Novel one‐dimensional polymeric Cu(II) complexes via Cu(II)‐assisted hydrolysis of the 2,4‐ bis (3,5‐dimethyl‐1 H ‐pyrazol‐1‐yl)‐6‐methoxy‐1,3,5‐triazine pincer ligand: Synthesis, structure, and antimicrobial activities

Deciphering the Mechanism of MRSA Targeting Copper(II) Complexes of NN2 Pincer-Type Ligands

WHO lists AMR as one of the top ten global public health issues. Therefore, constant effort is needed to develop more efficient antimicrobial drugs. As a result, earth-abundant transition-metal complexes have emerged as an excellent solution. In this regard, new aminoquinoline-based copper(II) pincer complexes 1-3 were designed, synthesized, and characterized by modern spectroscopic techniques. It is worth mentioning that, at the highest concentration (1024 μg/mL) of complexes (1-3), the hemolysis was found to be <15%, implying their less toxicity. Further, the complexes effectively interfered with the growth of Gram positive MRSA and the fungus Candida albicans. Among them, complex 2 was promising (MIC = 16 μg/mL) against MRSA, which was better than the known antibacterial drug kanamycin (64 μg/mL) under identical conditions. The Alamar blue cell viability test and the MBC/MFC identified by spot assay were in accordance with MIC values. Moreover, the insilico studies explained the most probable mechanism of action as inhibition of cell wall biosynthesis and dysfunction of antibiotic sensing proteins. Similarly, the antifungal action might be due to the cell surface adhesion protein dysfunction by the complexes. Furthermore, we are expecting to draw these compounds for clinical applications.

Membrane-active substituted triazines as antibacterial agents against Staphylococcus aureus with potential for low drug resistance and broad activity

A library of new naphthalimide-triazine analogues was synthesized as broad-spectrum antibacterial agents to overcome drug resistance. Bioactivity assay reveals that derivative 8e, with benzylamine in its structure, exhibits strong antibacterial properties against multi-drug resistance Staphylococcus aureus at a concentration of 1.56 μg/ml. It was also found to be better than chloromycin and amoxicillin. The active compound 8e efficiently inhibits the development of drug resistance within 11 passages. In addition, compound 8e inhibits the formation of biofilms in S. aureus and acts rapidly in bactericidal efficacy. Furthermore, mechanistic studies reveal that compound 8e effectively destroys the cytoplasmic membrane of bacteria, leading to leakage of intercellular protein content and loss in metabolic activity. Compound 8e binds to HSA readily with a binding constant of 1.32 × 10⁵ M^-1, indicating that the compound could be delivered to the target site effectively. Compound 8e can also form a supramolecular complex with DNA to obstruct DNA replications. These results suggest that analogue 8e could be further developed as a potential antibacterial agent. Furthermore, the cytotoxicity of all the synthesized compounds was evaluated against 60 human cancer cell lines to test their potential for anticancer agents.

Co (II) Complexes Based on the Bis-Pyrazol-S-Triazine Pincer Ligand: Synthesis, X-ray Structure Studies, and Cytotoxic Evaluation

Four pincer-type Co (II) complexes of the 2,4-bis (3,5-dimethyl-1H-pyrazol-1-yl)-6-methoxy-1,3,5-triazine ligand (L) were evaluated for their cytotoxic activities against lung and breast cancer cell lines using cell viability assay. The X-ray single crystal structure of [Co(L)(H2O)2Br]Br (1) confirmed the pincer coordination behavior of the ligand L as an N-tridentate chelate. The hexa-coordination environment of Co (II) is completed by one bromide ion completing the equatorial plane of the octahedral structure and two trans water molecules at the axial positions. It crystallized in the monoclinic crystal system and P21/m space group with crystal parameters of a = 11.3170(10) Å, b = 7.4613(7) Å, c = 12.6917(12) Å and β = 95.927(3)°. Based on Hirshfeld analysis, the most dominant contacts are H…H (48.8%), Br…H (17.6%), H…C (11.2%) and O…H (10.1%), where the Br…H interactions are the most significant. The cytotoxic evaluation of the studied systems indicated that complex [Co(L)(NO3)2] (4) has the highest activity against lung (A-549) and breast (MCF-7) cell lines. In contrast, complex [Co(L)(H2O)3](ClO4)2.H2O(3) has the lowest cytotoxic activity against both cell lines.

A Novel Centrosymmetric Fe(III) Complex with Anionic Bis-pyrazolyl-s-triazine Ligand; Synthesis, Structural Investigations and Antimicrobial Evaluations

Reaction of 2,4-bis(3,5-dimethyl-1H-pyrazol-1-yl)-6-methoxy-1,3,5-triazine (MBPT) pincer ligand with FeCl3 in acidic medium (1:1 v/v) afforded the [Fe(BPT)Cl2(CH3OH)] complex of the hydrolyzed monobasic ligand: 4,6-bis(3,5-dimethyl-1H-pyrazol-1-yl)-1,3,5-triazin-2(1H)-one (HBPT). In this complex, the Fe(III) ion is hexacoordinated with one anionic pincer ligand unit (BPT−1), two chloride ions, and one coordinated methanol molecule. It crystallized in the monoclinic crystal system and centrosymmetric P21/c space group with Z = 2 and unit cell parameters of a = 7.309(2) Å, b = 25.461(8) Å, c = 9.918(3) Å and β = 102.646(7)°. The structure of this complex is stabilized by C–H…Cl intramolecular hydrogen bonding interactions with donor acceptor distances ranging from 3.577(3)–3.609(3) Å while its supramolecular structure is controlled by intermolecular O–H…O, O–H…N, and C–H…Cl hydrogen bonding interactions. Hirshfeld analysis of molecular packing indicates that the percentages of the Cl…H, C…O, O…H, C…C, H…C, and N…H contacts are 21.1, 1.7, 10.2, 2.1, 8.6, and 10.4%, respectively. The nature and relative strength of the different coordination interactions in the [Fe(BPT)Cl2(CH3OH)] complex are discussed based on atoms in molecules theory. Antimicrobial evaluations indicated that the [Fe(BPT)Cl2(CH3OH)] complex showed moderate antibacterial and antifungal activities compared to amoxicillin and ampicillin antibiotics as standard drugs.

Synthesis, Structure and In Vitro Anticancer Activity of Pd(II) Complex of Pyrazolyl-s-Triazine Ligand; A New Example of Metal-Mediated Hydrolysis of s-Triazine Pincer Ligand

The square planar complex [Pd(PT)Cl(H2O)]*H2O (HPT: 6-(3,5-dimethyl-1H-pyrazol-1-yl)-1,3,5-triazine-2,4(1H,3H)-dione) was obtained by the reaction of 2-methoxy-4,6-bis(3,5-dimethyl-1H-pyrazol-1-yl)-1,3,5-triazine (MBPT) pincer ligand with PdCl2 in a molar ratio (1:1) under thermal conditions and using acetone as a solvent. The reaction proceeded via C-N cleavage of one C-N moiety that connects the pyrazole and s-triazine combined with the hydrolysis of the O-CH3 group. The reaction of the chloride salt of its higher congener (PtCl2) gave [Pt(3,5-dimethyl-1H-pyrazole)2Cl2]. The crystal structure of [Pd(PT)Cl(H2O)]*H2O complex is stabilized by inter- and intra-molecular hydrogen bonding interactions. Hirshfeld analysis revealed that the H...H (34.6%), O...H (23.6%), and Cl...H (7.8%) interactions are the major contacts in the crystal. The charges at Pd, H2O, Cl and PT are changed to 0.4995, 0.2216, −0.4294 and −0.2917 instead of +2, 0, −1 and −1, respectively, using the MPW1PW91 method. [Pd(PT)Cl(H2O)]*H2O complex has almost equal activities against MDA-MB-231 and MCF-7 cell lines with IC50 of 38.3 µg/mL.