Synthetic conditions for the single-phase LS polymorph of the potassium salt of Fe( iii ) 5-chlorosalicylicaldehyde thiosemicarbazone K[Fe(5Cl-thsa) 2 ] (1-a), crystallizing in the Pbcn space group, have been identified.

Neutral iron(III) and iron(II) complexes based on the pyruvic acid thiosemicarbazone (H2thpy) ligand [FeIII(Hthpy)(thpy)] (1) and [FeII(Hthpy)2] (2) were synthesized, and deeper insights into magneto-structural correlation were gained by FT-IR spectroscopy, single crystal X-ray crystallography, dc magnetic characterization, 57Fe Mössbauer spectroscopy, and DFT calculations. The X-ray structures of complex 1 were established for the HS (S = 5/2) state at 295 K and the LS (S = 1/2) state at 150 K. The crystal packing of 1 at these temperatures corresponds to the triclinic P1̄ symmetry and contains pairs of [FeIII(Hthpy)(thpy)] complexes interconnected by a shortened S⋯S contact. The crystal structure of 2 at 120 K is described by monoclinic I2/a symmetry and contains extended 1D chains of interconnected Fe(II) complexes in the HS (S = 2) state. According to dc magnetic measurements, a complete, abrupt spin-crossover with T1/2 = 226 K and a hysteresis loop of 8 K occurs in the temperature range of 210-240 K for complex 1, whereas complex 2 is stabilized in the HS state in the temperature range of 2-300 K. DFT calculations showed that the absence of spin-crossover for complex 2 is due to insufficient energy of splitting of d orbitals by the field of the Hthpy- ligand. BS-DFT calculations confirmed the presence of a weak antiferromagnetic exchange in the structures of 1 and 2.

The first covalently linked dimer has been prepared for cyclazine systems by regioselective oxidative homocoupling of 1,2-dicarbomethoxy-3-phenylcycl[3.2.2]azine. The regioselectivity of this reaction at 4-position, having been confirmed by X-ray diffraction analysis and NMR spectroscopy, has been also reliably predicted within the model of average local ionization energy on the molecular surface of the starting monomer at the BP86/def2-TZVP level of theory. Due to the planar it-it interaction of the cycl[3.2.2]azine subunits, the dimer is a green fluorophore (tem = 527 nm, toluene), characterized by a bathochromic shift of the main bands in the UV-vis and fluorescence spectra relative to the monomer by 41 and 71 nm, respectively. Furthermore, the dimer demonstrates an increased fluorescence quantum yield relative to the monomer (55 % vs. 35 % in toluene), and according to the data of X-ray diffraction analysis, DFT calculations and variable temperature 1D and 2D 1H NMR spectroscopy, is characterized by hindered rotation of the S1-state-involved cycl[3.2.2]azine cores along the C4-C4 ' bond axis. Such prerequisites determine good application potential of the 4-4 ' coupled cycl[3.2.2]azine derivatives as turn-on fluorescent, i.e. fluorogenic probes for advanced bioimaging in living systems. Finally, unlike the monomer, the dimer shows reversibility of both one- and two-electron reduction and oxidation processes, and therefore can become the basis of both n- and p-type semiconductors.

Single crystals of sodium zincophosphate chloride were obtained under medium-temperature hydrothermal conditions and its crystal structure was determined using low temperature X-ray diffraction.

We consider selfadjoint operators obtained by pasting a finite number of boundary relations with one-dimensional boundary space. A typical example of such an operator is the Schrödinger operator on a star-graph with a finite number of finite or infinite edges and an interface condition at the common vertex. A wide class of “selfadjoint” interface conditions, subject to an assumption which is generically satisfied, is considered. We determine the spectral multiplicity function on the singular spectrum (continuous as well as point) in terms of the spectral data of decoupled operators.

KMnPO 4 F represents a rare case of a quasi-two-dimensional Ising spin system with a rectangular lattice formed by antiferromagnetic Mn 3+ ( S = 2) chains, coupled ferromagnetically.

The hydrate of a neutral iron(III) complex based on the pyruvic acid thiosemicarbazone ligand [FeIII(Hthpy)(thpy)]·H2O (1) was synthesized and characterized using FT-IR spectroscopy, powder and single-crystal X-ray diffraction, dc magnetic measurements, EPR and 57Fe Mössbauer spectroscopy. The crystal structure of 1 was determined for the first time. Two distinct chelating ligands Hthpy- and thpy2- coordinate the Fe(III) ion to form the FeN2O2S2 octahedron which shows a low spin geometry at 150-350 K. The crystal packing contains infinite chains of the Fe(III) complexes as well as water molecules located in cavities. Along the chain, π-π interacting pairs of the Fe complexes are linked by H-bonding. According to the dc magnetic measurements, the complete abrupt spin-crossover with half-transition temperature T1/2 = 340 K and a hysteresis loop of 45 K occurs in the temperature range of 300-363 K. Based on the X-ray structure of 1, the Bleaney-Bowers equation for the isolated dimer model was used to approximate the temperature dependence of the magnetic susceptibility in the range of 2-50 K. The defined intradimer exchange constant Jexp = -0.498(1) K corresponds to a weak antiferromagnetic exchange between the iron(III) magnetic centers. DFT calculations of H- and π-π bonded fragments of the crystal structure of 1 in the HS and LS states were carried out. Moreover, BS-DFT calculations confirm the presence of antiferromagnetic exchange Jcalc = -0.92 K in the π-π bonded pairs of the ferric complexes and show the exchange pathway between Fe(III) ions by the calculated spin density distribution.

Under hydrothermal conditions emulating natural hydrothermalites, three oxo-salts with sodium and transition metal cations were obtained in the form of single crystals. Their compositions and crystal structures were studied using scanning electron microscopy, microprobe X-ray spectral analysis, and X-ray single-crystal diffraction. The sodium cobalt silicate, i.e., Na2CoSiO4, a structural analog of the mineral liberite, is well known as an ionic conductor. Its crystal structure consists of a framework derived from β-tridymite, built using the Co- and Si-centered tetrahedra sharing vertices. The sodium oxocuprate phosphate chloride Na2Cu3O(Cu0.8Na0.2)(PO4)2Cl belongs to a group of compounds, including fumarolic minerals, characterized by the presence of oxo-centered pyroxene-like chains in their structures. The crystal structure of mineralogically probable sodium vanadium phosphate hydroxide (Na3V(OH)(HPO4)(PO4)) is based on chains built using octahedra centered by magnetically active V3+. Magnetic susceptibility measurements indicate an antiferromagnetic arrangement of V3+ ions and no transition to an ordered state up to 2 K.

The report presents a method of making coloured plastic rings to mark small passerine birds with unique remote readable combinations of leg rings tested over 15 field seasons. As a material for making of the rings, we used plastic binding combs. During testing, we marked Sylvia and Phylloscopus warblers by rings with an inner diameter of 2.8 and 2.2 mm, respectively, using 0.6 mm thick plastic of all available colors. Over the years of testing the rings, we have found 9 colours of binding combs for sale. Rings of such bright colours as yellow, red, orange, and blue were the best. Tags with combinations of black, white, green, blue, and purple were somewhat more difficult to read. The proposed rings are formed on a hot rod; the ends of the rings are formed without overlap, in a joint, like standard aluminum rings. Rings made by the proposed method can be used similarly to the standard aluminum rings. It is necessary to separate the ends of the ring to a width slightly exceeding the diameter of the bird's leg, put the ring on the leg and squeeze until the ends touch. With the used thickness of the material and the diameter of the wall curvature, the strength of the proposed rings is similar to that of a standard aluminum ring. We have not registered any successful attempts to remove or deform rings by birds. The height of the rings is selected depending on the research tasks and the desired number of individual colours combinations, ranging from 3 to 6 mm. The production procedure is described in detail in the report.

The first molecular complexes of Cr(III) with chelating 2,6-diacetylpyridine-bis(thiosemicarbazone) Schiff-base ligand (H2daptsc), [Cr(Hdaptsc)(H2O)1.4(CH3OH)0.6](NO3)2·1.4CH3OH (1), [Cr(Hdaptsc)(H2O)2](NO3)2·1.3C2H5OH (2), [Cr(Hdaptsc)(H2O)2](NO3)2·H2O (3), [Cr(H2daptsc)(H2O)2](NO3)3·2h2O (4), [Cr(Hdaptsc)(N3)2]·CH3OH (5), [Cr(Hdaptsc)(N3)2]·1.25H2O (6) have been synthesized, and their crystal structures have been studied. Structural analysis has shown that in all the crystals, the Cr(III) cation is seven-coordinated by N3S2 atoms of the pentadentate ligand in the equatorial plane and two O or N atoms of water/methanol or N3‾ axial ligands. The pentadentate ligand is fully protonated in 4 and mono-deprotonated in one hydrazinic –NH group in all the other compounds. The degree of deprotonation depends on the pH of the reaction medium. The remaining proton in Hdaptscˉ is ordered and localized on one side of the ligand. As a result, the Hdaptscˉ ligand possesses a pronounced difference in Cr-S/N bond distances for the neutral protonated and negatively charged deprotonated halves due to the strong Jahn–Teller effect for the high-spin 3d3 configuration in the pentagonal bipyramidal (PBP) ligand field.

Sergey Naboko authored a large amount of papers on the spectral theory of Jacobi operators. The main themes of his work are the existence of eigenvalues embedded into the absolutely continuous spectrum; spectral phase transitions for specifically-chosen Jacobi matrices, where new asymptotic methods for spectral analysis were established; construction of Jacobi matrices with gaps in the essential spectrum; estimates of Green matrix for Jacobi operators, and inverse resonance problems. In his later years, Sergey Naboko worked on block Jacobi matrices where he found realizations having both similar and dissimilar properties to their scalar counterparts.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

We report crystal growth and characterization of 4 new ternary layered bismuthides with compositions KZn2Bi2 (I), RbZn2Bi2 (II), RbCd2Bi2 (III), and CsCd2Bi2 (IV) that belong to the vast 122 family of compounds. Single crystals were grown by self-flux technique and characterized by a combination of powder X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and single crystal X-ray diffraction. All new compounds crystallize in the layered ThCr2Si2 structure type and exhibit the plate-like morphology with weak bonding between layers. A significant structural difference between ACd(2)Bi(2) and AZn(2)Bi(2) is found and discussed.

The iron(III) anionic complex based on a pyruvic acid thiosemicarbazone ligand with the lithium cation Li[FeIII(thpy)2]·3H2O (1) has been synthesized and characterized by FTIR spectroscopy, powder and single crystal X-ray diffraction, direct current magnetic susceptibility measurements, and 57Fe Mössbauer spectroscopy. Moreover, the molecular structure of the [Fe(thpy)2]- anion has been determined for the first time. The [Fe(thpy)2]- units in the triclinic P1̄ lattice of 1 are assembled into layers parallel to the bc plane. The Li+ cations and water molecules are located between the layers and the structure is stabilized by hydrogen bonding. The [Fe(thpy)2]- anions form interconnected dimer pairs through hydrogen bonds and short contacts with Fe⋯Fe separation of 6.7861(4) Å. According to dc magnetic measurements, compound 1 demonstrates an incipient spin-crossover transition from the LS (S = 1/2) to the HS (S = 5/2) state above 250 K. The Bleaney-Bowers equation for a model of an isolated LS dimer with a mean-field correction was applied to fit the experimental data of magnetic susceptibility dependence on temperature in the temperature range of 2-250 K. The intra-dimer J1 = -1.79(1) K and inter-dimer J2 = -0.24(3) K antiferromagnetic coupling constants were defined. The analysis of the 57Fe Mössbauer spectra at 80 K and 296 K confirms the presence of the shortened distances between the iron nuclei. Moreover, the influence of the lithium cation on the stabilization of the LS state was shown for the [Fe(thpy)2]- anion. BS-DFT calculations for the optimized structure of two isolated [Fe(thpy)2]- anions also correctly predict a weak exchange J1(calc) = -0.92 K. DFT calculations revealed the OPBE (GGA-type) functional that correctly predicts the spin-crossover transition for the iron(III) thpy compounds. Besides, the effect of the N2O4, N2S2O2, and N2Se2O2 coordination environments on the energy stabilization of the LS state of iron(III) anionic thpy complexes was noted as well.

The synthesis and characterization of NaCo 7.38 (PO 4 ) 4 Cl 4 is reported. Its crystal chemical features allow us to consider the new phase as a potential multifunctional material with ionic conductivity and promising magnetic properties.

The family of 3-arylcycl[3.2.2]azine-1,2-dicarboxylic acids has been extended with a series of 4-alkylsubstituted derivatives. The corresponding water-soluble sodium salts were synthesized as well. The obtained compounds are characterized by intense light absorption up to 450 nm (lg epsilon 4-4.5), pronounced blue-green fluorescence in 430-550 nm region (phi F 10-30 %), good cellular uptake with the values of experimentally determined log D7.4 distribution coefficients ranging from-0.5 to 1.3, and cytotoxicity in HeLa cells classified as weak to moderate (for most of the compounds, IC50 >= 100 mu M) and being at levels typical of most fluorophores already widely used in molecular imaging. Moreover, a good correlation of cytotoxicity and log D7.4 values has been established implying that cytotoxicity tends to decrease with increasing hydrophilicity of the compounds. Finally, the compounds retain fluorescence after penetration into living cells, distributing discretely in the cytoplasm and perinuclear space, which characterizes them as promising blue-green fluorophores for biomedical applications.

ortho-Pyrovanadate (or ortho-diorthovanadate) K2Mn23+Mn2+O(OH)(VO4)(V2O7) synthesized hydrothermally crystallizes in the orthorhombic space group Pnma with a = 17.9155(5), b = 5.8940(2), c = 10.9971(3) Å, V = 1161.23(6) Å3, and Z = 4. Its crystal structure features linear chains of edge-sharing Mn3+O6 octahedra with every second pair of Mn3+O6 octahedra condensed with a Mn2+O6 octahedron on one side of a chain in a sawtooth pattern so that each sawtooth chain consists of a triangular trimer. These sawtooth chains, running parallel to the b axis and linked by the VO4 and V2O7 groups, form a framework with channels populated by K atoms. The new compound is a structural analogue of the mineral zoisite Ca2Al3O(OH)(SiO4)(Si2O7), showing a striking example of very different chemical compositions. K2Mn3O(OH)(VO4)(V2O7) undergoes a phase transition into an ordered antiferromagnetic (AFM) state at TN = 14.4 K, which was detected by high-frequency electron spin resonance as well as by both specific heat Cp and Fisher's specific heat d(χT)/dT measurements. However, this phase transition was not detected by magnetic susceptibility measurements. The origin of this puzzling observation was resolved by evaluating the spin exchanges of K2Mn3O(OH)(VO4)(V2O7), which revealed that each triangular trimer is a ferromagnetically coupled cluster, and the observed ordering involves an AFM ordering between the ferromagnetic (FM) clusters. This ordering is shrouded in magnetic susceptibility measurements due to the susceptibility contributions from the individual FM triangular trimers even below TN. We showed that the magnetic susceptibility of K2Mn3O(OH)(VO4)(V2O7) between ∼30 K and room temperature is satisfactorily described by an AFM chain made up of ferromagnetically coupled triangular clusters, as described by a few spin-exchange parameters.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

The synthesis and characterization of a first salt-inclusion aluminophosphate oxocuprate, (Na,Li)(3)(Cl,OH)[Cu3OAl(PO4)(3)], obtained as single crystals, is reported. A novel phase, with a strongly pseudo-orthorhombic structure, is described as a monoclinic crystal structure established by the study of a pseudomerohedric microtwin. It was investigated using scanning electron microscopy, microprobe analysis and low-temperature X-ray diffraction. The composite crystal structure represents an original framework assembled from Cu-centered polyhedra, AlO6 octahedra and PO4 tetrahedra with channels, which incorporate the Na/Li salt component [(Na,Li)3(Cl,OH)](2+) that ensures electroneutrality of the compound. Layers of strongly corrugated chains of Cucentered octahedra with shared edges and linked by PO4 tetrahedra are shown to be topologically identical with the layers also built from Cu-centered polyhedra and AsO4/VO4 tetrahedra forming the crystal structure of a fumarolic mineral aleutite, (M0.5Cl)[Cu5O2(AsO4)(VO4)] [Siidra et al. (2019). MinMag, 83, 847-853]. 'Sawtooth chains' and pairs of Cu-centered octahedra inherent in the title structure may be of interest in solid-state physics, engaging studies in the field of low-dimensional and frustrated magnetism.