Water-based Synthesis and Properties of a Scandium 1,4-Naphthalenedicarboxylate

A new scandium naphthalenedicarboxylate with the framework composition [Sc₂(1,4-NDC)₃] (H₂-1,4-NDC = 1,4-naphthalenedicarboxylic acid) was obtained under hydrothermal synthesis conditions. A structure model could be developed by a combination of 3D electron diffraction measurements and computationally assisted structure determination, which was further validated by a good agreement with the experimental powder X-ray diffraction pattern. The structure consists of isolated ScO₆ octahedra interconnected by the carboxylate groups of linker molecules to form chains. These chains are connected by the naphthalene-moieties to form a three-dimensional framework with square-shaped pores and the organic group pointing into the pores. Although very similar synthesis conditions were chosen, [Sc₂(1,4-NDC)₃] is not isostructural to aluminum naphthalenedicarboxylate [Al(OH)(1,4-NDC)], which crystallizes in a MIL-53 type structure. This can be traced back to the different inorganic building units that are observed. The compound was thoroughly characterized by elemental analysis, IR spectroscopy, sorption measurements, thermogravimetric analysis and luminescence measurements. [Sc₂(1,4-NDC)₃] exhibits a high thermal stability and a ligand-based blue luminescence in the solid state at room temperature.     

Real‐time Probing the Formation of [M(2,2‐bipyridine)2(NO3)3] (M = Ce,La, Tb) Complexes and Influence of Synthesis Parameters

Despite the strong technological importance of lanthanide complexes, their formation processes are rarely investigated. This work is dedicated to determining the influence of synthesis parameters on the formation of [Ce(bipy)₂(NO₃)₃] as well as Ce³⁺‐ and Tb³⁺‐substituted [La(bipy)₂(NO₃)₃] (bipy = 2,2′‐bipyridine) complexes. To this end, we performed in situ luminescence measurements, synchrotron‐based X‐ray diffraction (XRD) analysis, infrared spectroscopy (IR), and measured pH value and/or ion conductivity during their synthesis process under real reaction conditions. For the [Ce(bipy)₂(NO₃)₃] complex, the in situ luminescence measurements initially presented a broad emission band at 490 nm, assigned to the 5d→4f Ce³⁺ ions within the ethanolic solvation shell. Upon the addition of bipy, a red shift to 700 nm was observed. This shift was attributed to the changes in the environment of the Ce³⁺ ions, indicating their desolvation and incorporation into the [Ce(bipy)₂(NO₃)₃] complex. The induction time was reduced from 8 to 3.5 min, by increasing the reactant concentration by threefold. In contrast, [La(bipy)₂(NO₃)₃] crystallized within days instead of minutes, unless influenced by high Ce³⁺ and Tb³⁺ concentrations. Monitoring and controlling the influence of the reaction parameters on the structure of emissive complexes is important for the development of rational synthesis approaches and optimization of their structure‐related properties like luminescence.     

Is there a common reaction pathway for chromium sulfides as anodes in sodium-ion batteries? A case study about sodium storage properties of MCr2S4 (M = Cr,Ti, Fe)

Journal of Solid State Electrochemistry - We present new insights into the electrochemical properties of three metal sulfides MCr2S4 (M = Cr, Ti, Fe) probed as anode materials in...     

A Coordination Polymer based on Interconnection of Thioantimonate(III) and [Mn(terpy)]2+ Complexes: Synthesis,Crystal Structure,and Properties of {[(Mn(terpy))2Sb4S8]·0.5H2O}n

Applying Schlippe's salt, Na₃SbS₄ · 9H₂O, in the presence of the in-situ formed [Mn(terpy)]²⁺ complex (terpy = 2,2':6',2''-terpyridine) the new compound {[(Mn(terpy))₂Sb₄S₈] · 0.5H₂O}_n ( I ) could be obtained under solvothermal conditions. Interestingly, in the crystal structure the two unique Mn²⁺ cations adopt different environments to form a MnN₃S₃ octahedron and a MnN₃S₂ trigonal pyramid. The trigonal pyramidal SbS₃^3– anions share common edges yielding a Sb₈S₈ ring. Covalent bonds between Mn²⁺ and S^2– generate MnSb₂S₃ and Mn₂Sb₄S₆ heterocycles. The Sb₈S₈ and Mn₂Sb₄S₆ rings are condensed to form a chain. The MnN₃S₃ octahedron and the MnN₃S₂ polyhedron share a common S^2– anion and antiferromagnetic properties are observed mediated by superexchange interactions. {[(Mn(terpy))₂Sb₄S₈] · 0.5H₂O}_n shows luminescence in the blue-green spectral range, assigned to combined contributions from Mn²⁺ ions and from the organic ligand.     

Magnetism and Afterglow United: Synthesis of Novel Double Core–Shell Eu2+-Doped Bifunctional Nanoparticles

Afterglow–magnetic nanoparticles (NPs) offer enormous potential for bioimaging applications, as they can be manipulated by a magnetic field, as well as emitting light after irradiation with an excitation source, thus distinguishing themselves from fluorescent living cells. In this work, a novel double core–shell strategy is presented, uniting co-precipitation with combustion synthesis routes to combine an Fe₃O₄ magnetic core (≈15 nm) with an afterglow SrAl₂O₄:Eu²⁺,Dy³⁺ outer coat (≈10 nm), and applying a SiO₂ protective middle layer (≈16 nm) to reduce the luminescence quenching caused by the Fe core ions. The resulting Fe₃O₄@SiO₂@SrAl₂O₄:Eu²⁺,Dy³⁺ NPs emit green light attributed to the 4f⁶5d¹→4f⁷(⁸S_7/2) transition of Eu²⁺ under UV radiation and for a few seconds afterwards. This bifunctional nanocomposite can potentially be applied for the detection and separation of cells or diagnostically relevant molecules.     

Synthesis,Structures, Thermal and Luminescence Properties of Zn and Cd Halide Coordination Polymers with 2-Cyanopyrazine

Reaction of MX₂ (M = Cd, Zn; X = Cl, Br, I) with 2-cyanopyrazine leads to the formation of compounds with the composition CdX₂(2-cyanopyrazine)₂ (X = Cl; CdCl , X = Br; CdBr and X = I; CdI ) and ZnX₂(2-cyanopyrazine)₂ (X = Cl; ZnCl , X = Br; ZnBr and X = I; ZnI/I ). In the crystal structures of the Cd compounds and in ZnCl , the metal cations are octahedrally coordinated and are linked into chains by the halide anions via common edges. In contrast, in the crystal structures of ZnBr and ZnI/I the metal cations are tetrahedrally coordinated into discrete complexes. Further investigations show that a second modification of ZnCl₂(2-cyanopyrazine)₂ exists ( ZnI/II ), which is formed by kinetic control. The thermal properties of the 2-cyanopyrazine rich compounds were investigated by TG-DTA and temperature dependent XRPD measurements. Upon heating the Cd compounds, all 2-cyanopyrazine ligands are removed in a single step with no indication of the formation of a 2-cyanopyrazine deficient phase. A similar behavior is observed for ZnI , whereas for ZnCl and ZnBr , TG-DTA measurements suggest the formation of a 2-cyanopyrazine deficient phase that, in case of ZnBr , cannot be isolated and, for ZnCl , cannot be obtained pure. The emission of these compounds is shifted from the blue to orange depending on the crystal structure and the nature of the halide anion.     

Re-investigation of Barium-Gold(I)-Tetra-Thiostannate(IV), Ba[Au2SnS4], with Short AuI···AuI Separation Showing Luminescence Properties

New investigations combining single crystal- and synchrotron-based powder X-ray diffraction data revealed that Ba[Au₂SnS₄] crystallizes in the orthorhombic crystal system in space group C222₁ instead of P2₁2₁2 as reported earlier. While the principle crystal structure is not altered, there are significant differences of the interatomic distances Au-S and Sn-S. A salient property of this crystal structure is the partial framework composed of AuS₂ dumbbells and SnS₄ tetrahedra to form chains [(Au₂SnS₄)^2–]_∞ propagating in the [100] direction. Within the chains a short Au ··· Au separation of 2.9538(13) Å is observed, while the interchain Au ··· Au separation is longer at 3.383 Å. The Ba²⁺ cation is eightfold coordinated by S^2– anions in a distorted bicapped trigonal prismatic environment BaS₈. These polyhedra share all S^2– anions thus generating a three-dimensional network. This connection Scheme generates voids along [100] hosting [(Au₂SnS₄)^2–]_∞ chains. In addition, the compound has been shown to be luminescent at the blue-green spectral range with emission maximum at approximately 21000 cm^–1.     

Surface‐Anchored MOF‐Based Photonic Antennae

The loading of a metal‐organic framework (MOF), [Cu₃(btc)₂xH₂O] HKUST‐1, with europium β‐diketonate complexes is studied with the goal to using the porous molecular framework as a photonic antenna. Whereas loading of HKUST‐1 powder particles produced via the conventional solvothermal synthesis method was strongly hindered, for HKUST‐1 SURMOFs, thin MOF films fabricated using the liquid phase epitaxy method, a high filling factor can be achieved. The optical properties of the HKUST‐1‐MOFs before and after loading were analysed with the aid of luminescence spectroscopy. Careful analysis of the absorption spectra reveals the presence of an effective energy transfer between the HKUST‐1 framework and the Eu³⁺ centers.