New Layered Polyborates Cs(2)M(2)B(10)O(17) (M = Na, K)

The polyborates Cs(2)M(2)B(10)O(17) (M = Na, K) have been prepared and their structures determined by single-crystal X-ray diffraction methods. They crystallize in the monoclinic space group C2/c (Z = 8) with unit-cell parameters a = 21.643(3) ?, b = 6.558(2) ?, c = 11.072(2) ?, beta = 105.43(1) degrees, V = 1514.8(6) ?(3) for the Na compound and a = 22.547(9) ?, b = 6.614(2) ?, c = 11.288(4) ?, beta = 103.25 degrees, V = 1638.3(8) ?(3) for the K analogue. The new structural type contains a 2-dimensional borate matrix that is built from a complete condensation of the ring system B(5)O(11). The Cs atoms reside within the borate matrix, and the Na (K) atoms are placed between the thick Cs borate sheets.     

La[B5O8(OH)(H2O)]NO3•2H2O的合成与结构

采用熔融硼酸法合成了一种具有层状结构的新型水合稀土多硼酸盐, La[B₅O₈(OH)(H₂O)]NO₃•2H₂O, 并利用单晶X射线衍射技术确定了它的结构. 它属于单斜晶系, P21/n空间群. 其基本构建单元 (fundamental building block, 简称FBB)是由三个BO4和两个BO3基团所构成的一个双三元环[B5O12]基团. 结构中每一个FBB通过共顶点氧原子与周围四个同样的单元连接成具有九元环窗口的二维[B5O10]层, La³⁺位于九元环中心附近. [B5O10]层沿着b方向进行堆积, 硝酸根离子和结构中部分结晶水分子位于相邻的[B5O10]层之间.     

A new hydrated ammonium hydroxy­borate, (NH4)2[B10O14(OH)4]·H2O

The structure of a new synthetic compound, di­ammonium tetra­hydroxy­deca­borate monohydrate, has been determined by single‐crystal X‐ray diffraction. It crystallizes in triclinic space group and all atoms occupy general sites. The title compound is composed of [B₁₀O₁₅(OH)₄]⁴⁻ ions as the fundamental building blocks, and these are linked end‐to‐end by sharing two common O atoms, thus producing infinite chains of composition [B₁₀O₁₄(OH)₄]_n^2n–. These chains are linked by hydrogen bonds, thus forming borate sheets. Water mol­ecules and ammonium ions between these sheets connect adjacent sheets via hydrogen bonds.     

Synthesis,Crystal Structure,Vibrational Spectroscopy and Thermal Behavior of the First Alkali Metal Hydrated Hexaborate： K2[B6O9（OH）2]

New hydrated potassium hexaborate K2[B6O9（OH）2] has been synthesized under mild solvothermal conditions. The structure was determined by single-crystal X-ray diffraction and further characterized by FT-IR, Rarnan spectra and DTA-TG. It crystallizes in the monoclinic system with space group P21/n, a=0.9036（2） nm, b=0.66052（18） nm, c=1.5997（4） nm, β=91.862（4）°, V=0.9543（4） nm^3 and Z=4. Its crystal structure consists of K-O polyhedra and 1-D stepped polyborate chains constructed by new [B6O9（OH）2]2- fundamental building blocks. 1-D polyborate chains contain 3,8-membered boron rings. Adjacent chains are further linked via H-bonding interactions into 2-D layers. The K^＋ cations reside not only between the layers but also in the 8-membered boron rings of the chains, compensating the negative charges of the borate chains and holding the layers together into the 3-D structure through bonding with oxygen atoms of the chains.     

Synthesis and characterization of processable polyborate precursors

Polyborates have been formed by disproportionation and polycondensation of trimethoxyboroxine and also of trimethoxyboroxine and boric acid. The crtiical role of stoichiometry in the formation of polyborates without requiring incorporation of a metal counter ion is revealed. The emphasis is on integration of this chemistry with fabrication processes. Incorporation of an appropriate linear organic polymer is shown to yield the required rheological and thermal characteristics in this regard. These polyborates are inferred to be suitable as precursors for boron nitride in geometrical forms that can be processed as supported structures. However, they are also determined to be unsuitable as precursors for boron nitride fibers, oriented or isotropic, primarily due to their low glass transition temperature.     

Novel supramolecular assemblies based on coordination of samarium cation to cucurbit[5]uril

In the present study, we introduce the coordination of samarium-Q[5] systems in the absence and presence of the third species, and the corresponding supramolecular assemblies are dependent upon the addition of the third species. In the absence of the third species, a samarium cation (nitrate salt) coordinates to a Q[5] molecule and forms a molecular bowl; in the presence of an organic molecule (hydroquinone), a one-dimensional polymer of ···Sm-Q[5]-Sm-Q[5]-Sm··· is formed through direct coordination of Sm cation to the portal carbonyl oxygens. In the presence of nickel cations (chloride salt), an infinite 1D supramolecular chain is constructed of samarium/cucurbit[5]uril molecular bowl through ion-dipole interaction and hydrogen binding; in addition, the stacking of the supramolecular chains forms a novel hexagonal open framework. Remarkably, in the presence of copper cations (chloride salt), Q[5]-based hexagonal netting sheets are constructed of 6-Q[5]-ring structures.     

Synthesis and theoretical analysis of samarium nanoparticles: perspectives in nuclear medicine

The use of lanthanides as radionuclides in nuclear medicine is well-known, because they can be used for detecting and treating cancerous tumors. Due to the fact that the doses are directly related to the number of unstable atoms involved, the possibility of obtaining controlled-size lanthanide nanoparticles opens a wide scope for their application in nuclear medicine. In this work, we report the synthesis of anew samarium nanoparticle by using the bioreduction method, where the pH conditions play an important role in the size control of the produced clusters. The nanoparticles were characterized by using an transmission electron microscope, in addition to the use of a quantum mechanical method to relate the atomic and electronic structures to the chemical selectivity, which allows us to predict a direct coordination between the DTPA-bis-biotin molecules with the samarium nanoparticles larger than 55 atoms. This work involves experimental and theoretical methods to propose a totally new application for nanotechnology in nuclear medicine.     

High‐pressure synthesis of ν‐DyBO3

ν‐Dysprosium borate (ν‐DyBO₃) was synthesized under conditions of high temperature and pressure in a Walker‐type multi‐anvil apparatus at 3 GPa and 1323 K. The compound is isotypic with the already known ν‐samarium and ν‐europium orthoborates.     

K3B6O10Cl: a new structure analogous to perovskite with a large second harmonic generation response and deep UV absorption edge

Introduction of the Cl(-) anion in the borate systems generates a new perovskite-like phase, K(3)B(6)O(10)Cl, which exhibits a large second harmonic response, about four times that of KH(2)PO(4) (KDP), and is transparent from the deep UV (180 nm) to middle-IR region. K(3)B(6)O(10)Cl crystallizes in the noncentrosymmetric and rhombohedral space group R3m. The structure consists of the A-site hexaborate [B(6)O(10)] groups and the BX(3) Cl-centered octahedral [ClK(6)] groups linked together through vertices to form the perovskite framework represented by ABX(3).     

Edta-linked 5p–4f trinuclear heterometallic complex: syntheses,X-ray structure and luminescent properties

A new heterometallic antimony–samarium complex, [Sb₂(edta)₂Sm(H₂O)₄]NO_3?·?3.55H₂O (edta?=?ethylenediaminetetraacetate) (1), has been synthesized and characterized by elemental analyses (EA), Fourier transform infrared spectroscopy, thermogravimetry-differential scanning calorimetry, and X-ray crystallography. The X-ray crystal structure analysis reveals that in 1 the bridging carboxylate-O,O′ of edta^4? connects samarium(III) and antimony(III) to form 2-D sheets. The 2-D sheets are further linked by bridging carboxylates from adjacent layers, resulting in 3-D coordination polymers. Complex 1 exhibits fluorescence in the solid state at room temperature.     

Syntheses and crystal structures of two new bismuth hydroxyl borates containing [Bi2O2]2+ layers: Bi2O2[B3O5(OH)] and Bi2O2[BO2(OH)

Two new bismuth hydroxyl borates, Bi(2)O(2)[B(3)O(5)(OH)] (I) and Bi(2)O(2)[BO(2)(OH)] (II), have been synthesized under hydrothermal conditions. Their structures were determined by single-crystal and powder X-ray diffraction data, respectively. Compound I crystallizes in the orthorhombic space group Pbca with the lattice constants of a = 6.0268(3) ?, b = 11.3635(6) ?, and c = 19.348(1) ?. Compound II crystallizes in the monoclinic space group Cm with the lattice constants of a = 5.4676(6) ?, b = 14.6643(5) ?, c = 3.9058(1) ?, and β = 135.587(6)°. The borate fundamental building block (FBB) in I is a three-ring unit [B(3)O(6)(OH)](4-), which connects one by one via sharing corners, forming an infinite zigzag chain along the a direction. The borate chains are further linked by hydrogen bonds, showing as a borate layer within the ab plane. The FBB in II is an isolated [BO(2)(OH)](2-) triangle, which links to two neighboring FBBs by strong hydrogen bonds, resulting in a borate chain along the a direction. Both compounds contain [Bi(2)O(2)](2+) layers, and the [Bi(2)O(2)](2+) layers combine with the corresponding borate layers alternatively, forming the whole structures. These two new bismuth borates are the first ones containing [Bi(2)O(2)](2+) layers in borates. The appearance of Bi(2)O(2)[BO(2)(OH)] (II) completes the series of compounds Bi(2)O(2)[BO(2)(OH)], Bi(2)O(2)CO(3), and Bi(2)O(2)[NO(3)(OH)] and the formation of Bi(2)O(2)[B(3)O(5)(OH)] provides another example in demonstrating the polymerization tendency of borate groups.     

Spin dimer analysis of the anisotropic spin exchange interactions in the distorted wolframite-type oxides CuWO4, CuMoO4-III, and Cu(Mo(0.25)W0.75)O4

The distorted wolframite-type oxides CuWO4 and CuMoO4-III have a structure in which CuO4 zigzag chains, made up of cis-edge-sharing CuO6 octahedra, run along the c-direction and hence exhibit low-dimensional magnetic properties. We examined the magnetic structures of these compounds and their isostructural analogue Cu(Mo(0.25)W0.75)O4 on the basis of the spin-orbital interaction energies calculated for their spin dimers. Our study shows that these compounds consist of two-dimensional (2D) magnetic sheets defined by one superexchange (intrachain Cu-O-Cu) and three super-superexchange (interchain Cu-O.O-Cu) paths, the strongly interacting spin units of these 2D magnetic sheets are the two-leg antiferromagnetic (AFM) ladder chains running along the (a + c)-direction, and the spin arrangement between adjacent AFM ladder chains leads to spin frustration. The similarities and differences in the magnetic structures of CuWO4, CuMoO4-III, and Cu(Mo(0.25)W0.75)O4 were discussed by examining how adjacent AFM ladder chains are coupled via the superexchange paths in the 2D magnetic sheets and how adjacent 2D magnetic sheets are coupled via another superexchange paths along the c-direction. Our study reproduces the experimental finding that the magnetic unit cell is doubled along the a-axis in CuWO(4) and along the c-axis in CuMoO4-III and predicts that the magnetic unit cell should be doubled along the a- and b-axes in Cu(Mo(0.25)W0.75)O4. In the understanding of the strength of a super-superexchange interaction, the importance of the geometrical factors controlling the overlap between the tails of magnetic orbitals was pointed out.     

Synthesis, characterization, and complexation of tetraarylborates with aromatic cations and their use in chemical sensors

Five aromatic borate anions, namely tetrakis(4-phenoxyphenyl)borate (1), tetrakis(biphenyl)borate (2), tetrakis(2-naphthyl)borate (3), tetrakis(4-phenylphenol)borate (4), and tetrakis(4-phenoxy)borate (5), have been prepared and tested as ion-recognition sites in chemical sensors for certain aromatic cations and metal ions. To gain further insight into the complexation of the cations, some complexes have been prepared and structurally characterized. The complexation behavior of 1 and 2 towards N-methylpyridinium (6), 1-ethyl-4-(methoxycarbonyl)pyridinium (7), tropylium (8), imidazolium (9), and 1-methylimidazolium (10) cations has been studied, and the stability constants of the complexes of 1 with cations 6 and 8 have been measured to compare them with the values for the previously studied complexes of tetraphenylborate. The structures of the borate anions and their complexes have been characterized by NMR and mass spectrometric methods. X-ray crystal structures have been determined for potassium tetrakis(4-phenoxyphenyl)borate (K(+)1), N-methylpyridinium tetrakis(4-phenoxyphenyl)borate (61), 1-ethyl-4-(methoxycarbonyl)pyridinium tetrakis(4-phenoxyphenyl)borate (71), tropylium tetrakis(4-phenoxyphenyl)borate (81), and imidazolium tetrakis(biphenyl)borate (92). The results show that borate derivatives are potential candidates for a completely new family of charged carriers for use in cation-selective electrodes.     

四（对甲氧基苯基）卟啉钐配合物的合成及光谱

利用自制的四（对甲氧基苯基）卟啉,与氯化钐在四氢呋喃溶剂中反应,得到一个未见文献报道的四（对甲氧基苯基）卟啉钐(Ⅲ)化合物。 利用UV-Vis、IR、¹H NMR 及元素分析测试技术对化合物结构进行了表征,并对其配位反应条件、配体及配合物的荧光性能进行了研究。 反应条件简单,易于操作,产率为62.4％。     

Edge Capping of 2D‐MXene Sheets with Polyanionic Salts To Mitigate Oxidation in Aqueous Colloidal Suspensions

MXenes have shown promise in myriad applications, such as energy storage, catalysis, EMI shielding, among many others. However, MXene oxidation in aqueous colloidal suspensions when stored in water at ambient conditions remains a challenge. It is now shown that by simply capping the edges of individual MXene flakes, Ti₃C₂T_z and V₂CT_z, by polyanions such as polyphosphates, polysilicates or polyborates, it is possible to quite significantly reduce their propensity for oxidation even when held in aerated water for weeks. This breakthrough resulted from the realization that the edges of MXene sheets are positively charged. It is thus an example of selectively functionalizing the edges differently from the MXene sheet surfaces.     

A series of chiral coordination polymers containing helicals assembled from a new chiral (R)-2-(4'-(4'-carboxybenzyloxy)phenoxy)propanoic acid: syntheses, structures and photoluminescent properties

Ten new chiral coordination polymers, namely, [Ni(L)(H(2)O)(2)] (1), [Co(L)(H(2)O)(2)] (2), [Cd(L)(H(2)O)] (3), [Cd(L)(phen)] (4), [Mn(2)(L)(2) (phen)(2)]·H(2)O (5), [Cd(2)(L)(2)(biim-4)(2)] (6), [Zn(2)(L)(2)(biim-4)(2)] (7), [Cd(L)(pbib)] (8), [Cd(L)(bbtz)] (9) and [Cd(L)(biim-6)] (10), where phen = 1,10-phenathroline, biim-4 = 1,1'-(1,4-butanediyl)bis(imidazole), pbib = 1,4-bis(imidazole-1-ylmethyl)benzene, bbtz = 1,4-bis(1,2,4-triazol-1-ylmethyl)benzene, biim-6 = 1,1'-(1,6-hexanedidyl)bis(imidazole), and H(2)L = (R)-2-(4'-(4'-carboxybenzyloxy)phenoxy)propanoic acid, have been synthesized under hydrothermal conditions. Their structures have been determined by single-crystal X-ray diffraction analyses and further characterized by infrared spectra (IR), powder X-ray diffraction (PXRD), elemental analyses and thermogravimetric (TG) analyses. Compounds 1 and 2 exhibit similar 1D left-handed helical chains, which are further extended into 3D supramolecular structures through O-H···O hydrogen-bonding interactions, respectively. Compound 3 shows a 2D double-layer architecture containing helical chains. Compound 4 features two types of 2D undulated sheets with helical chains, which are stacked in an ABAB fashion along the c direction. Compound 5 possesses a 1D double chain ribbon structure containing unusual meso-helical chains, which is linked by π-π interactions into a 2D supramolecular layer. These layers are further extended by hydrogen-bonding interactions to form a 3D supramolecular assembly. Compounds 6 and 7 are isostructural and exhibit 2D (4(4))-sql networks with helical chains. Neighboring sheets are further linked by C-H···O hydrogen-bonding interactions to generate 3D supramolecular architectures. Compounds 8-10 are isostructural and display 3D 3-fold interpenetrating diamond frameworks with helical chains. The effects of coordination modes of L anions, metal ions and N-donor ligands on the structures of the coordination polymers have been discussed. The luminescent properties of 3, 4 and 6-10 have also been investigated in detail.     

Evaluation of a new linker system cleaved using samarium(II) iodide. Application in the solid phase synthesis of carbonyl compounds

A new linker design for solid phase synthesis has been developed that is cleaved under mild, neutral conditions using samarium(II) iodide. The feasibility of the linker approach has been illustrated in the solid phase synthesis of ketones and amides using an oxygen linker. Insights into the mechanism of the samarium(II) iodide cleavage reaction are described and the potential of a sequential cleavage carbon-carbon bond forming process is assessed.     

Structure determination and characterization of two rare-earth molybdenum borate compounds: LnMoBO(6) (Ln = La, Ce)

The structural, optical, and electronic properties of two rare-earth molybdenum borate compounds, LnMoBO(6) (Ln = La, Ce), have been investigated by means of single-crystal X-ray diffraction, elemental analyses, and spectral measurements, as well as calculations of energy band structures, density of states, and optical response functions by the density functional method. The title compounds, which crystallize in monoclinic space group P2(1)/c, possess a similar network of interconnected [Ce(2)(MoO(4))(2)](2+) chains and [BO(2)](-) wavy chains. Novel 1D molybdenum oxide chains are contained in their three-dimensional (3D) networks. The calculated results of crystal energy band structure by the density functional theory (DFT) method show that the solid-state compound LaMoBO(6) is a semiconductor with indirect band gaps.     

Anion-dependent self-assembly of silver(I) and diaminotriazines to coordination polymers: non-covalent bonds and role interchange between silver and hydrogen bonds

New coordination polymers have been obtained by the self-assembly of silver salts AgX (X = BF 4, PF 6, CF 3SO 3) and 2,4-diamino-6-R-1,3,5-triazines L (R = phenyl and p-tolyl) of formulas AgLX ( 1- 6). A complex of different stoichiometry, [Ag 3L 2(H 2O)(acetone) 2](BF 4) 3, 7 (R = phenyl), has also been synthesized. The three-dimensional structures of five compounds have been determined by X-ray diffraction studies. For the AgLX complexes, when X = BF 4 and R = phenyl or p-tolyl, chiral chains with alternating Ag and L are formed. The chains are cross-linked by the counteranions in a three-dimensional fashion through hydrogen bonds and weak Ag...F interactions giving rise to a structure with solvent-filled channels. Different and more compact structures have been found when the counteranion is CF 3SO 3 (OTf). When R = phenyl, sheets are formed which consist of [Ag 2(OTf) 2L 2] units with double triflate bridges and which contain columns of pi-pi stacked arenes. Hydrogen bonds connect the sheets. When AgOTf is used and R is p-tolyl, a different and unusual ladderlike structure is obtained in which the rungs are double asymmetric bridges consisting of the triflate groups bonded to Ag in kappa (2) O,mu 2- O and kappa (1) O,mu 2- O fashion. The ladders are parallel to each other and are mutually linked by N-H...N hydrogen bonds to give a 3D architecture. A very similar ladderlike structure has been found for 7 but with a water molecule and a BF 4 (-) group acting as bridges. The role played by the hydrogen bonds in complex 6 to form the 3-D structure is played in 7 by [Ag(acetone) 2] fragments. The noncovalent interactions play an important role in the different solid-state 3D structures. The behavior of the new derivatives in solution has also been analyzed. A new species has been detected at low temperatures, and this exhibits restricted rotation of the phenyl ring.     

Structural changes in the molecular sheets along (hk0) planes derived from cellulose Iβ by molecular dynamics simulations

We studied the stability of molecular sheets with four cellotetraoses in an aqueous environment by molecular dynamics simulation to identify the molecular details of first structure as one of the possibilities in the course of crystallization of cellulose I. After simulation, the molecular sheets formed by van der Waals forces along the (11?0) and (110) crystal plane did not change their structures in an aqueous environment, whereas the other ones formed by hydrogen bonds along the (100) and (200) crystal plane changed into a van der Waals associated molecular sheet, similar to the former. These simulated molecular sheets formed by van der Waals forces were structurally stable in water because of their hydrophilic exterior and hydrophobic interior. Therefore, if the molecular sheet structures are formed in the real system, the sheets formed by van der Waals forces are probably the initial structure of crystallization. A close analysis indicated that these sheets could be classified into two groups in terms of the hydrogen bonding networks, camber angle, and main and side chain conformations. One group was the molecular sheets corresponding to the (110) after simulation. This sheet is probably rigid because intramolecular hydrogen bonds of the chains in the sheet are highly developed. The other group was the molecular sheets corresponding to (200), (100), and (11?0) crystal plane: the chains in these sheets seemed to be rather flexible due to their moderately developed intramolecular hydrogen bonds.