Ligands L1 Research Articles

Analysis of Novel Schiff Base-Fe Complexes Against Breast Cancer Cells’ Viability

Two potential novels Schiff base iron (Fe) complexes Fe-L2 and Fe-L3 (where L2= N, N'-bis (o-hydroxyacetophenone) ethylenediamine and L3= N, N'-bis (o-hydroxybenzaldehyde) phenylenediamine) were synthesized from interaction a hot methanolic solution of each ligand L2 or L3 (0.01mole) with the appropriate amount of Fe (NO3)3.9H2O metal salt (0.01mole). This study investigated the cytotoxicity induced by both complexes (0.1 to 100 µg/ml) in MCF-7 and MDA-MB 231 cell lines. After 24 hours of treatment, the cell viabilities of both MCF-7 and MDA-MB-231 cells were linearly proportional to the Fe-L2 concentrations. A higher concentration of Fe-L2 would cause higher cell killings. On the other hand, most of the Fe-L3 concentrations caused total cell deaths for both cell lines, except for the lowest concentration (0.1 µg/ml). Fe-L2 and Fe-L3 also caused lower cell viability of MDA-MB-231 cells compared to MCF-7 cells. Overall, the obtained Fe-L3 is more toxic than Fe-L2 in breast cancer cells. It is suggested that the Fe-L3 is an excellent agent against breast cancer cells; meanwhile, the Fe-L2 is biocompatible and a good support in medical applications, especially as a radiosensitizer in radiotherapy.

Preclinical Evaluation of Zn(II) Self-Assemblies with Selective Cytotoxic Activity Against Cancer Cells In Vitro and In Ovo.

Dipodal pyridylthiazole amine ligands L1 and L2 both form different metallo-supramolecular self-assemblies with Zn2+ and Cu2+ and these are shown to be toxic and selective towards cancer cell lines in vitro. Furthermore, potency and selectivity are highly dependent upon the metal ions, ligand system and bound anion, with significant changes in chemosensitivity and selectivity dependent upon which species are employed. Importantly, significant anti-tumor activity was observed in ovo at doses that are non-toxic.

Origin of Ligand and Acid Effects on the Pd-Catalyzed Regiodivergent Coupling Reaction of Indazoles and Isoprene: A DFT Study.

Comprehensive computational studies were carried out to explore the mechanisms and origin of regioselectivity in the Pd-catalyzed regiodivergent coupling reaction of indazoles and isoprene. Three different insertion models were investigated for regioselectivity 1,2- or 4,3-insertion with respect to the electrophilic sites on isoprene under two different ligands (L1 and L2) and acids ((PhO)2PO2H, (nBuO)2PO2H) via PdII-H species, allyl-π-PdII-O, and indazoles-acid-assisted PdII-π-allyl. The calculated results show that the PdII-π-allyl coordinated mechanism is the most preferred one. The noncovalent interactions between the less bulky ligand L1, substrates, and (PhO)2PO2- are found to be key factors for 1,2-insertion. The 4,3-insertion selectivity is primarily controlled by the steric repulsion of the t-Bu group of bulky ligand L2 and substrate, as well as the geometry distortion. Therefore, the regioselectivity difference of the 1,2- and 4,3-insertion on electrophilic sites is controlled by the synergistic effect of ligands and acids instead of the size of the ligand. Similarly, nucleophilic site selectivity at N1 or N2 of indazoles is governed by cooperative acid BF3 and solvent iPrOH rather than BF3 alone. Overall, our findings might open a new avenue for designing more efficient regioselective 1,2- or 4,3-addition or N1-/N2-selective nucleophilic reactions.

An structural study of nine-membered monometallocycles of Pd(II) and Pt(II) employing the 1,4-bis(3,5-dimethyl-1H-pyrazol-1-yl)butane ligand

Two nine-membered metallocycles of PdII (1) and PtII (2) containing 1,4-bis(3,5-dimethyl-1H-pyrazol-1-yl)butane ligand (L1) have been prepared and their structures were determined by IR, NMR spectroscopy, and by single-crystal X-ray diffraction analysis. The molecular structures of L1 display that the pyrazolyl groups adopt an anti-conformation, while in 1 and 2 a discrete nine-membered monometallic macrocycle is generated by the assembly of one ligand and one metal atom, and the ring adopts a twist-chair-boat conformation. The ligand L1 in complexes 1 and 2 acts as cis-chelating ligand via a κ2 N,N coordination mode by the nitrogen atoms of the pyrazolyl rings. In compounds 1 and 2 the metal center adopts a planar geometry. The molecular structure of 1 and 2 also revealed two intramolecular anagostic interactions M•••Hγ–C(sp3) (M = Pd and Pt) with M•••H distances between 2.689 and 2.780 Å, which are important to stabilize the nine membered ring formed. Considering those two M•••Hγ interactions, the ligand L1 generates a κ4 N,N,H,H coordination mode and the metal centers adopt a trigonal prism geometry. The crystal packing of L1, 1 and 2 displayed supramolecular networks promoted mainly by C–H•••π interactions, which were analyzed by Hirshfeld Surface Analysis

Hansen solubility parameters sphere calculations and thermodynamic model fitting of two novel copper complexes supported by bis(imino)pyridine ligands

In this paper, two novel five-coordinated copper(II) metal complexes, [2,6-(ArN = CMe)2C5H3NCuCl2] (Ar = 2-EtC6H4, L1CuCl2; Ar = 4-EtC6H4, L2CuCl2), bearing bulky 2,6-bis[1-(2-ethylphenylimino)ethyl]pyridine ligands L1 (L1 = 2,6-(ArN = CMe)2C5H3N, Ar = 2-EtC6H4), 2,6-bis[1-(4-ethylphenylimino)ethyl]pyridine ligands L2 (L2 = 2,6-(ArN = CMe)2C5H3N, Ar = 4-EtC6H4) have been synthesized and characterized, and the thermodynamic properties of these complexes are reported in a variety of mono-solvents. The copper(II) metal complexes based on bis(imino)pyridine are widely used in catalysis, photoelectric material, biopharmaceuticals and other fields. In this paper, the solubility of L1 and L2 in four solvents, the solubility of L1CuCl2 in four solvents and the solubility of L2CuCl2 in five solvents were studied by static analysis. The solubility of these compounds was investigated in a certain temperature range to provide data to support the selection of optimal solvents for organic reactions, coating and crystallization separations. Hansen solubility parameters (HSPs) were used to explain the dissolution behavior of solutes and were found to be consistent with experimentally measured results. Moreover, the values of HSPs for L1CuCl2 and L2CuCl2 lacking Cu data were simulated by the Hansen Solubility Parameters in Practice (HSPiP) software, which allowed the prediction of solvents with good dissolution behavior. The values of total solubility parameter of Hildebrand (δ) for L1CuCl2 and L2CuCl2 are 24.5 and 23.0, respectively. Besides, solubility properties of L1CuCl2 and L2CuCl2 in two solvent mixtures at different percentages were predicted. In addition, seven thermodynamic models were used to correlate the solubility data. For L1 and L2, Polynomial models fit better with an average absolute relative deviation (ARD) less than 1 %; for L1CuCl2 and L2CuCl2, Polynomial model fits best (ARD < 1 %). In addition, the enthalpy–entropy compensation relationship in the dissolution process was analyzed by calculating the thermodynamic parameters of the substances, and the results showed that the dissolution process of L1 and L2 was an enthalpy-driven heat absorption process.

Unravelling the Roles of Solvophobic Effects and π⋅⋅⋅π Stacking Interactions in the Formation of [2]Catenanes Featuring Di‐(N‐Heterocyclic Carbene) Building Blocks

AbstractA series of [2]catenanes has been prepared from di‐NHC building blocks by utilizing solvophobic effects and/or π⋅⋅⋅π stacking interactions. The dinickel naphthobiscarbene complex syn‐[1] and the kinked biphenyl‐bridged bipyridyl ligand L2 yield the [2]catenane [2‐IL](OTf)4 by self‐assembly. Solvophobic effects are pivotal for the formation of the interlocked species. Substitution of the biphenyl‐linker in L2 for a pyromellitic diimide group gave ligand L3, which yielded in combination with syn‐[1] the [2]catenane [3‐IL](OTf)4. This assembly exhibits enhanced stability in diluted solution, aided by additional π⋅⋅⋅π stacking interactions. The π⋅⋅⋅π stacking was augmented by the introduction of a pyrene bridge between two NHC donors in ligand L4. Di‐NHC precursor H2‐L4(PF6)2 reacts with Ag2O to give the [Ag2L42]2 [2]catenane [4‐IL](PF6)4, which shows strong π⋅⋅⋅π stacking interactions between the pyrene groups. This assembly was readily converted into the [Au2L42]2 gold species [5‐IL](PF6)4, which exhibits exceptional stability based on the strong π⋅⋅⋅π stacking interactions and the enhanced stability of the Au‐CNHC bonds.

Unravelling the Roles of Solvophobic Effects and π⋅⋅⋅π Stacking Interactions in the Formation of [2]Catenanes Featuring Di-(N-Heterocyclic Carbene) Building Blocks.

A series of [2]catenanes has been prepared from di-NHC building blocks by utilizing solvophobic effects and/or π⋅⋅⋅π stacking interactions. The dinickel naphthobiscarbene complex syn-[1] and the kinked biphenyl-bridged bipyridyl ligand L2 yield the [2]catenane [2-IL](OTf)4 by self-assembly. Solvophobic effects are pivotal for the formation of the interlocked species. Substitution of the biphenyl-linker in L2 for a pyromellitic diimide group gave ligand L3 , which yielded in combination with syn-[1] the [2]catenane [3-IL](OTf)4 . This assembly exhibits enhanced stability in diluted solution, aided by additional π⋅⋅⋅π stacking interactions. The π⋅⋅⋅π stacking was augmented by the introduction of a pyrene bridge between two NHC donors in ligand L4 . Di-NHC precursor H2 -L4 (PF6 )2 reacts with Ag2 O to give the [Ag2 L4 2 ]2 [2]catenane [4-IL](PF6 )4 , which shows strong π⋅⋅⋅π stacking interactions between the pyrene groups. This assembly was readily converted into the [Au2 L4 2 ]2 gold species [5-IL](PF6 )4 , which exhibits exceptional stability based on the strong π⋅⋅⋅π stacking interactions and the enhanced stability of the Au-CNHC bonds.

Size-controlled synthesis and near-infrared photothermal response of Cp* Rh-based metalla[2]catenanes and rectangular metallamacrocycles

A variety of research reports on novel supramolecular topologies have been published over the last years. However, it is still a great challenge to tap into the inner functional properties of these complexes. Herein, two tetranuclear metallamacrocycles 1 and 2 and four octonuclear [2]catenanes 3–6 were constructed successfully via a coordination-driven self-assembly strategy, by conscious design and use of the tetramethyl bidentate pyridine ligand L1, and the appropriate selection of six binuclear half-sandwich rhodium building units with different longitudinal dimensions. The complexes have been fully characterized by single crystal X-ray diffraction analysis and NMR spectroscopy. Furthermore, near-infrared photothermal studies of the obtained [2]catenanes reveal different photothermal response in solid and solution states, which may be attributed to a strong fluorescence quenching effect of the half-sandwich organometallic fragment and different conjugated effect of Cp*Rh based building blocks in the interlocking structures. The photothermal conversion efficiencies of [2]catenanes 4–6 fall in the range 30.5%–16.5% respectively. This contribution aims to play a key role in the experimental development of Cp*-based photothermal materials.

Diverse Post-Metathesis Reactivities of Mixed Amido-Isothiocyanato Molybdenum Complexes.

Attempts to prepare mixed isothiocyanato-bis(imido) MoVI complexes led to the discovery of post-metathesis rearrangements toward three distinct products (1-3), which feature the NCS-derived chelators [N(NMe2)CS]2- (L1 in dinuclear 1 and 2) and [N(SiMe3)(NMe2)CS]- (L2 in mononuclear 3). Notably, the preparation of bidentate ligand L1 and its coordination chemistry are unprecedented. Together with computational studies, it is proposed that the putative "mono-substituted" intermediate [Mo(NtBu)2(NMe2)(NCS)] serves as the common starting point for the observed molecular transformations. Construction of the [Mo(NtBu)2(NCS)2] core was ultimately possible in the presence of additional stabilizing donors (THF or PMe3), which yielded the complexes [Mo(NtBu)2(NCS)2(THF)2] (4) and [Mo(NtBu)2(NCS)2(PMe3)2] (5).

Preparation and characterization of new Mixed ligand complexes For some transition metal ions (bivalent) with Schiff- Mannich and Schiff base ligands

In this research, new mixed ligand complexes were prepared for complexes of some transitional element ions from the first transition series, which are: cobalt (II), nickel (II), and copper (II). The research included two paths:&#x0D; First: The first path included the preparation of three polycyclic ligands derived from Isatin (L1, L2, and L3), all of these ligands were identified by measuring the melting point and infrared and ultraviolet-visible spectroscopy.&#x0D; Second: The second path included the preparation of Mixed ligand complexes (L1and L2) with cobalt (II), nickel (II), and copper (II) ions. And Mixed ligand complexes (L1and L3) with ions of cobalt (II) and nickel (II). All the complexes of the new Mixed ligand were identified by the available analytical and spectroscopic methods. Based on the analytical data, the metal to ligands ratio was (1:1:1) and all complexes were characterized by various analytical techniques including (FT-IR and UV-Vis spectroscopy), CHN elemental analysis and determination using flame atomic absorption spectroscopy The percent magnetic susceptibility and molar conductivity of metal ions in the prepared complexes and these metal complexes dissolved in DMSO at a laboratory temperature of 1 × 10-3 M were also studied. by means of infrared (IR) spectra, and when compared to the spectrum of the free ligands, it was observed that some bands were displaced and others disappeared, or a change in shape and intensity occurred, which indicates a coordination occur between the metal ions and the prepared ligands. As well as the ultraviolet-visible spectrum. And detecting the presence of chloride ion inside or outside the coordination sphere. Depending on these obtained results, we were able to conclude that ligands of L1 and L2 behaves like a bi-chelate ligands, which led to the formation of mixed ligand complexes (L1, L2) with the proposed geometry of the proposed hexahedral symmetry in the presence of two chloride ions inside the coordination sphere. . Whereas, the L3 ligand behaved like a tetragonal ligand, which led to the formation of mixed ligand complexes (L2, L3) with the proposed geometry of the proposed hexahedral symmetry

Effect of substituents in tuning the inter- and intra-molecular interactions in the dinuclear Pt(II) complexes

Substituents play a vital role in the formation of inter- and intra-molecular interactions in the Pt(II) complexes, especially Pt···Pt interactions have a tendency to tune the emission wavelength and the efficiency which has the potential applications in the field of organic light-emitting diodes (OLEDs). In this regard, the pyridazine-based bidentate ligands L1 (-CH3) and L2 (-CF3) are designed and synthesized. Subsequently, the ligands are carefully utilized for the preparation of dinuclear Pt(II) complexes 1 and 2. Complexes were analyzed by various analytical and spectroscopic studies and further confirmed by single crystal X-ray studies, which revealed both complexes show much shortened intra-molecular Pt···Pt distance (2.903 Å in 1 and 2.883 Å in 2) which helps to tune the emission towards the NIR region (up to 850 nm). Further, both complexes show various intermolecular interactions which lead to the formation of a multi-dimensional framework. Complexes 1 and 2 show strong emission at 705 nm and 725 nm, respectively, and further, DFT and TD-DFT studies were performed which confirms that complexes 1 and 2 show strong MMLCT character.

Excited-Multimer Mediated Supramolecular Upconversion on Multicomponent Lanthanide-Organic Assemblies.

Upconversion (UC) is a fascinating anti-Stokes-like optical process with promising applications in diverse fields. However, known UC mechanisms are mainly based on direct energy transfer between metal ions, which constrains the designability and tunability of the structures and properties. Here, we synthesize two types of Ln8L12-type (Ln for lanthanide ion; L for organic ligand L1 or L2R/S) lanthanide-organic complexes with assembly induced excited-multimer states. The Yb8(L2R/S)12 assembly exhibits upconverted multimer green fluorescence under 980 nm excitation through a cooperative sensitization process. Furthermore, upconverted red emission from Eu3+ on the heterometallic (Yb/Eu)8L12 assemblies is also realized via excited-multimer mediated energy relay. Our findings demonstrate a new strategy for designing UC materials, which is crucial for exploiting photofunctions of multicomponent lanthanide-organic complexes.

Synthesis, Structural Characterization and Photocatalytic CO2 Reduction Activity of a New Gd(III) Coordination Polymer with 6-Phenylpyridine-2-carboxylic acid and 4,4’-Bipyridine Ligands

A new Gd(III) coordination polymer, {[Gd(L1)3(H2O)2]∙L2}n (1) (HL1 = 6-phenylpyridine-2-carboxylic acid, L2 = 4,4’-bipyridine) was synthesized using 6-phenylpyridine-2-carboxylic acid, 4,4’-bipyridine, NaOH and GdCl3∙6H2O. The structure of Gd(III) coordination polymer has been characterized by IR and X-ray single crystal diffraction. The result of single crystal analysis indicates that fundamental unit of Gd(III) coordination polymer contains one Gd(III) ion, three L1 ligands, two coordinated water molecules and one uncoordinated 4,4’-bipyridine. In 1, the Gd(III) ion is eight-coordinated and surrounded by six O atoms from three L1 ligands and two O atoms from two coordinated water molecules, respectively. The complex 1 exhibits 1D chained structure by the bridging interactions of two carboxyl-oxygen atoms and O−H∙∙∙N hydrogen bonds interactions. The 1D chains are further connected by - stacking interactions to form 3D network architecture. The photocatalytic CO2 reduction activity of complex 1 has also been investigated. The complex 1 exhibits good CO2 reduction activity. With the increase of time, the yield of CO from 18.2 mmol/g in the first hour to 60.3 mmol/g in the third hour. And the CO selectivity has reached 100%. Copyright © 2023 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Controllable Topological Transformations of 818 Molecular Metalla-knots by Oxidation of Thiazole-Based Ligands.

By exploiting coordination-driven self-assembly, high yields of two 818 molecular metalla-knots could be obtained using a thiazole-moiety-containing asymmetric dipyridyl ligand 2-(pyridin-4-yl)-5-(pyridin-4-ylethynyl)benzo[d]thiazole (L1 ), as confirmed using X-ray crystallographic analysis, electrospray ionization-time-of-flight/mass spectrometry (ESI-TOF/MS), and detailed liquid-state nuclear magnetic resonance (NMR) spectroscopy. To modulate the self-assembled structures, m-chloroperbenzoic acid (m-CPBA) was utilized to oxidize thiazole-based ligand L1 to N-thiazole-oxide-based ligand 2-(pyridin-4-yl)-5-(pyridin-4-ylethynyl)benzo[d]thiazole 3-oxide (L2 ), which enabled the selective construction of the corresponding tetranuclear macrocycles. Notably, two molecular metalla-knots could be topologically transformed from 818 knots to simple monocycles because the L1 alkyne bond was inert toward m-CPBA, as confirmed by liquid-state NMR spectroscopy, ESI-TOF/MS, and elemental analysis.

Controllable Topological Transformations of 818 Molecular Metalla‐knots by Oxidation of Thiazole‐Based Ligands

AbstractBy exploiting coordination‐driven self‐assembly, high yields of two 818 molecular metalla‐knots could be obtained using a thiazole‐moiety‐containing asymmetric dipyridyl ligand 2‐(pyridin‐4‐yl)‐5‐(pyridin‐4‐ylethynyl)benzo[d]thiazole (L1), as confirmed using X‐ray crystallographic analysis, electrospray ionization‐time‐of‐flight/mass spectrometry (ESI‐TOF/MS), and detailed liquid‐state nuclear magnetic resonance (NMR) spectroscopy. To modulate the self‐assembled structures, m‐chloroperbenzoic acid (m‐CPBA) was utilized to oxidize thiazole‐based ligand L1 to N‐thiazole‐oxide‐based ligand 2‐(pyridin‐4‐yl)‐5‐(pyridin‐4‐ylethynyl)benzo[d]thiazole 3‐oxide (L2), which enabled the selective construction of the corresponding tetranuclear macrocycles. Notably, two molecular metalla‐knots could be topologically transformed from 818 knots to simple monocycles because the L1 alkyne bond was inert toward m‐CPBA, as confirmed by liquid‐state NMR spectroscopy, ESI‐TOF/MS, and elemental analysis.

Benzothiadiazolyl‐pyridine and ‐2,2′‐bipyridine Ligands for Luminescent and Magnetic Complexes

AbstractTwo new luminescent ligands, 4‐(2‐pyridine)‐7‐methyl‐2,1,3‐benzothiadiazole (L1) and 4‐(2,2‐bipyridine)‐7‐methyl‐2,1,3‐benzothiadiazole (L2), based on 2,1,3‐benzothiadiazole and pyridine or bipyridine were obtained by Suzuki coupling reactions. DFT and TD‐DFT type calculations have been performed on L1 and L2 in order to assign their experimental UV‐visible and emission bands. Reaction of L1 and L2 with metal(II) chlorides (M=Zn, Mn, Cu) provided the neutral complexes of formulas [ZnL1Cl2] (1), [Zn(L1)2Cl2] (2), [ZnL2Cl2] (3), [MnL2Cl2] ⋅ 0,5CH2Cl2 (4) and [CuL2Cl2] ⋅ H2O (5) which have been structurally characterized. The Zn(II) ions in 1 and 2 are four‐coordinate in somewhat distorted tetrahedral N2Cl2 surroundings with L1 adopting bidentate (1) and monodentate (2) coordination modes. Complexes 3–5 are isostructural and their metal atoms are five‐coordinate in distorted square pyramidal environments with three nitrogen atoms from the tridentate L2 ligand and a chlorine building the basal plane and another chlorine atom occupying the apical position. The three Zn(II) complexes are strongly luminescent in solution and the solid state, while the cryomagnetic study of the paramagnetic compounds 4 and 5 in the temperature range 2.9–300 K shows a Curie‐Weiss behaviour typical of small antiferromagnetic interactions which are mediated by weak intermolecular contacts.

Half‐sandwich Ru (II) complexes: Effect of ligands on aerobic oxidation of benzylamine

In this study, we compared carbene and pyridine substituted ligands {3‐Me‐1‐[2‐(CH2CH2SPh)]‐C7H4N2} (L1) and {2‐[(2,6‐iPr2‐C6H3)N=CH]‐6‐(MeO)C5H3N}(L2) for synthesis of ionic C,S‐ and N,N‐coordinated Ru (II) complexes [(κ2‐L1)RuCl(η6‐p‐cymene)]+Cl− (1), [(κ2‐L1)RuI(η6‐p‐cymene)]+I− (2), and [(κ2‐L2)RuCl(η6‐p‐cymene)]+Cl− (3), respectively. Stannylene ligand [{2,6‐(Me2NCH2)2C6H3}SnCl] (L3), as heavy carbene analog, was also used in this study to prepare neutral Sn‐coordinated Ru (II) complex [(κ1‐L3)RuCl2(η6‐p‐cymene)] (4). Finally, reaction of SnCl2 with 1, 3, and 4 was also studied to yield [(κ2‐L1)RuCl(η6‐p‐cymene)]+[SnCl3]− (5), [(κ2‐L2)RuCl(η6‐p‐cymene)]+[SnCl3]− (6), and [(κ1‐L3)RuCl (SnCl3)(η6‐p‐cymene)] (7). The catalytic activity of 1–7 was tested on aerobic oxidation of benzylamine. The effect of different ligands L1–3 as well as the effect of the SnCl3− moiety is discussed.

Enhancement of the Cytotoxicity of Quinazolinone Schiff Base Derivatives with Copper Coordination

Two copper(II) complexes (Cu-L1, Cu-L2) derived from 2,3-substituted quinazolinone Schiff base ligands (L1, L2) were prepared to examine their anticancer activity. Compounds were characterized using various spectroscopic methods (FTIR, NMR, UV-vis) and quantum-chemical calculations. The biological effects of Cu(II) complexes bearing quinazolinone scaffolds were evaluated on two cancers’ cell lines (breast—MCF-7 and lung—A549), as well as on untransformed cells (keratinocytes—HaCaT). Copper complexes were highly cytotoxic, with IC50 in the low micromolar range, while the quinazoline ligands L1 and L2 remained inactive in inhibiting cell proliferation. Antioxidant activity was investigated in the model systems using DPPH and FRAP assays. The Cu-L1 and Cu-L2 complexes exhibited enhanced DPPH free radical scavenging efficiency compared to the L1 and L2 ligands, but their reducing ability was comparable to that of the free ligands. Evaluation of oxidative stress in vitro carried out by staining cells with various ROS-specific indicators showed reduced production of superoxide anion radical and hydrogen peroxide after treatment of cells with copper complexes. Such a negative impact on ROS formation in cells can lead to cellular redox imbalance and consequent cell death, among others, by inducing apoptosis and/or necrosis, depending on the copper complex used. We hypothesize that the high cytotoxic activity of the investigated copper complexes is apparently the result of multiple mechanisms of action, and the imbalance in the cellular antioxidant system partly contributes to the overall cytotoxic effect.

Features of Cadmium(II) Complexation with N-Donor Heterocyclic Ligands in the Presence of the Octadecahydroeicosaborate Anion

The process of cadmium(II) complexation with 1-ethyl-2-(4-methoxyphenyl)azobenzimidazole (L1), 2,2′-bipyridyl (L2), and 1,10-phenanthroline (L3) in the presence of the [trans-B20H18]2– anion has been studied. It has been found that the nature of the organic ligand affects the composition and structures of the resulting compounds. Complexation with ligand L1, a benzimidazole derivative, has yielded binuclear complex [CdL12NO3(μ-NO3)CdL1(NO3)2] (1), which contains no boron cluster anion. In the case of azaheterocyclic ligands L2 and L3, depending on the Cd : L ratio, heteroleptic complexes [CdL2NO3]2[trans-B20H18] (L = L2 (2); L3 (3)) with coordinated nitrate ions (Cd : L = 1 : 2) or tris-chelate complexes [CdL3][trans-B20H18] (L = L2 (4); L3 (5)) with the boron cluster anion as a counterion (Cd : L = 1 : 3) have been isolated. The structures of complexes [CdL12NO3(μ-NO3)CdL1(NO3)2] (1) and [Cd(L2)2NO3]2[trans-B20H18] (2) have been determined by X-ray diffraction.

Synthesis of block copolymer with cis-1,4-polybutadiene and isotactic-rich polystyrene using α-diimine nickel catalysts.

A series of styrene-butadiene di-block copolymers with high cis-1,4 unit content (greater than 92%) polybutadiene (PB) and isotactic-rich polystyrene (PS) (mmmm > 65%) was synthesized using α-diimine nickel catalysts (Ni-diimine). Four different Ni-diimine catalysts were synthesized via a complexing reaction between nickel (II) naphthenate and laboratory-made α-diimine ligands L1, L2, L3 and L4, which have different steric volume structures. The results indicate that the Ni-diimine catalyst prepared using the L4 ligand with a higher steric volume can effectively initiate the block polymerization of butadiene and styrene, and the resulting polymer has distinguished cis-1,4 structure unit PB and high isotactic-selective PS block. Differential scanning calorimetry and electrochemical performance tests show that these block copolymers with cis-1,4-regulated and isotactic-selective polymerization have advantages in terms of high-temperature and low-temperature resistance as well as corrosion resistance. Therefore, these copolymers are expected to be widely used in some harsh industrial environments.