Vol.:(0123456789) 1 3 Journal of the Iranian Chemical Society https://doi.org/10.1007/s13738-018-1411-2 ORIGINAL PAPER Biological aspects of Schif base–metal complexes derived from benzaldehydes: an overview Ranjan K. Mohapatra 1  · Pradeep K. Das 2  · Manoj K. Pradhan 3  · Abdussalam A. Maihub 4  · Marei M. El‑ajaily 5 Received: 19 February 2018 / Accepted: 25 May 2018 © Iranian Chemical Society 2018 Abstract Schif bases are stable imines containing C=N, where N is bonded to an alkyl or aryl group, but not with hydrogen and are prepared by condensation of aliphatic or aromatic primary amine with carbonyl compounds. They have the general formula R 1 R 2 C = NR 3 , where R 3 ≠ H. The presence of the basic donor N atom and the stability of the imine function render Schif bases as the most favored ligands that have the ability to stabilize metal ions in diferent oxidation states. The chelating envi- ronment in a Schif base profoundly infuences the electron distribution in the coordination sphere of metal in a complex and thereby regulates the property of the compounds in a big way. The structural diversity in some of the metal complexes with multidentate Schif base ligands has triggered a wide range of applications of this class of compounds in sensors, catalysis, biology, medicines, and photonics. This review compiles the synthesis and biological activities (antimicrobial, antioxidant, anticancer, antitubercular, DNA interaction studies) of benzaldehyde-based Schif bases and their metal complexes. Keywords Schif base · Benzaldehyde · Biological activities · Metal complexes Abbreviations DMSO Dimethyl sulfoxide DMF Dimethylformamide Fig Figure MIC Minimum inhibition concentration MBC Minimum bactericidal concentration MFC Minimum fungicidal concentration UV–Vis Ultraviolet–visible IR Infrared FTIR Fourier transform infrared NMR Nuclear magnetic resonance XRD X-ray difraction ROS Reactive oxygen species DPPH 2,2′-Diphenyl-1-picrylhydrazyl BHT Butylated hydroxytoluene ABTS 2,2′-Azinobis(3-ethylbenzothiazoline-6-sul- phonic acid) BSA Bovine serum albumin CT DNA Calf thymus DNA ESR Electron spin resonance SEM Scanning electron microscope EDX Energy-dispersive X-ray SRB Sulfo-rhodamine-B stain Salen Salicylaldehyde ethylenediamine HOMO Highest occupied molecular orbital LUMO Lowest unoccupied molecular orbital PPh3 Triphenylphosphine MIC50 Minimal inhibitory concentration (50%) DNA Deoxyribose nucleic acid TB Tuberculosis MDR Multidrug resistant IC50 Half-maximal inhibitory concentration NHDF Normal human dermal fbroblast MTT Microculture tetrazolium test H 2 O 2 Hydrogen peroxide DFT Density functional theory TDDFT Time-dependent density functional theory ICT Intramolecular charge transfer CHEF Chelation-enhanced fuorescence * Ranjan K. Mohapatra ranjank_mohapatra@yahoo.com 1 Department of Chemistry, Government College of Engineering, Keonjhar, Odisha 758002, India 2 P. G. Department of Chemistry, G. M. University, Sambalpur, Odisha 768004, India 3 Department of Applied Chemistry, Jabalpur Engineering College, Jabalpur, MP 482011, India 4 Chemistry Department, Faculty of Science, Tripoli University, Tripoli, Libya 5 Chemistry Department, Faculty of Science, Benghazi University, Benghazi, Libya