Most of the d-metals are familiar with their distinctive properties and their applications have been extended in vast industry fields. Though they are doing outstanding work in industries and help to boost the economy of dependence. The excess uptake of d-metals explores significant health issues, and detrimental effects on the environment, and corrodes the biological species. Fluorescent probes based on Schiff base chemical compounds give more accuracy, and low-level detection for metal ions in water, chemicals, and in biological cells through commendable and quick fluorescence signals. So, it empowers the successful detection of d-metals in terms of dissimilar fluorescence responses by probes in light of metals. Based on the recent research in the field of Schiff base-based fluorescent probes and interpretation on effects for binding like ON-OFF PET, ICT, CHEF, and CHEQ this imperative review is framed.

A new salicylaldehyde-based sensor N'-(5-bromo-2-hydroxybenzylidene)-4-methylbenzohydrazide (P4) was designed, and its sensing ability towards various metal ions was assessed using UV-visible spectroscopy. The structure of P4 was spectroscopically characterized by UV-Visible, Infrared, ¹H-NMR, ¹³C-NMR spectroscopy and mass spectrometry. UV-Visible absorption spectral study showed selective sensing ability of P4 for Cd²⁺ and Ni²⁺ ions in presence of diverse transition metal ions. The results revealed that the detection limit for Cd²⁺ and Ni²⁺ was 3.14 µM and 0.92 µM, respectively. Moreover, the compound P4 was fully implemented for detection of Cd²⁺ and Ni²⁺ in simulated samples.

In the present work, we synthesized new thiosemicarbazone based Schiff base ligands and their Mn(II), Ni(II), Cu(II) and Zn(II) complexes. The synthesized compounds were characterized and their antimicrobial activities were studied. Elemental analysis, IR, ¹H-NMR and mass spectrometry were done to fully characterize all the compounds. The ligands and their complexes were screened for in-vitro biological study against Gram positive (Bacillus subtilis) and Gram negative (E. coli, Klebsiella pneumonia, Pseudomonas aeruginosa) bacteria for the Zone of Inhibition method. The thiosemicarbazone based complexes showed better activity than the ligands.

The chemistry of Schiff base has received remarkable attention in different applications, both organic synthesis and industries. Over the past few years many reports have been on the synthesis, characterization and application of vanadium Schiff base complexes. However, heterogeneous vanadium Schiff base catalysts are active for various oxidation reactions, making catalytic oxidation of hydrocarbons a great interest. This review summarizes the recent development of organic substrate oxidation with heterogeneous vanadium Schiff base catalysts.

The corrosion inhibition efficiency of the Schiff base N,N’-(5,5-dimethylcyclohexane-1,3-diylidene)dianiline (DmChDa) on mild steel in 1M HCl and 0.5M H₂SO₄ was evaluated using gravimetric, electrochemical impedance spectroscopy, potentiodynamic polarization and electrochemical noise measurement. Experimental results established that DmChDa possess relatively high corrosion inhibition capacity. Langmuir and El-Awady adsorption isotherms were obeyed by the Schiff base in 1M HCl and 0.5M H₂SO₄ respectively. SEM analysis showed that DmChDa was adsorbed on the steel surface during corrosion inhibition. The variation of metal dissolution with temperature was also examined using gravimetric study.

New ruthenium(III) complexes with 3-(Benzothiazol-2-yliminomethyl)-phenol (HL) ligand have been synthesized and characterized with the aid of elemental analysis, IR, electronic, and electron paramagnetic resonance spectroscopic techniques. The binding mode of the ligand and complexes with DNA and their ability to bind DNA have been investigated by UV-vis absorption titration. In addition, the ligand and complexes have been subjected to antioxidant activity tests which showed that HL and its ruthenium(III) complexes possess significant scavenging effect against DPPH and OH radicals. Cytotoxic activities of the ligand and ruthenium(III) complexes showed that the ruthenium(III) complexes exhibited more effective cytotoxic activity against HeLa and MCF-7 cells than the corresponding ligand.

A group of new fluoroaniline Schiff bases (3a–3f) were synthesized and structurally characterized by various spectroscopic techniques such as ¹H-NMR, LC-MS and FT-IR spectral studies. All compounds were evaluated for in vitro antibacterial activity. Compounds exhibited good to moderate antibacterial activity. Compound 3f (Zone of Inhibition = 10.08±0.06 µM) was found to be the most active one, and comparable to the standard Streptomycin (IC50 = 15.95±0.08 µM). The compounds having chloro substituent exhibit good membrane damage property against Methicillin-resistant Staphylococcus aureus (MRSA) confirmed by SEM analysis. Structure-activity relationship (SAR) was rationalized by looking at the varying structural features of the molecules.

A new series of transition metal complexes of Co(III), Ni(II) and VO(IV) was synthesized with the bidentate Schiff base ligand (HL) derived from the condensation of 2-amino-3-benzyloxypyridine and 5-bromo salicylaldehyde. The synthesized Schiff base ligand and its metal complexes C1-C6 were structurally characterized by satisfactory elemental analysis, spectral studies such as (Mass, IR, ¹H and ¹³C NMR, conductance measurement, UV-vis and magnetic measurements) and thermal studies. The structure of HL was authenticated by X-ray single-crystal analysis. Hirshfeld surface analysis was carried out to understand the nature of intermolecular contacts, the fingerprint plot provides the information about the percentage contribution. Square-pyramidal geometry is proposed for VO(IV) complexes whereas octahedral geometry for Co(III) and Ni(II) complexes. The Schiff base ligand and its metal complexes have been tested in vitro for their antibacterial activities by using well diffusion method against Gram positive bacteria B. subtilis, S. aureus and Gram negative bacteria S. typhi, E. coli and antifungal activities against A. niger, A. flavus, C. albicans and A. Solani. The antimicrobial activity data show that metal complexes are more potent than the parent ligand.

The corrosion inhibition efficiencies of two novel Schiff bases, namely (E)-3-[thiophen-2-ylmethyleneamino]benzoic acid (T2YMABA) and (E)-4-(5-[(2-phenylhydrazono) methyl]thiophen-2-yl)benzoic acid (PHMT2YBA) on mild steel (MS) in 1.0M HCl solution has been investigated and compared using electrochemical impedance spectroscopy and potentiodynamic polarization analysis. The Schiff bases exhibited very good corrosion inhibitions on mild steel in 1.0M HCl medium and the inhibition efficiency increased with the increase in concentration of the inhibitor. Polarization studies revealed that T2YMABA acted as a mixed type inhibitor whereas PHMT2YBA molecules acted as anodic inhibitor.