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Luminescent coatings may provide low-cost techniques for studying the corrosion mechanism of coatings and for getting an early indication of corrosion processes. Here, a series of conducting copolymers and their nanocomposites has been synthesized and the effect of adding bulky moieties and/or nanocomposite formation on the solubility, thermal stability, corrosion inhibition, and photoluminescence of these copolymer coatings has been investigated. A significant enhancement in both solubility and thermal stability of the copolymers has been demonstrated upon the nanocomposite formation or presence of bulky groups. The nanocomposites displayed an inhibition efficiency of 97% for mild steel corrosion in an acidic environment which is much higher than that of the corresponding copolymers. Interestingly, the as-prepared copolymers and nanocomposites with tert-butyl group displayed an aggregation-induced emission with quantum yields higher than analogs without the tert-butyl group. Quantum chemical calculations attributed this enhancement in the quantum yields to the change in the degree of π-π interactions between the polymer chains. Moreover, aggregation-controlled luminescence has been demonstrated for the prepared copolymers.

Pyrazoles and pyrazolones constitute a group of organic compounds that have various medical applications such as antimicrobial, antipyretic, anti-inflammatory, antitumor and antioxidants. Pyrazolones can exist in different isomeric forms (CH, NH, OH) due to keto-enol, lactam-lactim and imine-enamine tautomerism. Determination of the most stable tautomeric form is thus important for understanding their biological roles at the molecular level. We performed a theoretical investigation of the structural and antioxidant properties of three synthetic pyrazolones (1–3), one synthetic pyrazole (4), one natural pyrazole (5) and two engineered hydroxyl derivatives of 1 (7, 8) and of 5 (9, 10) using the density functional theory at the B3LYP/6-311++G(d,p) level of theory in gas phase and in methanol (using the polarizable continuum model). It is found that substituents and solvents may influence the relative stability of pyrazolone isomers and that the CH tautomer is typically the least stable. Vertical ionization potentials, vertical electron affinities and X–H bond dissociation energies (X = C, N, O, S) are calculated for the global minimum structures and compared with those of the standard antioxidant flavonoid quercetin (6). Calculations predict that compounds 1 and 5 have antioxidant activity similar to 6 and that their mono and dihydroxyl derivatives (7–10) are more efficient antioxidants. Results also indicate that compounds 1–10 preferably interact with free radicals adopting the H atom transfer rather than the sequential electron transfer proton transfer mechanism. The study gives insight into the structural requirements for the design of highly efficient antioxidants. Keywords: Pyrazoles, Pyrazolones, Natural pyrazole, Tautomerism, DFT calculations, Antioxidants, Structural design

To find out effective new antibacterial agents, a series of novel aryl-hydrazothiazolyl-sulfonamide derivatives 3a-e were synthesized and well characterized by analytical and spectroscopic techniques. All the compounds were evaluated for their antibacterial and antifungal potential and the results showed excellent antimicrobial activity of 3d against all strains, especially B. cereus (MIC = 5.54 μM vs. 17.6 μM), P. aeruginosa (MIC = 7.3 μM vs.12.8 μM), E. coli (MIC = 6.4 μM vs. 21.3 μM) and C. albicans (MIC = 6.8 μM vs. 26.4 μM) in comparison to the commercial antibiotics, tetracycline and amphotericin B, respectively. The others analogues dispalyed potent to moderate antimicrobial activity. Structure-activity relationships (SARs) provides specially that incorporation of pyrimidin-2-ylsulfamoyl group at the para-phenyl position (3d) is good contributor for improving the antimicrobial activity. Further, Density Functional Theory (DFT) on 3d revealed its high stability and strongest electron-donating capability. Molecular docking and dynamic simulation studies on 3d inside the active site of S. aureus tyrosyl-tRNA synthetase (PDB ID: 1JIJ), E. coli dihydropteroate synthetase (PDB ID: 1AJ0), C. albicans dihydropteroate synthetase (PDB ID: 4HOE), and C. albicans N-myristoyl transferase (PDB ID: 1IYL) showed good binding profiles with the targets proteins, in particular with 1IYL and 4HOE receptors via the involvement of hydrogen bonding and that the formed complexes were thermodynamically highly stable. Taken together, our results make 3d as a promising lead for further drugs development.

The present work investigates some triazene compound's anti-corrosion properties as novel corrosive inhibitors by experimental and theoretical studies. Different electrochemical and morphological techniques were used to study the compound's corrosion inhibition. The experiments were performed in 1 M H2SO4 at different inhibitor concentrations and temperatures. The results showed that triazene compounds are effective inhibitors for mild steel corrosion in an acidic medium. Gaussian 09W software was used to calculate the compound's quantum chemical data, and there was an excellent approval between the experimental and quantum chemical calculations.

Highly selective spectrofluorimetric detection of Fe3+ ions in acidic medium is developed using novel fluorescent sensor, namely 4-(2-(3-Methyl-5-oxo-1-tosyl-1H-pyrazol-4(5H)-ylidene) hydrazinyl)-N-(pyrimidin-2-yl) benzenesulfonamide (PHBS-sensor), which gives an selective fluorescence quenching response at λEmission 379 nm. The factors affecting fluorescence detection process, such as the pH, solvent type, buffer type, probe concentration, reaction time and co-existing ions were systematically studied and optimized. Theoretical modeling of Fe3+ monitoring through DFT calculation was investigated to display the mechanism of PHBS-Fe3+ complexation. The proposed PHBS-sensor can detect Fe3+ ions at ultra-trace levels with limit of detection 1.7 × 10−5 M. Moreover, this applied method was effectively utilized for the monitoring/detection of Fe3+ ions in real water, such as ground, tap and Nile river water, and pharmaceutical samples, such as hard gelatin capsule and syrup.

In this work, we have successfully designed a new simple salicylaldehyde azine-functionalized benzoxazine (Azine-BZ−CH3) monomer via Mannich condensation reaction of 1,2-bis(2,4-dihydroxybenzylidene)hydrazine and paraformaldehyde with p-toluidine. FT-IR and NMR spectroscopy were carried to confirm the chemical structure of Azine-BZ−CH3. Based on DSC analyses, our BZ monomer showed the lowest maximum exothermic peak (237 °C) compared with 3-phenyl-3,4-dihydro-2H-benzooxazine monomer (263 °C), which ascribed to the basic characteristics of phenolic groups (OH) and the presence of the azine group in the benzoxazine monomer. Furthermore, the anticorrosion behavior of mild steel electrodes coated by Azine-BZ−CH3, poly(Azine-BZ−CH3), poly(Azine-BZ−CH3)/nanoclay and poly(Azine-BZ−CH3)/ E-SBO (epoxidized soybean) and E-bpc (epoxy resin of bisphenol-C) exposed to 1.0 M H2SO4 aqueous solution is studied by the potentiodynamic polarization. The results show decrease in both anodic and cathodic slopes of Tafel plots of the used inhibitors than a mild steel bar exposed to acidic media to indicate that these inhibitors act as mixed type inhibitors. Moreover, these inhibitors can be used as hybrid inhibitors where the anode and cathode slope of their Tafel curves used were lower than those of mild steel exposed to acidic media. In addition, the mild steel coated by epoxy E-SBO with poly(Azine-BZ−CH3)/nanoclay has more efficient corrosion protection (99.63%) than other used inhibitors. SEM images also confirmed that the protective layer of that inhibitor on the mild steel surface retards the corrosion when the electrodes are exposed to acidic media.