenyl groups on the outer faces and the substituents directed towards the regions between them. The ferrocenyl groups are linked by C—H...π(ring) interactions. A Hirshfeld surface analysis of the crystal structure indicates that the most important contributions for the crystal packing are from H...H (46.1%), H...C/C... H (35.4%) and H...Cl/Cl...H (13.8%) interactions. Thus C—H...π(ring) and van der Waals interactions are the dominant interactions in the crystal packing.

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