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9-Amino­acridinium chloride N,N-di­methyl­formamide monosolvate was found to crystallize in the monoclinic space group P21/c. The crystal structure of this compound is stabilized by N—H⋯O and N—H⋯Cl hydrogen bonds, as well as π–π stacking., 9-Amino­acridinium chloride N,N-di­methyl­formamide monosolvate, C13H11N2 +Cl−·C3H7NO, crystallizes in the monoclinic space group P21/c. The salt was crystallized from N,N-di­methyl­formamide. The asymmetric unit consists of two C13H11N2 +Cl− formula units. The 9-amino­acridinium (9-AA) mol­ecules are protonated with the proton on the N atom of the central ring. This N atom is connected to an N,N-di­methyl­formamide mol­ecule by a hydrogen bond. The H atoms of the amino groups create short contacts with two chloride ions. The 9-AA cations in adjacent layers are oriented in an anti­parallel manner. The mol­ecules are linked via a network of multidirectional π–π inter­actions between the 9-AA rings, and the whole lattice is additionally stabilized by electrostatic inter­actions between ions.

Hypoplastic anemia is a disease that is associated with a decrease in the number of red blood cells and / or hemoglobin per unit volume of blood due to hematopoietic disorders and is manifested by changes in metabolism and growth retardation. Particular attention was paid to changes in the body of piglets of the experimental group compared with the control in the probable period of manifestation of iron deficiency anemia. The uniqueness of the chemical structure of iron (IV) clatrochelate allowed us to assume that intramuscular administration of a solution of this substance to sows will provide the necessary need for iron during the first months of life of piglets. The influence of the proposed scheme of prevention of this pathology on the further development of young pigs was analyzed. The results of the study of erythrocyte count, hemoglobin content and hematocrit were scientifically significant, because the gradual decrease in these indicators after the birth of piglets is a physiologically determined phenomenon for animals of this species. The aim of our study was to evaluate the effectiveness of the use of Iron (IV) clatrochelate in pregnant sows in order to prevent iron deficiency anemia in piglets and to determine its effect on hemoglobin content, hematocrit and morphological parameters of piglets' blood. To achieve this goal, 2 groups of newborn piglets-analogues were formed during their retention with suckling sows – control and experimental, 15 animals in each. The experiment lasted 60 days. Piglets from the experimental group were selected from sows who were injected 10 ml 10 % Iron (IV) clatrochelate solution twice intramuscularly during pregnancy. The results of the studies show that the content of hemoglobin in the blood of piglets of the experimental group was the same as in animals of the control group at 1 and 60 days of life, and 1.1–1.3 times lower in other periods of the study; hematocrit - was the same on the first day of life and 1.3–1.9 times lower in other study periods. Quantitative indicators of blood cells of piglets of the control and experimental groups did not exceed the normative values, but the number of erythrocytes in the blood of piglets of the experimental group was probably lower than the control indicator at 5, 9 and 30 days of life. Therefore, a double injection of 10 % Iron (IV) clatrochelate solution into pregnant sows 14 and 7 days before the expected farrowing provides a preventive effect on iron deficiency anemia in piglets born to them.

Hofmann-like cyanometallic complexes represent one of the biggest and well-known classes of FeIIspin-crossover compounds. In this paper, we report on the first FeIIHofmann clathrate analogues with unsubstituted 1,2,3-triazole, which exhibit temperature induced spin transition. Two new coordination polymers with the general formula [FeII(1,2,3-triazole)2MII(CN)4] (M = Pt, Pd) undergo abrupt hysteretic spin crossover in the range of 190–225 K as revealed by magnetic susceptibility measurements. Two compounds are isostructural and are built of infinite cyanometallic layers which are supported by 1,2,3-triazole ligands. The thermal hysteresis loop is very stable at different scan rates from 0.5 to 10 K min−1. The compounds display strong thermochromic effect, changing their colour from pink in the low-spin state to white in the high-spin state. Our findings show that 1,2,3-triazole is suitable for elaboration of spin-crossover Hofmann clathrate analogues, and its use instead of more classical azines can advantageously expand this family of complexes.

Mn cage complexes are rare, and the ones successfully isolated in the solid state are not stable in water and organic solvents. Herein, we present the first report of mononuclear Mn clathrochelates, in which the encapsulated metal exists in the oxidation state +4. The complexes are extremely stable in the crystalline state and in solutions and show rich redox chemistry.

Chiral hybrid organic–inorganic perovskites (HOIPs) attract attention due to their potential for application in optoelectronic, spintronic and photovoltaic devices. However, to this day the range of available chiral HOIPs is still scarce. In this context, we synthesized and thoroughly characterized two pairs of enantiomeric HOIPs incorporating enantiopure α-alanine, the simplest chiral amino acid: (AlaH)PbX3 (Ala = R-alanine or S-alanine, X = Br or I). Single-crystal XRD measurements revealed an unusual 2D anionic motif, which consists of haloplumbate octahedra bonded together in an edge-sharing manner along the c axis and in a corner-sharing manner along the b axis. Four compounds undergo melting/crystallization at unusually low temperatures. New compounds also display photoluminescence in the visible range: 380–640 nm (X = Br) and 480–640 nm (X = I). Electronic spectroscopy reveals an optical response typical for semiconductive materials with optical band gaps of 3.12 eV (X = Br) and 2.48 eV (X = I). These results show that the incorporation of simple and easily accessible α-alanine (and other chiral amino acids) as a cationic part is an efficient way for obtaining highly demanding chiral HOIPs.

У статті наведені результати досліджень протианемічної дії в організмі поросят Феруму у формі клатрохелату та у рідкісній нетрадиційній валентності IV. Дослідження проведено на поросятах-аналогах, яких розподілили у дві групи – контрольну та дослідну. Поросята дослідної групи були відібрані від свиноматок, яким у період вагітності двічі внутрішньом’язово вводили по 10 мл 10 % розчину клатрохелату Феруму(IV). Матеріалом для досліджень були маса тіла та сироваткa крові поросят. Дослід тривав 60 діб. Результати досліджень засвідчили відсутність загибелі та анемії серед поросят дослідної групи, високу інтенсивність їх росту, що вказує на профілактичний ефект клатрохелату Феруму(IV), застосованого поросним свиноматкам. Встановлено, що маса тіла поросят дослідної групи не відрізнялась від маси тіла поросят контрольної групи; була меншою на 5 добу їх життя та перевищувала в усі послідуючі періоди вирощування, аж до відлучення. Нижчий вміст Феруму у сироватці крові поросят дослідної групи, ніж у контролі до 12 добового віку пояснюється особливостями його фармакокінетики – впливом плацентарного бар’єру.

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 novel copper(II) polynuclear complexes with deprotonated 4-iodopyrazole (Ipz) of composition [Cu3(µ3-OH)(µ-Ipz)3Cl2 · 2CH3CN]2 (1) and [Cu3(µ3-OH)(µ-Ipz)3Br2]n (2) have been synthesized and isolated in crystalline state. Crystal and molecular structure of both compounds has been studied by single crystal X-ray diffraction. The structure of complex 1 consists of dimerized 9-azametallacrown-3 fragments Cu3(µ3-OH)(µ-Ipz)3Cl2 · 2CH3CN connected between each other by chlorine anions. The dimeric molecules are united into polymeric chains with the help of hydrogen bonds between the hydrogen atoms of μ3-OH-group and the chlorine anions of the neighboring fragment. Complex 2 is crystallized as polymeric structure, consisting from the trinuclear fragments Cu3(µ3-OH)(µ-Ipz)3Br2 united by bridging bromine atoms. It is established that in the case of complex 1 the Cu(II) coordination number is complemented up to 5 on account of acetonitrile molecule, whereas in complex 2 the pentacoordinated geometric environment of copper(II) ions is formed by two bridging bromine anions belonging to the neighboring structure subunit.

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.

One of the main tasks in the fight against anemia is to carry out preventive measures, to develop and to introduce new preparations containing iron, to provide the pharmaceutical market with anti-anemic agents. That's why to investigate the chronic toxic effect of Iron(IV) hexahydrazide clathrochelate (new iron-containing drug) in mice was the article's aim. The study of chronic toxic effect of Iron(IV) clathrochelate was performed on 45 white mice (19–25 g) separated into 3 groups: control (I) and two experimental (II and III). Animals of II and III groups were daily fed the water solution of Iron(IV) clathrochelate at a rate of 125.8 and 251.6 mg/kg of body weight, respectively. It was monitored the dynamics of body weight of white mice, relative coefficients of the mass of internal organs, hemoglobin content and morphological parameters of blood, biochemical indices of blood serum on the 10th, 20th and 30th day of the experiment. It was established a decrease of body weight by 16–21% and relative weight indices of internal organs (liver, kidney, heart, and spleen) – by 5– 43% in white mice of II and III experimental groups, respectively. Changes in the morphological composition of the blood showed stimulation of leukocytopoiesis. A significant decrease in creatinine (hypocreatinemia) and uric acid (hypouricemia) was observed, which indicates an increase in the filtration capacity of the renal glomeruli. Complex studies of the effect of Iron(IV) clathrochelate solution (at a dose of 125.8 and 251.6 mg/kg of body weight) did not cause any visible signs of intoxication and death of animals at the first time. Iron(IV) clathrochelate solution (at a dose of 125.8 mg/kg of body weight) is demonstrated more safe effect. 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In mol­ecule of the title compound, the benzene ring is inclined to the mean plane of the anthracene ring system (r.m.s. deviation = 0.024 Å) by 75.21 (9)°. In the crystal, a classical carb­oxy­lic acid inversion dimer is formed enclosing an (8) ring motif., In the mol­ecule of the title anthracene derivative, C22H17NO2, the benzene ring is inclined to the mean plane of the anthracene ring system (r.m.s. deviation = 0.024 Å) by 75.21 (9)°. In the crystal, mol­ecules are linked by pairs of O—H⋯O hydrogen bonds, forming classical carb­oxy­lic acid inversion dimers with an R 2 2(8) ring motif. The dimers are linked by C—H⋯π inter­actions, forming a supra­molecular framework.

Dege, Necmi/0000-0003-0660-4721; Fritsky, Igor/0000-0002-1092-8035 WOS: 000501540200025 PubMed: 31871760 The title compound, C14H12BrNO2, was synthesized by the condensation reaction of 2,3-dihydroxybenzaldehyde and 2-bromo-3-methylaniline. It crystallizes in the centrosymmetric triclinic space group P (1) over bar. The configuration about the C=N bond is E. The dihedral angle between the planes of the 5-(2-bromo-3-methylphenyl ring and the catechol ring is 2.80 (17)degrees. In the crystal, O-H center dot center dot center dot O hydrogen-bond interactions consolidate the crystal packing. Faculty of Arts and Sciences, Ondokuz Mayis University, TurkeyOndokuz Mayis University [F.279] The authors acknowledge the Faculty of Arts and Sciences, Ondokuz Mayis University, Turkey, for the use of the Stoe IPDS 2 diffractometer (purchased under grant F.279 of the University Research Fund).

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.

The title structure has a square-planar coordination sphere around the copper(II) ion. In the crystal, mol­ecules are linked by weak C—H⋯O and C—H⋯π hydrogen bonds and very weak π-stacking inter­actions, forming a three-dimensional supra­molecular architecture., In the title com­plex, [Cu(C18H12F6N2O4)]·0.5C6H6O2, the CuII ion has a square-planar coordination geometry, being ligated by two N and two O atoms of the tetra­dentate open-chain Schiff base ligand 6,6′-{(1E,1′E)-[ethane-1,2-diylbis(aza­nylyl­idene)]bis­(methanylyl­idene)}bis­[2-(tri­fluoro­meth­oxy)phenol]. The crystal packing is stabilized by intra­molecular O—H⋯O and inter­molecular C—H⋯F, C—H⋯O and C—H⋯π hydrogen bonds. In addition, weak π–π inter­actions form a three-dimensional structure. Hirshfeld surface analysis and two-dimensional fingerprint plots were performed and created to analyze the inter­molecular inter­actions present in the crystal, indicating that the most important contributions for the crystal packing are from F⋯H/H⋯F (25.7%), H⋯H (23.5%) and C⋯H/H⋯C (12.6%) inter­actions.

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

The title compound, C9H11NO2, was synthesized and characterized in the solid state. The mol­ecular Hirshfeld surfaces were obtained to determine the inter­actions between the mol­ecules and explore the nature of the packing of the mol­ecules in the crystal., The title compound, C9H11NO2, was obtained as unexpected product from the reaction of (4-{2-benz­yloxy-5-[(E)-(3-chloro-4-methyl­phen­yl)diazen­yl]benzyl­idene}-2-phenyl­oxazol-5(4H)-one) with 2-meth­oxy­aniline in the presence of acetic acid as solvent. The amide group is not coplanar with the benzene ring, as shown by the C—N—C—O and C—N—C—C torsion angles of −2.5 (3) and 176.54 (19)°, respectively. Hirshfeld surface analysis and two-dimensional fingerprint plots indicate that the most important contributions to the crystal packing are from H⋯H (53.9%), C⋯H/H⋯C (21.4%), O⋯H/H⋯O (21.4%) and N⋯H/H⋯N (1.7%) inter­actions.

In the title complex, the nickel(II) ion has a square-planar coordination sphere, being ligated by two N and two O atoms of the tetra­dentate Schiff base ligand 6,6′-{(1E,1′E)-[ethane-1,2-diylbis(aza­nylyl­idene]bis­(methanylyl­idene)}bis­[2-(tri­fluoro­meth­oxy)phenol]., In the title complex, (6,6′-{(1E,1′E)-[ethane-1,2-diylbis(aza­nylyl­idene)]bis(methanylyl­idene)}bis­[2-(tri­fluoro­meth­oxy)phenol]-κ4 O,N,N′,O′)nickel(II), [Ni(C18H12F6N2O4)], the nickel(II) ion has a square-planar coordination sphere, being ligated by two N and two O atoms of the Schiff base ligand 6,6′-{(1E,1′E)-[ethane-1,2-diylbis(aza­nylyl­idene)]bis­(methanylyl­idene)}bis­[2-(tri­fluoro­meth­oxy)phenol] (L). Inversion-related mol­ecules are linked by a short Ni⋯Ni inter­action of 3.2945 (6) Å forming a dimer. In the crystal, the dimers stack up the a axis, with a closest Ni⋯Ni separation of ca 3.791 Å. There are no other significant inter­molecular inter­actions present. However, the Hirshfeld surface analysis and the two-dimensional fingerprint plots indicate that the packing is dominated by H⋯F/F⋯H, H⋯H, O⋯H/H⋯O and C⋯H/H⋯C contacts.

The title compound, [Fe(C27H41N10O3)](PF6)2, is an example of an iron(II) spin-crossover compound. In this compound, C⋯F and CH⋯F/O contacts, present between the cations and anions, extend the structure into a three-dimensional supra­molecular network., In the complex cation of the title compound, [Fe(C27H41N10O3)](PF6)2, the tripodal tris­{4-[1-(2-meth­oxy­eth­yl)imidazol-2-yl]-3-aza­but-3-en­yl}amine ligand is coordinated to an FeII ion through the nitro­gen atoms of three imidazole and three imino groups. The Fe atom exhibits a distorted octa­hedral geometry. In the crystal, l and d anti­podes are arranged in layers in the bc plane. Weak C⋯F and C—H⋯F/O contacts exist between the ligands of the complex cation and the PF6 − anions, generating a three-dimensional network. At 120 K, the FeII ion is in a low-spin state, with an average Fe—N bond distance of 1.970 (2) Å. On heating, the FeII ion converts to the high-spin state, as demonstrated by magnetic susceptibility measurements.

Increasing attention has been recently devoted to 89Zr(IV) and 68Ga(III) radionuclides, due to their favorable decay characteristics for positron emission tomography (PET). In the present paper, a deep investigation is presented on Ga(III) and Zr(IV) complexes with a series of tri-(H3L1, H3L3, H3L4 and desferrioxamine E, DFOE) and tetrahydroxamate (H4L2) ligands. Herein, we describe the rational design and synthesis of two cyclic complexing agents (H3L1 and H4L2) bearing three and four hydroxamate chelating groups, respectively. The ligand structures allow us to take advantage of the macrocyclic effect; the H4L2 chelator contains an additional side amino group available for a possible further conjugation with a biomolecule. The thermodynamic stability of Ga(III) and Zr(IV) complexes in solution has been measured using a combination of potentiometric and pH-dependent UV–vis titrations, on the basis of metal–metal competition. The Zr(IV)-H4L2 complex is characterized by one of the highest formation constants reported to date for a tetrahydroxamate zirconium chelate (log β = 45.9, pZr = 37.0), although the complex-stability increase derived from the introduction of the fourth hydroxamate binding unit is lower than that predicted by theoretical calculations. Solution studies on Ga(III) complexes revealed that H3L1 and H4L2 are stronger chelators in comparison to DFOB. The complex stability obtained with the new ligands is also compared with that previously reported for other hydroxamate ligands. In addition to increasing the library of the thermodynamic stability data of Ga(III) and Zr(IV) complexes, the present work allows new insights into Ga(III) and Zr(IV) coordination chemistry and thermodynamics and broadens the selection of available chelators for 68Ga(III) and 89Zr(IV)., Solution equilibria studies on Ga(III) and Zr(IV) complexes with a series of tri- and tetrahydroxamate ligands are presented. For this purpose, the rational design and synthesis of two cyclic complexing agents bearing three and four hydroxamate chelating groups was performed. The thermodynamic and speciation studies allow a discussion of the structure−complex stability dependence. The Zr(IV)-tetrahydroxamate complex is characterized by one of the highest formation constants reported to date for a hydroxamate zirconium chelator.

International audience; Nucleation and growth phenomena associated with the thermally-induced spin transition was studied using optical microscopy in single crystals of a cyanoheterometallic coordination polymer [Fe(1,6-naphthyridine)2(Ag(CN)2)2]. Despite the fact that the spin-crossover phenomenon occurs near room temperature (ca. 290–300 K), the experimental results show the existence of significant kinetic effects on the hysteretic behaviour of the spin transition in this compound. Ultra-slow switching rates and phase-boundary propagation velocities were observed (down to 3 nm s−1), several orders of magnitude lower than customary. Our observations indicate that these peculiar spin-crossover properties (slow switching kinetics, scan-rate-dependent transition temperatures) are presumably related to the presence of numerous microstructural defects in the crystals, which is an intrinsic characteristic of this compound.

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.

Two new 2D spin-crossover (SCO) analogues of Hofmann clathrates of composition [Fe(phth)2MII(CN)4] (where phth = phthalazine; MII= Pd, Pt) have been synthesized and their structures and switchable behaviour have been characterized. Single-crystal X-ray analysis reveals that the Pt and Pd derivatives contain FeIIcentres equatorially surrounded by four equivalent μ4-[MII(CN)4]2−groups. Two crystallographically equivalent phthalazine (phth) ligands occupy the axial positions of each FeIIsite, completing its octahedral coordination environment. The stabilization of these structures is realizedviasupramolecular C–H⋯M interactions and π–π stacking. Temperature-dependent magnetic susceptibility measurements showed that Pt (T1/2↓ = 211 K andT1/2↑ = 218 K) and Pd (T1/2↓ = 202 K andT1/2↑ = 207 K) derivatives display cooperative spin crossover with narrow thermal hysteresis loops. In addition, spin crossover in these complexes was characterized by optical measurements, differential scanning calorimetry, and IR and Raman spectroscopy. This research shows that the use of phthalazine leads to the production of new SCO systems with attractive transition characteristics and opens up new perspectives for the design of switchable complexes based on fused bicyclic azine ligands.

1,2,4-triazoles attract attention as actively used medications and ligands for constructing coordination architectures. In this paper we describe four optically active 4-substituted 1,2,4-triazoles that have been prepared by Bayer's synthesis from the corresponding aliphatic chiral amines. This approach tends to be universal towards different triazoles and permits to conserve a homochirality of substrates. Novel asymmetric molecules have been characterized by spectroscopic techniques and their structures have been retrieved from the single crystal X-ray analysis. Chiro-optical studies of these heterocycles have been made by means of circular dichroism spectroscopy.

Four different crystal structures for quinolinehydroxamic acid (QuinHA) and picolinehydroxamic acid (PicHA) MCs with Cu(II) and Ni(II), and solution studies on the formation of Cu(II), Ni(II), and ...

Fast visible light-driven water oxidation catalyzed by the FeIV cage complex relies on its efficient hole scavenging activity in the system utilizing [Ru(bpy)3]2+ as a photosensitizer., An efficient water oxidation system is a prerequisite for developing solar energy conversion devices. Using advanced time-resolved spectroscopy, we study the initial catalytic relevant electron transfer events in the light-driven water oxidation system utilizing [Ru(bpy)3]2+ (bpy = 2,2′-bipyridine) as a light harvester, persulfate as a sacrificial electron acceptor, and a high-valent iron clathrochelate complex as a catalyst. Upon irradiation by visible light, the excited state of the ruthenium dye is quenched by persulfate to afford a [Ru(bpy)3]3+/SO4˙– pair, showing a cage escape yield up to 75%. This is followed by the subsequent fast hole transfer from [Ru(bpy)3]3+ to the FeIV catalyst to give the long-lived FeV intermediate in aqueous solution. In the presence of excess photosensitizer, this process exhibits pseudo-first order kinetics with respect to the catalyst with a rate constant of 3.2(1) × 1010 s–1. Consequently, efficient hole scavenging activity of the high-valent iron complex is proposed to explain its high catalytic performance for water oxidation.

A water-stable FeIV clathrochelate complex catalyses fast and homogeneous photochemical oxidation of water to dioxygen with a turnover frequency of 2.27 s1 and a maximum turnover number of 365. An FeV intermediate generated under catalytic conditions is trapped and characterised using EPR and Mo¨ssbauer spectroscopy.

In the title compound, the ZnII ion is coordinated by two N atoms of the N,N,N′,N′-tetra­methyl­ethylenedi­amine ligand and two S atoms from two 2-meth­oxy­ethyl xanthate ligands. Two C—H⋯O and two C—H⋯S intra­molecular inter­actions occur. In the crystal, mol­ecules are linked by C—H⋯O and C—H⋯S hydrogen bonds, forming a three-dimensional supra­molecular architecture., In the title compound, bis­(2-meth­oxy­ethyl xanthato-κS)(N,N,N′,N′-tetra­methyl­ethylenedi­amine-κ2 N,N′)zinc(II) acetone hemisolvate, [Zn(C4H7O2S2)2(C6H16N2)]·0.5C3H6O, the ZnII ion is coordinated by two N atoms of the N,N,N′,N′-tetra­methyl­ethylenedi­amine ligand and two S atoms from two 2-meth­oxy­ethyl xanthate ligands. The amine ligand is disordered over two orientations and was modelled with refined occupancies of 0.538 (6) and 0.462 (6). The mol­ecular structure features two C—H⋯O and two C—H⋯S intra­molecular inter­actions. In the crystal, mol­ecules are linked by weak C—H⋯O and C—H⋯S hydrogen bonds, forming a three-dimensional supra­molecular architecture. The mol­ecular structure was optimized using density functional theory (DFT) at the B3LYP/6–311 G(d,p) level. The smallest HOMO–LUMO energy gap (3.19 eV) indicates the suitability of this crystal for optoelectronic applications. The mol­ecular electrostatic potential (MEP) further identifies the positive, negative and neutral electrostatic potential regions of the mol­ecules. Half a mol­ecule of disordered acetone was removed with the solvent-mask procedure in OLEX2 [Dolomanov et al. (2009 ▸). J. Appl. Cryst. 42, 339–341] and this contribition is included in the formula.

Dege, Necmi/0000-0003-0660-4721; Kansiz, Sevgi/0000-0002-8433-7975; Fritsky, Igor/0000-0002-1092-8035 WOS: 000467419100016 PubMed: 31161063 In the title compounds, 9-bromo-2,5-dimethyl-11,12-dihydro-5H-5,11-methanobenzo[g][1,2,4]triazolo[1,5-c][1,3,5]oxadiazocine,C13H13BrN4O(I),and 7-methoxy-5-methyl-2-(pyridin-4-yl)-11,12-dihydro-5H-5,11-methanobenzo[g][1,2,4] triazolo[1,5-c][1,3,5]oxadiazocine, C18H17N5O2 (II), the triazole ring is inclined to the benzene ring by 85.15 (9) and 76.98 (5)degrees in compounds I and II, respectively. In II, the pyridine ring is almost coplanar with the triazole ring, having a dihedral angle of 4.19 (8)degrees. In the crystal of I, pairs of N-H center dot center dot center dot N hydrogen bonds link the molecules to form inversion dimers with an R-2(2)(8) ring motif. The dimers are linked by C-H center dot center dot center dot pi and C-Br center dot center dot center dot pi interactions forming layers parallel to the bc plane. In the crystal of II, molecules are linked by N-H center dot center dot center dot N and C-H center dot center dot center dot O hydrogen bonds forming chains propagating along the b-axis direction. The intermolecular interactions were investigated using Hirshfeld surface analysis and two-dimensional fingerprint plots, and the molecular electrostatic potential surface was also analysed. The Hirshfeld surface analysis of I suggests that the most significant contributions to the crystal packing are H center dot center dot center dot H (42.4%) and O center dot center dot center dot H/H center dot center dot center dot O (17.9%) contacts. For compound II, the H center dot center dot center dot H (48.5%), C center dot center dot center dot H/H center dot center dot center dot C (19.6%) and N center dot center dot center dot H/H center dot center dot center dot N (16.9%) interactions are the most important contributions. Faculty of Arts and Sciences, Ondokuz Mayis University, TurkeyOndokuz Mayis University [F. 279]; Council of Higher Education of Turkey, Mevlana Exchange Program [MEV-2016-027] The authors acknowledge the Faculty of Arts and Sciences, Ondokuz Mayis University, Turkey, for the use of the Stoe IPDS 2 diffractometer (purchased under grant F. 279 of the University Research Fund) and the Council of Higher Education of Turkey, Mevlana Exchange Program (MEV-2016-027).

Spin-crossover (SCO) compounds represent a huge class of switchable coordination complexes that can change their electronic configurations under the influence of different external stimuli. SCO provokes a spectacular switch of physical and chemical properties of complexes making them perspective as active elements of sensors, actuators, electronic and optical components, and other devices. In this article we offer a brief overview of cyanometallic frameworks exhibiting SCO properties. Building blocks that tend to provide new materials with desired spin-crossover characteristics are discussed. Special attention is paid on how the host–guest interactions in SCO frameworks affect their transition properties making them suitable for sensing applications. The effect of size reduction to nanometre scale on switchable properties of cyanometallates is described. Additionally, some outstanding features of SCO cyanometallates such as multistep transitions, mechanical actuation and switchable luminescence are highlighted.

The new cis-dioxomolybdenum (VI) complexes [MoO2(L2)(H2O)] (2) and [MoO2(L3)(H2O)] (3) containing the tridentate hydrazone-based ligands (H2L2 = N'-(3,5-di-tert-butyl-2-hydroxybenzylidene)-4-methylbenzohydrazide and H2L3 = N'-(2-hydroxybenzylidene)-2-(hydroxyimino)propanehydrazide) have been synthesized and characterized via IR, 1H and 13C NMR spectroscopy, mass spectrometry, and single crystal X-ray diffraction analysis. The catalytic activities of complexes 2 and 3, and the analogous known complex [MoO2(L1)(H2O)] (1) (H2L1 = N'-(2-hydroxybenzylidene)-4-methylbenzohydrazide) have been evaluated for various oxidation reactions, viz. oxygen atom transfer from dimethyl sulfoxide to triphenylphosphine, sulfoxidation of methyl-p-tolylsulfide or epoxidation of different alkenes using tert-butyl hydroperoxide as terminal oxidant. The catalytic activities were found to be comparable for all three complexes, but complexes 1 and 3 showed better catalytic performances than complex 2, which contains a more sterically demanding ligand than the other two complexes.

Metallacrowns (MCs) obtained by changing the [C C O] fragments of organic crown ethers on [M N O] or [M N N] units have been developed extensively in the past few decades. A vast array of unique MCs with diverse structural patterns and accessible topologies can provide non-trivial functional properties. This review describes the applications of MCs in catalysis, luminescence, and magnetism. Examples of porous lattices based on MCs as secondary building units are also discussed, including their thermal stability, sorption properties, and applications in the separation or exchange of cations or anions.

Ion association in solutions of lithium salts in mixtures of alkyl carbonates carries significant impact on the performance of lithium ion batteries. Focusing on lithium bis(oxalato)borate, LiBOB, in binary solvents based on ethylene carbonate, EC, we show that neither continuum nor discrete solvation approaches are capable of predicting physically meaningful results. So-called mixed or the discrete–continuum solvation approach, based on explicit consideration of an ion solvatocomplex combined with estimation of the medium polarization effect, is required in order to characterize the ion association at the quantitative level. The calculated changes of the Gibbs free energy are overestimated by nearly an order of magnitude by the purely continuum and purely discrete approaches, with the values having the opposite signs. The physically balanced discrete–continuum description predicts weak ion association. The numerical data obtained with density functional theory are validated using coupled-cluster calculat...

Discovery of spin-crossover (SCO) behavior in the family of Fe(II)-based Hofmann clathrates has led to a "new rush" in the field of bistable molecular materials. To date this class of SCO complexes is represented by several dozens of individual compounds, and areas of their potential application steadily increase. Starting from Fe(2+), square planar tetracyanometalates M(II)(CN)4(2-) (M(II) = Ni, Pd, Pt) and 2-substituted pyrazines Xpz (X = Cl, Me, I) as coligands we obtained a series of nine new Hofmann clathrate-like coordination frameworks. X-ray diffraction reveals that in these complexes Fe(II) ion has a pseudo-octahedral coordination environment supported by four μ4-tetracyanometallates forming its equatorial coordination environment. Depending on the nature of X and M, axial positions are occupied by two 2X-pyrazines (X = Cl and M(II) = Ni (1), Pd (2), Pt (3); X = Me and M(II) = Ni (4), Pd (5)) or one 2X-pyrazine and one water molecule (X = I and M(II) = Ni (7), Pd (8), Pt (9)), or, alternatively, two distinct Fe(II) positions with either two pyrazines or two water molecules (X = Me and M(II) = Pt (6)) are observed. Temperature behavior of magnetic susceptibility indicates that all compounds bearing FeN6 units (1-6) display cooperative spin transition, while Fe(II) ions in N5O or N4O2 surrounding are high spin (HS). Structural changes in the nearest Fe(II) environment upon low-spin (LS) to HS transition, which include ca. 10% Fe-N distance increase, lead to the cell expansion. Mössbauer spectroscopy is used to characterize the spin state of all HS, LS, and intermediate phases of 1-9 (see abstract figure). Effects of a pyrazine substituent and M(II) nature on the hyperfine parameters in both spin states are established.

A series of spin transition neutral compounds [FeL(NCS)2] has been synthesized and characterized by means of magnetic susceptibility studies, X-ray diffraction, IR and Mossbauer spectroscopic, and calorimetric measurements (L = N,N-bis((3-alkoxypyridin-2-yl)methylene)-propane-1,3-diamine, number of carbon atoms in chains (n) = 4, 12, 14, 16, 18, 20). The shortest chain compound is crystalline and displays a gradual spin transition above ambient temperature. Growing the aliphatic substituent up to n = 12 and 14 leads to loss of crystalline order and deterioration of magnetic properties. At the critical chain length n = 16 and above, the compounds undergo a phase transition reflected by a spin transition and resulting in the appearance of susceptibility hysteresis initially not observed for the short chain congener. For the compound with n = 20, hysteresis becomes the most pronounced. The study shows the importance of chain length optimization for effective feedback between phase and spin transitions.

The diversity of spin crossover (SCO) complexes that, on the one hand, display variable temperature, abruptness and hysteresis of the spin transition, and on the other hand, are spin-sensitive to the various guest molecules, makes these materials unique for the detection of different organic and inorganic compounds. We have developed a homochiral SCO coordination polymer with a spin transition sensitive to the inclusion of the guest 2-butanol, and these solvates with (R)- and (S)-alcohols demonstrate different SCO behaviours depending on the chirality of the organic analyte. A stereoselective response to the guest inclusion is detected as a shift in the temperature of the transition both from dia- to para- and from para- to diamagnetic states in heating and cooling modes respectively. Furthermore, the Mössbauer spectroscopy directly visualizes how the metallic centres in a chiral coordination framework differently sense the interaction with guests of different chiralities.

Three complexes [Ca(ClO4)(H2O)Cu5(o-picHA-2H)5(H2O)]ClO4 (1), [Pr(NO3)2(py)Cu5(o-picHA-2H)5(py)5]ClO4 (2), and [Nd(NO3)(H2O)(py)Cu5(o-picHA-2H)5(py)5](ClO4)2·5py (3) (o-picHA = 2-picolinehydroxamic acid) were synthesized in order to retrace structural trends caused by the change of the ionic radius of the central metal ion as well as to assess the effect of the axial ligands on the arrangement of metallacrowns. The complexes were characterized by elemental analysis, ESI-mass spectrometry, IR spectroscopy, and single-crystal X-ray analysis. The heterometallic complexes have 15-MC-5 molecular topology with CaII or LnIII ion in the center of the metallamacrocyclic cavity. The Ca–O and Ln–O bond lengths follow the trend of changes of the corresponding metal ionic radii. While the CaII complex cation (without axial ligands) in 1 is almost flat, the LnIII containing cations in 2 and 3 have a “partially opened umbrella“ environment.

Synthesis, structural, magnetic, Mossbauer and thermal studies of isothiocyanate iron (II) complexes with substituted pyrazines (iodo-, bromo- and amino-derivatives) are discussed here. Complexes with iodo- and bromo-derivatives were found to have the composition [Fe(Ipz)2(SCN)2(H2O)2]·2Ipz (1) and [Fe(Brpz)2(SCN)2(H2O)2]·2Brpz (2), whereas in the case of amino-functionalized pyrazine the formation of [Fe(NH2pz)4(SCN)2] (3) was observed. 3D organization of the molecular complexes is stabilized within different hydrogen, halogen and lone pair–π interactions. Spin state of iron (II) ions in 1–3 was determined as high spin by Mossbauer and magnetic measurements. DFT calculations for the obtained iron (II) complexes were carried out to analyze the electronic structure and to support experimentally measured Mossbauer parameters with theoretical predictions.

Spin crossover iron(II) 1,2,4-triazole-based coordination compounds in the form of nanoparticles were prepared using a reverse microemulsion technique. Ligand substitution approach was applied to decrease the spin crossover temperature towards room temperature in the well-known [Fe(Htrz)2(trz)]BF4 complex. The compositions of the particles were determined by elemental analysis and thermogravimetry. The morphology was monitored by transition electron microscopy (TEM). The effect associated with the ligand substitution was investigated by optical and magnetic measurements. Transition temperature has been reduced by 33 K comparing the unsubstituted sample to that with 5 % substitution.

Five new mononuclear complexes formed by the polynucleating ligand 2-[1-(3,5-dimethyl)pyrazolyl]-2-hydroxyimino-N′-[1-(2-pyridyl)ethylidene]acetohydrazide (HL): [Ni(L)(HL)]ClO4·2CH3OH (1), [Ni(L)2]·CH3OH (2), [Zn(L)(HL)]ClO4·2CH3OH (3), [Zn(L)2]·CH3OH (4) and [Cu(L)2]·CH3OH (5) were synthesized and characterized by elemental analysis, mass-spectrometry, IR-spectroscopy and X-ray analysis. The complexes reveal distorted octahedral N4O2 coordination arrangement formed by both protonated and deprotonated (1, 3) or two deprotonated ligand molecules (2, 4, 5). The presence of non-coordinated oxime and pyrazole groups resulted in the formation of extensive systems of hydrogen bonds in the crystal packing of 1–5. Potentiometric titrations, ESI-MS and spectrophotometric studies of complex formation in MeOH/H2O solutions indicated the presence of mono- and polynuclear complexes with Cu(II), Ni(II) and Zn(II) ions. The solution studies carried out for an excess of Cu(II) over HL ligand (2:1 and 3:2 M ratio) indicated also the formation of polynuclear Cu3L2Hx species, with an involvement of additional nitrogen donors in copper coordination. In binuclear complex [Cu2(L)2(DMF)2](ClO4)2·DMF(6) obtained in solid state, the Cu(II) coordination, analogous to the one in 1–5, was supported by pyrazole N atom. peerReviewed

A series of copper(II) complexes with 3- and 4-picolinehydroxamic acids has been synthesized and characterized by a variety of spectroscopic methods, X-ray structure analysis and magnetic susceptibility measurements. The ligands show the tendency to form 1D- and 2D-polymeric structures with copper(II) ions due to the chelating-and-bridging binding mode involving the (O,O′)-hydroxamate chelate formation combined with N-coordination of the pyridine moiety. In some cases the (O, μ2-O′) chelating-and-bridging modes are realized, in which either amide or hydroxamic oxygen atoms play a μ2-bridging role. Molecular and crystal structures of two discrete complexes: mononuclear [Cu(3-HPicHA)2(ClO4)2] (1) and binuclear [{Cu(4-HPicHA)(bpy)(ClO4)}2](ClO4)2 (4a), and five coordination polymers catena-[Cu(3-PicHA)(phen)]n(ClO4)n (7), catena-[Cu(4-PicHA)(bpy)]n(OH)n·3.25nH2O (8), catena-[Cu(4-PicHA)(DMSO)2]2n(ClO4)2n (9), [Cu(3-PicHA)(DMSO)(ClO4)]nm·nmDMSO (10), and [{Cu(4-PicHA)(phen)}2]n(ClO4)2n (11) were determined by single crystal X-ray analysis. In structures 1 and 4a the hydroxamate ligands exist in a zwitterionic form with the O-deprotonated hydroxamate groups and protonated pyridine rings. The following types of coordination polymers have been structurally characterized: (i) single-stranded zigzag-shaped 1D polymers (7 and 8); (ii) double-stranded 1D polymer comprising binuclear subunits formed on account of μ2(O)-carbonyl oxygen bridging coordination to the axial position of the copper(II) ion (9); (iii) 2D netted coordination polymers of two different types comprising μ2(O)-bridged binuclear subunits (10 and 11). Magnetic susceptibility measurements (2–300 K) of powdered samples revealed the presence of moderate antiferromagnetic interaction in the binuclear complex 4a (2J = −7.164(6) cm−1), while the coordination polymers exhibit weak antiferromagnetic interaction with a cryomagnetic behaviour obeying the Curie–Weiss law.

Solution and solid state studies on Cu(II) complexes of pyridine-2-hydroxamic acid (HPicHA) and pyridine-2,6-dihydroxamic acid (H2PyDHA) were carried out. The use of methanol/water solvent allowed us to investigate the Cu(II)-HPicHA equilibria under homogeneous conditions between pH 1 and 11. In agreement with ESI-MS indication, the potentiometric data fitted very well with the model usually reported for copper(II) complexes of α-aminohydroxamate complexes ([CuL](+), [Cu5(LH-1)4](2+), [CuL2], [CuL2H-1](-)), however with much higher stability of the 12-MC-4 species. A series of copper(II) complexes has been isolated in the solid state and characterized by a variety of spectroscopic methods, X-ray structure analysis, and magnetic susceptibility measurements. The ligands show the tendency to form bi- and trinuclear species with copper(II) ions due to the {(N,N'); (O,O')} bis-(bidentate) chelating-and-bridging mode involving (O,O')-hydroxamate chelate formation combined with (N,N') chelating with participation of the pyridine and hydroxamic nitrogen atoms, so that the hydroxamate groups play a μ2-(N,O)-bridging role. Molecular and crystal structures of three synthesized complexes [Cu3(PicHA-H)2(dipy)2](ClO4)2·4/3DMSO·2/3H2O (1), [Cu2(PyDHA)(dipy)2(ClO4)2]·DMF·H2O (4), and [Cu3(PyDHA-2H)(tmeda)3](ClO4)2 (5) (dipy, 2,2'-dipyridyl; tmeda, N,N,N',N'-tetramethyl-1,2-diaminoethane) have been determined by single crystal X-ray analysis. In 1, two trans-situated doubly deprotonated hydroxamic ligands play a {(O,O')(N,N')}-(bis)bidentate-bridging function forming bridges between the medial, Cu(2) (CuN4), and the terminal, Cu(1) and Cu(3) (CuN2O2), copper(II) ions; the chelating dipy ligands are coordinated to the latter. In 4, the ligand is coordinated in a classical (O,O')-hydroxamate chelating mode with the help of two separate hydroxamic groups while the central tridentate donor compartment remains vacant. In 5, the hydroxamate ligand is coordinated by the {(O,O');(N,N',N″);(O″,O"')}-tridentate-(bis)bidentate mode, bridging three copper(II) ions, while the chelating tmeda ligands are coordinated to all three copper(II) ions. Magnetic susceptibility measurements (1.7-300 K) of powdered samples of the trinuclear complexes 1 and 5 revealed strong antiferromagnetic coupling between the copper(II) ions mediated by the hydroxamate bridges.

The synthesis and characterization of two new CuII complexes with pyrazole ligands formulated as [Cu3(μ-Pz)3(μ3-OH)(Pz)2Cl2][Cu3(μ-Pz)3(μ3-OH)(Pz)2Cl2(DMF)]·2DMF (1) and [Cu3(μ-DMPz)3(DMF)4(OAc)(μ3-OH)(H2O)]+[Cu3(μ-DMPz)3(DMF)(NCS)3(μ3-OH)]– (2) (where Pz = 1H-pyrazole and DMPz = 3, 5-dimethyl-1H-pyrazole) are reported. The compounds were prepared by the reaction of zero valent copper metal and Pz or DMPz in the dimethylformamide solution in the presence of the different additional components (chloride or thiocyanate ligands). The crystal structures of both compounds were determined by single-crystal X-ray diffraction analysis. Both compounds 1 and 2 are hexanuclear clusters comprising from neutral (1) or charged (2) trinuclear triangular fragments Cu3(μ3-OH)(μ-Pz)3 of inverse azametallacrowns aza9-MCCuII-3 topology. Nevertheless, they exhibit relevant differences in their molecular structures. The magnetic measurement shows the isotropic antiferromagnetic interaction in 2 with J1 = –140 cm–1 for the cationic and J2 = –109 cm–1 (–2JSi·Sj model) for the anionic part of the molecule above 100 K and significant influence of antisymmetric exchange at lower temperatures.

This paper describes the synthesis of the Zn(II) complex with H2L = 2-hydroxyiminopropanoic acid. The final structure incorporated two linear dimeric anions with two Zn2+ atoms, which are linked by a carbonate anion into a tetranuclear unit. In each dinuclear unit, the two Zn(II) ions are coordinated by three molecules of the doubly deprotonated ligand in two different coordination modes. This result is confirmed both by X-ray crystallography and by ESI-MS investigations of the crystals dissolved in water. Equilibrium studies of the zinc(II) complexes formed by H2L in aqueous solution based on independent pH-metric titrations and zinc ion-selective electrode (ISE) titrations indicate that the mononuclear ZnLH complex appears to be the dominating equilibrium species at pH 4–6 at various ligand-to-metal ratios. Under excess of the ligand at pH 6–8, the ZnL2H species, further stabilized by a hydrogen bond between the deprotonated and protonated oxime groups, becomes the predominating species besides the ZnL complex.

Self-assembling iron(II), 2-fluoropyrazine (Fpz), and [MII(CN)4] 2− (MII = Ni, Pd, Pt) or [AuI (CN)2] − building blocks have afforded a new series of two- (2D) and threedimensional (3D) Hofmann-like spin crossover (SCO) coordination polymers with strong cooperative magnetic, calorimetric, and optical properties. The iron(II) ions, lying on inversion centers, define elongated octahedrons equatorially surrounded by four equivalent centrosymmetric μ4-[MII(CN)4]2− groups. The axial positions are occupied by two terminal Fpz ligands affording significantly corrugated 2D layers {Fe(Fpz)2([MII(CN)4]}. The Pt and Pd derivatives undergo thermal- and light-induced SCO characterized by T1/2 temperatures centered at 155.5 and 116 K and hysteresis loops 22 K wide, while the Ni derivative is high spin at all temperatures, even at pressures of 0.7 GPa. The great stability of the high-spin state in the Ni derivative has tentatively been ascribed to the tight packing of the layers, which contrasts with that of Pt and Pd derivatives in the high- and low-spin states. The synthesis and structure of the 3D frameworks formulated {Fe(Fpz)[Pt(CN)4]}·1/2H2O and {Fe(Fpz)[Au(CN)2]2}, where Fpz acts as bridging ligand, which is also discussed. The former is high spin at all temperatures, while the latter displays very strong cooperative SCO centered at 243 K accompanied by a hysteresis loop 42.5 K wide. The crystal structures and SCO properties are compared with those of related complexes derived from pyrazine, 3-fluoropyridine, and pyridine., The research reported here was supported by the Spanish Ministerio de Economia y Competitividad (MINECO) and FEDER funds (CTQ2013-46275-P and Unidad de Excelencia Maria de Maeztu MDM- 2015-0538) and Generalitat Valenciana (PROMETEO/2016/147). F.J.V.M. thanks the MINECO for a predoctoral FPI fellowship.

Spin transitions are a spectacular example of molecular switching that can provoke extreme electronic and structural reorganizations in coordination compounds. A new 3D cyanoheterometallic framework, [Fe(pz)(Au(CN)2)2], has been synthesized in which a highly cooperative spin crossover has been observed at 367 and 349 K in heating and cooling modes, respectively. Mössbauer spectroscopy revealed a complete transition between the diamagnetic and paramagnetic states of the iron centres. The low-spin-to-high-spin transition induced a drastic structural distortion involving a large one-directional expansion (ca. 10.6%) and contraction (ca. 9.6%) of the lattice. Negative thermal expansion along the c axis was detected below and above the transition temperature.

5-Acetyl-substituted pyrazole-3-carboxylic acid (H2L) forms [2 x 2] grid-like tetranuclear Cu(II) complexes with four five-coordinated copper(II) ions bridged by pyrazolate groups. Despite a significant dissociation of [Cu4L4(H2O)(4)]center dot 4H(2)O (1) in aqueous solution(1), it was possible to substitute the coordinated water molecules by pyridine ligands or azide anions. The resulting tetranuclear complexes [Cu4L4Py4]center dot 2H(2)O (2) and Na-4[Cu4L4(N-3)(4)]center dot 7MeOH (3) were isolated and studied by X-ray diffraction analysis. In 2 and 3 the azide anions or pyridine molecules complete the distorted square-pyramidal coordination of each copper(II) center. Magnetic susceptibilities of the obtained compounds have been measured by SQUID techniques. Simulation of the data using a Heisenberg spin Hamiltonian approach showed that the bridges between the metals mediate weak intramolecular antiferromagnetic coupling (J in the range -13.3 to -17.1 cm (1)) and lead to a singlet ground state in all cases. (C) 2012 Elsevier B.V. All rights reserved.

International audience; New methods are proposed for the synthesis of spin‐crossover nano‐ and micro‐objects. Several nano‐objects that are based upon the spin‐crossover complex [Fe(hptrz)3](OTs)2 (hptrz=4‐heptyl‐1,2,4‐triazole, Ts=para‐toluenesulfonyl) were prepared in homogeneous media. The use of various reagents (Triton X‐100, PVP, TOPO, and PEGs of different molecular weights) as stabilizing agents yielded materials of different size (6 nm–2 μm) and morphology (nanorods, nanoplates, small spherical particles, and nano‐ and micro‐crystals). In particular, when Triton X‐100 was used, a variation in the morphology from nanorods to nanoplates was observed by changing the nature of the solvent. Interestingly, the preparation of the nanorods and nanoplates was always accompanied by the formation of small spherical particles. Alternatively, when PEG was used, 200–400 nm crystals of the complex were obtained. In addition, a very promising polymer‐free synthetic method is discussed that was based on the preparation of relatively stable FeII–triazole oligomers in CHCl3. Their specific treatment led to micro‐crystals, small nanoparticles, or gels. The size and morphology of all of these objects were characterized by TEM and by dynamic light scattering (DLS) where possible. Their spin‐crossover behavior was studied by optical and magnetic measurements. The spin‐transition features for large particles (>100 nm) were very similar to that of the bulk material, that is, close to room temperature with a hysteresis width of up to 8 K. The effects of the matrix and/or size‐reduction led to modification of the transition temperature and an abruptness of the spin transition for oligomeric solutions and small nanoparticles of 6 nm in size.

Degradation of a strained, thermodynamically destabilized pentanuclear copper(II) 12-metallacrown-4 complex based on a picoline hydroxamic acid resulted in the formation of the tetranuclear compounds which are the first examples of solely hydroxamate-based Cu(II) metallacrown complexes with a collapse of the metallamacrocyclic cavity.

Two [2 × 2] grid-like complexes, [Cu 4 ( L 1 ) 4 ]·2МеОН·2Н 2 О·dmf ( 1 ) and [Cu 4 ( L 2 ) 4 ]·2NaClO 4 ·2МеОН ( 2 ) based on new substituted pyrazole ligands 5-(1-((2-aminoethyl)imino)ethyl)-4-methyl-1 H -pyrazole-3-carboxylic (H 2 L 1 ) acid and 5-(1-((3-aminopropyl)imino)ethyl)-4-methyl-1 H -pyrazole-3-carboxylic acid (H 2 L 2 ) have been synthesized and characterized spectroscopically and crystallographically. It was found that the ligand H 2 L 2 condenses with 3-acetyl-4-methyl-pyrazole-5 carbonic acid (H 2 L ) to produce a new dinuclear Cu(II) complex upon reaction with Cu(ClO 4 ) 2 ·6H 2 O and CuAc 2 ·2H 2 O. In the grid complexes the four Cu(II) atoms are in square-pyramidal environment formed by two pyrazole, imine and amine N atoms, and the carboxylate O atom and occupy the corners of a [2 × 2] grid with the Cu⋯Cu separations, varying from 3.998(1) to 4.2049(9) and 4.794(1) to 5.091(1) A for the adjacent and diagonal atoms, respectively. In the dinuclear complex 3 the metal ions are found in square planar environment with their coordination planes lying roughly within the plane of the pyrazolate heterocycle. The separation between Cu(II) centers is 3.921(1) A. Magnetic susceptibility measurements of 3 revealed the presence of strong antiferromagnetic interaction, with a J value of −207.5 cm −1 . This is larger than the J values found for the 1 and 2 grid complexes, which are −20.2 and −18.3 cm −1 , respectively.

Two new pyrazolate-based ligands, N'-[1-(3-acetyl-4-methyl-1H-pyrazol-5-yl)ethylidene]-2-(hydroxyimino)propanehydrazide (L1) and 5-[(E)-1-(2-{(E)-2-(hydroxyimino}propanoyl}hydrazono)ethyl]-4-methyl-1H-pyrazole-3-carboxylic acid (L2), were synthesized and studied for zinc(II) complexation. A set of pH-dependent UV/Vis measurements has been performed to determine the complex formation properties of L2. According to the calculations, in solution, L2 forms variously protonated mononuclear (ZnII/L2 = 1:1) and dinuclear (ZnII/L2 = 2:1) complexes. The reaction of the deprotonated ligands with hydrated ZnII salts and slow diffusion of ammonia into the reaction mixtures gave mononuclear [Zn(L1-2H)(NH3)2]center dot DMF (1) and trinuclear mu-pyrazolato-bridged [Zn3(L2-3H)2(NH3)5]center dot 4H2O (3). In both complexes, the zinc ions are in the same distorted trigonal-bipyramidal environment, coordinated to two nitrogen atoms of the ammonia and one oxygen and two nitrogen atoms of the pyrazolate and hydrazide groups. The molecular structures of all of the ligands and complexes have been elucidated by X-ray crystallography. (Less)