Derivative Ligands Research Articles

Cytotoxic Cu(II) Complexes with a Novel Quinoline Derivative Ligand: Synthesis, Molecular Docking, and Biological Activity Analysis.

The utilization of metallodrugs as a viable alternative to organic molecules has gained significant attention in modern medicine. We hereby report synthesis of new imine quinoline ligand (IQL)-based Cu(II) complexes and evaluation of their potential biological applications. Syntheses of the ligand and complexes were achieved by condensation of 7-chloro-2-hydroxyquinoline-3-carbaldehyde and 2,2'-thiodianiline, followed by complexation with Cu(II) metal ions. The synthesized ligand and complexes were characterized using UV-vis spectroscopy, TGA/DTA, FTIR spectroscopy, 1H and 13C NMR spectroscopy, and pXRD. The pXRD diffractogram analysis revealed that the synthesized ligand and its complexes were polycrystalline systems, with nanolevel average crystallite sizes of 13.28, 31.47, and 11.57 nm for IQL, CuL, and CuL 2 , respectively. The molar conductivity confirmed the nonelectrolyte nature of the Cu(II) complexes. The biological activity of the synthesized ligand and its Cu(II) complexes was evaluated with in vitro assays, to examine anticancer activity against the MCF-7 human breast cancer cell line and antibacterial activity against Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli and Pseudomonas aeruginosa) bacterial strains. The CuL complex had the highest cytotoxic potency against MCF-7 breast cancer cells, with an IC50 of 43.82 ± 2.351 μg/mL. At 100 μg/mL, CuL induced the largest reduction of cancer cell proliferation by 97%, whereas IQL reduced cell proliferation by 53% and CuL 2 by 28%. The minimum inhibitory concentration for CuL was found to be 12.5 μg/mL against the three tested pathogens. Evaluation of antioxidant activity using 2,2-diphenyl-1-picrylhydrazyl revealed that CuL exhibited the highest antioxidant activity with IC50 of 153.3 ± 1.02 μg/mL. Molecular docking results showed strong binding affinities of CuL to active sites of S. aureus, E. coli, and estrogen receptor alpha, indicating its high biological activity compared to IQL and CuL 2 .

New chelating quinoxalyl hydrazone derivative, as tridentate ligand for complexation with Co(II), Ni(II), and Cu(II) ions. Development of antitumor, antimicrobial, and DNA reactivity

With the facile condensed carbonyl gourp of 2-hydorxybenzaldehyde with the amino group of quinoxalyl-2-carbohydrazide, a new chelating quinoxalyl hydrazone derivative ligand (H2Lpx) was constructed. Its coordination behavior towards three divalent Co2+, Ni2+, and Cu2+ ions was discovered by building up three new metallo-organic complexes (CoLpx, NiLpx, and CuLpx, respectively). Confirmation of their chemical structure was formulated by applying different spectroscopic methods, as well as, the micro-elemental (C,H,N) and thermogravimetric analyses, the conductance, and magnetic evaluations. The inhibition behavior of the free ligand and its metallo-organic complexes against the cell growth of six entitled microorganisms (three fungal and three bacterial types) and three tumors of humans was estimated considering the effective role of the divalent metal ions (Co2+, Ni2+, and Cu2+ ions in their metallo-organic complexes). The interacting nature of H2Lpx, CoLpx, NiLpx, and CuLpx, with calf thymus DNA (ctDNA) was manifested within the viscometric, spectrophotometric titrations and gel electrophoresis.The three complexes (CoLpx, NiLpx, and CuLpx) exposed a respectable inhibition attitude more than that of H2Lpx depending on the inhibition zone areas of the microbial series growth in mm and the half-inhibition concentration in µM (IC50) for the tumor cell lines’ growth. Establishing of the interacted modes between H2Lpx and MLpx with ctDNA was built upon the shifts of the spectral scans for their solutions. In addition, chromism type, Gibb’s free energy, and binding constant values (ΔGb≠ and Kb, respectively) helped to distinguish their interacted modes, which supported DNA damage. The bio-action of MLpx complexes was highly modified compared to that of H2Lpx towards ctDNA.

Investigation of half-sandwich platinum group metal complexes featuring benzamide derived ligands and their diazido derivatives: Synthesis, molecular structures and biological studies

Benzamide derivative ligands L1 and L2 were synthesized and reactions of these ligands with metal dimers [Ru(p-cymene)Cl2]2 and [Cp*MCl2]2 (M = Rh/Ir) yielded a series of “piano-stool”-type neutral mononuclear metal-arene-benzamide complexes (1, 2, 3, 4, 5 and 6) of the general formula [(arene)M(κ1(N)L)Cl2] (where arene = p-cymene and Cp*, M = Ru, Rh and Ir and L = L1 and L2). Further treatment of the neutral complexes 1-6 with sodium azide in methanol resulted in the formation of diazido complexes 7, 8, 9 and 10. Crystallographic studies of the complexes 2, 5, 7 and 8 revealed the ligands coordinated to the metal centers through the nitrogen atom of thiazole/thiadiazole ring in a monodentate fashion. The complexes were characterized by NMR, FTIR, UV-Vis spectroscopy and ESI-mass spectrometry. All the ligands and metal complexes were screened for their antibacterial and antioxidant activities. Interestingly, it was observed that only the diazido complexes were active towards the Gram-positive Staphylococcus aureus bacterial strains, with activities more than the standard. Antioxidant study revealed that the compounds possess insignificant activities.

Ruthenium(II) Polypyridyl Complexes with Benzoxazole Derivatives and Non-Innocent Ligands as Effective Antioxidants in Human Neuroblasts.

Ruthenium(II) polypyridyl complexes continue to raise increasing interest for the encouraging results in several biomedical areas. Considering their vast chemical-physical repertoire, in particular the possibility to switch from the sensitization of reactive oxygen species (ROS) to ROS-scavenging abilities by tuning the nature of their ligands, it is therefore surprising that their potential as antioxidants has not been largely investigated so far. Herein, we explored the antioxidant behaviour of the novel ruthenium compound [Ru(dbpy)(2,3-DAN)Cl]PF6 (Ru1), featuring a benzoxazole derivative (dpby=2,6-bis(4-methyl-2-benzoxazolyl)pyridine) and the non-innocent 2,3-diamminonaftalene (2,3-DAN) ligand, along with the reference tpy-containing analogue [Ru(tpy)(2,3-DAN)Cl]PF6 (Ru2) (tpy=2,2':6',2''-terpyridine). Following the synthesis and the electrochemical characterization, chemical antioxidant assays highlighted the beneficial role of dpby for the ROS-scavenging properties of Ru1. These data have been corroborated by the highest protective effect of Ru1 against the oxidative stress induced in SH-SY5Y human neuroblastoma, which exerts pro-survival and anti-inflammatory actions. The results herein reported highlight the potential of Ru1 as pharmacological tool in neurodegenerative diseases and specially prove that the antioxidant properties of such compounds are likely the result of a non-trivial synergetic action involving the bioactive ligands in their chemical architectures.

All‐in‐One: Photo‐Responsive Lanthanide‐Organic Framework for Simultaneous Sensing, Adsorption, and Photocatalytic Reduction of Uranium

AbstractThe selective removal and immobilization of uranyl ions from aqueous solutions is essential for the sustainable development of nuclear energy. Herein, a robust lanthanide‐organic framework material (IHEP‐24) is developed for simultaneous fluorescence sensing, selective adsorption, and photocatalytic reduction of uranium, integrating three different functions in one material. The confined space formed by the coordination assembly of viologen derivative ligands and metal‐oxygen clusters can act as precise recognition sites for uranyl, allowing IHEP‐24 to efficiently detect and capture uranyl ions. In addition, the presence of a viologen‐based radical ligand enables IHEP‐24 to a further photocatalytic reduction of the adsorbed uranyl to amorphous UO2. The mechanisms of adsorption and photocatalysis are revealed by batch experiments, photoelectrochemical characterizations, and theoretical calculations. This study provides a reference for the construction of robust multi‐functional MOF materials and also provides support for the deep removal and immobilization of radionuclides from aqueous solution.

Structure-bioactivity relationship study on anticancer Pd and Pt complexes with aliphatic glycine derivative ligands

To investigate the structure and bioactivity relationship, six Pd(II)/Pt(II) complexes with N-isobutylglycine (L1) and cyclohexylglycine (L2) as N^O amino acid bidentate ligands, 1,10′-phenanthroline (phen) and 2,2′-bipyridine (bipy) as N^N donor ligands, and [Pd(L1)(bipy)]NO3 (1), [Pd(L2)(bipy)]NO3 (2), [Pd(L1)(phen)]NO3 (3), [Pd(L2)(phen)]NO3·2H2O (4), [Pt(L1)(phen)]NO3 (5), along with [Pt(L2)(phen)]NO3 (6) were prepared and then characterized. The geometry of each compound was validated by doing a DFT calculation. Furthermore, tests were conducted on the complexes’ water solubilities and lipophilicity. All bipy complexes had superior aqueous solubility and less lipophilicity in comparison with phen complexes, as well as complexes containing cyclohexyl-glycine compared to isobutyl-glycine complexes, probably because of the steric effects and polarity of cyclohexylglycine. The in-vitro anticancer activities of these compounds were examined against HCT116, A549, and MCF7 cancerous cell lines. Data revealed that all Pd/Pt complexes demonstrate higher anticancer activity than carboplatin, and complexes 3 and 4 are more cytotoxic than cisplatin against the HCT116 cell line, particularly against MCF7 cancerous cells. In addition, among all compounds, complex 4 has more anticancer ability than oxaliplatin. Due to different solubility and lipophilicity behavior, the accumulation of Pt complexes and clinical Pt drugs in each cancerous cell was investigated. The binding capabilities of these complexes to DNA, as the main target in chemotherapy, occur through minor grooves and intercalate into DNA, which was done using absorption, fluorescence, and circular dichroism spectroscopy. Finally, the docking simulation study showed the mode of DNA bindings is in good agreement with the spectral binding data.

Synthesis and polyester printing applications of transition metal complexes of tridentate 5-(m-tolyldiazenyl)salicylaldehyde thiosemicarbazone derivatives

Thiosemicarbazone metal complexes are intriguing molecules with a variety of applications in several fields, including the pharmaceutical sector, analytical chemistry, and textile industries. Here, we designed and synthesized 12 transition metal complexes based on thiosemicarbazone as a tridendate group and azo moiety as a chromophore part, in addition to evaluating their color strength and fastness properties. The tridentate ligand derivatives of 5-(m-tolyldiazenyl)salicylaldehyde thiosemicarbazone reacted with four transition metal salts (copper, cobalt, nickel, and iron salts) in refluxing alkaline ethanol to afford the corresponding thiosemicarbazone complexes. The ligands behaved as double-deprotonated tridentate ligands that connected to the transition metal ions through the deprotonation of phenolic-OH and thiol-SH, as well as the azomethine nitrogen atom, to generate fused five- and six-membered heterocycle rings. The obtained metal complexes were characterized by elemental analyses, atomic absorption, IR, and UV–Vis spectra. The color strength and fastness properties of the printed fabrics were tested, showing good to excellent properties.

Zn(II)-Coordination Polymers Constructed from Isomeric Bis(Imidazole) Derivative Ligands and Tetracarboxylic Acid for the Detection of Iron Ions

Three Zn(II)-coordination polymers, namely, {[Zn2(µ4-L)(µ-obix)2]·4DMF}n (1), {[Zn2(µ4-L)(µ-mbix)2]·6H2O}n (2) and {[Zn2(µ4-L)(µ-pbix)2]·5H2O}n (3), (L4−: 5,5’-(terephthaloylbis(azanediyl))diisophthalate and obix (y = 2), mbix (y = 3), pbix (y = 4): 1,y-bis((1H-imidazol-1-yl)methyl)benzene) were prepared with a tetracarboxylic acid and flexible isomeric bis(imidazole) linkers and characterized. The compounds displayed structural diversity depending on the rotation of imidazole rings around the –CH2- groups on bis(imidazole) ligands. Compounds 1–3 showed 2-fold interpenetrated 3D framework, 2D structure and 3D framework, respectively. The compounds showed high emissions in solid-state and solutions. Luminescence experiments showed that compounds 1–3 displayed sensitive detection towards Fe3+ ions with detection limits of 2.31 ppm, 5.17 ppm and 2.61 ppm, respectively. Moreover, the compounds could selectively detect Fe3+ ions over the other interfering metal ions via luminescence quenching. The detection mechanism could be ascribed to the competitive light absorption between Fe3+ ions and the compounds.

Structural, theoretical and biological studies on Cu2+ and Co2+ complexes of new thiosemicarbazone ligands

Two sets of Cu2+, and Co2+ complexes of two 4 – Pyridyl thiosemicarbazone derivatives ligands symbolized by (H3L1), and (H3L2), were synthesized and examined utilizing different analytical, and spectroscopic techniques such as (FT-IR, Elemental Analysis, Magnetic studies, PXRD, UV–Vis, and GCMS–). Thermal stability along with kinetic parameters of both Co2+ complexes were studied. 1H NMR technique was used to confirm the structures of both ligands. The proposed geometries of complexes were recognized by density function theory (DFT) calculations using Material software. Additionally, Quantum theory of atoms in molecules (QTAIM) topological analyses for both ligands were obtained using Multiwfn software. The cyclic voltammogram revealed that copper ions are electroactive and exhibited two reduction waves. Fluorescence studies for both ligands showed a direct increase in the intensity of emissions because of increasing Co2+ concentration in solution. Moreover, several biological evaluations were carried out for all six compounds to evaluate their potential use as biological agents, including antioxidant activity using 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS) radical scavenging approach, anti-microbial activity against Staphylococcus aureus, Escherichia coli, and Candida albicans, DNA degradation activity, in addition to anticancer activity, along with molecular docking theoretical study against MCF-7 breast cancer cell line to determine the compounds ability to act as antitumor. It was found that the investigated compounds (especially the free ligands) have beneficial effects such as antimicrobial, antitumor, and DNA degradation agents. Furthermore, Co2+ complex (2) has the highest ABTS scavenging activity.

Design, synthesize, physicochemical characterization, nonlinear optical properties structural elucidation, biomedical studies, and DNA interaction of some new mixed ligand complexes incorporating 4,6‐dimethylpyrimidine derivative and imidazole ligand

This study was planned to prepare new mixed ligand chelates derived from N‐(4,6‐dimethylpyrimidin‐2‐yl)‐3a,4,5,6,7,7a‐hexahydro‐1H‐benzimidazol‐2‐amine (BIP), and imidazole (I). They identified through CHN study, spectroscopic (NMR, FT‐IR, and UV–Vis), conductivity, magnetic susceptibility, mass analysis, and thermal analysis. Correlation between all results exposed that the BIP ligand performed as a bi‐dentate ligand through NN donation locations, where the co‐ligand shows as N–H monodentate. The optimization for the studied chelates led to the formation of distorted octahedral geometry for BIPICu and BIPIVO chelates, distorted (tetrahedral and square planar) geometry for BIPIAg and BIPIPd chelates, respectively, around the metal salt. The B3LYP level, B3LYP/6‐311G** level for the free ligand, and B3LYP/6–311G**‐LANL2DZ functional level for the solid chelates were used in density functional theory (DFT) calculations. The findings showed that DFT calculations produce conclusions that are consistent with those of the experiments. The resulting compounds' nonlinear optical properties were examined by calculating the hyperpolarizability (β) and molecular polarizability (α) parameters, which gave rise to several unexpected optical properties for the synthesized compounds. Using the agar well diffusion method, the antimicrobial activity of the produced compounds was experimentally confirmed against a subset of G+ and G− bacteria. To ascertain how these substances attach to the targeted protein binding sites, a molecular docking mechanism between the microbially resistant chelates and their suppressed microbial protein pocket receptors was investigated. Also, DNA binding estimated for studied structures was tested by electronic absorption spectrum, viscosity estimation, and gel electrophoresis. Data proposed that all tested compounds link with DNA using an intercalation, electrostatic, and covalent binding mechanism. Moreover, antioxidant performance for studied compounds was governed by radical scavenging techniques in vitro. In addition, an MTT assay has been worked out to explore in vitro cytotoxic impending. All the tested chelates assumed antimicrobial, antitumor, and antioxidant performances that cause them to suggest drugs.

Targeting proto-oncogene B-MYB G-quadruplex with a nucleic acid–based fluorescent probe

The B-MYB gene encodes a transcription factor (B-MYB) that regulates cell growth and survival. Abnormal expression of B-MYB is frequently observed in lung cancer and poses challenges for targeted drug therapy. Oncogenes often contain DNA structures called G-quadruplexes (G4s) in their promoter regions, and B-MYB is no exception. These G4s play roles in genetic regulation and are potential cancer treatment targets.In this study, a probe was designed to specifically identify a G4 within the promoter region of the B-MYB gene. This probe combines an acridine derivative ligand with a DNA segment complementary to the target sequence, enabling it to hybridize with the adjacent sequence of the G4 being investigated.Biophysical studies demonstrated that the acridine derivative ligands C5NH2 and C8NH2 not only effectively stabilized the G4 structure but also exhibited moderate affinity. They were capable of altering the G4 topology and exhibited enhanced fluorescence emission in the presence of this quadruplex. Additionally, these ligands increased the number of G4s observed in cellular studies. Through various biophysical studies, the target sequence was shown to form a G4 structure, even with an extra nucleotide tail added to its flanking region. Cellular studies confirmed the co-localization between the target sequence and the developed probe.

Palladium(II) complexes of thiobenzamide derivative ligands: Synthesis, crystal structure, supramolecular architecture, Hirshfeld surface analysis, and in vitro antibacterial and antifungal activities

Three thiobenzamide derivative ligands and their palladium complexes were synthesized. The synthesized compounds were characterized by several instrumental methods, such as 1H NMR, 13C NMR, and FT–IR. Additionally, the appropriate crystal of the [PdIICl2(L3H)2] complex was analyzed to determine the molecular structure. The single–crystal X–ray diffraction (SC–XRD) revealed that [PdIICl2(L3H)2] complex has a monoclinic crystal system, C2/c space group, a = 12.2969(11) Å, b = 18.7618(16) Å, c = 16.899(2) Å, β = 97.875(4)°. The intramolecular and intermolecular interactions in the crystal structure led to the formation of two synthon systems. In addition, a quantitative investigation of the noncovalent interactions in the structure was carried out through the utilization of Hirshfeld surface and 2D–fingerprint plot analyzes. Analysis of [PdIICl2(L3H)2] using 2D fingerprint analysis revealed a range of intermolecular interactions responsible for its stabilization. Among these interactions, intermolecular H···H (51.90%), Br···H/H···Br (16.00%), and Cl⋯H/H···Cl (10.40%) were found to be the most prominent types of interaction. The 3D layout of the crystal packing was evaluated during the energy framework computations, demonstrating that the electrostatic energy framework had a significant impact over the dispersion energy framework. Antibacterial and antifungal activities of the thiobenzamide derivative palladium complexes were also tested against Gram–positive (E. faecalis, S. aureus, B. subtilis, and S. pneumonia) and Gram–negative (P. aeruginosa and E. coli) bacterises and against fungi (C. glabrata and C. albicans). Palladium complexes exhibited to be more effective against fungi than against bacteria according to the MIC values. Particularly, [PdIICl2(L2H)]2 complex showed an excellent antifungal effect among the other palladium complexes, with low MIC values of 3.90 and 7.81 μg/mL against C. glabrata and C. albicans fungi, respectively.

Dual-Targeting Gold Nanoparticles: Simultaneous Decoration with Ligands for Co-Transporters SGLT-1 and B0AT1

Sodium–glucose co-transporter 1 (SGLT1) and sodium-dependent neutral amino acid transporter (B0AT1) are mainly expressed on the membrane of enterocytes, a type of epithelial cell found in the intestines. In addition to their physiological role in the absorption of nutrients, a protective role in the integrity of the intestinal barrier has been established. The natural ligands of SGLT1 (d-glucose) and of B0AT1 (l-glutamine) can trigger a protective anti-inflammatory effect on the intestinal epithelium. The literature suggests the activation of common intracellular pathways upon engagement of the two transporters, whose functional forms are composed of oligomers or clusters. Simultaneous activation of these two co-transporters could lead to a potential multitarget and synergistic anti-inflammatory effect. Therefore, nanoplatforms containing multiple copies of the ligands could represent chemical tools to study the potential simultaneous activation of the two co-transporters. For these reasons, in this study, a set of different gold nanoparticles decorated with derivatives of d-glucose and of l-glutamine were designed and prepared. In particular, the synthesis of suitable sulfur-ending functionalized ligand derivatives, including a C-glucoside derivative, their anchoring to gold nanoparticles and their physical–chemical characterization have been carried out. The obtained nanostructures could represent promising multifunctional platforms for further investigation of the existence of possible multitarget and synergistic effects toward the two co-transporters SGLT1 and B0AT1.

Spectroscopic Rationalization of Selective Colorimetric Chemosensing of Fe(lll) in Aqueous Medium by a New Mono-Substituted Dibenzodiaza-Crown Ether Macrocyclic Ligand Appended with Mono 2-Benzimidazole N-Pendant Side Arm.

Optical chemosensor L comprising of a new mono-N-substituted derivative of dibenzodiaza-crown ether macrocyclic ligand bearing a 2-benzimidazole (2Bim) side arm was synthesized, and characterized by FT-IR, elemental microanalyses, 1H NMR, and 13C NMR, UV-visible, fluorescence (FL) spectroscopy. The colorimetric chemosensing behavior of L toward the library metal ions was examined, wherein L represented a prompt and selective yellow-to-purple color change for Fe(III) cation in a 25µM solution with LOD as 0.23 µM in ethanol:water (9:1, v/v), even in the presence of the other library metal ions (LMI). Based on the 1H NMR, UV-visible, and FL observations the coordination sphere of Fe(III) was shared with two 2-benzoimidazole (2Bim) side arms which were also confirmed by the elemental microanalyses (in the solid state) and the Job plot method (in the solution) of the complex. Moreover, the above-mentioned color change was attributed to the presence of a strong charge transfer (LMCT) band for the Fe(III)/L interaction in the solution. Furthermore, the viscosity measurement in the presence of Fe(III) uncovered an increase at 0.5-1.0 ratios for Fe(III)/L, attributable to the formation of a self-assembly in the solution. A TLC paper strip was impregnated by L for selective detection of Fe(III), demonstrating a live color change for Fe(III) at 0-5 mM in the presence of LMI.

The effect of ligand/ metal-ligand ratio on the structural architectures of five different 1D zinc(II) coordination polymers with pyridyl derivative ligands

Five coordination compounds, [Zn(bppc)Cl]n·0.5nH2O (1) [Zn2(bppc)2(suc)]n (2), [Zn(dppb)Cl]n·nH2O (3) [Zn(dppb)Cl]n (4) [Zn2(dppb)2(bdc)]n·2nH2O(5) (Hbppc =2,6-bis(pyrazin-2-yl)pyridine-4-carboxylic acid, H2suc=succinic acid, Hdppb=4-(2,6-di(pyrazin-2-yl)pyridine-4-yl)-benzoic acid, H2bdc=1,4-benzenedicarboxylic acid), with the same one dimensions but different patterns have been hydrothermally synthesized and structurally characterized. Single crystal X-ray analysis revealed that compound 1 shows one-dimensional wave chain structure, compound 2 to 5 show one-dimensional ladder chain structure, one-dimensional V-shaped chain structure, one-dimensional linear chain structure and one-dimensional A-shaped chain structure, respectively. The structure differences of 1–5 show that ligand including auxiliary ligand and metal-ligand ratio have important influence on the final structures. Additionally, the luminescent properties of 1–5 have been investigated with fluorescent spectra in the solid state and fluorescence sensing experiments show that compound 1 exhibit a great selectivity and sensitivity for detection of Cu2+ion and nitrobenzene.

Functional evaluation of novel chromon derivative compounds for recognition of G-quadruplex structure

Currently, G-quadruplex structure targeting strategies are considered as a promising anticancer approach. The purpose of this research is to expand the options for G-quadruplex targeting ligands, particularly emphasizing fluorescent ligands. Our study contributes to the field by providing additional choices for G-quadruplex binders with a notable focus on selectivity towards G-quadruplex topology over duplex DNA. In the search of selective and potent G-quadruplex binders, here we discuss an analysis of a few chroman derivatives ligands named A and C and their respective borondifluoride complexes B and D as a quadruplex targeting compounds which found to stabilize G-quadruplex structure. To investigate the binding characteristics of these molecules with G-quadruplex vs. duplex selectivity, In vitro biophysical studies were performed by steady-state fluorescence, UV–visible titration, fluorescent TO displacement assay, CD thermal melting, circular dichroism spectroscopy, and cellular imaging by employing both telomeric and PRCC G-quadruplex forming sequences. Our investigation shows that these chromam ligands and their complexes are able to selectively bind and stabilize parallel and mixed hybrid topology of G-quadruplex both In vitro and in cellular conditions. A molecular docking and MD simulation study also suggests the binding of these compounds with G-quadruplex conformation. Collectively our study suggests these chroman complexes for the first time as a potentially useful fluorescent chemical product for G-quadruplex specific ligands and expands an option for G-quadruplex targeting ligands.

Selective Construction and Structural Transformation of Homogeneous Linear Metalla[4]catenane and Metalla[2]catenane Assemblies.

Although the synthesis of mechanically interlocked molecules has been extensively researched, selectively constructing homogeneous linear [4]catenanes remains a formidable challenge. Here, we selectively constructed a homogeneous linear metalla[4]catenane in a one-step process through the coordination-driven self-assembly of a bidentate benzothiadiazole derivative ligand and a binuclear half-sandwich rhodium precursor. The formation of metalla[4]catenanes was facilitated by cooperative interactions between strong sandwich-type π-π stacking and non-classical hydrogen bonds between the components. Moreover, by modulating the aromatic substituents on the binuclear precursor, two homogeneous metalla[2]catenanes were obtained. The molecular structures of these metallacatenanes were unambiguously characterized by single-crystal X-ray diffraction analysis. Additionally, reversible structural transformation between metal-catenanes and the corresponding metallarectangles could be achieved by altering their concentration, as confirmed by mass spectrometry and NMR spectroscopy studies.

Selective Construction and Structural Transformation of Homogeneous Linear Metalla[4]catenane and Metalla[2]catenane Assemblies

AbstractAlthough the synthesis of mechanically interlocked molecules has been extensively researched, selectively constructing homogeneous linear [4]catenanes remains a formidable challenge. Here, we selectively constructed a homogeneous linear metalla[4]catenane in a one‐step process through the coordination‐driven self‐assembly of a bidentate benzothiadiazole derivative ligand and a binuclear half‐sandwich rhodium precursor. The formation of metalla[4]catenanes was facilitated by cooperative interactions between strong sandwich‐type π‐π stacking and non‐classical hydrogen bonds between the components. Moreover, by modulating the aromatic substituents on the binuclear precursor, two homogeneous metalla[2]catenanes were obtained. The molecular structures of these metallacatenanes were unambiguously characterized by single‐crystal X‐ray diffraction analysis. Additionally, reversible structural transformation between metal‐catenanes and the corresponding metallarectangles could be achieved by altering their concentration, as confirmed by mass spectrometry and NMR spectroscopy studies.

Melatonin Derivative-Conjugated Formulations of Pd(II) and Pt(II) Thiazoline Complexes on Mesoporous Silica to Enhance Cytotoxicity and Apoptosis against HeLa Cells.

The search for alternatives to cisplatin has led to the development of new metal complexes where thiazoline derivatives based on platinum(II) and palladium(II) stand out. In this sense, the Pt(II) and Pd(II) complexes coordinated with the thiazoline derivative ligand 2-(3,4-dichlorophenyl)imino-N-(2-thiazolin-2-yl)thiazolidine (TdTn), with formula [PtCl2(TdTn)] and [PdCl2(TdTn)], have previously shown good results against several cancer lines; however, in this work, we have managed to improve their activity by supporting them on mesoporous silica nanoparticles (MSN). The incorporation of metal compounds with a melatonin derivative (5-methoxytryptamine, 5MT), which is a well-known antioxidant and apoptosis inducer in different types of cancer, has been able to increase the cytotoxic activity of both MSN-supported and isolated complexes with only a very low amount (0.35% w/w) of this antioxidant. The covalently functionalized systems that have been synthesized are able to increase selectivity as well as accumulation in HeLa cells. The final materials containing the metal complexes and 5MT (MSN-5MT-PtTdTn and MSN-5MT-PdTdTn) required up to nine times less metal to achieve the same cytotoxic activity than their corresponding non-formulated counterparts did, thus reducing the potential side effects caused by the use of the free metal complexes.

Towards sustainable battery recycling: selective dynamic adsorption of nickel(II) and cobalt(II) in an adsorbent fixed-bed reactor at elevated temperature

Caused by the scarce resources of critical heavy metals which are in high demand, e.g., for lithium-ion batteries, processes for the recovery of such materials for recycling are of high interest. Adsorption is an effective method in order to selectively separate metal ions from aqueous solutions. Unfortunately, the prerequisites in battery recycling, like acidic pH-value and high temperature, are in general impairing the adsorption process. In this study, the competitive dynamic adsorption of nickel(II) (Ni(II)) and cobalt(II) (Co(II)) by a silica adsorbent functionalized with amino-polycarboxylate derivative ligands (designated as HSU331) under recycling process conditions, (pH = 3.5, T = 20 °C, and T = 50 °C, respectively) and varying concentrations (Ni(II):Co(II) 1:1 (5.0, and 10 mmol·L−1, respectively), Ni(II):Co(II) 3:1 and 1:3 (3.0 mmol·L−1 and 1.0 mmol·L−1 vice versa)) were investigated. A displacement desorption of Co(II) in favor of the binding of Ni(II) was observed, achieving maximum loadings of 0.95 µmolNi(II)·µmolLigand−1 (28.3 mgNi(II)·gAdsorbent−1), and 0.48 µmolCo(II)·µmolLigand−1 (14.3 mgCo(II)·gAdsorbent−1) at T = 20 °C and 1.0 µmolNi(II)·µmolLigand−1 (29.9 mgNi(II)·gAdsorbent−1) and 0.18 µmolCo(II)·µmolLigand−1 (5.38 mgCo(II)·gAdsorbent−1) at T = 50 °C, respectively. These results demonstrate a distinctly selective separation of Ni(II) in the presence of Co(II) by HSU331, achieving an even higher efficiency at elevated temperatures.