Life and How to Live It

The reaction of Mn^III salen-type complexes with di- and tetraanionic α-Keggin-type polyoxometalates (POMs) was performed, and three types of Coulombic aggregations containing Mn^III out-of-plane dimeric units (abbreviated as [Mn₂]²⁺) that are potentially single-molecule magnets (SMMs) with an <i>S</i>_T = 4 ground state were synthesized: [Mn₂(5-MeOsaltmen)₂(acetone)₂]­[SW₁₂O₄₀] (<b>1</b>), [Mn₂(salen)₂(H₂O)₂]₂[SiW₁₂O₄₀] (<b>2</b>), and [Mn­(5-Brsaltmen)­(H₂O)­(acetone)]₂[{Mn₂(5-Brsaltmen)₂}­(SiW₁₂O₄₀)] (<b>3</b>), where 5-Rsaltmen^2– = <i>N</i>,<i>N</i>′-(1,1,2,2-tetramethylethylene)­bis­(5-R-salicylideneiminate) with R = MeO (methoxy), Br (bromo) and salen^2– = <i>N</i>,<i>N</i>′-ethylenebis­(salicylideneiminate). Compound <b>1</b> with a dianionic POM, [SW₁₂O₄₀]^2–, is composed of a 1:1 aggregating set of [Mn₂]²⁺/POM, and <b>2</b>, with a tetraanionic POM, [SiW₁₂O₄₀]^4–, is a 2:1 set. Compound <b>3</b> with [SiW₁₂O₄₀]^4– forms a unique 1D coordinating chain with a [−{Mn₂}–POM−]^2– repeating unit, for which a hydrogen-bonded dimeric unit ([Mn­(5-Brsaltmen)­(H₂O)­(acetone)]₂²⁺) is present as a countercation. Independent of the formula ratio of [Mn₂]²⁺/POM, Mn^III dimers and POM units in <b>1</b>–<b>3</b> form respective segregated columns along a direction of the unit cell, which make an alternate packing to separate evenly identical species in a crystal. The nearest intermolecular Mn···Mn distance is found in the order <b>2</b> < <b>3</b> < <b>1</b>. The segregation of the [Mn₂]²⁺ dimer resulted in interdimer distances long enough to effectively reduce the intermolecular magnetic interaction, in particular in <b>1</b> and <b>3</b>. Consequently, an intrinsic property, SMM behavior, of Mn^III dimers has been characterized in this system, even though the interdimer interactions are still crucial in the case of <b>2</b>, where a long-range magnetic order competitively affects slow relaxation of the magnetization at low ac frequencies

Coulombic Aggregations of Mn^III salen-Type Complexes and Keggin-Type Polyoxometalates: Isolation of Mn₂ Single-Molecule Magnets

The reaction of Mn^III salen-type complexes with di- and tetraanionic α-Keggin-type polyoxometalates (POMs) was performed, and three types of Coulombic aggregations containing Mn^III out-of-plane dimeric units (abbreviated as [Mn₂]²⁺) that are potentially single-molecule magnets (SMMs) with an <i>S</i>_T = 4 ground state were synthesized: [Mn₂(5-MeOsaltmen)₂(acetone)₂]­[SW₁₂O₄₀] (<b>1</b>), [Mn₂(salen)₂(H₂O)₂]₂[SiW₁₂O₄₀] (<b>2</b>), and [Mn­(5-Brsaltmen)­(H₂O)­(acetone)]₂[{Mn₂(5-Brsaltmen)₂}­(SiW₁₂O₄₀)] (<b>3</b>), where 5-Rsaltmen^2– = <i>N</i>,<i>N</i>′-(1,1,2,2-tetramethylethylene)­bis­(5-R-salicylideneiminate) with R = MeO (methoxy), Br (bromo) and salen^2– = <i>N</i>,<i>N</i>′-ethylenebis­(salicylideneiminate). Compound <b>1</b> with a dianionic POM, [SW₁₂O₄₀]^2–, is composed of a 1:1 aggregating set of [Mn₂]²⁺/POM, and <b>2</b>, with a tetraanionic POM, [SiW₁₂O₄₀]^4–, is a 2:1 set. Compound <b>3</b> with [SiW₁₂O₄₀]^4– forms a unique 1D coordinating chain with a [−{Mn₂}–POM−]^2– repeating unit, for which a hydrogen-bonded dimeric unit ([Mn­(5-Brsaltmen)­(H₂O)­(acetone)]₂²⁺) is present as a countercation. Independent of the formula ratio of [Mn₂]²⁺/POM, Mn^III dimers and POM units in <b>1</b>–<b>3</b> form respective segregated columns along a direction of the unit cell, which make an alternate packing to separate evenly identical species in a crystal. The nearest intermolecular Mn···Mn distance is found in the order <b>2</b> < <b>3</b> < <b>1</b>. The segregation of the [Mn₂]²⁺ dimer resulted in interdimer distances long enough to effectively reduce the intermolecular magnetic interaction, in particular in <b>1</b> and <b>3</b>. Consequently, an intrinsic property, SMM behavior, of Mn^III dimers has been characterized in this system, even though the interdimer interactions are still crucial in the case of <b>2</b>, where a long-range magnetic order competitively affects slow relaxation of the magnetization at low ac frequencies

Coulombic Aggregations of Mn^III salen-Type Complexes and Keggin-Type Polyoxometalates: Isolation of Mn₂ Single-Molecule Magnets

The reaction of Mn^III salen-type complexes with di- and tetraanionic α-Keggin-type polyoxometalates (POMs) was performed, and three types of Coulombic aggregations containing Mn^III out-of-plane dimeric units (abbreviated as [Mn₂]²⁺) that are potentially single-molecule magnets (SMMs) with an <i>S</i>_T = 4 ground state were synthesized: [Mn₂(5-MeOsaltmen)₂(acetone)₂]­[SW₁₂O₄₀] (<b>1</b>), [Mn₂(salen)₂(H₂O)₂]₂[SiW₁₂O₄₀] (<b>2</b>), and [Mn­(5-Brsaltmen)­(H₂O)­(acetone)]₂[{Mn₂(5-Brsaltmen)₂}­(SiW₁₂O₄₀)] (<b>3</b>), where 5-Rsaltmen^2– = <i>N</i>,<i>N</i>′-(1,1,2,2-tetramethylethylene)­bis­(5-R-salicylideneiminate) with R = MeO (methoxy), Br (bromo) and salen^2– = <i>N</i>,<i>N</i>′-ethylenebis­(salicylideneiminate). Compound <b>1</b> with a dianionic POM, [SW₁₂O₄₀]^2–, is composed of a 1:1 aggregating set of [Mn₂]²⁺/POM, and <b>2</b>, with a tetraanionic POM, [SiW₁₂O₄₀]^4–, is a 2:1 set. Compound <b>3</b> with [SiW₁₂O₄₀]^4– forms a unique 1D coordinating chain with a [−{Mn₂}–POM−]^2– repeating unit, for which a hydrogen-bonded dimeric unit ([Mn­(5-Brsaltmen)­(H₂O)­(acetone)]₂²⁺) is present as a countercation. Independent of the formula ratio of [Mn₂]²⁺/POM, Mn^III dimers and POM units in <b>1</b>–<b>3</b> form respective segregated columns along a direction of the unit cell, which make an alternate packing to separate evenly identical species in a crystal. The nearest intermolecular Mn···Mn distance is found in the order <b>2</b> < <b>3</b> < <b>1</b>. The segregation of the [Mn₂]²⁺ dimer resulted in interdimer distances long enough to effectively reduce the intermolecular magnetic interaction, in particular in <b>1</b> and <b>3</b>. Consequently, an intrinsic property, SMM behavior, of Mn^III dimers has been characterized in this system, even though the interdimer interactions are still crucial in the case of <b>2</b>, where a long-range magnetic order competitively affects slow relaxation of the magnetization at low ac frequencies

Principles of Dielectric Blood Coagulometry as a Comprehensive Coagulation Test

Dielectric blood coagulometry (DBCM) is intended to support hemostasis management by providing comprehensive information on blood coagulation from automated, time-dependent measurements of whole blood dielectric spectra. We discuss the relationship between the series of blood coagulation reactions, especially the aggregation and deformation of erythrocytes, and the dielectric response with the help of clot structure electron microscope observations. Dielectric response to the spontaneous coagulation after recalcification presented three distinct phases that correspond to (P1) rouleau formation before the onset of clotting, (P2) erythrocyte aggregation and reconstitution of aggregates accompanying early fibrin formation, and (P3) erythrocyte shape transformation and/or structure changes within aggregates after the stable fibrin network is formed and platelet contraction occurs. Disappearance of the second phase was observed upon addition of tissue factor and ellagic acid for activation of extrinsic and intrinsic pathways, respectively, which is attributable to accelerated thrombin generation. A series of control experiments revealed that the amplitude and/or quickness of dielectric response reflect platelet function, fibrin polymerization, fibrinolysis activity, and heparin activity. Therefore, DBCM sensitively measures blood coagulation via erythrocytes aggregation and shape changes and their impact on the dielectric permittivity, making possible the development of the battery of assays needed for comprehensive coagulation testing

Lanthanide Complexes of Macrocyclic Polyoxovanadates by VO₄ Units: Synthesis, Characterization, and Structure Elucidation by X-ray Crystallography and EXAFS Spectroscopy

Reactions of a tetravanadate anion, [V₄O₁₂]^4–, with a series of lanthanide­(III) salts yield three types of lanthanide complexes of macrocyclic polyoxovanadates: (Et₄N)₆[Ln^IIIV₉O₂₇] [Ln = Nd (<b>1</b>), Sm (<b>2</b>), Eu (<b>3</b>), Gd (<b>4</b>), Tb (<b>5</b>), Dy (<b>6</b>)], (Et₄N)₅[(H₂O)­Ho^III(V₄O₁₂)₂] (<b>7</b>), and (Et₄N)₇[Ln^IIIV₁₀O₃₀] [Ln = Er (<b>8</b>), Tm (<b>9</b>), Yb (<b>10</b>), Lu (<b>11</b>)]. Lanthanide complexes <b>1</b>–<b>11</b> are isolated and characterized by IR, elemental analysis, single-crystal X-ray diffraction, and extended X-ray absorption fine structure spectroscopy (EXAFS). Lanthanide complexes <b>1</b>–<b>6</b> are composed of a square-antiprism eight-coordinated Ln^III center with a macrocyclic polyoxovanadate that is constructed from nine VO₄ tetrahedra through vertex sharing. The structure of <b>7</b> is composed of a seven-coordinated Ho^III center, which exhibits a capped trigonal-prism coordination environment by the sandwiching of two cyclic tetravanadates with a capping H₂O ligand. Lanthanide complexes <b>8</b>–<b>11</b> have a six-coordinated Ln^III center with a 10-membered vanadate ligand. The structural trend to adopt a larger coordination number for a larger lanthanide ion among the three types of structures is accompanied by a change in the vanadate ring sizes. These lanthanide complexes are examined by EXAFS spectroscopies on lanthanide L_III absorption edges, and the EXAFS oscillations of each of the samples in the solid state and in acetonitrile are identical. The Ln–O and Ln···V bond lengths obtained from fits of the EXAFS data are consistent with the data from the single-crystal X-ray studies, reflecting retention of the structures in acetonitrile

Lanthanide Complexes of Macrocyclic Polyoxovanadates by VO₄ Units: Synthesis, Characterization, and Structure Elucidation by X-ray Crystallography and EXAFS Spectroscopy

Reactions of a tetravanadate anion, [V₄O₁₂]^4–, with a series of lanthanide­(III) salts yield three types of lanthanide complexes of macrocyclic polyoxovanadates: (Et₄N)₆[Ln^IIIV₉O₂₇] [Ln = Nd (<b>1</b>), Sm (<b>2</b>), Eu (<b>3</b>), Gd (<b>4</b>), Tb (<b>5</b>), Dy (<b>6</b>)], (Et₄N)₅[(H₂O)­Ho^III(V₄O₁₂)₂] (<b>7</b>), and (Et₄N)₇[Ln^IIIV₁₀O₃₀] [Ln = Er (<b>8</b>), Tm (<b>9</b>), Yb (<b>10</b>), Lu (<b>11</b>)]. Lanthanide complexes <b>1</b>–<b>11</b> are isolated and characterized by IR, elemental analysis, single-crystal X-ray diffraction, and extended X-ray absorption fine structure spectroscopy (EXAFS). Lanthanide complexes <b>1</b>–<b>6</b> are composed of a square-antiprism eight-coordinated Ln^III center with a macrocyclic polyoxovanadate that is constructed from nine VO₄ tetrahedra through vertex sharing. The structure of <b>7</b> is composed of a seven-coordinated Ho^III center, which exhibits a capped trigonal-prism coordination environment by the sandwiching of two cyclic tetravanadates with a capping H₂O ligand. Lanthanide complexes <b>8</b>–<b>11</b> have a six-coordinated Ln^III center with a 10-membered vanadate ligand. The structural trend to adopt a larger coordination number for a larger lanthanide ion among the three types of structures is accompanied by a change in the vanadate ring sizes. These lanthanide complexes are examined by EXAFS spectroscopies on lanthanide L_III absorption edges, and the EXAFS oscillations of each of the samples in the solid state and in acetonitrile are identical. The Ln–O and Ln···V bond lengths obtained from fits of the EXAFS data are consistent with the data from the single-crystal X-ray studies, reflecting retention of the structures in acetonitrile

A Bowl-Type Dodecavanadate as a Halide Receptor

The dodecavanadate framework, [V₁₂O₃₂]^4–, exhibits a unique bowl-type structure with an open molecular oxide cage having a cavity diameter of 4.4 Å, and different synthetic paths were required to construct the bowl-type structure with a different guest. A new dodecavanadate, {(<i>n</i>-C₄H₉)₄N}₄[V₁₂O₃₂(CH₃NO₂)] (<b>1</b>), is synthesized with a nitromethane guest, which is stacked above the entrance of the hemisphere rather than fully occupying the cavity, and it enables a guest-capturing reaction, while retaining the anionic cage structure. Compound <b>1</b> is a good precursor for halide-centered dodecavanadates, {(C₂H₅)₄N}₅[V₁₂O₃₂(X)] (X = Cl^– (<b>2</b>), Br^– (<b>3</b>), and I^– (<b>4</b>)). The position of the halide inside the cavity correlates with the ionic radius of the guest; the small chloride ion sat at the far bottom, and the large iodide floated at the entrance. The inclusion reaction rates were estimated through ⁵¹V NMR time-course measurements in nitromethane. The reaction rates increase in the order I^– < Br^– < Cl^–

Formal Total Synthesis of Manzacidin C Based on Asymmetric 1,3-Dipolar Cycloaddition of Azomethine Imines

An enantioselective formal total synthesis of (+)-manzacidin C is described. A key feature of the synthesis is the construction of two chiral centers via the asymmetric 1,3-dipolar cycloaddition of an azomethine imine to methallyl alcohol by the use of (<i>S,S</i>)-DIPT as a chiral auxiliary