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This study describes the rational development and synthesis of a benzothiazole-salicylaldehyde Schiff base probe 1. This probe is designed to function as a ratiometric fluorescent probe specifically for detecting ClO− ions, utilizing the imine bond as the fluorophore unit. Upon interaction with ClO− ions, probe 1 exhibits a redshift in its absorption spectrum from 435 nm to 450 nm. Moreover, in its emission spectrum, there is a ratiometric emission enhancement observed at 610 nm, providing a clear indication of the presence of ClO− ions. The sensitivity of probe 1 for detecting ClO− ions is quantified, revealing a lowest detection limit of 5.5 μM, indicating its potential for sensitive detection even at low concentrations of ClO− ions. Additionally, it has been successfully utilized for biological imaging purposes, demonstrating low cytotoxicity, which is crucial for its applicability in biological systems. [ABSTRACT FROM AUTHOR]

The increasing frequency of drug-resistant pathogens poses serious health issues to humans around the globe, leading to the development of new antibacterial agents to conquer drug resistance and bacterial infections. In view of this, we have synthesized a series of bis-naphthalimides to respond to awful drug resistance. Bioactivity assay and structure–activity relationship disclosed that compounds 5d and 5o exhibit potent antibacterial activity against E. faecalis, outperforming the marketed antibiotics. These drug candidates not only inhibit the biofilm formation of E. faecalis but also display rapid bactericidal properties, thus delaying the development of drug resistance within 20 passages. To explore the mechanism of antibacterial activity against E. faecalis, biofunctional examination was carried out which unveiled that 5d and 5o effectively disrupt bacterial cell membranes, causing the leakage of cytoplasmic contents and metabolic activity loss. Concurrently, 5d and 5o effectively intercalate with DNA to block DNA replication, causing the build-up of excessive reactive oxygen species and inhibiting the glutathione activity, ultimately leading to oxidative damage of E. faecalis and cell death. In addition, these compounds readily bind with HSA with a high binding constant, indicating that these drug candidates could be easily delivered to the target site. The above finding manifested that these newly synthesized bis-naphthalimides with multitargeting antibacterial properties offer a new prospect to overcome drug resistance. [ABSTRACT FROM AUTHOR]

Corrosion inhibition mechanism of two aromatic amino acids, phenylalanine (Phe) and tryptophan (Trp), was explored for steel in an alkaline pore solution simulating a carbonated concrete environment. The electrochemical impedance spectroscopy and potentiodynamic polarization test results revealed that both compounds can be used effectively as corrosion inhibitors for carbonated concrete environments with high inhibition efficiency. The dissolution of steel got controlled as Phe and Trp acted as anodic‐type inhibitors. Phe and Trp adsorbed on the steel surface by physiochemisorption process following the Langmuir isotherm. The inhibitive solution analysis through UV–visible technique confirmed the formation of inhibitor–Fe complexes. The surface of steel was analyzed after submergence in corrosive solutions with and without inhibitors by means of optical microscopy, scanning electron microscopy–energy‐dispersive X‐ray spectroscopy, Fourier transformed infrared, and X‐ray photoelectron spectroscopy, which highlights the formation of a compact, barrier layer comprised of metal–inhibitor complex. Subsequently, with the help of the aforementioned techniques, an inhibition mechanism for Phe and Trp was conjectured, which revealed that the presence of additional heterocycle in amino acids can raise the chances of chelation and formation of a more adherent and thermodynamically stable layer. Phe bound with Fe ions through the carboxylate functional group only, while Trp chelated the Fe ions via a nitrogen atom of the pyrrole ring and carboxylate functional group. [ABSTRACT FROM AUTHOR]

This paper presents the performance of a multifunctional generic compound, 4-Aminobenzoic acid (4ABA) as migratory inhibitor applied on hardened concrete surface to curb corrosion due to combined chloride and carbonated environment. Electrochemical techniques (LPR and EIS), gravimetric analysis were applied to evaluate the corrosion performance and the inhibition mechanism of 4ABA. Chloride and carbonation profiles were developed to investigate the dominant cause of corrosion during the exposure. Visual and microscopic analysis of concrete surface and rebar surface was also done. Compressive strength test was performed to study the effect of corrosion inhibitor on strength property of hardened concrete. Results confirm that 4ABA prolonged the passive state of rebar when used as preventive measure and restrained the on-going corrosion process when employed as repair strategy. Combined exposure by chlorides and CO2 leads to redistribution of chloride ions in concrete matrix. The results also conclude that during the combined exposure, chloride ions initiate the corrosion process and carbonation aggravates this process. Application of 4ABA does not influence the strength properties of concrete. ABA has performed the inhibition by protective layer development and shield formation against the negatively charged corrosive ions. Blended cement concrete system which was observed to be more vulnerable to corrosion was seen to attain similar corrosion resistance as OPC concrete after inhibitor application. [ABSTRACT FROM AUTHOR]