Structure Transformation of Methylammonium Polyoxomolybdates via In-Solution Acidification and Solid-State Heating from Methylammonium Monomolybdate and Application as Negative Staining Reagents for Coronavirus Observation.

We prepared polyoxomolybdates with methylammonium countercations from methylammonium monomolybdate, (CH3NH3)2[MoO4], through two dehydrative condensation methods, acidifying in the aqueous solution and solid-state heating. Discrete (CH3NH3)10[Mo36O112(OH)2(H2O)14], polymeric ((CH3NH3)8[Mo36O112(H2O)14])n, and polymeric ((CH3NH3)4[γ-Mo8O26])n were selectively isolated via pH control of the aqueous (CH3NH3)2[MoO4] solution. The H2SO4-acidified solution of pH < 1 produced "sulfonated α-MoO3", polymeric ((CH3NH3)2[(MoO3)3(SO4)])n. The solid-state heating of (CH3NH3)2[MoO4] in air released methylamine and water to produce several methylammonium polyoxomolybdates in the sequence of discrete (CH3NH3)8[Mo7O24-MoO4], discrete (CH3NH3)6[Mo7O24], discrete (CH3NH3)8[Mo10O34], and polymeric ((CH3NH3)4[γ-Mo8O26])n, before their transformation into molybdenum oxides such as hexagonal-MoO3 and α-MoO3. Notably, some of their polyoxomolybdate structures were different from polyoxomolybdates produced from ammonium molybdates, such as (NH4)2[MoO4] or (NH4)6[Mo7O24], indicating that countercation affected the polyoxomolybdate structure. Moreover, among the tested polyoxomolybdates, (CH3NH3)6[Mo7O24] was the best negative staining reagent for the observation of the SARS-CoV-2 virus using transmission electron microscopy.

Time-resolved EPR observation of blue-light-induced radical ion pairs in a flavin-Trp dyad.

A dyad of flavin and Trp bridged by a p-phenylamide linker was synthesized as an artificial model system to investigate molecular-based magnetic-field sensors relevant to blue-light photoreceptor proteins. The results demonstrated that intramolecular electron transfer generates a radical pair, only the triplet-born one of which has a microsecond lifetime at room temperature.

A Chiral Prussian Blue Analogue Pushes Magneto-Chiral Dichroism Limits.

Here we report on magneto-chiral dichroism (MChD) detected with visible light on the chiral Prussian Blue Analogue [MnII(X-pnH)(H2O)][CrIII(CN)6]·H2O (X = S, R; pn = 1,2-propanediamine). Single crystals suitable for magneto-optical measurements were grown starting from enantiopure chiral ligands. X-ray diffraction and magnetic measurements confirmed the 2D-layered structure of the material, its absolute configuration, and its ferrimagnetic ordered state below a critical temperature TC of 38 K. Absorption and MChD spectra were measured between 450 and 900 nm from room temperature down to 4 K. At 4 K the electronic spectrum features spin-allowed and spin-forbidden transitions of CrIII centers, spin-forbidden transitions of the MnII centers, and metal-to-metal charge transfer bands. The MChD spectra below the magnetic ordering temperature exhibit intense absolute configuration-dependent MChD signals. The temperature dependence of these signals closely follows the material magnetization. Under a magnetic field of 0.46 T, the most intense contribution to MChD represents 2.6% T-1 of the absorbed intensity, one of the highest values observed to date.

Pressure-Controlled Migration of Paramagnetic Centers in a Heterospin Crystal.

A study of the single-crystal-to-single-crystal transformation induced by temperature variation for the chain polymer Cu(II) complex with nitronyl nitroxide showed that an increase in the hydrostatic pressure of up to ∼0.07 GPa completely changes the intracrystalline displacements of molecules relative to one another. This, in turn, significantly affects the interaction energy of the unpaired electrons of the paramagnetic centers and hence the form of the temperature dependence of the magnetic susceptibility χT. The cooling of crystals under normal conditions causes a rearrangement of the intrachain exchange clusters {>N-•O-Cu(II)-O•-N<} accompanied by a shortening of the distances between the paramagnetic centers. This changes the character of exchange interactions and generates multistage spin transitions. An increase in the hydrostatic pressure leads to a drastic change in the O···O distances between the nitroxyl fragments of adjacent chains, an increase in the antiferromagnetic exchange between them, and complete suppression of spin transitions.

Ferroelectric Behavior of a Hexamethylenetetramine-Based Molecular Perovskite Structure.

We report the development of a molecular ferroelectric material inspired by the hexamethylenetetramine (hmta) non-centrosymmetric molecular rotator. The bromide salt of diprotonated hmta (hmtaH2 ) crystalized as (hmtaH2 )(NH4 )Br3 in a metal-free ABX3 perovskite-type structure, in which the A and B sites are occupied by hmtaH2 2+ and ammonium cations, respectively. The compound crystallized in the Pma2 polar space group. A distorted polar perovskite structure formed owing to the distortion of {(NH4 )Br6 } octahedrons that are stabilized through the formation of NH⋅⋅⋅Br hydrogen bonds and the orientational ordering of positive charges on the non-centrosymmetric hmtaH2 molecules. This spontaneous polarization exhibited ferroelectric behavior with a nominally high Curie temperature (>400 K), in which the electrical switching of polarization originates from the rotation of the hmtaH2 unit.

Selective Ion Exchange in Supramolecular Channels in the Crystalline State.

Artificial ion channels are of increasing interest because of potential applications in biomimetics, for example, for realizing selective ion permeability through the transport and/or exchange of selected ions. However, selective ion transport and/or exchange in the crystalline state is rare, and to the best of our knowledge, such a process has not been successfully combined with changes in the physical properties of a material. Herein, by soaking single crystals of Li2 ([18]crown-6)3 [Ni(dmit)2 ]2 (H2 O)4 (1) in an aqueous solution containing K+ , we succeeded in complete ion exchange of the Li+ ions in 1 with K+ ions in the solution, while maintaining the crystalline state of the material. This ion exchange with K+ was selectively conducted even in mixed solutions containing K+ as well as Na+ /Li+ . Furthermore, remarkable changes in the physical properties of 1 resulted from the ion exchange. Our finding enables not only the realization of selective ion permeability but also the development of highly sensitive biosensors and futuristic ion exchange agents, for example.

Giant Hysteretic Single-Molecule Electric Polarisation Switching above Room Temperature.

Continual progress has been achieved in information technology through unrelenting miniaturisation of the single memory bit in integrated ferromagnetic, ferroelectric, optical, and related circuits. However, as miniaturisation approaches its theoretical limit, new memory materials are being sought. Herein, we report a unique material exhibiting single-molecule electric polarisation switching that can operate above room temperature. The phenomenon occurs in a Preyssler-type polyoxometalate (POM) cluster we call a single-molecule electret (SME). It exhibits all the characteristics of ferroelectricity but without long-range dipole ordering. The SME affords bi-stability as a result of the two potential positions of localisation of a Tb3+ ion trapped in the POM, resulting in extremely slow relaxation of the polarisation and electric hysteresis with high spontaneous polarisation and coercive electric fields. Our findings suggest that SMEs can potentially be applied to ultrahigh-density memory and other molecular-level electronic devices operating above room temperature.

Two New Sandwich-Type Manganese {Mn5}-Substituted Polyoxotungstates: Syntheses, Crystal Structures, Electrochemistry, and Magnetic Properties.

Herein we report two pentanuclear MnII-substituted sandwich-type polyoxotungstate complexes, [{Mn(bpy)}2Na(H2O)2(MnCl)2{Mn(H2O)}(AsW9O33)2]9- and [{Mn(bpy)}2Na(H2O)2(MnCl){Mn(H2O)}2(SbW9O33)2]8- (bpy = 2,2'-bipyridine), whose structures have been obtained by single-crystal X-ray diffraction (SCXRD), complemented by results obtained from elemental analysis, electrospray ionization mass spectrometry, Fourier transform infrared spectroscopy, and thermogravimetric analysis. They consist of two [B-α-XW9O33]9- subunits sandwiching a cyclic assembly of the hexagonal [{Mn(bpy)}2Na(H2O)2(MnCl)2{Mn(H2O)}]9+ and [{Mn(bpy)}2Na(H2O)2(MnCl){Mn(H2O)}2]10+ moieties, respectively, and represent the first pentanuclear MnII-substituted sandwich-type polyoxometalates (POMs). Both compounds have been synthesized by reacting MnCl2·4H2O with trilacunary Na9[XW9O33]·27H2O (X = AsIII and SbIII) POM precursors in the presence of bpy in a 1 M aqueous sodium chloride solution under mild reaction conditions. SCXRD showed that the alternate arrangement of three five-coordinated MnII ions and two six-coordinated MnII ions with an internal Na cation formed a coplanar six-membered ring that was sandwiched between two [B-α-XW9O33]9- (X = AsIII and SbIII) subunits. The results of temperature-dependent direct-current (dc) magnetic susceptibility data indicated ferromagnetic interactions between Mn ions in the cluster. Moreover, alternating-current magnetic susceptibility measurements with a dc-biased magnetic field showed the existence of a ferromagnetic order for both samples. Electrochemistry studies revealed the presence of redox processes assigned to the Mn centers. They are associated with the deposition of material on the working electrode surface, possibly MnxOy, as demonstrated by electrochemical quartz crystal microbalance experiments.

Synthesis of ε-Keggin-Type Cobaltomolybdate-Based 3D Framework Material and Characterization Using Atomic-Scale HAADF-STEM and XANES.

We describe the preparation of ε-Keggin-type cobaltomolybdate-based 3D frameworks with sodium cations, NaH9[ε-CoIIMoV8MoVI4O40CoII2], and their characterization by high-resolution high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) and X-ray absorption fine structure (XAFS) spectroscopy. Atomic-scale HAADF-STEM images of ε-Keggin compounds were obtained for the first time, and positions of Mo and Co were confirmed. Furthermore, clear evidence of the presence of a CoO4 tetrahedron was obtained by X-ray absorption near-edge structure (XANES) analysis. Their characterization clearly revealed that ε-Keggin-type cobaltomolybdate units, [ε-CoMo12O40]n-, constructed by a central CoIIO4 tetrahedron and 12 surrounding MoO6 octahedra, are linked with CoII to form 3D frameworks.

Coupling of Magnetic and Elastic Domains in the Organic-Inorganic Layered Perovskite-Like (C6 H5 C2 H4 NH3 )2 FeII Cl4 Crystal.

Multiferroic materials coupling ferroelasticity and ferromagnetism show strong magnetoelastic effects as magnetization is induced by mechanical stress or alternately strain induced by applying a magnetic field. These effects were reported for inorganic multiferroics such as LaCox Sr1-x O3 . (C6 H5 C2 H4 NH3 )2 FeII Cl4 is the first example of an organic-inorganic perovskite to exhibit such effects below the canted antiferromagnetism at TC =98 K and ferroelasticity at TC =433 K. This is shown by switching the magnetic hysteresis on and off by uniaxial pressure through the strong coupling of the magnetic and elastic domains. The spin-canting direction was controlled by mechanical stress in the heating and cooling cycles. This unique observation gives additional impetus in the search for coupled hysteretic effect in organic-inorganic multiferroics.

Progressive Transformation between Two Magnetic Ground States for One Crystal Structure of a Chiral Molecular Magnet.

We report the exceptional observation of two different magnetic ground states (MGS), spin glass (SG, T(B) = 7 K) and ferrimagnet (FI, T(C) = 18 K), for one crystal structure of [{Mn(II)(D/L-NH2ala)}3{Mn(III)(CN)6}]·3H2O obtained from [Mn(CN)6](3-) and D/L-aminoalanine, in contrast to one MGS for [{Mn(II)(L-NH2ala)}3{Cr(III)(CN)6}]·3H2O. They consist of three Mn(NH2ala) helical chains bridged by M(III)(CN)6 to give the framework with disordered water molecules in channels and between the M(III)(CN)6. Both MGS are characterized by a negative Weiss constant, bifurcation in ZFC-FC magnetizations, blocking of the moments, both components of the ac susceptibilities, and hysteresis. They differ in the critical temperatures, absolute magnetization for 5 Oe FC (lack of spontaneous magnetization for the SG), and the shapes of the hysteresis and coercive fields. While isotropic pressure increases both T(crit) and the magnetizations linearly and reversibly in each case, dehydration progressively transforms the FI into the SG as followed by concerted in situ magnetic measurements and single-crystal diffraction. The relative strengths of the two moderate Mn(III)-CN-Mn(II) antiferromagnetic (J1 and J2), the weak Mn(II)-OCO-Mn(II) (J3), and Dzyaloshinkii-Moriya antisymmetric (DM) interactions generate the two sets of characters. Examination of the bond lengths and angles for several crystals and their corresponding magnetic properties reveals a correlation between the distortion of Mn(III)(CN)6 and the MGS. SG is favored by higher magnetic anisotropy by less distorted Mn(III)(CN)6 in good accordance with the Mn-Cr system. This conclusion is also born out of the magnetization measurements on orientated single crystals with fields parallel and perpendicular to the unique c axis of the hexagonal space group.

Synthesis, Crystal Structure, and Magnetic Properties of a Chiral Cyanide-Bridged Bimetallic Framework K3[Mn(II)(L-asp)]6[Cr(III)(CN)6]·2H2O.

All five coordinating atoms of the amino-acid dianion L-aspartate (L-asp = NH2CH(COO)CH2COO(2-)) are found to be involved in coordination with Mn(II) in the presence of [Cr(III)(CN)6](3-) to self-assemble into a chiral three-dimensional cyanide-bridged K3[Mn(L-asp)]6[Cr(CN)6]·2H2O containing the highest ratio of Mn:Cr of 6:1. It adopts the chiral P3 (no. 143) space group consisting of zigzag Mn-OCO-Mn chains sharing edges of hexagonal channels with central [Cr(CN)6](3-), while K(+) and H2O occupy another parallel star-shaped channel. Its magnetic susceptibility above 100 K is dominated by the nearest neighbor (Mn-Cr at 5.08 and 5.31 Å) antiferromagnetic (AF) exchange interactions (θ = -15(1) K) and below 40 K by further AF interaction between Mn and Mn at 5.32 Å. It finally reaches a steady value at 4.5 K, where a bifurcation of the zero-field-cooled and field-cooled magnetizations is observed in small fields (<1 kOe). The isothermal magnetization is linear in field and deviating toward saturation above 60 kOe at 2 K. No imaginary component of the ac susceptibilities is observed. This behavior is associated with long-range antiferromagnetic order of a helical or conic nature where the magnetic sublattices are numerous [2n × (6Mn + 1Cr)], leading to a domain of sufficient size to allow for the presence of the bifurcation. A model is proposed based on the local anisotropy and symmetry multiplicity of the space group.

Lanthanoid Template Isolation of the α-1,5 Isomer of Dicobalt(II)-Substituted Keggin Type Phosphotungstates: Syntheses, Characterization, and Magnetic Properties.

A new series of heterometallic 3d-4f sandwich type phosphotungstates, [Ln{PCo2W10O38(H2O)2}2](11-) (Ln = Sm(III), Eu(III), Gd(III), Tb(III), Dy(III), Ho(III), Er(III), Tm(III), Yb(III), and Lu(III), denoted 1a-10a, respectively), have been synthesized by a one-pot reaction procedure on reacting the dilacunary K14[P2W19O69(H2O)]·24H2O precursor with Ln(NO3)3·nH2O and Co(NO3)2·6H2O in an aqueous potassium chloride solution. All the compounds were isolated as potassium salts and further characterized with different analytical techniques such as single-crystal X-ray diffraction, Fourier transform infrared spectroscopy, high-resolution electrospray ionization mass spectrometry, elemental analysis by inductively coupled plasma atomic emission spectroscopy, magnetic measurement, and thermogravimetric analysis. Single-crystal X-ray diffraction analysis of the compounds reveals that all these compounds are isostructural and crystallized in the orthorhombic crystal system in space group Iba2. The polyanions contain the α-1,5 isomer of dicobalt-substituted α-Keggin phosphotungstate, which sandwiched lanthanoid cation and formed novel heterometallic dimer species. The temperature-dependent magnetic susceptibilities of 1a, 2a, 4a, and 7a-10a indicate the dominant contribution of the ferromagnetic interaction between Co(II) and Co(II) within the cluster, while the antiferromagnetic interaction between Co(II) and Ln(III) dominates for 3a, 5a, and 6a. The isothermal magnetizations of 1a-10a show a gradual increase in magnetization at low fields and do not reach saturation even at 50 kOe.

High magnetic hardness for the canted antiferromagnetic, ferroelectric, and ferroelastic layered perovskite-like (C2H5NH3)2[Fe(II)Cl4].

An unusual high magnetic hardness for the layered perovskite-like (C2H5NH3)2[Fe(II)Cl4], in addition to its already found canted antiferromagnetism, ferroelasticity, and ferroelectricity, which are absent for (CH3NH3)2[Fe(II)Cl4], has been observed. The additional CH2 in the ethylammonium compared to methylammonium allows more degrees of freedom and therefore numerous phase transitions which have been characterized by single-crystal structure determinations from 383 to 10 K giving the sequence from tetragonal to orthorhombic to monoclinic (I4/mmm ↔ P42/ncm ↔ Pccn ↔ Pcab ↔ C2/c) accompanied by both tilting and rotation of the FeCl6 octahedra. The magnetic properties on single crystal and powder samples at high temperature are similar for both compounds, but at TN (C2H5NH3)2[Fe(II)Cl4] is a proper canted antiferromagnet unlike the hidden canting observed for (CH3NH3)2[Fe(II)Cl4]. The canting angle is 0.6° toward the c-axis, and thus the moments lie in the easy plane of the iron-chloride layer defined by a critical exponent ß = 0.18. The isothermal magnetizations for the field along the three orthogonal crystallographic axes show wider hysteresis for H ∥ c and is present at all temperature below 98 K. The coercive field increases as the temperature is lowered, and at T < 20 K it is difficult to reverse all the moments with the available 50 kOe of the SQUID for both single crystal and powder samples. The shape of the virgin magnetization after zero-field-cool (ZFC) indicates that the high coercive field is due to domain wall pinning. Thus, there are unusual associated anomalies such as asymmetric hysteresis and history dependence. The difference in magnetic hardness of the two compounds suggests that magnetic, electric, and elastic domains are intricately manifested and therefore raise the key question of how the different domains interact.

On the nature of the structural and magnetic phase transitions in the layered perovskite-like (CH3NH3)2[Fe(II)Cl4].

In view of renewed interest in multiferroic for molecular systems, we re-examine the structural and magnetic properties of the potentially ferroic layered perovskite-like (CH3NH3)2[Fe(II)Cl4] due to its high-temperature magnetic ordering transition. The structures from several sets of diffraction data of single crystals consist of square-grid layers of corner-sharing FeCl6 octahedra and changes from the high-symmetry I4/mmm (T > 335 K) to the low-symmetry Pccn (T < 335 K). In the former the iron and bridging chlorine atoms are within the layer and the organic cations sit in the middle of each square grid, while in the latter the octahedra are tilted in pairs, two in and two out, progressively by up to 12° and the nitrogen atoms follow their motion to be nearer to the two-in pairs. Crystals are stable up to 450 K and display three phase transitions, two structural at 332 and 233 K and one magnetic at 95 K. The temperature dependences of the dc magnetization (zero-field and field-cooling modes) in different applied fields (10-10,000 Oe) on several aligned single crystals independently reveal a hidden-canted antiferromagnetic ground state of at least four sublattices and not the reported canted antiferromagnetic ground state. A metamagnetic critical field of only 200 Oe transforms it to a canted antiferromagnet. The estimated canting angle is 1.4° in zero field, and it folds to ca. 2.8° in a field of 50 kOe at 2 K. The easy axis is along 010, the hard axis is along 100, and the intermediate and canting axis is 001. Using the available extracted parameters the phase diagram has been constructed. This study provides evidence of a complex and intricate manifestation of the orientation, temperature, and field dependence of the interplay between anisotropy and coherent lengths, which would need further studies.

Electrical network of single-crystalline metal oxide nanoclusters wired by π-molecules.

In a mixed-valence polyoxometalate, electrons are usually delocalized within the cluster anion because of low level of inter-cluster interaction. Herein, we report the structure and electrical properties of a single crystal in which mixed-valence polyoxometalates were electrically wired by cationic π-molecules of tetrathiafulvalene substituted with pyridinium. Electron-transport characteristics are suggested to represent electron hopping through strong interactions between cluster and cationic π-molecules.

Impact of diradical character on two-photon absorption: bis(acridine) dimers synthesized from an allenic precursor.

The two-photon absorption (TPA) of a bis(acridine) dimer (8) having singlet diradical character in its ground state was found to be enhanced by more than 2 orders of magnitude as compared to its closed-shell counterpart (12), which has the same structural backbone and atom composition. The dimer, a tetracation species consisting of two connected acridinium cation moieties with high coplanarity, was obtained during our attempts to synthesize triplet carbenes by double oxidation of an allenic precursor (3b). High conjugation over the two aromatic rings connected by dimerization was revealed by X-ray analysis, and a small HOMO-LUMO gap was found in the visible-near-infrared one-photon absorption spectrum in solution and in the crystalline state, exhibiting that the ground state of 8 has singlet diradical nature. Ab initio molecular orbital calculations of the ground state also suggested that 8 has an intermediate diradical character (y) of 0.685. Interconversion between diradical tetracation dimer 8 and closed-shell dication dimer 12 was achieved by oxidation/reduction in good yields and was accompanied by formation of monoradical trication dimer 13 as an intermediate. TPA measurements at near-infrared wavelengths revealed that diradical dimer 8 has large TPA cross sections (3600 GM at 1200 nm), while closed-shell 12 has TPA cross sections of <21 GM. This result represents a straightforward comparison between the TPA activity of molecules with the same structural backbone and atom composition but with different degree of the diradical character, supporting the theoretical prediction that enhanced TPA intensity can be observed in the intermediate y region (0 < y < 1).

Long-range magnetic ordering at 5.5 K for cobalt(II)-hydroxide diamond chains isolated by 17 Å with α-phenylcinnamate.

[Co(4)(phcina)(6)(OH)(2)(H(2)O)(4)]·2H(2)O (1) (phcina = α-phenylcinnamate), obtained as pink needles by hydrothermal technique, consists of two edge-sharing pairs of octahedral CoO(6) connected by their apexes to form diamond-chains. The magnetic chains are isolated from one another without chemical bond at 17 Å by the nonmagnetic bulky organic ligand. It exhibits hidden canting below the long-range antiferromagnetic (AF) ordering at 5.5 K. A metamagnetic critical field of only 30 Oe at 2 K suffices to overcome the weak through space magnetic interaction between chains and reverse the moments within the chains to give a canted AF reaching only (1)/(4) of the required moment for all parallel moment alignment. The anisotropy measured on aligned crystals, using dc and ac modes, estimates g(||b) = 6.5 and g(⊥b) = 3.25, thus eliminating an Ising or a Heisenberg magnetic dimensionality while suggesting an easy-plane AF. Weak frequency dependence of the ac-susceptibilities below the transition temperature is associated with domain structure in the ordered state, and absence of it well above T(N) eliminates single-chain magnetism. It is inferred that the competition between the strong AF coupling between the edge-sharing pairs, which dominates the high temperature susceptibility, and the ferromagnetic coupling within the pairs, results in a canting of the moments within each chain, where the moments are out of the ac-plane by an estimated 13°. In zero-field the moments of adjacent chains are antiparallel resulting in a compensated system, i.e., hidden canting.

Molecular photoconductor with simultaneously photocontrollable localized spins.

UV irradiation reversibly switches a new insulating and nonmagnetic molecular crystal, BPY[Ni(dmit)(2)](2) (BPY = N,N'-ethylene-2,2'-bipyridinium; Ni(dmit)(2) = bis(1,3-dithiole-2-thione-4,5-dithiolato)nickelate(III)), into a magnetic conductor. This is possible because the bipyridyl derivative cations (BPY(2+)) trigger a photochemical redox reaction in the crystal to produce a change of ∼10% in the filling of the Ni(dmit)(2) valence band, leaving localized spins on the BPY themselves. In the dark, almost all of the BPY molecules are closed-shell cations, and most of the Ni(dmit)(2) radical anions form spin-singlet pairs; thus, this material is a diamagnetic semiconductor. Under UV irradiation, a photocurrent is observed, which enhances the conductivity by 1 order of magnitude. Electron spin resonance measurements indicate that the UV irradiation reversibly generates carriers and localized spins on the Ni(dmit)(2) and the BPY, respectively. This high photoconductivity can be explained by charge transfer (CT) transitions between Ni(dmit)(2) and BPY in the UV region. In other words, the photoconduction and "photomagnetism" can be described as reversible optical control of the electronic states between an ionic salt (BPY(2+)/[Ni(dmit)(2)](-), nonmagnetic insulator) and a CT complex (BPY(2(1-δ)+)/[Ni(dmit)(2)]((1-δ)-) (δ ≈ 0.1), magnetic conductor) in the solid state.

Three-Dimensional Supramolecular Architectures with MnII Ions Assembled from Hydrogen Bonding Interactions: Crystal Structures and Antiferromagnetic Properties.

Two novel cocrystal MnII compounds were successfully synthesized. The composition of two kinds crystals correspond to [Mn(hfac)2La 2·Mn(hfac)2La(H2O)·Mn(hfac)2(H2O)2] (1) and [Mn(hfac)2Lb 2·Mn(hfac)2(H2O)2·0.5(C6H14)] (2) [La = 1,3-bis(1'-oxyl-3'-oxido-4',4',5',5'-tetramethyl-4,5-dihydro-1H-imidazol-2-y1)benzene; Lb = 1-(1'-oxyl-4',4',5',5'-tetramethylimidazolin-2-yl)-3-(1'-oxyl-3'-oxo-4',4',5',5'-tetramethylimidazolin-2-yl)benzene; hfac = hexafluoroacetylacetonato). Surprisingly, the compounds were not polymeric or clusters but, more interestingly, different ratio biradical-metal coordination compound cocrystals. The extensive intramolecular H-bonds are the cause of formation of the cocrystal structures by assembly in the two manganese(II) derivatives; and another factor is the halogen bonds between CF3 of hfac groups. Furthermore, three-dimensional supramolecular architectures were formed. The magnetic susceptibility of both compounds showed strong antiferromagnetic interactions involving the coordinated radical unit and the metal and lesser contribution from ferromagnetic interactions between the radical units. For compound 1, a good fit was obtained for g Mn = 2.08, g rad = 2.00 (fixed), J 1 = -294.3 cm-1, J 2 = 6.2 cm-1 and J 3 = 10.8 cm-1. A reasonable fit for compound 2 was obtained for g Mn = 2.04, g rad = 2.00 (fixed), J 1' = -273.4 cm-1 and J 2' = 8.6 cm-1.