Complexes 2c Research Articles

CuII Pyrazolyl-Benzimidazole Dinuclear Complexes with Remarkable Antioxidant Activity.

Three dinuclear coordination complexes generated from 1-n-butyl-2-((5-methyl-1H-pyrazole-3-yl)methyl)-1H-benzimidazole (L), have been synthesized and characterized spectroscopically and structurally by single crystal X-ray diffraction analysis. Reaction with iron(II) chloride and then copper(II) nitrate led to a co-crystal containing 78 % of [Cu(NO3 )(μ-Cl)(L')]2 (C1 ) and 22 % of [Cu(NO3 )(μ-NO3 )(L')]2 (C2 ), where L was oxidized to a new ligand L' . A mechanism is provided. Reaction with copper chloride led to the dinuclear complex [Cu(Cl)(μ-Cl)(L)]2 (C3 ). The presence of N-H⋅⋅⋅O and C-H⋅⋅⋅O intermolecular interactions in the crystal structure of C1 and C2 , and C-H⋅⋅⋅N and C-H⋅⋅⋅Cl hydrogen bonding in the crystal structure of C3 led to supramolecular structures that were confirmed by Hirshfeld surface analysis. The ligands and their complexes were tested for free radical scavenging activity and ferric reducing antioxidant power. The complex C1 /C2 shows remarkable antioxidant activities as compared to the ligand L and reference compounds.

Facile synthesis of InIII-salen complexes from indium metal and their use as catalysts for the chemical fixation of carbon dioxide in mild conditions

An alternative, very simple and improved route to obtain indium(III) tetrahaloindate salts of tetrabutylammonium (TBA)[InX4] – 1a (X = Cl), 1b (X = Br) and 1c (X = I) – in high yields (74 – 82%) was developed. Indium(III) tetrahaloindates were then used as starting materials for the synthesis of In(salen)X complexes 2a (X = Cl, 88%), 2b (X = Br, 94%) and 2c (X = I, 88%). Compounds 2a-c were characterized by FT-IR, Raman, and 1H and 13C NMR spectroscopies. The In-salen complexes were able to promote the CO2 cycloaddition reaction with styrene oxide in mild and solvent-free conditions; complex 2a presented the best performance in the initial screening, achieving quantitative conversion (>99%). The parameters of the catalytic system were optimized, and a series of epoxides were tested as substrates for the production of cyclic carbonates with conversions varying from 38% to quantitative. The present study provides a simple method to cheaply and easily prepare indium(III) complexes and employ them to produce value-added chemicals from CO2.

Azide‐Alkyne Cycloaddition Reaction Catalyzed by Cu(II) Complexes: Studies on the effect of Different Ligand Systems

AbstractA series of bidentate ligands L1–L6 (where L1=2‐(2‐(diphenylmethylene)‐1‐phenylhydrazinyl)pyridine, L2=(E)‐2‐(2‐benzylidene‐1‐phenylhydrazinyl)pyridine, L3=(E)‐2‐(2‐(4‐methoxybenzylidene)‐1‐phenylhydrazinyl)pyridine, L4=(E)‐2‐(2‐(4‐chlorobenzylidene)‐1‐phenylhydrazinyl)pyridine, L5=(E)‐2‐(2‐(4‐nitrobenzylidene)‐1‐phenylhydrazinyl)pyridine, L6=(E)‐N,N‐dimethyl‐4‐((2‐phenyl‐2‐(pyridin‐2‐yl)hydrazono)methyl)aniline) were synthesized and characterized using reported literature.[1–4] Ligands were reacted with Cu(NO3)2 metal salt to synthesize metal complexes [Cu(L1‐6)(ONO2)(H2O)]NO3 i. e., (C1–C6). Metal complexes were characterized by IR, UV‐Visible, TGA and ESI‐MS spectral methods. The molecular structure of complex C2 was analyzed by single crystal X‐ray technique. Complexes were employed as catalysts to perform click reaction. The catalytic reaction was also observed in situ by reacting ligands with Cu(NO3)2 metal salt in presence of sodium ascorbate. The role of substituents present in the ligand frame of metal complexes were studied, and a probable mechanism was proposed.

Novel SCCmec variants in clonal complex 398 and lineage-specific pseudo-SCCmec identified in ST88 MRSA from invasive bloodstream infections in China.

Methicillin resistance in Staphylococcus aureus is primarily due to the mecA gene found in highly diverse staphylococcal cassette chromosome mec (SCCmec) elements, with an increasing number of variants being continually discovered. To characterize two novel SCCmec variants identified in clonal complex (CC) 398 strains and lineage-specific pseudo-SCCmec elements in the ST88 clone. WGS and comparative genomic analysis were used to elucidate the SCCmec element diversity of representative isolates. The non-typeable 47 kb SCCmec found in the CC398 strain SKLX55795 represents a novel subtype of XIV, showing significant differences in structural organization and genetic content within the joining regions compared with the XIV element from the prototype strain SC792. This unique subtype comprised remnants from various mobile genetic elements that encode antimicrobial resistance genes, ultimately forming a large MDR region. Genome analysis of CC398 strain SKLX61416 revealed the presence of a novel 50 kb composite SCCmec with two distinct domains, carrying the ccr gene complexes 5/8 and containing genes for the detoxification of arsenic and sulphide. Further sequence analysis disclosed that 44.23% (23/52) of ST88 strains in our collection carried a lineage-specific pseudo-SCCmec, termed ΨSCCmecST88. This ΨSCCmecST88 harboured the mec gene complex C2, along with a series of genes associated with heavy metal resistance, but lacked an approximately 28 kb region encompassing the ccr gene complex. Our findings provide evidence for the ongoing evolution of SCCmec elements within the CC398 and ST88 clones, underscoring the need for further surveillance to understand the biological significance of these elements.

Sensing response of pentagonal B2C nanosheet towards VOCs: A study combining DFT and molecular dynamics simulations

The adsorbing and sensing behavior of the volatile organic compounds (VOCs), e.g., formaldehyde, acetaldehyde, acetone, methanol, ethanol, ethylene oxide, and propylene oxide by pentagonal B2C nanosheet (penta-B2C), have been investigated with the periodic density functional theory approach. The results reveal that adsorbed VOCs on a penta-B2C nanosheet have reduced the band gap ranges from 6 to 60 %. So, the penta-B2C nanosheet can sense these VOC molecules well. Adsorption energy values for the formaldehyde, acetaldehyde, acetone, methanol, ethanol, ethylene oxide, and propylene oxide complexes with desired penta-B2C nanosheet are −1.07, −1.06, −1.17, −1.00, −1.04, −0.88, and −1.04 eV, respectively. The calculated recovery time at 400 K for the considered complexes without radiation is 35, 24, 685, 4, 13, 0.13, and 13 s, respectively. Computed sensitivity values for the studied VOCs/penta-B2C complexes range from 5 to 36034955. So the penta-B2C nanosheet could be a noteworthy substrate for detecting the presented VOCs.

New palladium (II) and platinum (II) complexes with coumarin based O,N,N pincer: Synthesis, structure elucidation, BSA protein binding studies, and anticancer activity

New Pd (II) and Pt (II) complexes (C1/C2) with a O,N,N donor pincer ligand, 4‐hydroxy‐3‐((E)‐1‐(((Z)‐phenyl (pyridin‐2‐yl)methylene)hydrazono)ethyl)‐2H‐chromen‐2‐one (HL) were synthesized and methodically characterized by several spectroscopic and XRD techniques. Absorption and fluorescence techniques were used to assess the mechanism of interaction of the complexes with bovine serum albumin protein. MTT assay was executed to investigate the antiproliferative activity of the complexes with several cancer cell lines (MCF‐7, HCT116, A549, and HepG2) along with a normal cell line (PBMC). Both C1 and C2 showed better antiproliferative activity with HepG2 cell line (IC50 value of 15.3 and 5.1 μM, respectively). A cytotoxicity study was performed, and complex C2 exhibited a better antiproliferative activity as compared to C1. The morphological changes were also examined by staining methods, and fragmented DNA unveiled that the cell death took place through apoptosis.

Synthesis, Characterization, Antimicrobial and Antimalarial Activities of Azines Based Schiff Bases and their Pd(II) Complexes.

Herein, we report synthesis, characterization, antimicrobial and antimalarial activities of azines Schiff base ligands (L1 -L4 ) and their palladium (II) complexes (C1 -C4 ) of [Pd(L)(OAc)2 ] type. The azine ligands (L1 -L4 ) were prepared by condensation of carbonyl compounds with hydrazine hydrate and their complexes by the reaction of palladium acetate with L1 -L4 ligands in 1 : 1 molar ratio. The prepared ligands and their complexes were characterized by spectral characterization using 1 H &13 C-NMR, FT-IR and mass spectral studies, which revealed that the ligands coordinates via azomethine nitrogen and heteroatom or aryl carbon with palladium. Moreover, Schiff bases and their palladium (II) complexes have been screened for their antibacterial (S. aureus, B. subtillis, and S. typhi, P. aeruginosa), antifungal (C. albicans, A. niger, and A. clavatus) and antimalarial (P. falciparum) activities. The Schiff base L4 showed good results for antibacterial against S. aureus (MIC, 50 μg/mL) and antimalarial against P. falciparum (IC50 , 0.83 μg/mL). The complex C1 showed best antibacterial activity (MIC, 62.5 μg/mL) against S. typhi and the complex C4 exhibited remarkable antimalarial activity (IC50 , 0.42 μg/mL) among the tested compounds. Thus, azines based ligands and their Pd complexes can be good antimicrobial and antimalarial agents if explored further.

Regioselective cycloruthenation of N‐(benzylidene)benzylamines: Enantiopure catalysts for transfer hydrogenation

The reaction between N‐(benzylidene)benzylamines (p‐RC6H4CH=NCH2C6H5; R = Cl, H, NO2, F, OMe), [RuCl2(η6‐p‐cymene)]2 and potassium acetate has cleanly furnished the corresponding cycloruthenated complexes C1–C5. The process is completely regioselective, with the formation in all cases of the endo‐derivative, independently of the substituent of the aromatic ring. The five‐membered endo‐metallacycles C6 and C7 can also be obtained from the enantiopure imines (RC)‐p‐RC6H4CH=NCHMeC10H7 (R = Cl, H, respectively) working under similar conditions. The crystal structures of the seven metallated compounds have been determined by X‐ray diffraction. These complexes are active as catalyst precursors for the reduction of acetophenone and benzophenone by transfer hydrogenation. An enantiomeric excess of up to 77% at room temperature has been obtained with the complex C7 in the reduction of acetophenone.

“Half-Sandwich” Ruthenium Complexes with Alizarin as Anticancer Agents: In Vitro and In Vivo Studies

Upon exploration of the chemistry of the combination of ruthenium/arene with anthraquinone alizarin (L), three new complexes with the general formulas [Ru(L)Cl(η6-p-cymene)] (C1), [Ru(L)(η6-p-cymene)(PPh3)]PF6 (C2), and [Ru(L)(η6-p-cymene)(PEt3)]PF6 (C3) were synthesized and characterized using spectroscopic techniques (mass, IR, and 1D and 2D NMR), molar conductivity, elemental analysis, and X-ray diffraction. Complex C1 exhibited fluorescence, such as free alizarin, while in C2 and C3, the emission was probably quenched by monophosphines and the crystallographic data showed that hydrophobic interactions are predominant in intermolecular contacts. The cytotoxicity of the complexes was evaluated in the MDA-MB-231 (triple-negative breast cancer), MCF-7 (breast cancer), and A549 (lung) tumor cell lines and MCF-10A (breast) and MRC-5 (lung) nontumor cell lines. Complexes C1 and C2 were more selective to the breast tumor cell lines, and C2 was the most cytotoxic (IC50 = 6.5 μM for MDA-MB-231). In addition, compound C1 performs a covalent interaction with DNA, while C2 and C3 present only weak interactions; however, internalization studies by flow cytometry and confocal microscopy showed that complex C1 does not accumulate in viable MDA-MB-231 cells and is detected in the cytoplasm only after cell permeabilization. Investigations of the mechanism of action of the complexes indicate that C2 promotes cell cycle arrest in the Sub-G1 phase in MDA-MB-231, inhibits its colony formation, and has a possible antimetastatic action, impeding cell migration in the wound-healing experiment (13% of wound healing in 24 h). The in vivo toxicological experiments with zebrafish indicate that C1 and C3 exhibit the most zebrafish embryo developmental toxicity (inhibition of spontaneous movements and heartbeats), while C2, the most promising anticancer drug in the in vitro preclinical tests, revealed the lowest toxicity in in vivo preclinical screening.

Synthesis, Characterization, and Catalytic Reactivities of Novel Dinuclear Cu(II) Complexes : Efficient Ring Opening Reaction of Epoxide

Synthesis, Characterization, and Catalytic Reactivities of Novel Dinuclear Cu(II) Complexes : Efficient Ring Opening Reaction of Epoxide

Ruthenium (II) Complexes of CNC Pincers and Bipyridine in the Photocatalytic CO2 Reduction Reaction to CO Using Visible Light: Catalysis, Kinetics, and Computational Insights

A series of five ruthenium (II) complexes containing a tridentate CNC pincer ligand, a bidentate 2,2′-bipyridine (bpy) ligand, and a monodentate ligand (chloride, bromide, or acetonitrile) were synthesized. The CNC pincer ligands used imidazole or benzimidazole-derived N-heterocyclic carbenes (NHCs) as the C donors and a 4-methoxy-substituted central pyridyl ring as the N donor. All of the complexes were characterized by analytical, spectroscopic, and single-crystal X-ray diffraction methods. These complexes were used as catalysts for visible-light-driven CO2 reduction in the presence and absence of an external photosensitizer (PS). Notably, complex 4C with a benzimidazole-derived CNC pincer ligand and bromide as the monodentate ligand was the most active catalyst tested for both sensitized and self-sensitized CO2 reduction. Thus, this catalyst was the subject of further mechanistic studies using transient absorption spectroscopy (TAS), absorption spectroelectrochemistry (SEC), and computational studies. A mechanism has been proposed for self-sensitized CO2 reduction involving (1) light excitation of the catalyst, (2) reduction by sacrificial donors, (3) halide loss, and (4) CO2 binding to form [RuCO2]+ as the catalyst resting state. The timeline for these steps and the structures of key intermediates are all supported by experimental observations (including TAS and SEC) and supporting computational studies. Subsequent steps in the cycle past [RuCO2]+ were not experimentally observable, but they are supported by computations. Experiments were also used to explain the differences observed for sensitized catalysis. Catalyst 4C is an unusually active catalyst for both sensitized and self-sensitized CO2 reduction, and thus being able to understand how it functions and which steps are turnover-limiting is an important development facilitating the design of commercially viable catalysts for solar fuel formation.

Synthesis of chiral salen-MnIII complexes tagged with ionic liquid as recoverable homogeneous catalysts for the oxidative kinetic resolution of (±)-secondary alcohols

New chiral salen ligands tagged with imidazolium based ionic liquids (ILs) were synthesized from the 5-bromopentyl benzoate functionality at C-5 position of salicylaldehyde moiety, N-methylimidazole, and (1R,2R)-1,2-diphenylethane-1,2-diamine/(1R,2R)-cyclohexane-1,2-diamine in 81–92% yields. The chiral salen ligands were further reacted with Mn(OAc)2.4H2O in dry methanol under N2 atmosphere, followed by air oxidation with LiCl to produce the IL tagged chiral salen-MnIII complexes 1(a–c) and 2(a–c) in 79-86% yields. The catalytic activities of these complexes were evaluated in the oxidative kinetic resolution of (±)-1-phenylethanol (8a) with N-bromosuccinimide (NBS) as an oxidizer in biphasic solvent system [H2O - organic solvent (2: 1, v/v)] at 0 °C. The enantioselective oxidation of various (±)-secondary alcohols catalyzed by complex 1c (1 mol%) afforded the chiral secondary alcohols with up to 99% enantiomeric excess and 29.6 krel (selectivity factor) value. The IL tagged chiral salen-MnIII complex 1c was easily recovered with hexane and subsequently reused for five recycles with no significant loss in conversion of (±)-1-phenylethanol (8a) and ee of the resolved product.

Design, synthesis, characterization, crystal structure, in silico studies, and inhibitory properties of the PEPPSI type Pd(II)NHC complexes bearing chloro/fluorobenzyl group

This work contains synthesis, characterization, crystal structure, and biological activity of a new series of the PEPPSI type Pd(II)NHC complexes [(NHC)Pd(II)(3-Cl-py)]. NMR, FTIR, and elemental analysis techniques were used to characterize all (NHC)Pd(II)(3-Cl-py) complexes. Also, molecular and crystal structures of complex 1c were established by single-crystal X-ray diffraction. Regarding the X-ray studies, the palladium(II) atom has a slightly distorted square-planar coordination environment. Additionally, the enzyme inhibitory effect of new (NHC)Pd(II)(3-Cl-py) complexes (1a-1g) was studied. They exhibited highly potent inhibition effect on acetylcholinesterase (AChE), butyrylcholinesterase (BChE) and carbonic anhydrases (hCAs) (Ki values are in the range of 0.08 ± 0.01 to 0.65 ± 0.06 µM, 10.43 ± 0.98 to 22.48 ± 2.01 µM, 6.58 ± 0.30 to 10.88 ± 1.01 µM and 6.34 ± 0.37 to 9.02 ± 0.72 µM for AChE, BChE, hCA I, and hCA II, respectively). Based on the molecular docking, among the seven synthesized complexes, 1c, 1b, 1e, and 1a significantly inhibited AChE, BChE, hCA I, and hCA II enzymes, respectively. The findings highpoint that (NHC)Pd(II)(3-Cl-py) complexes can be considered as possible inhibitors via metabolic enzyme inhibition.

Preparation, Structures and Antimicrobial Activity of Ni(II) Complexes on the Base of Enrofloxacin with Dicumarol Derivative

Objective: To synthesize Ni(II) complexes on the base of enrofloxacin with dicumarol derivative and to investigate their antioxidant and antimicrobial potentials. Methods: Ni(II) complexes have been synthesized by classical thermal methods by mixing aqueous metal solutions with ethanol ligands and enrofloxacin in a 1:1 molar ratio. A biologically strong ligand was prepared by refluxing a dicoumarol derivative in aldehyde and ethanol. The structures of the ligands and their nickel complexes were investigated and confirmed by elemental analysis, FT-IR, 1H-NMR, 13C-NMR and mass spectroscopy. The thermal behavior of newly synthesized mixed-ligand Ni(II) complexes was studied by thermogravimetric analysis. Ferric-reducing antioxidant power (FRAP) (antioxidant activity) of all complexes were measured. All the compounds were screened for their antimicrobial activity against E. coli; P. aeruginosa; S. pyogenes; C. albicans and A. niger using Luria Broth dilution method for MIC values. Both the ligand and its complex were screened for antioxidant and antimicrobial activity in vitro. Findings: Antioxidant and antimicrobial activities of complexes were found to be better than the parent ligands used for complex formation. MIC values for complex C5 (-CH3 derivative) were found to be between 40-70 mg/mL and FRAP values was 82.44 mmol/100g, indicative of its ferric reducing antioxidant power. These result show that complex C5 (-CH3 derivative) was found more potential as antimicrobial and antioxidant agent. Novelty : The coordination of metal complex with enrofloxacin (antibiotic) draws a scheme for the synthesis of new drug as well as increasing the activity of enrofloxacin that is currently in use. Current work supports that the activity of antibiotics could be increased by coordination of metal ion complex. There could be a possibility that these complexes allow to reduce the dose of drug introduced into the body. Keywords: Dicumarol; Antimicrobial; Antioxidant; Thermal Analysis; TGA

Synthesis, crystal structures and biological activities of halogeno-(O-alkylphenylcarbamothioate)bis(triarylphosphine)copper(I) complexes

The aim of this work was to synthesize and characterize a new series of copper(I) complexes with thiocarbamate ligands and to evaluate their biological activity. Treatment of CuX salts (X = Cl, Br, I) with O-alkyl N-phenylcarbamothioates in the presence of two equivalents of PAr3 (Ar = Ph, p-C6H4OMe) affords a series of mononuclear thione complexes [(Ar3P)2Cu{ROC(=S)N(H)Ph}X)] C1-C10. According to X-ray diffraction analyses, all complexes adopt a distorted tetrahedral geometry and feature intramolecular NH···Hal bonding, giving rise to six-membered cycles. Like in the case of the literature-known chloro‑compounds C1 and C2 (d(NH···Cl) ∼ 2.29 Å), the bromo‑derivatives C3–C6 exhibit strong NH···Hal distances varying from 2.48 to 2.63 Å. This intramolecular bonding, which is weaker for the iodo complexes C7-C10 (∼ 2.75 Å), has also been studied by Hirshfeld surface analysis of C1, C3, C4 and C6. The crystal structure of two 1D-polymeric intermediates occurring during the synthesis of C7 and C9, namely [{Cu(μ2-I)2Cu}(μ2-L)2]nCP1 and CP2, has also been elucidated. The complexes display weak luminescence in solution centered on the triarylphosphine ligands. In contrast, in the solid state a high-energy band around 350–450 nm centered on the thioamidate and triarylphosphine ligands is observed, along with a second low energy band typical for MLCT/XLCT states around 450–550 nm. The screening of the biological activity of these complexes reveals the absence of any significant antibacterial capacity. However, the presence of an antioxidant activity with a maximum activity for complexes C3 and C4 has been evidenced using the colorimetric DDPH method. This has been probed in vivo on Wistar rats for the preservation of hepatocytes integrity after liver hypothermic conservation (4 °C) for 24 h in Krebs solution with normal cellular state by addition of [(Ph3P)2Cu{EtOC(=S)N(HPHh}I] C8.

1,4-Divinylphenylene-bridged diruthenium complexes with 2-hydroxypyridine- and 2- or 8-hydroxyquinoline-olate ligands

Abstract Four divinylphenylene-bridged diruthenium complexes [{Ru(CO)(P i Pr3)2(L-κ 2 [N,O] – )}2(μ-CH=CH-C6H4-CH=CH-1,4)] (2a–2d) with N,O-chelating 2-hydroxypyridine and 2-hydroxy- or 8-hydroxyquinoline ligands are presented. They were studied by NMR spectroscopy, electrochemical methods and, in their neutral and oxidized states, by IR, UV/Vis/NIR and, if applicable, by EPR spectroscopy. The experimental studies are complimented by (TD-)DFT calculations. Our results indicate that the pyridine-olate complexes 2a,b exist as three isomers with a ratio of about 78:20:2 that differ with respect to the orientation of the N and O donors relative to the CO and alkenyl ligands in the equatorial coordination plane. Only the isomer with both imine N donors trans to the alkenyl ligand is observed for complexes 2c,d with quinolinato ligands. All complexes undergo two consecutive, chemically and electrochemically reversible one-electron oxidations at low potentials. Our results indicate strong contributions of the divinylphenylene bridge to the redox processes and an even delocalization of the electron hole and the unpaired spin density over the entire π-conjugated divinylphenylene diruthenium backbone with only minor involvement of the peripherally attached κ 2 [N,O] – donor ligands.

Expanding the Horizon of Bio-Inspired Catalyst Design with Tactical Incorporation of Drug Molecules.

The development of potent H2 production catalysts is a key aspect in our journey toward the establishment of a sustainable carbon-neutral power infrastructure. Hydrogenase enzymes provide the blueprint for designing efficient catalysts by the rational combination of central metal core and protein scaffold-based outer coordination sphere (OCS). Traditionally, a biomimetic catalyst is crafted by including natural amino acids as OCS features around a synthetic metal motif to functionally imitate the metalloenzyme activity. Here, we have pursued an unconventional approach and implanted two distinct drug molecules (isoniazid and nicotine hydrazide) at the axial position of a cobalt core to create a new genre of synthetic catalysts. The resultant cobalt complexes are active for both electrocatalytic and photocatalytic H2 production in near-neutral water, where they significantly enhance the catalytic performance of the unfunctionalized parent cobalt complex. The drug molecules showcased a dual effect as they influence the catalytic HER by improving the surrounding proton relay along and exerting subtle electronic effects. The isoniazid-ligated catalyst C1 outperformed the nicotine hydrazide-bound complex C2, as it produced H2 from water (pH 6.0) at a rate of 3960 s-1 while exhibiting Faradaic efficiency of about 90 %. This strategy opens up newer avenues of bio-inspired catalyst design beyond amino acid-based OCS features.

Reactions of PNCNP and POCOP Pincer Platinum Hydride Complexes with Phenylacetylene and Carbon Disulfide: The Influence of the Pincer Backbone on the Structures of Unsaturated Auxiliary Ligands

In order to get information about the influence of the pincer backbone on the structure and reactivity of a pincer complex, bisphosphiamine PNCNP and bisphosphinite POCOP pincer platinum hydride complexes, [2,6-(tBu2PY)2C6H3]PtH (Y = NH, 1a; O, 2a), were reacted with phenylacetylene and carbon disulfide. The reactions with phenylacetylene in the presence of CuI/Et2NH produced the corresponding σ-alkynyl complexes [2,6-(tBu2PY)2C6H3]PtC≡CPh (Y = NH, 1b; O, 2b). The reactions with carbon disulfide produced the corresponding dithioformato complexes [2,6-(tBu2PY)2C6H3]PtSC(S)H (Y = NH, 1c; O, 2c). The PNCNP complex 1a is easier to react with carbon disulfide than the POCOP complex 2a. X-ray crystal structure analysis indicated that the PNCNP pincer backbone influences the phenylacetylido and dithioformato auxiliary ligands in the resulting complexes more significantly than the POCOP pincer backbone. The dithioformato auxiliary ligand adopts different coordination modes in complexes 1c and 2c. The results provide useful information about how PNCNP and POCOP pincer backbones influence the reactivity of the metal center and the coordination of unsaturated auxiliary ligands.

Synthesis, characterization, biological and dielectric studies of a proton transfer compound of pyridine-2,6-dicarboxylic acid with 1H-benzimidazole-2-amine and its vanadium and iron complexes

A proton transfer salt, (HBIA+)(HPDA−)·H2O (L), and its vanadium (HBIA)[VO2(PDA)] (C1) and iron complexes, (HBIA)[Fe(PDA)2]·2H2O (C2) [H2PDA = pyridine-2,6-dicarboxylic acid; BIA = 1H-benzimidazole-2-amine] have been synthesized and characterized by elemental analysis, FT-IR, UV–Visible, 1H and 13C NMR and single crystal X-ray diffraction (SC-XRD) studies. According to SC-XRD, compound L and C2 crystalizes in Monoclinic (P21/c) and C1 in Triclinic (P-1) crystal system and exist as multi-component proton transfer systems stabilized by COO−NH+ ion pair interactions. Thermal, biological and material aspects of compounds were explored by TG-DTA study, antimicrobial, antidiabetic and dielectric study. Antibacterial activity was evaluated against the microorganisms, Escherichia coli (ATCC 25,922), Staphylococcus aureus (ATCC 25,923), Pseudomonas aeroginosa (ATCC 2783), Streptococcus mutans (MTCC 890) and Klebsiella pneumonia (ATCC 13,883). Antifungal activity was evaluated against Aspergillus niger (ATCC16404) and Candida albicans (ATCC 10,231). Band gap energy values with UV–Visible spectra reveal the semiconducting nature of compounds. The vanadium complex shows significant antidiabetic activity (IC50value = 315 µg/mL) compared with the standard reference. Presence of easily polarizable water molecule is responsible for the high dielectric constant value (ԑ = 41.96 at 1 Hz) and ac conductivity (σac) for the iron complex C2.

Tumor-Targeting NHC-Au(I) Complex Induces Immunogenic Cell Death in Hepatocellular Carcinoma.

Immunogenic cell death (ICD) is a promising direction of cancer immunotherapy in hepatocellular carcinoma (HCC). A series of novel NHC-Au(I) complexes derived from 4,5-diarylimidazole, containing glycyrrhetinic acid (GA) as an efficient targeting ligand for HCC, were herein designed and synthesized. Among these, complex 4C exhibited excellent effectiveness for tumor targeting and antitumor activity, which induced the occurrence of ICD in HCC cells. Additionally, 4C can effectively inhibit TrxR enzyme activity, increase reactive oxygen species (ROS) expression, lead to redox homeostasis disorder, mediate mitochondrial dysfunction and endoplasmic reticulum stress (ERS), and cause the characteristic discharge of damage-associated molecular patterns (DAMPs) in HCC cells. More importantly, 4C showed a great ICD-inducing effect in a vaccination mouse model and activated antitumor immunity in a tumor-bearing C57BL/6 mouse model, which is consistent with the in vitro results. In conclusion, we found the potential of Au(I) complex with HCC-targeted capability for effective tumor immunotherapy.