Synthesis Of Ligands Research Articles

Metal ion complexes of 2-thioxoimidazolidine-4-one derivatives mixed ligand synthesis, characterization, in-vitro biological activities and in-silico studies

A series of complexes of [Mn (III), Co(II), Cu(II), and Cd(II)] were synthesized with two new 2-thioxoimidazolidin-4-one derivates ligands. These ligands were characterized using an elemental analyzer (CHNS), 1H NMR spectroscopy, FT-IR spectroscopy, and UV–Vis spectroscopy. The synthesized complexes were characterized by magnetic susceptibility measurements, electrical conductance analysis, and atomic absorption spectroscopy. The biological activity of the ligands and complexes were determined against E. coli, B. subtilis, A. niger, and P. chrysogenum. To determine the influence of different metal-ion concentrations on microbial growth, we used molecular docking to evaluate antibacterial activity targeting antimicrobial sites. Our findings indicate that the metal ion complexes exhibited varying degrees of antimicrobial activity, affecting the growth of the tested organisms.

In vitro molluscicidal activity and biochemical impacts of some thiophene derivatives against the glassy clover snail, Monacha obstructa (Pfeiffer)

BackgroundThe glassy clover snail, Monacha obstructa (Pfeiffer), is considered one of the major agricultural pests that ruin many field crops, vegetables, orchards of fruits, plants of ornament as well as many other plantations. Synthesis of the Schiff base ligand, namely bis-[4-benzylidene-thiophene-2′-yl] methane (L), produced from the reaction between thiophene-2-carboxaldehyde and diaminodiphenylmethane (MDA), alongside its copper complex were conducted. The output chemical compounds were evaluated in vitro for their molluscicidal activity against the glassy clover snail, M. obstructa by performing the contact technique. Stock solutions were prepared via using (distilled water + DMF) mixture. Furthermore, the impact of these compounds on some critical biochemical indicators: cholesterol, total protein, and acetylcholinesterase (AChE), was evaluated.ResultsThe outcome results demonstrated the significantly higher molluscicidal activity of the Cu(II) chelate compared to its free ligand (L), which in turn reveals the importance of metal chelation in enhancing toxicity against the target species. Particularly, the LC25 and LC50 values are (27.25, 34.65) and (17.88, 25.31) ppm for the ligand (L) and its copper construction, respectively. Additionally, the data confirmed the significant effectiveness of the tested compounds on the assessed biochemical indicators of treated snails. Total protein and cholesterol levels were elevated after treatment with both the ligand (L) and its copper complex while AChE activity increased after treatment with the ligand (L) and reduced upon the exposure to the Cu(II) chelate.ConclusionsThe findings established that the copper complex exhibited a markedly higher molluscicidal activity compared to the free ligand (L). Also, the results confirmed the significant effects of the investigated compounds on the assessed biochemical indicators of treated M. obstructa snails.

Rational synthesis of Azo ligands and copper complexes: Insights into potential therapeutic agents

In the pursuit of innovation, four distinct mono Azo dyes D1-D4 were synthesized. These dyes were crafted through a coupling reaction involving 1-naphthol, resorcinol and salicylic acid with diazonium salts derived from a diverse array of aromatic amines, including aniline and sulphanilic acid. Subsequently, they are transformed into copper Azo complexes, namely (D1CuC-D4CuC). The structural underpinnings of these mono Azo dyes and their corresponding copper complexes were unveiled using an arsenal of analytical techniques: FTIR, 1H NMR, 13C NMR, and UV-visible spectroscopy which unequivocally confirmed their synthesis. A computational protein-ligand docking approach was used to assess the binding affinity of ligands and metal complexes to an anti-oxidant receptor protein (PDB ID:2HCK) which showed excellent binding interactions. The findings from an in vitro antioxidant activity using the DPPH scavenging method exhibited: Complexes > Ligands. As an antioxidant agent, the synthesized compounds may prove to be a great therapeutic option. This research introduces a novel approach by utilizing Azo dyes as ligands, leveraging their exceptional electronic tunability and stability to form innovative copper complexes. Their pharmacological applications will be explored, potentially yielding drugs with improved efficacy and selectivity.

Recent Advances in Carborane-Based Crystalline Porous Materials.

The field of carborane research has witnessed continuous development, leading to the construction and development of a diverse range of crystalline porous materials for various applications. Moreover, innovative synthetic approaches are expanding in this field. Since the first report of carborane-based crystalline porous materials (CCPMs) in 2007, the synthesis of carborane ligands, particularly through innovative methods, has consistently posed a significant challenge in discovering new structures of CCPMs. This paper provides a comprehensive summary of recent advances in various synthetic approaches for CCPMs, along with their applications in different domains. The primary challenges and future opportunities are expected to stimulate further multidisciplinary development in the field of CCPMs.

Ligand-controlled UV light absorption property and neuromorphic behavior of a new Th(IV)- bisphosphoramide complex

This article describes the synthesis and photophysical properties of a new furan-based bisphosphoramide ligand (L) and its Th(IV) complex characterized by various analytical and spectroscopic techniques. As expected, L, associated with several double bonds within the structure and the possible π → π* transitions, displays strong absorption in the UV region. Notably, the absorption of UV light decreases significantly in an exclusive manner for the L-Th4+ complex, and such behavior was not observed with most of the transition metals as well as f-metal ions. The ligand-to-metal binding ratio of L-Th4+ was found to be 1:1 through the Job’s plot. This photophysical property was successfully explored in the selective determination of Th4+ ions in aqueous solutions. The limit of detection (LOD) for Th4+ and limit of quantitation (LOQ) were determined to be 1.04 x 10-7 M and 3.472 x 10-7 M, respectively. In order to get an insight at the molecular level, a density functional theory (DFT) investigation was performed to comprehend the sensing mechanism and interaction in the detection of Th4+ by L. Furthermore, this salient UV light absorption phenomenon was employed in exploring the artificial synaptic behavior of the L-Th4+ complex which can have remarkable memory and applications in neuromorphic devices.

N-Heterocyclic Carbene Enabled Copper Catalyzed Asymmetric Synthesis of Pyrimidinyl Phosphine with both Axial and P- Stereogenicity.

P-stereogenic phosphines, renowned for their utility as ligands and catalysts, have been instrumental in the field of asymmetric catalysis. However, the catalytic asymmetric synthesis of chiral ligands possessing both axial and phosphine chirality remains a significant challenge. Here, we present the successful demonstration of a Cu-catalyzed asymmetric C-P construction using in situ generated secondary phosphine and heteroaryl chloride. By introducing a chiral NHC ligand and an achiral diphosphine auxiliary ligand, we effectively alleviated the poisoning effect caused by phosphine(III) compounds and suppressed the nonenantioselective background reaction. The reaction exhibited excellent enantioselectivity, with up to 96% ee, and good diastereoselectivity, with up to 14:1 dr, when employing less sterically hindered secondary phosphines. This particular substrate poses a significant challenge due to its strong poisoning effect in copper catalysis.

Pristine Metal-Organic Frameworks for Efficient Oxygen Evolution Electrocatalysis

Green energy technologies propose the use of hydrogen as fuel instead of fossil fuels that have drawbacks of limited supplies and greenhouse gas emission during their combustion. Though hydrogen is the most abundant element on the Earth, hydrogen gas is commonly not found in pure form, but bound in compounds such as water or hydrocarbons. Thus, hydrogen gas is a synthetic fuel that needs to be produced. For the energy to be completely green, hydrogen should be produced using renewable energy. Currently, most of the hydrogen is produced using fossil fuels and only ca. 5% is produced using electrolytic water splitting. It is the high cost of the water-splitting process that limits its use on the wider scale. To reduce the associated high energy input to break a water molecule, resulting in high cost of hydrogen produced by water splitting, expensive electrocatalysts are typically used.The aim of this work is to design novel and low cost metal-organic frameworks (MOF) or coordination polymers (CP) utilizing different ligands (for instance, amide functionalized ligands) towards their application in energy conversion reactions such as oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). MOFs are rarely used in their pristine form; literature reports typically focus on MOF-derived carbon materials. Moreover, herein special attention is given to OER as the efficiency-limiting reaction within the water electrolysis process.The first part of the work focuses on the synthesis and characterization of ligands and MOFs/CPs based on transition metals, nickel and cobalt. The morphology and structure of these composites is examined using electron microscopy and X-ray diffraction analysis. The second part of the work focuses on the pristine materials’ electrocatalytic activity involving standard electrochemical techniques, i.e., voltammetry, impedance spectroscopy, and chronoamperometry to identify the material with the optimum performance and stability. Main reactions parameters including onset potential, overpotential at defined current density as well as current density at defined potential and Tafel slope, are determined.This work presents step towards green hydrogen production within search for solutions for the current energy crisis. Acknowledgments This work was supported by the Science Fund of the Republic of Serbia, grant number 7750219, Advanced Conducting Polymer-Based Materials for Electrochemical Energy Conversion and Storage, Sensors and Environmental Protection-AdConPolyMat (IDEAS programme).

(Invited) Synthetic Strategies to Lower the Barrier for Making High Quality Quantum Dot Probes

Quantum dot (QD)-based bioimaging requires QDs with exceptional optical quality and well-controlled surface properties. Although extensive research has been carried out to produce high-quality nanocrystals and to design biocompatible ligands, significant expertise is required to synthesize the best quality QDs and ligands reported. Commercially available QDs often fail to meet the required quality and suffer from irreproducibility in their performance. These restrictions have limited the wide adoption of QDs for biomedical imaging in non-expert groups. My group strives to lower the barrier to preparing high-quality QD probes in a wide range of wavelengths. In this talk, I will discuss the synthetic strategies that we have developed to systematically grow high-quality nanocrystals of various sizes and materials with minimal human intervention and simplify the synthesis of polyimidazole ligands without compromising their quality. By lowering the synthetic barrier to high-quality QDs, we envision unleashing the full potential of QDs in various fields.

Long-Term Comparisons of Photoluminescence Affected by Organic Cations of Formamidinium and Methylammonium in Monophasic Lead Iodide Perovskite Quantum Dots.

This study compared the photoluminescence (PL) stabilities of formamidinium (FA) and methylammonium (MA) in lead iodide perovskite quantum dots (QDs). To exclude other factors, such as size and purity, that may affect stability, MAPbI3 and FAPbI3 QDs with nearly identical sizes (~10.0 nm) were synthesized by controlling the ligand concentration and synthesis temperature. Transmission electron microscopy images and X-ray diffraction patterns confirmed homogeneous single-phase perovskite structures. Additionally, the bandgaps and sizes of the synthesized QDs closely matched those of the infinite quantum well model, which guaranteed that the photostability was solely caused by the different organic molecules in the two QDs. We analyzed the PL peak centers and full-width at half maximum of the QDs for 32 days. The enhanced stability of FAPbI3 was found to be caused by the nearly zero redshift (1.615 eV) of its PL peak, in contrast to the redshift (1.685→1.670 eV) of MAPbI3.

Thionitrosyl Complexes of Rhenium and Technetium with PPh3 and Chelating Ligands—Synthesis and Reactivity

In contrast to corresponding nitrosyl compounds, thionitrosyl complexes of rhenium and technetium are rare. Synthetic access to the thionitrosyl core is possible by two main approaches: (i) the treatment of corresponding nitrido complexes with S2Cl2 and (ii) by reaction of halide complexes with trithiazyl chloride. The first synthetic route was applied for the synthesis of novel rhenium and technetium thionitrosyls with the metals in their oxidation states “+1” and “+2”. [MVNCl2(PPh3)2], [MVNCl(PPh3)(LOMe)] and [MVINCl2(LOMe)] (M = Re, Tc; {LOMe}− = (η5-cyclopentadienyl)tris(dimethyl phosphito-P)cobaltate(III)) complexes have been used as starting materials for the synthesis of [ReII(NS)Cl3(PPh3)2] (1), [ReII(NS)Cl3(PPh3)(OPPh3)] (2), [ReII(NS)Cl(PPh3)(LOMe)]+ (4a), [ReII(NS)Cl2(LOMe)] (5a), [TcII(NS)Cl(PPh3)(LOMe)]+ (4b) and [TcII(NS)Cl2(LOMe)] (5b). The triphenylphosphine complex 1 is partially suitable as a precursor for ongoing ligand exchange reactions and has been used for the synthesis of [ReI(NS)(PPh3)(Et2btu)2] (3a) (HEt2btu = N,N-diethyl-N′-benzoyl thiourea) containing two chelating benzoyl thioureato ligands. The novel compounds have been isolated in crystalline form and studied by X-ray diffraction and spectroscopic methods including IR, NMR and EPR spectroscopy and (where possible) mass spectrometry. A comparison of structurally related rhenium and technetium complexes allows for conclusions about similarities and differences in stability, reaction kinetics and redox behavior between these 4d and 5d transition metals.

Structural and Potential Biological Properties of SBDTC and SMDTC Containing Metal Complexes: A Brief Review

S-benzyldithiocarbazate (SBDTC) and S-methyldithiocarbazate (SMDTC) are working as a preliminary reactant for the synthesis of several Schiff base ligands. SBDTC and SMDTC can act as NS, SNNS, SNNNS, and NOS chelating agents and have biological and chemical potential for synthesizing many transition and inner transition metal complexes. The metal complexes prepared from SBDTC, SMDTC, and their derivatives have shown promising biological activities like antibacterial, cytotoxicity, antioxidant, antitumor, and anticancer activity. Last few decades, a lot of works have been reported on SBDTC and SMDTC containing Schiff base metal complexes. In this review, it is cosidered to show the various synthesis procedures, and structural and biological activities of SBDTC and SMDTC-containing metal complexes.

A Resorcin[4]arene-Based Phosphite-Phosphine Ligand for the Branched-Selective Hydroformylation of Alkyl Alkenes.

Synthesis of a chelating phosphite-phosphine ligand from a tris(quinoxaline) extended resorcin[4]arene and its application in the rhodium-catalyzed hydroformylation of terminal alkyl alkenes are reported. Rhodium complexes are formed within the cavity of the macrocycle and branched-selective hydroformylation of 1-octene with a b/l ratio of 5.9 has been achieved at 60 °C under 1:1 H2/CO (20 bar).

Tactics and Strategies for the Synthesis of Cereblon Ligands

AbstractTargeted protein degradation (TPD) has emerged as an important strategy to target disease-relevant proteins that were previously considered difficult to drug or even undruggable. Cereblon (CRBN) plays an outsized role in TPD as a preferred degradation-inducing effector protein for several reasons, including its anticipated broad protein substrate scope and its ligandability with drug-like small molecules. Notably, CRBN-based molecular glue degraders (MGDs) and proteolysis targeting chimeras (PROTACs) have shown success in clinical trials and, in some cases, as approved drugs. Thus, the interest in CRBN ligands within the pharmaceutical industry and academia has increased dramatically in recent years, highlighting the need for robust synthetic approaches towards them. This short review summarizes tactics and strategies to synthesize CRBN ligands, including the most recent developments in the field. Particular emphasis is put on the construction and direct functionalization of key CRBN binding motifs such as glutarimides and dihydrouracils.1 Introduction2 Cereblon Ligands with Glutarimide Binding Motif3 Cereblon Ligands with Dihydrouracil Binding Motif4 Cereblon Ligands with Other Binding Motifs5 Conclusions and Outlook

PSMA-targeted combination brusatol and docetaxel nanotherapeutics for the treatment of prostate cancer

Active targeting to cancer involves exploiting specific interactions between receptors on the surface of cancer cells and targeting moieties conjugated to the surface of vectors such that site-specific delivery is achieved. Prostate specific membrane antigen (PSMA) has proved to be an excellent target for active targeting to prostate cancer. We report the synthesis and use of a PSMA-specific ligand (Glu-NH-CO-NH-Lys) for the site-specific delivery of brusatol- and docetaxel-loaded poly(lactide-co-glycolide) (PLGA) nanoparticles to prostate cancer. The PSMA targeting ligand covalently linked to PLGA-PEG3400 was blended with methoxyPEG-PLGA to prepare brusatol- and docetaxel-loaded nanoparticles with different surface densities of the targeting ligand. Flow cytometry was used to evaluate the impact of different surface densities of the PSMA targeting ligand in LNCaP prostate cancer cells at 15 min and 2 h. Cytotoxicity evaluations of the targeted nanoparticles reveal differences based on PSMA expression in PC-3 and LNCaP cells. In addition, levels of reactive oxygen species (ROS) were measured using the fluorescent indicator, H2DCFDA, by flow cytometry. PSMA-targeted nanoparticles loaded with docetaxel and brusatol showed increased ROS generation in LNCaP cells compared to PC-3 at different time points. Furthermore, the targeted nanoparticles were evaluated in male athymic BALB/c mice implanted with PSMA-producing LNCaP cell tumors. Evaluation of the percent relative tumor volume show that brusatol-containing nanoparticles show great promise in inhibiting tumor growth. Our data also suggest that the dual drug-loaded targeted nanoparticle platform improves the efficacy of docetaxel in male athymic BALB/c mice implanted with PSMA-producing LNCaP cell tumors.

Co(II)-Catalyzed Additive-Free Transfer Hydrogenation of N-Heteroarenes at Room Temperature.

Traditional catalyst development relies on multistep synthesis and isolation of ligand and precatalyst. Designing a catalytic system that can be assembled in situ from easily accessible starting materials can decrease the reaction complexity and enhance the synthetic utility. Herein, we report an inexpensive and commercially available CoBr2·H2O/terpyridine-catalyzed effective and straightforward transfer hydrogenation (TH) protocol for N-heteroarenes, utilizing NH3·BH3 (AB) under ambient conditions. Synthesis of diverse substrates and bioactive molecules demonstrated a practical applicability. Control experiments and DFT studies elucidate the mechanism.

PROTAC<sup>®</sup> technology and potential for its application in infection control

Objectives. To describe the pharmaceutical technology of controlled degradation of protein molecules (PROTAC®, Proteolysis Targeting Chimera), approaches to the design of the PROTAC® molecule, methods of ligand and linker selection and synthesis, as well as the application of this technology in dealing with a variety of diseases and the possible limitations of its use.Results. The review covers 77 sources, mostly from 2020–2023. The review outlines the principle of PROTAC® technology: the construction of a chimeric molecule consisting of three fragments. One fragment specifically binds to the biotarget, another recruits the proteolytic system of the host cell, and the third binds them together. The main areas of the current development of the technology are described herein, as well as the opportunities and limitations of chimeric molecules in the fight against different types of infectious diseases.Conclusion. The potential to use PROTAC® technology to combat cancer as well as neurodegenerative, autoimmune, and infectious diseases is shown.

Extended MOF-74-Type Variant with an Azine Linkage: Efficient Direct Air Capture and One-Pot Synthesis.

Direct air capture (DAC) shows considerable promise for the effective removal of CO2; however, materials applicable to DAC are lacking. Among metal-organic framework (MOF) adsorbents, diamine-Mg2(dobpdc) (dobpdc4- = 4,4-dioxidobiphenyl-3,3'-dicarboxylate) effectively removes low-pressure CO2, but the synthesis of the organic ligand requires high temperature, high pressure, and a toxic solvent. Besides, it is necessary to isolate the ligand for utilization in the synthesis of the framework. In this study, we synthesized a new variant of extended MOF-74-type frameworks, M2(hob) (M = Mg2+, Co2+, Ni2+, and Zn2+; hob4- = 5,5'-(hydrazine-1,2-diylidenebis(methanylylidene))bis(2-oxidobenzoate)), constructed from an azine-bonded organic ligand obtained through a facile condensation reaction at room temperature. Functionalization of Mg2(hob) with N-methylethylenediamine, N-ethylethylenediamine, and N,N'-dimethylethylenediamine (mmen) enables strong interactions with low-pressure CO2, resulting in top-tier adsorption capacities of 2.60, 2.49, and 2.91 mmol g-1 at 400 ppm of CO2, respectively. Under humid conditions, the CO2 capacity was higher than under dry conditions due to the presence of water molecules that aid in the formation of bicarbonate species. A composite material combining mmen-Mg2(hob) and polyvinylidene fluoride, a hydrophobic polymer, retained its excellent adsorption performance even after 7 days of exposure to 40% relative humidity. In addition, the one-pot synthesis of Mg2(hob) from a mixture of the corresponding monomers is achieved without separate ligand synthesis steps; thus, this framework is suitable for facile large-scale production. This work underscores that the newly synthesized Mg2(hob) and its composites demonstrate significant potential for DAC applications.

Synthesis, characterization, DFT, biological activities and molecular docking analysis of Schiff base ligand and its transition metal complexes

Synthesis, characterization, DFT, biological activities and molecular docking analysis of Schiff base ligand and its transition metal complexes

New Semicarbazone-Schiff Base Coordination; Synthesis, Characterization and Biological Evaluation

The synthesis and characterisation of a new azo Schiff base ligand generated from a semicarbazone moiety are reported in this study, in addition to its metal complexes. The title ligand, (E)-2-((2-hydroxy-3-((E)-(2-nitrophenyl) diazenyl) naphthalen-1-yl) methylene) hydrazine-1-carboxamide (HL), was synthesised by reacting ((E)-2-hydroxy-3-((2-nitrophenyl) diazenyl)-1-naphthaldehyde) with semicarbazidein a 1:1 molar ratio. Afterward, the interplay between HL and other metal ions (CrШ, MnII, CoII, NiII and CuII) produced monomeric coordination complexes in a 1:1 ligand-to-metal ratio. A range of spectroscopic and analytical techniques, such as magnetic susceptibility, conductance tests, 1H and 13C-NMR, FT-IR, electronic and mass spectroscopy, and elemental microanalysis, were used to extensively characterize these complexes. The synthesis of coordination compounds with six-coordinate geometries was verified by the characterization data. The study also assessed the antimicrobial efficacy of the synthesised compounds against various bacterial and fungal species, revealing that After the complex formed, the ligand's antimicrobial activity was greatly increased.

Chiral α-Aminophosphonates as Ligands in Copper-Catalyzed Asymmetric Oxidative Coupling of 2-Naphthols.

Chiral α-aminophosphonates with adjacent carbon and phosphonate stereogenic centers have been employed as ligands in the copper-catalyzed oxidative coupling of 2-naphthols, resulting in the production of chiral BINOLs in favorable yields and moderate to good enantiomeric excess. This represents the first application of chiral P-based ligands to enable such a transformation. The synthesis of these chiral α-aminophosphonate ligands offers a significant advantage over approaches that typically necessitate elaborate synthetic processes for chiral ligand production.