Depicting the DNA Binding and Cytotoxicity Studies against Human Colorectal Cancer of Aquabis (1-Formyl-2-Naphtholato-k2O,O′) Copper(II): A Biophysical and Molecular Docking Perspective

In this study, we attempted to examine the biological activity of the copper(II)–based small molecule aquabis (1-formyl-2-naphtholato-k2O,O′)copper(II) (1) against colon cancer. The characterization of complex 1 was established by analytical and spectral methods in accordance with the single-crystal X-ray results. A monomeric unit of complex 1 exists in an O4 (H2O) coordination environment with slightly distorted square pyramidal geometry (τ = ~0.1). The interaction of complex 1 with calf thymus DNA (ctDNA) was determined by employing various biophysical techniques, which revealed that complex 1 binds to ctDNA at the minor groove with a binding constant of 2.38 × 105 M–1. The cytotoxicity of complex 1 towards human colorectal cell line (HCT116) was evaluated by the MTT assay, which showed an IC50 value of 11.6 μM after treatment with complex 1 for 24 h. Furthermore, the apoptotic effect induced by complex 1 was validated by DNA fragmentation pattern, which clarified that apoptosis might be regulated through the mitochondrial-mediated production of reactive oxygen species (ROS) causing DNA damage pathway. Additionally, molecular docking was also carried out to confirm the recognition of complex 1 at the minor groove.

Biological Activity of Triazolopyrimidine Copper(II) Complexes Modulated by an Auxiliary N-N-Chelating Heterocycle Ligands

Novel complexes of type [Cu(N-N)(dmtp)2(OH2)](ClO4)2·dmtp ((1) N-N: 2,2′-bipyridine; (2) L: 1,10-phenantroline and dmtp: 5,7-dimethyl-1,2,4-triazolo[1,5-a]pyrimidine) were designed in order to obtain biologically active compounds. Complexes were characterized as mononuclear species that crystallized in the space group P-1 of the triclinic system with a square pyramidal geometry around the copper (II). In addition to the antiproliferative effect on murine melanoma B16 cells, complex (1) exhibited low toxicity on normal BJ cells and did not affect membrane integrity. Complex (2) proved to be a more potent antimicrobial in comparison with (1), but both compounds were more active in comparison with dmtp—both against planktonic cells and biofilms. A stronger antimicrobial and antibiofilm effect was noticed against the Gram-positive strains, including methicillin-resistant Staphylococcus aureus (MRSA). Both electron paramagnetic resonance (EPR) and Saccharomyces cerevisiae studies indicated that the complexes were scavengers rather than reactive oxygen species promoters. Their DNA intercalating capacity was evidenced by modifications in both absorption and fluorescence spectra. Furthermore, both complexes exhibited nuclease-like activity, which increased in the presence of hydrogen peroxide.

Study of DNA Interaction and Cytotoxicity Activity of Oxidovanadium(V) Complexes with ONO Donor Schiff Base Ligands

Two new oxidovanadium(V) complexes, (HNEt3)[VVO2L] (1) and [(VVOL)2μ-O] (2), have been synthesized using a tridentate Schiff base ligand H2L [where H2L = 4-((E)-(2-hydroxy-5-nitrophenylimino)methyl)benzene-1,3-diol] and VO(acac)2 as starting metal precursor. The ligand and corresponding metal complexes are characterized by physicochemical (elemental analysis), spectroscopic (FT-IR, UV–Vis, and NMR), and spectrometric (ESI–MS) methods. X-ray crystallographic analysis indicates the anion in salt 1 features a distorted square-pyramidal geometry for the vanadium(V) center defined by imine-N, two phenoxide-O, and two oxido-O atoms. The interaction of the compounds with CT–DNA was studied through UV–Vis absorption titration and circular dichroism methods. The results indicated that complexes showed enhanced binding affinity towards DNA compared to the ligand molecule. Finally, the in vitro cytotoxicity studies of H2L, 1, and 2 were evaluated against colon cancer (HT-29) and mouse embryonic fibroblast (NIH-3T3) cell lines by MTT assay. The results demonstrated that the compounds manifested a cytotoxic potential comparable with clinically referred drugs and caused cell death by apoptosis.

Bis(2-nitrophenyl) selenide, bis(2-aminophenyl) selenide and bis(2-aminophenyl) telluride: structural and theoretical analysis

Three organoselenium and organotellurium compounds containing ortho substitutents, namely, bis(2-nitrophenyl) selenide, C12H8N2O4Se, 2, bis(2-aminophenyl) selenide, C12H12N2Se, 3, and bis(2-aminophenyl) telluride, C12H12N2Te, 7, have been investigated by both structural and theoretical methods. In the structures of all three compounds, there are intramolecular contacts between both Se and Te with the ortho substituents. In the case of 2, this is achieved by rotation of the nitro group from the arene plane. For 3, both amino groups exhibit pyramidal geometry and are involved in intramolecular N—H...Se interactions, with one also participating in intermolecular N—H...N hydrogen bonding. While 3 and 7 are structurally similar, there are some significant differences. In addition to both intramolecular N—H...Te interactions and intermolecular N—H...N hydrogen bonding, 7 also exhibits intramolecular N—H...N hydrogen bonding. In the packing of these molecules, for 2, there are weak intermolecular C—H...O contacts and these, along with the O...N interactions mentioned above, link the molecules into a three-dimensional array. For 3, in addition to the N—H...N and N—H...Se interactions, there are also weak intermolecular C—H...Se interactions, which also link the molecules into a three-dimensional array. On the other hand, 7 shows intermolecular N—H...N interactions linking the molecules into R 2 2(16) centrosymmetric dimers. In the theoretical studies, for compound 2, AIM (atoms in molecules) analysis revealed critical points in the Se...O interactions with values of 0.017 and 0.026 a.u. These values are suggestive of weak interactions present between Se and O atoms. For 3 and 7, the molecular structures displayed intramolecular, as well as intermolecular, hydrogen-bond interactions of the N—H...N type. The strength of this hydrogen-bond interaction was calculated by AIM analysis. Here, the intermolecular (N—H...N) hydrogen bond is stronger than the intramolecular hydrogen bond. This was confirmed by the electron densities for 3 and 7 [ρ(r) = 0.015 and 0.011, respectively].

Synthesis and crystal structure analyses of tri-substituted guanidine-based copper(II) complexes

Three guanidine-derived tri-substituted ligands viz. N-pivaloyl-N′,N″-bis-(2-methoxyphenyl)guanidine (L1), N-pivaloyl-N′-(2-methoxyphenyl)-N″-phenylguanidine (L2) and N-pivaloyl-N′-(2-methoxyphenyl)-N″-(2-tolyl)guanidine (L3) were reacted with Cu(II) acetate to produce the corresponding complexes. The significance of the substituent on N″ for the resulting molecular structures and their packing in the solid state has been studied with respect to the structural specifics of the corresponding Cu(II) complexes. The key characteristic of the guanidine-based metal complexation with Cu(II) is the formation of an essentially square planar core with an N2O2 donor set. As an exception, in the complex of L1, the substituent’s methoxy moiety also interacts with the Cu(II) center to generate a square-pyramidal geometry. The hydroxyl groups of the imidic acid tautomeric forms of L1–L3, in addition to N″, are also bonded to Cu(II) in all three complexes rather than the nitrogen donor of the guanidine motif.

Spectral manifestations of the exciton-plasmon interaction of Ag2S quantum dots with silver and gold nanoparticles

The purpose of our study was to develop methods for creating hybrid nanostructures based on colloidal Ag2S quantum dots, pyramidal silver nanoparticles, Au nanorods, and to determine the spectral-luminescent manifestations of exciton-plasmon interactions in these structures. The objects of the study were Ag2S quantum dots passivated with thioglycolic acid (Ag2S/TGA QDs) and 2-mercaptopropionic acid (Ag2S/2-MPA QDs), gold nanorods (Au NRs), silver nanoparticles with pyramidal geometry (Ag NPs), and their mixtures. The spectral properties were studied using a USB2000+ with a PMC-100-20 photomultiplier system (Becker & Hickl Germany). The article considers the transformation of the luminescence spectra of colloidal Ag2S/TGA QDs and Ag2S/2-MPA QDs in mixtures with pyramidal Ag NPs and Au NRs. The study demonstratedthe presence of the effects of the contour transformation of the luminescence spectra due to the Fano effect, as well as the luminescence quenching following direct contact between QDs and NPs

Syntheses, Structures, Magnetic Properties and Antibacterial Activities of Two Copper(II) Azido Complexes with Varied Nuclearities Containing Symmetrical 1,3-Diammine as Chelator

Two copper(II) azido complexes of the types mononuclear [Cu(TMEDA)2(N3)2] (1) and dinuclear [Cu(TMEDA)(μ1,1-N3)(N3)]2 (2) [TMEDA = trimethylenediamine; N3 – = azide ion] have been synthesized and characterized. X-ray structural analysis revealed that each copper(II) center in complex 1 adopts a distorted octahedron geometry with a CuN6 chromophore ligated through four N atoms of two different symmetrical TMEDA ligands as bidentate chelator and two N atoms of two terminal azides. In complex 2, each copper(II) center adopts a distorted square pyramidal geometry with a CuN5 chromophore ligated through two N atoms of TMEDA as bidentate chelator and two N atoms of two different azides as μ1,1-N3 bridging mode and one N atom of terminal azide ion. The two copper centers are connected through double μ1,1-N3 bridges affording a dinuclear structure with Cu···Cu separation 3.327(2) Å. In crystalline state, mononuclear units in complex 1 are associated through intermolecular N-H···N and C-H···N hydrogen bonds to form a 2D sheet structure viewed along crystallographic b-axis, whereas dinuclear entities in complex 2 are propagated through intermolecular N-H···N and C-H···N hydrogen bonds to form a 3D network structure viewed along crystallographic a-axis. The Variable-temperature magnetic susceptibility measurement evidenced a dominant antiferromagnetic interaction between the metal centers through μ1,1-azide bridges in complex 2 with J = − 0.40 cm-1. The antibacterial activities of the complexes have also been studied.

Synthesis and spectral characterizations of vanadyl(ii) and chromium(iii) mixed ligand complexes containing metformin drug and glycine amino acid

Metformin is one of the most effective drugs for the treatment of type II diabetes. Two new mixed ligand complexes of vanadyl(ii) and chromium(iii) ions with the general formula [VOL1L2]SO4 and [CrL1L2(Cl)2]Cl, respectively, where L1 is the metformin and L2 is the glycine amino acid, have been synthesized in MeOH solvent with 1:1:1 stoichiometry and characterized by several spectroscopic techniques. The spectroscopic data suggested that the [VOL1L2]SO4 complex possesses a square pyramidal geometry, where the [CrL1L2(Cl)2]Cl complex possesses an octahedral geometry. The L1 ligand coordinated to the VO(ii) and Cr(iii) ions via the N atoms of the imino (‒C═NH) groups, where the L2 ligand coordinated via the O atom of the carboxylate group (COO) and the N atom of the amino group (NH2). The interaction of ligands L1 and L2 with the metal ions leads to complexes that have organized nanoscale structures with a main diameter of ∼14 nm for the [CrL1L2(Cl)2]Cl complex and ∼40 nm for the [VOL1L2]SO4 complex.

Tetradentate organophosphines in Pt(η4–A4L) (A = P4, P3Si, P2X2 (X2 = N2, S2, C2), PX3 (X3 = N3, N2O)): Structural aspects

We report herein structural characterization of monomeric platinum complexes of the composition: Pt(η4–P4L), Pt(η4–P3SiL), Pt(η4–P2N2L), Pt(η4–P2S2L), Pt(η4–P2C2L), Pt(η4–PN3L), and Pt(η4–PN2OL). The tetradentate ligands with 10-, 11-, 12-, 14-, and 16-membered macrocycles create a variety of chelate bond angles. A distorted square-planar geometry about Pt(II) atoms with cis–configuration by far prevail. There is an example Pt(η4–P3SiL) in which the respective donor atoms build up a trigonal-pyramidal geometry about Pt(II) atom.

Structure-reactivity studies on hypervalent square-pyramidal dithieno[3,2-b:2′,3′-d]phospholes

Reaction of dithienophospholes with quinones provides hypervalent phosphorus species with square-pyramidal geometry and promising reactivity.