Coordination behavior of new bis(tridentate ONO, ONS and ONN) donor hydrazones towards some transition metal ions: Synthesis, spectral, thermal, antimicrobial and antitumor studies

1-D MOF [Ag2(C10H10N3O3S)2(C4H8N)2]n: photocatalytic treatment, crystallographic evaluation, ADMET parameters, CT-DNA and anticancer activity

Newly synthesized dinuclear crystalline polymer, the silver complex of bidentate Sulfamethoxazole (Ag-SMX) in the presence of secondary ligand pyrrolidine has been characterized by elemental, spectral (1H-NMR spectra, FT-IR spectra, UV-Vis spectra.), powder XRD, and single-crystal X-ray diffraction (single-crystal) analysis. The synthesis molecular structure of the dinuclear [Ag2(C10H10N3O3S)2(C4H8N)2]n complex reveals a one-dimensional polymeric chain with seesaw geometry (τ4 = 0.71): two silvers interlink each other by argentophilic interaction with Ag1…Ag2 separation distance of 3.0047(6) Å. The Hirshfeld surfaces (HS) and 2D fingerprint plots were used to examine the interconnects in the crystal packing. Molecule properties including MEP, MPA, HOMO-LUMO energy, and global reactivity descriptor parameters were computed to understand the molecule's stability. From ADMET parameters, human Intestinal Absorbance data revealed that the compound has the potential to be well absorbed, and also Ag-smx complex cannot cross the blood-brain barrier (BBB). The capacity of the silver complex to interact with CtDNA was investigated using absorption spectroscopy and viscosity tests. The interaction between CT-DNA reveals that the Ag-SMX complex exhibits the strongest binding affinity among all known sulfonamide derivatives and their metal complexes. The silver complex has higher inhibitory action than the free SMX ligand, according to data from a panel of gram (+ve) and gram (-ve) organisms' minimum inhibitory concentrations. In vitro cytotoxicity investigation revealed that the IC50 value for Ag-SMX is 57.12 g/mL and for SMX is 100.90 g/mL against human lung cancer cell line (A549). This study revealed that, when compared to SMX free-ligand, Ag-SMX is the most effective in terms of cytotoxicity toward the human lung cancer cell line (A549 cell line). In under 120 min, the synthesized Ag-smx complex showed exceptional photo-degradation characteristics against methylene blue (MB) (10 ppm) in visible light radiation.Communicated by Ramaswamy H. Sarma.

Design, synthesis, characterization, in vitro cytotoxic, antimicrobial, antioxidant studies, DFT, thermal and molecular docking evaluation of biocompatible Co(II) complexes of N4O4-macrocyclic ligands

Bioactive cobalt (II) macrocyclic complexes [Co(N4O4ML1)Cl2]-[Co(N4O4ML3)Cl2] have been synthesized by using the macrocyclic ligands [N4O4ML1], [N4O4ML2], and [N4O4ML3] that have an N4O4 core. These three macrocyclic ligands were all isolated in pure form, together with their complexes. Microanalytical investigations, FT-IR NMR, Mass, magnetic moments, electronic, PXRD, TGA, and EPR spectrum studies were used to analyse their structures. For these complexes, an octahedral geometry is proposed for the metal ion. By using molecular weights and conductivity measurements the monomeric and non-electrolytic nature has been confirmed. The Coats-Redfern and FWO methods are used to determine the thermodynamic characteristics of the ligands and their Co(II) complexes. The molecular modelling using the DFT technique displays the bond angle, bond lengths and quantum chemical properties. To determine their ability to prevent the growth of harmful fungus and bacteria, the ligands [N4O4ML1]- [N4O4ML3] and their complexes were tested in vitro against A. Niger, C. albicans and B. subtilis, S. aureus, E. coli and S. typhi fungal and bacterial organisms, respectively. By using DPPH free radical scavenger assays, the in vitro antioxidant capabilities of each compound were evaluated. The [Co(N4O4ML3)Cl2] antioxidative capabilities revealed significant radical scavenging power. The MTT assay was used to assess the toxicity of all the synthesised compounds under inquiry on MCF-7, HeLa, and A549 cancer cells. The findings revealed that the ligand and the compounds gave outstanding IC50 values in the range of 9.07-36.25 (uM) at a concentration of 25 ppm. Among all the substances evaluated, [Co(N4O4ML3)Cl2] complex was discovered to be the most active and least cytotoxic. Additionally, docking investigations of the produced compounds were carried out in order to validate the biological outcomes.

Spectroscopic, theoretical and computational investigations of novel benzo[b]thiophene based ligand and its M(II) complexes: As high portentous antimicrobial and antioxidant agents

The reaction of 3-chlorobenzo[b]thiophene-2-carbohydrazide with 4-(diethylamino) salicylaldehyde gave the new ligand; 3-chloro-N'-(4-(diethylamino)-2-hydroxybenzylidene)-benzo[b]thiophene-2-carbohydrazide. The Cu(II), Co(II), Ni(II), and Zn(II) complexes have been successfully prepared. The ligand and the complexes were characterized by analytical, FT-IR, 1H NMR, mass, UV-visible spectroscopy, molar conductivity, and magnetic susceptibility measurements. The FT-IR spectral data showed that the ligand adopted a tridentate fashion when binding with the metal ions via the nitrogen atoms of the imine (C = N), carboxyl (C = O), and phenolic oxygen (O-H) donor atoms. Density Functional Theory (DFT) estimations for the ligand at the DFT/B3LYP level via 6-31G++ (d, p) replicate the structure and geometry. Finally, HOMO and LUMO analyses were used for the charge transfer interface of the structure. Furthermore, molecular docking and ADME calculations were also performed to correlate and interpret the experimental results. The antimicrobial activity study illustrated enhancement in the activity of the free ligand upon complex formation, and the Cu(II) complex (MIC 25 µg mL-1) may be considered a promising antibacterial agent, and the Ni(II) and Zn(II) complexes (MIC 25 µg mL-1) as promising antifungal agents. Also, synthesized Cu(II) and Zn(II) metal complexes (MIC 3.125 µg mL-1) showed promising anti-TB activity against M. tuberculosis. Further, benzo[b]thiophene-based ligand and its metal complexes were evaluated for in vitro antioxidant activity, and in silico docking studies were carried out against Cytochrome c Peroxidase (PDB ID: 2X08).

Study of novel bidentate heterocyclic amine-based metal complexes and their biological activities: cytotoxicity and antimicrobial activity evaluation

Metallic antitumor drugs with heterocyclic ligands, such as novel AMI (amino methyl imidazole) complexes [Pd(AMI)Cl₂](1), [Cu(AMI)L¹](2), and [Cu(AMI)L²·2H₂O](3) where L¹ = oxalate and L² = malonate, were synthesized and characterized. Assessments included elemental analyses, mass spectrometry, Fourier transform-infrared spectroscopy, ultraviolet-visible spectroscopy, and thermal analysis. The cytotoxicity of AMI complexes compared to cisplatin was assessed using MTT (3-[4,5-dimethylthiazol-2-yl] 2,5diphenyl tetrazolium bromide) assay with breast (MCF-7) and cervical (HeLa) cancer cell lines. After treating these cells with the AMI complexes' IC₅₀ values for 48 h, malondialdehyde levels and catalase activity were used to assess oxidative stress, antioxidant activity was evaluated with DPPH radical scavenging method, comet assays assessed DNA damage, and DNA fragmentation was evaluated using the gel electrophoresis. In vitro, antimicrobial activity was assessed using a disc diffusion method. The anticancer activity results showed that IC₅₀ (half-maximal inhibitory concentration) values of complex one, two, and three against MCF-7 and HeLa cancer cells are 0.156 ± 0.0006, 0.125 ± 0.001, 0.277 ± 0.002 μM respectively for MCF-7 cells and 0.222 ± 0.0005, 0.126 ± 0.0009, 0.152 ± 0.001 μM respectively for HeLa cells. Complex two demonstrated strong anticancer activity against MCF-7 and Hela cells. The study of oxidative stress parameters revealed that Malondialdehyde levels increased in cancer cell lines treated with complexes compared to untreated cells. Catalase activity decreased in cells treated with palladium chelate. The DPPH radical scavenging assay results identified that complex one was a more potent antioxidant in MCF-7 and Hela cells than other complexes with SC₅₀ values of 227.5 ± 0.28 and 361 ± 1.2 μL/mL, respectively. The comet assay results showed that complex two caused significant DNA damage in MCF-7 and HeLa cancer cells treated. Antimicrobial assays identified complex three as the most effective. Copper complexes give better antifungal activity against A. flavus than the palladium complex. We conclude that complex two is the most active in both cell types and might be assessed as a clinically useful drug for breast cancer treatment. The significance of the current study is the synthesis of antitumor drugs containing heterocyclic ligands, such as novel AMI complexes, and the study of their biological activities.

NiII and CoII binary and ternary complexes of 3-formylchromone: spectroscopic characterization, antimicrobial activities, docking and modeling studies

Reactions of 3-formylchromone (L) with Ni(ii) and Co(ii) ions having different anions (acetate, perchlorate, nitrate, and chloride) yielded a series of binary and ternary octahedral complexes with the general formula [ML n L' m X y (S) a ]Z y ·bS, where M = Ni or Co, n = 1-3, L' = auxiliary ligand = 8-hydroxyquinoline or 1,10-phenanthroline, m = 1 or 2, X = acetate or chloride, y = 0 or 2, S = H2O or MeOH, a = 0-2, Z = nitrate or perchlorate and b = 0-1.5. Elemental and thermal analyses and infra-red, electronic, mass, magnetic susceptibility and molar conductivity measurements were successfully utilized to characterize the structures of the chromone complexes. The chromone ligand acts as a neutral bidentate ligand through its formyl and γ-pyrone oxygen atoms. The obtained complexes were formed with molar ratios 1 : 2 and 1 : 3 M : L for the binary and 1 : 2 : 1 and 1 : 1 : 1 M : L : L' for the ternary complexes. The kinetic parameters of the thermal degradation steps were estimated and explained using the Coats-Redfern equations. The synthesized complexes showed antimicrobial activity with higher activity toward Candida albicans and Bacillus subtilis. Docking studies showed good agreement with the antimicrobial activity. Molecular modeling of the synthesized complexes was performed using Hyperchem at the PM3 level and the calculated structures correlate with the experimental data.

Experimental and theoretical studies of new Co(III) complexes of hydrazide derivatives proposed as multi-target inhibitors of SARS-CoV-2

Cobalt(III) complexes with Schiff base ligands derived from hydrazone, (HL 1  = (E)-N'-(3,5-dichloro-2-hydroxybenzylidene)-4-hydroxybenzohydrazide, HL 2  = (E)-N'-(3,5-dichloro-2-hydroxybenzylidene)-4-hydroxybenzohydrazide (3,5-dibromo-2-hydroxybenzylidene), and HL 3  = (E)-4-hydroxy-N'-(2-hydroxy-3-ethoxybenzylidene)benzohydrazide), were synthesized and characterized by elemental analysis, Fourier transform infrared (FT-IR) spectroscopy, UV-Vis spectroscopy, and cyclic voltammetry. X-ray diffraction was used to determine the single crystal structure of the complex (1). Co(III) was formed in a distorted, very regular octahedral coordination in this complex; three pyridine moieties complete this geometry. Schiff base complexes' redox behaviors are represented by irreversible (1), quasi-reversible (2), and quasi-reversible (3) voltammograms. A density functional theory (DFT)/B3LYP method was used to optimize cobalt complexes with a base set of 6-311G. Furthermore, fragments occupying the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) were investigated at the same theoretical level. Quantum theory of atoms in molecules (QTAIM) computations were also done to study the coordination bonds and non-covalent interactions in the investigated structures. Hirshfeld surface analysis was used to investigate the nature and types of intermolecular exchanges in the crystal structure of the complex (1). The capacity of cobalt complexes to bind to the major protease SARS-CoV-2 and the molecular targets of human angiotensin-converting enzyme-2 (ACE-2) was investigated using molecular docking. The molecular simulation methods used to assess the probable binding states of cobalt complexes revealed that all three complexes were stabilized in the active envelope of the enzyme by making distinct interactions with critical amino acid residues. Interestingly, compound (2) performed better with both molecular targets and the total energy of the system than the other complexes.

Pincer Complexes Derived from Tridentate Schiff Bases for Their Use as Antimicrobial Metallopharmaceuticals

Within the current challenges in medicinal chemistry, the development of new and better therapeutic agents effective against infectious diseases produced by bacteria, fungi, viruses, and parasites stands out. With chemotherapy as one of the main strategies against these diseases focusing on the administration of organic and inorganic drugs, the latter is generally based on the synergistic effect produced by the formation of metal complexes with biologically active organic compounds. In this sense, Schiff bases (SBs) represent and ideal ligand scaffold since they have demonstrated a broad spectrum of antitumor, antiviral, antimicrobial, and anti-inflammatory activities, among others. In addition, SBs are synthesized in an easy manner from one-step condensation reactions, being thus suitable for facile structural modifications, having the imine group as a coordination point found in most of their metal complexes, and promoting chelation when other donor atoms are three, four, or five bonds apart. However, despite the wide variety of metal complexes found in the literature using this type of ligands, only a handful of them include on their structures tridentate SBs ligands and their biological evaluation has been explored. Hence, this review summarizes the most important antimicrobial activity results reported this far for pincer-type complexes (main group and d-block) derived from SBs tridentate ligands.

Thiophene-containing compounds with antimicrobial activity

Thiophene, as a member of the group of five-membered heterocycles containing one heteroatom, is one of the simplest heterocyclic systems. Many synthetic strategies allow the accurate positioning of various functionalities onto the thiophene ring. This review provides a comprehensive, systematic and detailed account of the developments in the field of antimicrobial compounds featuring at least one thiophene ring in their structure, over the last decade.

Synthesis of Novel Tritopic Hydrazone Ligands: Spectroscopy, Biological Activity, DFT, and Molecular Docking Studies

Polytopic organic ligands with hydrazone moiety are at the forefront of new drug research among many others due to their unique and versatile functionality and ease of strategic ligand design. Quantum chemical calculations of these polyfunctional ligands can be carried out in silico to determine the thermodynamic parameters. In this study two new tritopic dihydrazide ligands, N’2, N’6-bis[(1E)-1-(thiophen-2-yl) ethylidene] pyridine-2,6-dicarbohydrazide (L1) and N’2, N’6-bis[(1E)-1-(1H-pyrrol-2-yl) ethylidene] pyridine-2,6-dicarbohydrazide (L2) were successfully prepared by the condensation reaction of pyridine-2,6-dicarboxylic hydrazide with 2-acetylthiophene and 2-acetylpyrrole. The FT-IR, 1H, and 13C NMR, as well as mass spectra of both L1 and L2, were recorded and analyzed. Quantum chemical calculations were performed at the DFT/B3LYP/cc-pvdz/6-311G+(d,p) level of theory to study the molecular geometry, vibrational frequencies, and thermodynamic properties including changes of ∆H, ∆S, and ∆G for both the ligands. The optimized vibrational frequency and (1H and 13C) NMR obtained by B3LYP/cc-pvdz/6-311G+(d,p) showed good agreement with experimental FT-IR and NMR data. Frontier molecular orbital (FMO) calculations were also conducted to find the HOMO, LUMO, and HOMO−LUMO gaps of the two synthesized compounds. To investigate the biological activities of the ligands, L1 and L2 were tested using in vitro bioassays against some Gram-negative and Gram-positive bacteria and fungus strains. In addition, molecular docking was used to study the molecular behavior of L1 and L2 against tyrosinase from Bacillus megaterium. The outcomes revealed that both L1 and L2 can suppress microbial growth of bacteria and fungi with variable potency. The antibacterial activity results demonstrated the compound L2 to be potentially effective against Bacillus megaterium with inhibition zones of 12 mm while the molecular docking study showed the binding energies for L1 and L2 to be −7.7 and −8.8 kcal mol−1, respectively, with tyrosinase from Bacillus megaterium.

Structural, theoretical and biological activity of mono and binuclear nickel(II) complexes with symmetrical and asymmetrical 4,6-diacetylresorcinol-dithiocarbazate ligands

The present work reports the synthesis and a structural study of two novel dithiocarbazate, the 4,6-diacetylresorcinol-S-benzyldithiocarbazate (H₃L¹) and the 4,6-diacetylresorcinol-bis(S-benzyldithiocarbazate) (H₄L²), and their Ni(II) complexes, [Ni(HL¹)(Py)] (1) and [Ni₂(L²)(PPh₃)₂] (2). Single crystal X-ray analyzes reveal mono and binuclear complexes and the metal centers with distorted square planar geometry. The analyses of the Hirshfeld surface and fingerprints plots revealed intermolecular contacts attributed to the H···H and C···H/H···C bonds. The Density Functional Theory (DFT), with the B3LYP functional and 6-311-G(d,p)/LanL2DZ basis sets, was employed to optimize the geometries of synthesized compounds. From the resulting geometries, the highest occupied and lowest unoccupied molecular orbital maps (HOMO-LUMO), orbital energy gap, electron localization function (ELF), electron density, natural bond orbital (NBO) analysis, and complexation of the ligands with Ni(II) were calculated supporting the experimental data. The ESI (+)-MS/MS data indicated the presence in solution of the characteristic fragmentation with the [H₃L¹]⁺ and [H₄L²]⁺ molecular ions for the ligands. The pharmacological potential of the dithiocarbazate ligands and their Ni(II) complexes were evaluated in vitro against MDA-MB-231 human breast cancer cells. A remarkable cytotoxic activity was observed, more evident for free ligands than complexes at low concentrations; however, this latter showed a better dose-response pattern, being more attractive in terms of pharmacokinetics and therapeutic window.

A Review on Anticancer Activities of Thiophene and Its Analogs

Cancer is the world's second-largest cause of mortality and one of the biggest global health concerns. The prevalence and mortality rates of cancer remain high despite significant progress in cancer therapy. The search for more effective, as well as less toxic treatment methods for cancer, is at the focus of current studies. Thiophene and its derivatives have surged as an influential scaffold, which, because of their appreciable diversity in biological activities, has drawn the concerned interest of the researchers in the field of medicinal chemistry. By the affluent introduction of its derivatives, which have antioxidant, anti-inflammatory, antimicrobial, and anticancer activities, the adaptability of the thiophene moiety has been displayed. The nature and positioning of the substitutions significantly impacted thiophene moiety activity. This decent array in the living response account about this moiety has picked plentiful researcher's consideration to inquire about it to its peculiar potential across certain activities. In the field of cancer therapy against different cancer cells, the structure-activity relationship for each of the derivatives showed an excellent understanding of thiophene moiety. Information from the various articles revealed the key role of thiophene moiety and its derivatives to develop the vital lead compound. The essential anticancer mechanisms identified include inhibition of the topoisomerase, inhibition of tyrosine kinase, tubulin interaction and apoptosis induction through the activation of reactive oxygen species. This review is an endeavor to promote the anticancer potential of the derivatives, whether having thiophene or condensed thiophene as a core moiety or as a substituent that can lead in the future to synthesize varieties of chemotherapeutic entities in the field of cancer treatment.

Structure and biological profile of transition metal complexes with (E)-4-(2-(pyridin-2-ylmethylene)hydrazinyl)quinazoline

The interaction of the recently reported quinazoline derivative (E)-4-(2-(pyridin-2-ylmethylene)hydrazinyl)quinazoline (L) with a series of metal(II) (= copper(II), nickel(II), cobalt(II) and cadmium(II)) chlorides or nitrates resulted in the formation of mononuclear complexes which were characterized by spectroscopic techniques and single-crystal X-ray crystallography, i.e. [Cu(L)₂]Cl₂·4H₂O (1·4H₂O), [Ni(L)₂]Cl₂·4H₂O (2·4H₂O), [Ni(L)₂](NO₃)₂·MeOH (3·MeOH), [Co(L)₂]Cl₂·4H₂O (4·4H₂O), [Co(L)₂](NO₃)₂·H₂O (5·H₂O), [Co(L)₂](NO₃)₃·2.5H₂O (6·2.5H₂O), [Cd(L)(Cl)₂]·H₂O (7·H₂O) and [Cd(L)(CH₃OH)(H₂O)(NO₃)](NO₃) (8). The biological profile of the complexes was further assessed in regard to their binding affinity with calf-thymus DNA, their cleavage ability towards pBluescript II KS plasmid DNA in the absence or presence of irradiation of various wavelengths, their interaction with bovine serum albumin and finally, their ability to scavenge 1,1-diphenyl-picrylhydrazyl and 2,2΄-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) radicals and to reduce H₂O₂.