Synthesis, Biological and In Silico Studies of a Tripodal Schiff Base Derived from 2,4,6-Triamino-1,3,5-triazine and Its Trinuclear Dy(III), Er(III), and Gd(III) Salen Capped Complexes

Exploring the versatility of sulfur-containing heterocyclic metal complexes: Application in medical and prospects of visible-light-driven photocatalysis

Numerous heterocyclic moieties serve as the foundational structure for clinically employed drugs, underscoring the significance of heterocycles in the innovation of pharmacologically active compounds. In the present investigation, a heterocyclic skeleton of thiophene-clubbed benzimidazole (tmb) was developed and utilized to synthesize seven novel series of metal (M(II) = Co, Ni, Cu, and Zn) complexes to explore diverse applications including pharmacological and photocatalytic performance. A sharp singlet peak appeared at 5.72 ppm (tmb) and 5.94 ppm for the Zn(II)-tmb complex corresponding to -CH2 protons, as evidenced by 1H NMR results, confirming the formation of targeted compounds. Antimicrobial assay and docking studies confirmed that the mixed metal complex; [Cu(tmb)2(1,10-phen)Cl2] possesses the highest activity and displayed significant biofilm inhibition, achieving 86.35 and 89.8% at concentrations of 1 and 0.020 mg/mL, respectively against E. coli. Furthermore, the photocatalytic activity was monitored by the degradation of methylene blue dye under direct sunlight and [Cu(tmb)2Cl2] exhibited a maximum degradation efficiency of 96.15% in 45 min. These findings could serve as inspiration for the development of benzimidazole-based metal complexes as effective anti-biofilm and photocatalytic agents.

Erbium(III) complexes with fluoroquinolones: Structure and biological properties

Four erbium(III) complexes with the fluoroquinolones enrofloxacin, levofloxacin, flumequine and sparfloxacin as ligands were synthesized and characterized by a wide range of physicochemical and spectroscopic techniques as well as single-crystal X-ray crystallography. The compounds were evaluated for their activity against the bacterial strains Staphylococcus aureus, Bacillus subtilis, Escherichia coli and Xanthomonas campestris, which was higher than that of the corresponding free quinolones. The interaction mode of the complexes with calf-thymus DNA is via intercalation, as suggested by diverse studies such as UV-vis spectroscopy, DNA-viscosity measurements and competitive studies with ethidium bromide. Fluorescence emission spectroscopy revealed the high affinity of the complexes for bovine and human serum albumin and the determined binding constants suggested a tight and reversible binding of the compounds with both albumins.

C3-Symmetric ligands in drug design: An overview of the challenges and opportunities ahead

C3-symmetry is a type of star-shaped molecule consisting of a central core and three symmetrically attached chains. These molecules are used in drug discovery due to their unique three-fold rotational symmetry, which allows for specific binding interactions and improved molecular recognition. In this text, we provide an overview of synthetic approaches with C3-symmetry as a pharmaceutical tool: progress, challenges, and opportunities. C3-symmetric ligands offer both challenges and opportunities in drug design. Their unique symmetry can enhance binding interactions, but careful consideration of rigidity, synthetic complexity, and target compatibility is crucial. Further research and advancements in synthetic methods and modeling tools will likely drive their exploration in drug discovery, leading to the discovery of potent C3-symmetric ligands.

Erbium(III) coordination compounds with substituted salicylaldehydes: Characterization and biological profile

Five erbium(III) complexes with salicylaldehyde (saloH for 1), and mono- (5-X-saloH; X = NO₂ and Me for 2 and 3, respectively) or di-substituted salicylaldehydes (3,5-diX-saloH; X = Cl and Br for 4 and 5, respectively) were synthesized and characterized by physicochemical and spectroscopic techniques and single-crystal X-ray crystallography. All five complexes have the general formula [Er(deprotonated salicylaldehyde)₃(MeOH)(H₂O)]. The structure of complexes [Er(3,5-diCl-salo)₃(MeOH)(H₂O)]·1.5MeOH (complex 4) and [Er(3,5-diBr-salo)₃(MeOH)(H₂O)]·1.75MeOH (complex 5) were verified by single-crystal X-ray crystallography. The evaluation of antioxidant activity of the complexes was focused on their ability to scavenge 1,1-diphenyl-picrylhydrazyl and 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) free radicals and to reduce H₂O₂. The interaction of the complexes with calf-thymus DNA was investigated by UV-vis spectroscopy, viscosity measurements and via competitive studies with ethidium bromide in order to evaluate the possible DNA-binding mode and to determine the corresponding DNA-binding constants. The affinity of the complexes for bovine and human serum albumins was explored by fluorescence emission spectroscopy and the corresponding binding constants were determined.

Structure and Computational Studies of New Sulfonamide Compound: {(4-nitrophenyl)sulfonyl}tryptophan

Synthesis of sulfonamide through an indirect method that avoids contamination of the product with no need for purification has been carried out using the indirect process. Here, we report the synthesis of a novel sulfonamide compound, ({4-nitrophenyl}sulfonyl)tryptophan (DNSPA) from 4-nitrobenzenesulphonylchloride and L-tryptophan precursors. The slow evaporation method was used to form single crystals of the named compound from methanolic solution. The compound was characterized by X-ray crystallographic analysis and spectroscopic methods (NMR, IR, mass spectrometry, and UV-vis). The sulfonamide N-H NMR signal at 8.07–8.09 ppm and S-N stretching vibration at 931 cm−1 indicate the formation of the target compound. The compound crystallized in the monoclinic crystal system and P21 space group with four molecules of the compound in the asymmetric unit. Molecular aggregation in the crystal structure revealed a 12-molecule aggregate synthon sustained by O-H⋯O hydrogen bonds and stabilised by N-H⋯O intermolecular contacts. Experimental studies were complemented by DFT calculations at the B3LYP/6-311++G(d,p) level of theory. The computed structural and spectroscopic data are in good agreement with those obtained experimentally. The energies of interactions between the units making up the molecule were calculated. Molecular docking studies showed that DNSPA has a binding energy of −6.37 kcal/mol for E. coli DNA gyrase (5MMN) and −6.35 kcal/mol for COVID-19 main protease (6LU7).