Synthesis, Thermal, Structural Analyses and Photoluminescent Properties of a New Family of Malonate-containing Lanthanide(III) Coordination Polymers

X.C is grateful for the financial support from the National Natural Science Foundation of China (Grants 21771057). S. H acknowledges Higher Education Commission of Pakistan for IRSIP fellowship and Henan Normal University for postdoctoral support. The authors from KKU also extend their appreciation to Deanship of Scientific Research at King Khalid University for support through Research Groups Project under grant number (R.G.P.2/17/40). We also acknowledge the technical support of Dr. Abdullah for computations.Peer reviewedPublisher PD

Negative differential conductance effect and electrical anisotropy of 2D ZrB2 monolayers

Two-dimensional (2D) metal-diboride ZrB2 monolayers was predicted theoretically as a stable new electronic material [A. Lopez-Bezanilla, Phys. Rev. Mater., 2018, 2, 011002 (R)]. Here, we investigate its electronic transport properties along the zigzag (z-ZrB2) and armchair (a-ZrB2) directions, using the density functional theory and non-equilibrium Green's function methods. Under low biases, the 2D ZrB2 shows a similar electrical transport along zigzag and armchair directions as electric current propagates mostly via the metallic Zr-Zr bonds. However, it shows an electrical anistropy under high biases, and its I-V curves along zigzag and armchair directions diverge as the bias voltage is higher than 1.4 V, as more directional B-B transmission channels are opened. Importantly, both z-ZrB2 and a-ZrB2 show a pronounced negative differential conductance (NDC) effect and hence they can be promising for the use in NDC-based nanodevices

Synthesis, thermal, structural analyses and photoluminescent properties of a new family of malonate-containing lanthanide(III) coordination polymers

Five new Lanthanide(III) complexes of malonic acid (HOOC-CH2-COOH); {[Gd(C3H2O4)(H2O)4]•NO3}n (1), {[Tb(C3H2O4)(H2O)4]•NO3}n (2),{[Ho(C3H2O4)(H2O)4]•NO3}n (3), [Er(C3H2O4)(C3H3O4)(H2O)2]n (4) and {[Eu2(C3H2O4)2(C3H3O4)2(H2O)6]•4H2O}n (5) are synthesized and characterized by elemental, infrared spectral and thermal analyses. The structures of compounds 1-5 are determined by single crystal X-ray diffraction technique. The X-ray analysis reveals that compounds 1, 2 and 3 are isostructural and crystallized in the orthorhombic space group Pmn21. The lanthanide(III) ions are coordinated by four carboxylate and four water oxygen atoms adopting a distorted square antiprism geometry. The LnO8 square antiprisms are linked into infinite layers by malonate (C3H2O42–) dianions sandwiching sheets of nitrate counter ions. Compound 4 contains ErO8 square antiprisms linked into a two-dimensional network by hydrogen malonate (C3H3O4–) anions and malonate dianions. The europium complex, 5 is dinuclear having the two europium(III) ions (Eu1 and Eu2) bridged by carboxylate groups of hydrogen malonate ligands. The europium ions in 5 are nine-coordinate and exhibit a distorted monocapped square antiprism geometry. All the structures are consolidated by O–H∙∙∙O hydrogen bonds. The photoluminescence spectra of 1-5 exhibit characteristics emission in the visible region. The IR spectra and thermal data are consistent with the structural results. The room-temperature effective magnetic moments for 1–4 are in good agreement with those expected for the free ions, while the data for 5 indicates that low-lying excited states contribute to the observed moment. The compound 1 was further subjected to quantum computational calculations to explore its optoelectronic properties including; density of states (DOS), dielectric function, refractive index, extinction coefficient and absorption spectrum, to highlight the possible applications of such materials in the optoelectronics

Synthesis, Crystal Structures and Photoluminescent Properties of One-Dimensional Europium(III)- and Terbium(III)-Glutarate Coordination Polymers, and Their Applications for the Sensing of Fe3+ and Nitroaromatics

Acknowledgements X.C. thanks the National Natural Science Foundation of China (Grants No. 1771057 and U1804253). S.H. is grateful to Henan Normal University for a postdoctoral fellowship. Supplementary data CCDC numbers 1919755 and 1919756 for 1 and 2 respectively, contain the crystal data of this article. These data are available from Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/datarequest/cif. The supporting material of this article can be download from the journal webpage.Peer reviewedPublisher PD

Synthesis, crystal structures and photoluminescent properties of one-dimensional Europium(III)- and Terbium(III)-glutarate coordination polymers, and their applications for the sensing of Fe3+ and nitroaromatics

Two lanthanide–glutarate coordination polymers, viz.: {[Eu(C5H6O4)(H2O)4]Cl}n, (1) and [Tb(C5H7O4)(C5H6O4)(H2O)2]n, (2) have been synthesized and characterized by IR spectroscopy, thermogravimetric analysis and X-ray crystallography. In 1, the Eu(III) ions are coordinated by four O atoms from two bidentate chelating carboxylates, one O atom from a bridging carboxylate and four O atoms from water molecules adopting an EuO9 muffin shaped coordination geometry. In 2, the Tb(III) ions are coordinated by six O atoms from three bidentate chelating carboxylates, one O atom from a bridging carboxylate and two O atoms from water molecules to generate muffin like TbO9 polyhedron. In both compounds, the metal polyhedra share edges, producing centrosymmetric Ln2O2 diamonds, and are linked into [001] chains by bridging glutarate di-anions. The crystal structures are stabilized by O–HO and O–HCl hydrogen bonds in 1, and O–HO hydrogen bonds in 2. Compound 1 exhibits a red emission attributed to the 5D0 → 7FJ (J = 1–4) transitions of the Eu(III) ion, whereas 2 displays green emission corresponding to the 5D4 → 7FJ (J = 0–6) transitions of the Tb(III) ion. Both the compounds exhibit high sensitivity and selectivity for Fe3+ ions due to luminescence quenching compared to other metal ions, which include; Na+, Mg2+, Al3+, Cr3+, Mn2+, Fe2+, Co2+, Ni2+, Zn2+ and Cd2+. Compounds 1 and 2 also show high luminescence quenching sensitivity for 4-nitrophenol over the other aromatic and nitroaromatic compounds, namely; bromobenzene, 1,3-dimethylbenzene, nitrobenzene, 4-nitrotolune, 4-nitrophenol, 2,6-dinitrophenol and 2,4,6-trinitrophenol

Redetermination of di-μ-hydrido-hexa­hydridotetra­kis(tetra­hydro­furan)dialuminium(III)magnesium(II)

The structure of the title compound, [Mg(AlH4)2(C4H8O)4], has been redetermined at 150 K. The MgII ion is hexa­coordinated to four tetra­hydro­furan (THF) ligands, and two AlH4 − anions through bridging H atoms. The Al—H distances are more precise compared to those previously determined [Nöth et al. (1995 ▶). Chem. Ber. 128, 999–1006; Fichtner & Fuhr (2002 ▶). J. Alloys Compd, 345, 386–396]. The mol­ecule has twofold rotation symmetry

Silver-modified polyniobotungstate for the visible light-induced simultaneous cleavage of C–C and C–N bonds

Silver-modified polyniobotungstate based on Nb/W mixed-addendum polyoxometalate with formula Ag9[P2W15Nb3O62]·21H2O (Ag-Nb/W) was synthesized and then characterized by various analytical and spectral techniques. Ag-Nb/W was proven to be an efficient photocatalyst for the oxidative ring opening of 2-phenylimidazo[1,2-a]pyridine via the simultaneous cleavage of C–C and C–N bonds. Under visible light (430–440 nm) and with oxygen as an oxidant at room temperature, Ag-Nb/W can catalyze the rapid transformation of various 2-phenylimidazo[1,2-a]pyridine derivatives to produce the corresponding oxidative ring-opening product N-(pyridin-2-yl) amides in good isolated yields ranging from 65% to 78%. As a heterogeneous photocatalyst, Ag-Nb/W showed excellent sustainability and recyclability in the recycling experiments. Infrared (IR) spectroscopy and X-ray diffraction (XRD) analysis indicated that Ag-Nb/W could retain its integrity after catalysis. A possible mechanism involving the singlet oxygen for the catalytic reaction was proposed

Construction of an efficient Claviceps paspali cell factory for lysergic acid production

Lysergic acid (LA) is the key precursor of ergot alkaloids, and its derivatives have been used extensively for the treatment of neurological disorders. However, the poor fermentation efficiency limited its industrial application. At the same time, the hardship of genetic manipulation has hindered the metabolic engineering of Claviceps strains to improve the LA titer further. In this study, an efficient genetic manipulation system based on the protoplast-mediated transformation was established in the industrial strain Claviceps paspali. On this basis, the gene lpsB located in the ergot alkaloids biosynthetic gene cluster was deleted to construct the LA-producing cell factory. Plackett-Burman and Box-Behnken designs were used in shaking flasks, achieving an optimal fermentation medium composition. The final titer of LA and iso-lysergic acid (ILA) reached 3.7 g·L−1, which was 4.6 times higher than that in the initial medium. Our work provides an efficient strategy for the biosynthesis of LA and ILA and lays the groundwork for its industrial production

Desolvation and Dehydrogenation of Solvated Magnesium Salts of Dodecahydrododecaborate: Relationship between Structure and Thermal Decomposition

Attempts to synthesize solvent-free MgB_(12)H_(12) by heating various solvated forms (H_2O, NH_3, and CH_3OH) of the salt failed because of the competition between desolvation and dehydrogenation. This competition has been studied by thermogravimetric analysis (TGA) and temperature-programmed desorption (TPD). Products were characterized by IR, solution- and solid-state NMR spectroscopy, elemental analysis, and single-crystal or powder X-ray diffraction analysis. For hydrated salts, thermal decomposition proceeded in three stages, loss of water to form first hexahydrated then trihydrated, and finally loss of water and hydrogen to form polyhydroxylated complexes. For partially ammoniated salts, two stages of thermal decomposition were observed as ammonia and hydrogen were released with weight loss first of 14 % and then 5.5 %. Thermal decomposition of methanolated salts proceeded through a single step with a total weight loss of 32 % with the release of methanol, methane, and hydrogen. All the gaseous products of thermal decomposition were characterized by using mass spectrometry. Residual solid materials were characterized by solid-state 11B magic-angle spinning (MAS) NMR spectroscopy and X-ray powder diffraction analysis by which the molecular structures of hexahydrated and trihydrated complexes were solved. Both hydrogen and dihydrogen bonds were observed in structures of [Mg(H_2O_6B_(12)H_(12)]⋅6 H_2O and [Mg(CH_3OH)_(6)B_(12)H_(12)]⋅6 CH_3OH, which were determined by single-crystal X-ray diffraction analysis. The structural factors influencing thermal decomposition behavior are identified and discussed. The dependence of dehydrogenation on the formation of dihydrogen bonds may be an important consideration in the design of solid-state hydrogen storage materials