Clathrochelate Complexes Research Articles

Stepwise synthesis of heterotrimetallic FeII/PdII/AuI coordination cages

Heterotrimetallic molecular cages were obtained by linking FeII clathrochelate complexes, AuI3(pyrazolate)3 complexes, and [PdII(pyridine)4]2+ complexes.

Clathrochelate Complexes Containing Axial Cymantrene and Tromancenium Moieties.

New clathrochelate complexes of manganese, iron and cobalt containing peripheral organometallic manganese moieties cymantrene or tromancenium were synthesized via self-assembly from di/tri-topic dioximes, metal templates and cymantrene/tromancenium boronic acid pinacol esters. These air-stable, highly colored, oligometallic complexes are composed of various combinations of MnIFeIIMnI, MnICoIIMnI, MnIMnIIMnIIMnI and MnICoIICoIIMnI metal assemblies with corresponding complicated magnetic and electrochemical properties. Full spectroscopic and structural characterization by 1H/11B/13C NMR, HRMS, IR, UV-vis, single crystal XRD and CV (cyclic voltammetry) is provided. Tetrametallic complexes containing tromanceniumyl substituents with two CoII or MnII central metals exhibit promising anticancer properties against different tumor cell lines.

Electrochemical water oxidation using a stable water-soluble mononuclear manganese clathrochelate

A mononuclear manganese clathrochelate complex [MnIV(L-6H)]2− is found to be an efficient homogeneous water oxidation catalyst under near neutral conditions. Oxygen evolution occurs at a low onset overpotential of only 540 mV.

Dynamics of Morphological Indicators of Blood of Piglets under the Influence of Iron Clathrochelate Complex and Cyanocobalamin

Iron deficiency anemia is one of the most common non-contagious diseases of piglets. Veterinary antianemic drugs have several drawbacks, so finding new medicines is an important current task for scientists. Therefore, the present study investigated the antianemic effect of iron (IV) clathrochelate in the organism of piglets. The subsequent studies included the exploration of its antianemic actions, particularly in combination with cyanocobalamin when this combination was administered to sows for prophylaxis in piglets. The experiment was carried out on 30 suckling piglets during the period of their detention with sows. According to the method of analogue groups, two groups of control (I) and experimental (II, each containing 15 animals) were formed and they were studied for 30 days. The piglets from five sows (three from each) were selected for the experimental group. During the pregnancy of these sows, 10 ml of 10% solution of iron (IV) IV clathrochelate and solution of cyanocobalamin were injected intramuscularly twice 7 and 14 days before their expected farrowing. For prevention of iron deficiency anemia, the traditional solution of iron dextran was administered once intramuscularly to piglets of the control group. The investigative material included the blood samples of piglets considering the dynamics of probable changes in the number of erythrocytes, hemoglobin content and hematocrit, and other morphological indicators and blood indices of piglets. The dynamics of changes in erythrocyte count, hemoglobin content, hematocrit, leukocytes and platelets, indices of blood almost did not differ from the dynamics of these values when using only 10% solution of iron (IV) clathrochelate for pregnant sows. The proposed scheme for the prophylaxis of iron deficiency anemia in piglets, involving simultaneous intramuscular injections of IV clathrochelate and cyanocobalamin to pregnant sows, is somewhat inferior to the previous preventive measures, which included only the intramuscular injections of iron (IV) IV clathrochelate, but it can be recommended as highly effective.

Ligand Effects in Low‐Valent Co(I) Clathrochelate Complexes

AbstractClathrochelate complexes of cobalt are known in the oxidation states I, II, and III. Low‐valent Co(I) complexes are highly reactive compounds, and there is only limited knowledge about their structures in the solid state. Herein, we describe the crystallographic analyses of three low‐valent clathrochelate complexes, along with analyses of the corresponding Co(II) precursors. Two different ligand environments were studied: a) ligands with alkyl substituents, which render the complexes highly reducing, and b) potentially redox non‐innocent ligands. Our analyses show that the ligands have a large effect on the redox potentials, but only a small effect on the geometry and the electronic state of the central Co ion.

Polyaromatic-terminated iron(ii) clathrochelates as electrocatalysts for efficient hydrogen production in water electrolysis cells with polymer electrolyte membrane

Hydrogen-evolving cathodes were prepared using a series of iron( ii ) clathrochelates bearing various number of terminal phenanthrenyl groups via physisorption on carbon paper and employed in the polymer electrolyte membrane water electrolysis cells instead of typically used platinum. In situ electrochemical activation of the cathodes was carried out, after that the cells performance and durability were evaluated. These clathrochelate complexes represent a promising alternative to platinum as hydrogen-evolving cathode electrocatalysts.

Research antianemic action of the iron (IV) clathrochelate complexes on the sickling piglets

A lot of antianemic drugs for animals are presented on the modern pharmaceutical market of veterinary medicine, but they have several drawbacks. So finding new drugs with goal to treat ill animals by anemia and to prevent the iron deficiency anemia is a pressing issue. We previously reported the results of preclinical studies of iron in rare high valence IV. This allowed us to determine, supplement, and generalize the data on clinical studies of the new drugs with the active substance iron (IV) clathrochelate. Therefore, the article presents the results of studies of its antianemic effect on sickling piglets. Experiments were carried out on piglets-analogues neonates, which were divided into three groups: control and two experimental groups. Piglets were kept with sows on suckling. For the purpose of prevention iron deficiency anemia the traditional solution of iron dextran was administered once intramuscularly to piglets of I control group. The aqueous solution of iron (IV) clathrochelate complexes was administered once intramuscularly to piglets of II experimental group. Iron (IV) clathrochelate complexes was dissolved in a solvent of rheopolyglucin and administered once intramuscularly to piglets of III experimental group. 1 mL of test solutions contained 100 mg of active substance. The investigative material were the samples of blood and serum of piglets, their liver and spleen. The experiment lasted during a 30-day period since birth of piglets. According to the results of the experiments, iron (IV) clatrochelate complexes which was dissolved in a water for injection and rheopolyglucin had higher antianemic activity compared to the control. This is evidenced by the dynamics of probable changes in the number of erythrocytes, hemoglobin content and hematocrit, Iron content in serum and its mass fraction in the blood, liver and spleen of piglets. The effectiveness of the action of iron (IV) clatrochelate complexes is explained by the full supply of piglets with iron and its higher bioavailability.

Two-Step Synthesis of Linear and Bent Dicarboxylic Acid Metalloligands with Lengths of up to 3 nm.

Nanometer-sized polycarboxylate ligands are interesting building blocks for metallasupramolecular chemistry, but access to these compounds is often limited by complicated synthetic pathways. Here, we describe a simple two-step protocol, which allows preparing linear and bent dicarboxylate ligands with lengths of up to 3 nm from commercially available compounds. The ligands are prepared by iron-templated polycondensation reactions involving arylboronic acids and nioxime. The final products contain two iron clathrochelate complexes and two terminal carboxyphenylene groups. To demonstrate that the new ligands are suitable for the construction of more complex molecular nanostructures, we have prepared a Cu-based metal-organic polyhedron, which represents the largest M4L4 cage described so far.

Antianemic action of the iron (IV) clathrochelate complexes

Anemia is one of the most common non-contagious diseases of pigs. Modern antianemic drugs have several drawbacks, so finding new drugs is a pressing issue. We previously reported the results of preclinical studies of iron in rare high valence IV. This allowed us to determine, supplement, and generalize the data on clinical studies of the new drugs with the active substance iron (IV) clathrochelate. Therefore, we studied its antianemic effect on piglets. Experiments were carried out on piglets-analogues neonates, which were divided into three groups: control and two experimental groups. Piglets were kept with sows on suckling. For the purpose of prevention of iron deficiency anemia, the traditional solution of iron dextran was administered once intramuscularly to piglets of I control group. The aqueous solution of iron (IV) clathrochelate complexes was administered once intramuscularly to piglets of II experimental group. Iron (IV) clathrochelate complexes were dissolved in a solvent of rheopolyglucin and administered once intramuscularly to piglets of III experimental group. 1 mL of test solutions contained 100 mg of active substance. The investigative material were the samples of blood and serum of piglets, their liver and spleen. The experiment lasted during a 30-day period since the birth of the piglets. According to the results of the experiments, iron (IV) clatrochelate complexes which were dissolved in water for injection and rheopolyglucin had higher antianemic activity compared to the control. This is evidenced by the dynamics of probable changes in the number of erythrocytes, hemoglobin content and hematocrit, iron content in serum and its mass fraction in the blood, liver and spleen of piglets. The effectiveness of the action of iron (IV) clatrochelate complexes is demonstrated by the full supply of piglets with iron and its higher bioavailability.

New boron-capped cage manganese(II) complex with terminal thiophene-2-carboxaldehyde groups: Crystal structure and density functional theory investigation for electron transfer

A metal-containing clathrochelate complex [Mn2II(hmbd)3[(5–ftba)2]·Et3NH·CH3OH has been synthesized with 2-hydroxy-5-methyl-1,3-benzenedicarboxaldehyde dioxime (abbreviated as H3hmbd) and 5-formyl-2-thiopheneboronic acid (abbreviated as 5-ftba) by template method and characterized by elemental analysis, IR spectra, MS and single-crystal X-ray diffraction. Density functional theory (DFT) calculations have been performed to further understand the geometry, electronic structure and nature of electron transfer under various electric fields. Mayer bond order (MBO) analysis, electron localization function (ELF) analysis and atoms in molecules (AIM) analysis were carried out to study the electronic structure and the structural stability under applied electric fields. The deviation of natural population analysis (NPA) charge together with the charge density difference (CDD) plots in various electric fields was plotted to research the electron transfer process under applied electric fields. The density of states (DOS) analysis, distribution of highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO), the energy of the HOMO-LUMO gap (HLG) analysis were investigated to reveal the nature of electron transfer under the applied electric field.

Investigation of the irritant effects and allergenic properties of the Iron(IV) clathrochelate complexes

During the preclinical studies of new drugs, the study of the degree of manifestation of their irritant and allergenic effects affects subsequent clinical studies, for example the routes of administration, the need to add excipients to reduce irritation. The article presents the results of studies of the irritant effects and allergenic properties of the Iron in rare unconventional valence – IV. The irritant effect of the Iron(IV) clathrochelate complexes on the skin was studied comprehensively. 20 rabbits were divided into 4 groups (control and three experimental), 5 animals each. The ointment on the vaseline and aqueous solution of the Iron(IV) clathrochelate complexes was applied to the skin of rabbits of the experimental groups. Also this solution was introduced subcutaneously. The investigated dosage forms were used at a dose of 1 ml/kg body weight (based on the active ingredient 500 mg/kg body weight of the laboratory animal). The results of the studies showed that of the Iron(IV) clathrochelate complexes has no irritant properties when used externally and is characterized by a lack of local reaction by subcutaneous injection. Determination of allergenic properties was performed by detecting itching and swelling in the guinea pigs in animals which were sensitized with this substance. In addition, in order to assess the severity of the inflammatory reaction, the skin temperature was determined before the experiment and on the 20th day of the experiment, and the skin fold thickness was measured using a caliper. The results of the studies showed that there is no allergic action of the Iron(IV) clathrochelate complexes. The results of the ophthalmic test on laboratory animals confirmed the data obtained.Therefore, comprehensive studies of the irritant and allergenic effects of the Iron(IV) clathrochelate complexes were performed for the first time. The Iron(IV) clathrochelate complexes in the form of ointment and solution does not irritate the skin and mucous membranes and has no allergenic properties to the body of the laboratory animals.

Structural and Chemical Transformations of Ruthenium, Cobalt, and Iron Clathrochelates Used as Electrocatalysts for a Hydrogen Evolution Reaction in a Water Electrolyzer

The structural evolution of three electrocatalytic systems for hydrogen evolution reaction using iron, cobalt, and ruthenium(II) clathrochelate complexes as catalysts in a water electrolyzer is studied by X-ray absorption near-edge structure (XANES)/extended X-ray absorption fine structure (EXAFS) spectroscopy. The complexes are shown to display essentially different robustness under water electrolysis conditions in pilot-scale hydrogen generators. The iron and cobalt(II) clathrochelates preserve their cage, macrobicyclic structure, and the encapsulated metal(II) ion is reduced to metal(I) cation; whereas in the case of ruthenium(II) clathrochelate, the cage complex undergoes partial decomposition to form sulfur-containing products of decomposition of the encapsulating macrobicyclic hexasulfide ligand, which results in the accumulation of the ruthenium disulfide RuS2 in used clathrochelate-containing cathode material. Taking into account our experimental data on the chemical transformation of clathrochelate electrocatalysts under the conditions of 2Н+/Н2 reaction, we discuss the possibilities for boosting the efficiency of electrocatalytic systems based on this class of coordination compounds.

Chronic toxicity of the Iron (IV) clathrochelate complexes for white rats

The article presents the results of studies of chronic toxicity of the Iron in the rare unconventional valence – IV. During long-term use of the Iron(IV) clathrochelate complexes for white rats we have established the dynamics of the body weight of rats, the relative coefficients of mass of the internal organs, the content of hemoglobin and morphological parameters of blood, biochemical parameters of blood serum of animals of this species. The daily drinking of solution of the Iron(IV) clathrochelate complexes at the doses of 500 and 1000 mg/kg b. w. resulted in a decrease in body weight, an increase in the relative indices of masses of liver and kidney, and a decrease in the relative indices of masses of spleen and heart on 30th day. The hemoglobin content in the blood of rats of the experimental group was less than the control indicator by 3–47% (P < 0.05), which is evidence of inhibition of its synthesis under the influence of the Iron (IV) clathrochelatе. Changes in the morphological composition of the blood were characterized by marked leukocytopenia. The use of rats of a solution of the Iron (IV) clathrochelate complexes at doses of 500 and 1000 mg/kg b. w. caused the development of hypoproteinemia, hypercreatinemia and hyperurinemia. Iron(IV) clathrochelate complexes reduced alaninaminotransferase activity in the serum of rats of both experimental groups by 15–80% (P < 0.05); aspartataminotransferase activity increased significantly by day 10 and decreased by day 30; the activity of alkaline phosphatase was independent of the doses of the drug during the experimental period. The content of Calcium total, Phosphor inorganic and Iron in the serum of rats of the experimental groups was at the level of indicators in the animals of the control group. Consequently, comprehensive studies of the effects of solution of the Iron (IV) clathrochelate complexes at doses of 500 and 1000 mg/kg b. w. were performed for the first time with long-term administration to white rats, which revealed the main patterns of metabolic disorders and physiological functions.

Influence of iron (IV) clathrochelate complexon quail blood parameters and weight characteristics

We studied the chronic toxicity of the compounds of Iron(iv). We monitored the dynamics of the body weight, relative weight coefficients of the internal organs, the content of the hemoglobin, the morphological parameters of blood, and biochemical parameters of serum of blood of quails after use of Iron(IV) clathrochelate complexes at the doses 1/10 and 1/5 DL50 them for 30 days. Daily drinking of quails of experimental groups of solution of Iron(IV) clathrochelate complexes3 at the doses 76.43 and 152.86 mg/kg of body weight caused the reduction of body weight by 3 and 5% respectively on the thirtieth day. A tendency to increase the relative weight of the kidneys and to decrease the relative weight of the liver, heart and spleen showed an excessive load of Iron(IV) clathrochelate complexes on the internal organs of quails. Hemoglobin in the blood of the quails of the experimental groups was less by 2-34% (P 0.05) than the control indicator but the indicator of the number of erythrocytes in the quails of the control and experimental groups for 30 days was within the physiological values. The use of Iron(IV) clathrochelate complexes caused the development of hypoproteinemia, hypoalbuminemia, and short-term hypoglycemia in the serum of the blood of the quails of the experimental groups. Changes in an activity of alanine aminotransferase and aspartate aminotransferase for 30 days were not expressed, but the activity of alkaline phosphatase was significantly higher compared to the control indicators during the experimental period. Drinking the solution of Iron(IV) clathrochelate complexes caused hypercreatinemia and hyperuricemia, which indicates a decrease in the filtration capacity of the kidney glomeruli. We have seen an increase in the levels total Calcium and inorganic Phosphorus.

Acute toxicity of the iron clathrochelate complexes

A new class of highly valent iron compounds is formed by atmospheric oxidation in aqueous media and it is extremely stable both in solid and soluble conditions and may exist indefinitely in a medium without signs of degradation. The first clathrochelate complexes of iron (IV) are infinitely stable in water and readily available from simple, commercially available, inexpensive source materials with surprisingly mild reaction conditions. To create new drugs on their bases, research on their toxicity is required. In this study, the results of preclinical studies of a new iron clathrochelates drug are presented. Experiments were carried out on white rats and quails, which in the previous experiment were divided into five experimental and two control groups. The solution of iron clathrochelate complexes was administered intragastrically in doses 50, 500, 1000, 2000 and 5000 mg/kg, respectively. Our results have shown that there were no grounds for using rats in the advanced experiment because the conducted research has established that iron clathrochelate is non toxic to rats. Thus, the minimum dose of iron clathrochelate complexes did not cause death of quails, and the largest dose caused 100% mortality. The basic experiment was conducted on 6 groups of birds, each consisting of 7 quails. The drug was administered in the following doses: 500, 600, 700, 800, 900, 1000 mg/kg. The monitoring observation of the laboratory birds lasted for 14 days. It has been established that the average lethal dose of clathrochelate of the investigated drug for internal administration in quails is 764 ± 33 mg/kg. According to the classification of chemicals by the degree of danger (State ST 12.1.007-76), iron (IV) clathrochelate complexes correspond to the third class of hazard, and according to the classification of substances for toxicity they are classified as category 4 (low toxicity substances). The prospect of further research is to investigate the pharmacological and toxicological properties of iron (IV) clathrochelate for chronic toxicity.

Cages vs. Prisms: Controlling the Formation of Metallosupramolecular Architectures with Ligand Side‐Chains

Metallosupramolecular assemblies of the general formula M2nLn can adopt prismatic or cage‐like structures. The factors controlling the aggregation number n and the geometry of the final assembly are still not fully understood. Here, we describe the synthesis and the structural characterization of PtII8L4 complexes, which adopt tetragonal prismatic structures. The bridging ligand L features four pyridyl groups and an inert FeII clathrochelate complex at its core. Furthermore, the ligand has three phenanthrene groups, which are attached to the FeII complex in a divergent fashion. These polyaromatic side groups control the self‐assembly process by promoting the formation of a structure, which allows for an energetically favorable packing of the aromatic groups. Replacing the phenanthrene groups on the ligand by aliphatic n‐butyl groups results in a complete change of geometry: instead of tetragonal prisms, PtII8L4 complexes with cage‐like structures are observed.

Porous networks based on iron(ii) clathrochelate complexes.

Microporous networks based on boronate ester-capped iron(ii) clathrochelate complexes are described. The networks were obtained by covalent cross-linking of tetrabrominated clathrochelate complexes via Suzuki-Miyaura polycross-coupling reactions with diboronic acids, or by Sonogashira-Hagihara polycross-coupling of clathrochelate complexes with terminal alkyne functions and 1,3,5-tribromobenzene. The networks display permanent porosity with apparent Brunauer-Emmett-Teller surface areas of up to SABET = 593 m2 g-1. A clathrochelate complex based on an enantiopure dioximato ligand was used to prepare chiral networks. One of these networks was shown to preferentially absorb d-tryptophan over l-tryptophan.

Efficient visible light-driven water oxidation catalysed by an iron(iv) clathrochelate complex.

A water-stable FeIV clathrochelate complex catalyses fast and homogeneous photochemical oxidation of water to dioxygen with a turnover frequency of 2.27 s-1 and a maximum turnover number of 365. An FeV intermediate generated under catalytic conditions is trapped and characterised using EPR and Mössbauer spectroscopy.

Dicarboxyl-terminated iron(ii) clathrochelates as ICD-reporters for globular proteins.

Cage metal complexes iron(ii) clathrochelates, which are inherently CD silent, were discovered to demonstrate intensive output in induced circular dichroism (ICD) spectra upon their assembly to albumins. With the aim to design clathrochelates as protein-sensitive CD reporters, the approach for the functionalization of one chelate α-dioximate fragment of the clathrochelate framework with two non-equivalent substituents was developed, and constitutional isomers of clathrochelate with two non-equivalent carboxyphenylsulfide groups were synthesized. The interaction of designed iron(ii) clathrochelates and their symmetric homologues with globular proteins (serum albumins, lysozyme, β-lactoglobulin (BLG), trypsin, insulin) was studied by protein fluorescence quenching and CD techniques. A highly-intensive ICD output of the clathrochelates was observed upon their association with albumins and BLG. It was shown that in the presence of BLG, different clathrochelate isomers gave spectra of inverted signs, indicating the stabilization of opposite configurations (Λ or Δ) of the clathrochelate framework in the assembly with this protein. So, we suggest that the isomerism of the terminal carboxy group determined preferable configurations of the clathrochelate framework for the fixation in the protein binding site. MALDI TOF results show the formation of BLG–clathrochelate complex with ratio 1 : 1. Based on the docking simulations, the binding of the clathrochelate molecule (all isomers) to the main BLG binding site (calyx) in its open conformation is suggested. The above results point that the variation of the ribbed substituents at the clathrochelate framework is an effective tool to achieve the specificity of clathrochelate ICD reporting properties to the target protein.

Determination of Large Zero-Field Splitting in High-Spin Co(I) Clathrochelates.

Zero-field splitting (ZFS) of three high-spin Co(I) ( S = 1) clathrochelate complexes was determined by frequency-domain Fourier-transform THz-EPR (FD-FT THz-EPR). The following axial and rhombic ZFS values ( D and E, respectively) were determined: [N( n-Bu)4]CoI(GmCl2)3(BPh)2 (1, D/ hc = +16.43(1) cm-1, E/ hc = 0.0(1) cm-1), [P(Me2N)4]CoI(GmCl2)3(BPh)2 (2, D/ hc = +16.67(4) cm-1, E/ hc = 0.0(1) cm-1), and [P(C6H5)4]CoI(GmCl2)3(BPh)2 (3, D/ hc = +16.72(2) cm-1, E/ hc = 0.24(3) cm-1). Complementary susceptibility χ T measurements and quantum chemistry calculations on 1 revealed hard-axis-type magnetic anisotropy and allowed for a correlation of ZFS and the electronic structure. Increased rhombicity of 3 as compared to 1 and 2 was assigned to symmetry changes of the ligand structure induced by the change of the counterion. 1 and 3 exhibited temperature-dependent ZFS values. Possible reasons for this phenomenon, such as structural changes and weak chain-like intermolecular antiferromagnetic interactions, are discussed.