Spectroscopic studies of the intramolecular hydrogen bonding in o-hydroxy Schiff bases, derived from diaminomaleonitrile, and their deprotonation reaction products

Synthesis, crystal structure, biological and docking studies of 5-hydroxy-2-{[(2-methylpropyl)iminio]methyl}phenolate

Background: Schiff base compounds are potential drugs.Results: A Schiff base compound prepared by condensing 2,4-dihydroxy benzaldehyde and isobutylamine was characterized for structure, thermal, physicochemical and biological properties. The keto-enol tautomerism and azomethine functionality enhances electron delocaliZation and biological activity. The compound showed good antibacterial and antifungal activity at 40 μg/ml against bacteria such as Escherichia coli and Staphylococcus aureus and fungi like Candida albicans and Candida tropicalis. The docking study exhibits a moderate binding affinity for the GyrB protein in E. coli with a binding energy of -4.26 kcal/mol.Conclusion: The compound exhibits enhanced biological activity and suppression of cell growth at concentrations as low as 30 μg/ml. The IC50 for MFC-7 was found to be 41.5 μg/ml.

Semiconducting Soft Submicron Particles from the Microwave-Driven Polymerization of Diaminomaleonitrile

The polymers based on diaminomaleonitrile (DAMN polymers) are a special group within an extensive set of complex substances, namely HCN polymers (DAMN is the formal tetramer of the HCN), which currently present a growing interest in materials science. Recently, the thermal polymerizability of DAMN has been reported, both in an aqueous medium and in bulk, offering the potential for the development of capacitors and biosensors, respectively. In the present work, the polymerization of this plausible prebiotic molecule has been hydrothermally explored using microwave radiation (MWR) via the heating of aqueous DAMN suspensions at 170–190 °C. In this way, polymeric submicron particles derived from DAMN were obtained for the first time. The structural, thermal decomposition, and electrochemical properties were also deeply evaluated. The redox behavior was characterized from DMSO solutions of these highly conjugated macromolecular systems and their potential as semiconductors was described. As a result, new semiconducting polymeric submicron particles were synthetized using a very fast, easy, highly robust, and green-solvent process. These results show a new example of the great potential of the polymerization assisted by MWR associated with the HCN-derived polymers, which has a dual interest both in chemical evolution and as functional materials.

Synthesis, spectral studies, antioxidant and antibacterial evaluation of aromatic nitro and halogenated tetradentate Schiff bases

Herein, we report the synthesis, characterization, and biological properties of eleven (3a-3k) novel Schiff bases. The spectral data of FT-IR, ¹H NMR, ¹³C NMR, and LC-MS are associated with these synthesized compounds. From the FT-IR analysis, we confirmed the azomethine (-C=N-) group and from ¹H NMR data, the phenolic –OH proton is appeared at range δ 13.92–14.09ppm due to hydrogen bonding. The LC-MS analysis agreed with molecular ion peaks of synthesized Schiff bases. To evaluate the antibacterial activity of newly synthesized compounds were screened against b. licheniformis, b. species, e. coli, and s. aureus. Furthermore, the antioxidant activity was investigated by two methods 2,2-diphenyl-1-picryl hydrazyl (DPPH) and hydroxyl radical scavenging methods. The (-NO₂,-Cl,-Br,-I) substituted compounds have shown good antibacterial activity against tested organisms. Also, these compounds were exhibited higher antioxidant activity by given methods.

Diaminomaleonitrile derivatives as new potential antichagasic compounds: a study of structure-activity relationships

Background: Schiff bases are synthetically accessible compounds that have been used in medicinal chemistry. Methods & results: In this work, 27 Schiff bases derived from diaminomaleonitrile were synthesized in high yields (80-98%). Molecular docking studies suggested that the Schiff bases interact with the catalytic site of cruzain. The most active cruzain inhibitor, analog 13 (IC₅₀ = 263 nM), was predicted to form an additional hydrophobic contact with Met68 in the binding site of the enzyme. A strong correlation between the IC₅₀ values and ChemScore binding energies was observed (R = 0.99). Kernel-based 2D quantitative structure-activity relationship models for the whole dataset yielded sound correlation coefficients (R² = 0.844; Q² = 0.719). Conclusion: These novel and potent cruzain inhibitors are worthwhile starting points in further Chagas disease drug discovery programs.

Magnesium porphyrazine with peripheral methyl (3,5-dibromophenylmethyl)amino groups – synthesis and optical properties

Novel magnesium(II) porphyrazine with peripheral methyl(3,5-dibromophenylmethyl)amine groups was synthesized in a multi-step procedure starting from commercially available diaminomaleonitrile. All intermediates and the final macrocycle were characterized using UV–Vis, FT-IR, MS and various NMR techniques. The absorption and emission properties of the macrocycle were evaluated in N,N-dimethylformamide, dimethyl sulfoxide, and dichloromethane. The potential photosensitizing activity was evaluated by assessing the ability of the macrocycle to generate singlet oxygen in dimethyl sulfoxide and N,N-dimethylformamide.