Automated Sequential‐injection Chemiluminescence Determination of Glucosamine Sulphate via Luminol‐Hydrogen Peroxide System

A highly sensitive automated sequential‐injection chemiluminescence (SIA‐CL) method for determination of glucosamine sulphate (GLS) was developed. The goal of the present work is the evaluation of the enhancement effect of the investigated drug glucosamine sulphate on the chemiluminescence reaction between luminol and H₂O₂ in alkaline medium of 1.0 × 10^?2 mol L^?1 sodium hydroxide at pH 11. The experimental conditions affecting the CL reaction such as the sequence of the reagents, concentrations, flow rate and aspirated volumes of reactants were systematically investigated and optimized. Under optimum conditions 50 μL of 1.0 × 10^?3 mol L^?1 luminol, 30 μL of a GLS test solution and 50 μL of 1.0 × 10^?2 mol L^?1 H₂O₂ were used and the luminescing zone was pushed into the detector at a flow rate 100 μL s^?1. The proposed method recorded high sensitivity, accuracy and simplicity that could be clarified as linear concentration range 1.0‐2000 ng mL^?1 with rectilinear part (r = 0.9992, n = 9) and limit of detection 0.3 ng mL^?1, along with relative standard deviation 1.3%. It was found that the developed method can be used directly to determine the investigated drug GLS in its pharmaceutical dosage forms and in spiked serum and urine by diluting the samples for a 1000 fold. The obtained results were statistically analyzed and compared with those obtained by the reported method.     

A Novel Chemiluminescence Immunoassay Using Solid‐Phase Antigen for Free 17β‐Estradiol in Human Serum

A high‐performance chemiluminescence immunoassay, with long‐term durability, good precision and time‐saving, was proposed for the detection of free 17β‐estradiol (E₂) in human serum. Ninety‐six microplates were coated with bovine serum albumin conjugated E₂ antigen as solid phase for the immunoassay. The E₂‐BSA antigen coated on the microplate and the E₂ antigen in the sample competed for the binding sites on the horseradish peroxidase (HRP) labeled anti‐E₂ antibody. Chemiluminescence reaction was subsequently carried out by HRP catalyzing luminol‐H₂O₂ substrates, and the chemiluminescence intensity was inversely proportional to the amount of analyte in human sera samples. The concentration of immunoreagents, immunoreaction time, and other relevant variable conditions upon the immunoassay were studied and optimized. The proposed method exhibited detection limit as low as 5.94×10^?3 µg·L^?1 in a linear detection range from 0.01 to 1.00 µg·L^?1, good recoveries between 105% and 108%, and high precision with intra‐ and inter‐assay coefficients between 7.9% and 14.3%.     

A two‐dimensional cadmium(II) coordination polymer constructed from 4‐carboxy‐1‐(4‐carboxylatobenzyl)‐2‐propyl‐1H‐imidazole‐5‐carboxylate and 1‐(4‐carboxylatobenzyl)‐2‐propyl‐1H‐imidazole‐4‐carboxylate ligands

Crystals of poly[[aqua[μ₃‐4‐carboxy‐1‐(4‐carboxylatobenzyl)‐2‐propyl‐1H‐imidazole‐5‐carboxylato‐κ⁵O¹O^1′:N³,O⁴:O⁵][μ₄‐1‐(4‐carboxylatobenzyl)‐2‐propyl‐1H‐imidazole‐4‐carboxylato‐κ⁷N³,O⁴:O⁴,O^4′:O¹,O^1′:O¹]cadmium(II)] monohydrate], {[Cd₂(C₁₅H₁₄N₂O₄)(C₁₆H₁₄N₂O₆)(H₂O)]·H₂O}_n or {[Cd₂(Hcpimda)(cpima)(H₂O)]·H₂O}_n, (I), were obtained from 1‐(4‐carboxybenzyl)‐2‐propyl‐1H‐imidazole‐4,5‐dicarboxylic acid (H₃cpimda) and cadmium(II) chloride under hydrothermal conditions. The structure indicates that in‐situ decarboxylation of H₃cpimda occurred during the synthesis process. The asymmetric unit consists of two Cd²⁺ centres, one 4‐carboxy‐1‐(4‐carboxylatobenzyl)‐2‐propyl‐1H‐imidazole‐5‐carboxylate (Hcpimda²⁻) anion, one 1‐(4‐carboxylatobenzyl)‐2‐propyl‐1H‐imidazole‐4‐carboxylate (cpima²⁻) anion, one coordinated water molecule and one lattice water molecule. One Cd²⁺ centre, i.e. Cd1, is hexacoordinated and displays a slightly distorted octahedral CdN₂O₄ geometry. The other Cd centre, i.e. Cd2, is coordinated by seven O atoms originating from one Hcpimda²⁻ ligand and three cpima²⁻ ligands. This Cd²⁺ centre can be described as having a distorted capped octahedral coordination geometry. Two carboxylate groups of the benzoate moieties of two cpima²⁻ ligands bridge between Cd2 centres to generate [Cd₂O₂] units, which are further linked by two cpima²⁻ ligands to produce one‐dimensional (1D) infinite chains based around large 26‐membered rings. Meanwhile, adjacent Cd1 centres are linked by Hcpimda²⁻ ligands to generate 1D zigzag chains. The two types of chains are linked through a μ₂‐η² bidentate bridging mode from an O atom of an imidazole carboxylate unit of cpima²⁻ to give a two‐dimensional (2D) coordination polymer. The simplified 2D net structure can be described as a 3,6‐coordinated net which has a (4³)₂(4⁶.6⁶.8³) topology. Furthermore, the FT–IR spectroscopic properties, photoluminescence properties, powder X‐ray diffraction (PXRD) pattern and thermogravimetric behaviour of the polymer have been investigated.     

Benzo‐cis‐cyclo­hexano‐14‐crown‐4 and its lithium thio­cyanate complex

The structures of a 14‐crown‐4 ether containing both benzo and cyclo­hexano substituents, 2,6,13,17‐tetraoxatricyclo‐[16.4.0.0^7,12]docosa‐1(18),19,21‐triene, C₁₈H₂₆O₄, and its lith­ium complex, [2,6,13,17‐tetraoxatricyclo[16.4.0.0^7,12]docosa‐1(18),19,21‐triene‐κ⁴O](thio­cyanato‐N)­lith­ium(I), [Li(NCS)‐(C₁₈H₂₆O₄)], are presented. The conformation of the free crown, (I), is not preorganized for cation binding, as its donor dipoles are oriented towards opposite sides of the crown ring. The Li⁺‐crown complex, (II), exhibits two formula units in the asymmetric unit. The binding conformation observed in (II) does not completely reorient the dipoles to one point, resulting in a long Li—O bond length [2.068 (5) and 2.073 (5) Å].     

Bis­(di‐μ‐acetato‐aqua{2‐[N‐ethyl‐N‐(2‐hydroxy‐4‐methyl­benzyl)­amino­methyl]‐1‐methyl­benz­imid­az­ole}­nickel)­nickel(II) tetra­hy­drate

The previously unknown title compound, tetra‐μ‐ace­tato‐1:2κ²O;1:2κ²O:O′;­2:3κ²O;­2:3κ²O:O′‐di­aqua‐1κO,3κO‐bis­(μ‐2‐{[N‐ethyl‐N‐(2‐hy­droxy‐5‐methylbenzyl)­am­ino]­methyl}‐1‐methyl‐1H‐benz­imid­az­ole)‐1κ³N³,N,O:2κO;3κ³N³,N,O:2κO‐tri­nickel(II) tetra­hy­drate, [Ni₃(C₁₈H₂₂N₃O)₂(C₂H₃O₂)₄(H₂O)₂]·­4H₂O, (I), is a centrosymmetric linear trinuclear nickel(II) complex, where the Ni atoms are in an octahedral coordination and the ligand heteroatoms act so as to model amino acid residues.     

A two‐dimensional mixed‐valence CuII/CuI coordination polymer constructed from 2‐(pyridin‐3‐yl)‐1H‐imidazole‐4,5‐dicarboxylate

Coordination polymers are a thriving class of functional solid‐state materials and there have been noticeable efforts and progress toward designing periodic functional structures with desired geometrical attributes and chemical properties for targeted applications. Self‐assembly of metal ions and organic ligands is one of the most efficient and widely utilized methods for the construction of CPs under hydro(solvo)thermal conditions. 2‐(Pyridin‐3‐yl)‐1H‐imidazole‐4,5‐dicarboxylate (HPIDC²⁻) has been proven to be an excellent multidentate ligand due to its multiple deprotonation and coordination modes. Crystals of poly[aquabis[μ₃‐5‐carboxy‐2‐(pyridin‐3‐yl)‐1H‐imidazole‐4‐carboxylato‐κ⁵N¹,O⁵:N³,O⁴:N²]copper(II)dicopper(I)], [Cu^IICu^I₂(C₁₀H₅N₃O₄)₂(H₂O)]_n, (I), were obtained from 2‐(pyridin‐3‐yl)‐1H‐imidazole‐4,5‐dicarboxylic acid (H₃PIDC) and copper(II) chloride under hydrothermal conditions. The asymmetric unit consists of one independent Cu^II ion, two Cu^I ions, two HPIDC²⁻ ligands and one coordinated water molecule. The Cu^II centre displays a square‐pyramidal geometry (CuN₂O₃), with two N,O‐chelating HPIDC²⁻ ligands occupying the basal plane in a trans geometry and one O atom from a coordinated water molecule in the axial position. The Cu^I atoms adopt three‐coordinated Y‐shaped coordinations. In each [CuN₂O] unit, deprotonated HPIDC²⁻ acts as an N,O‐chelating ligand, and a symmetry‐equivalent HPIDC²⁻ ligand acts as an N‐atom donor via the pyridine group. The HPIDC²⁻ ligands in the polymer serve as T‐shaped 3‐connectors and adopt a μ₃‐κ²N,O:κ²N′,O′:κN′′‐coordination mode, linking one Cu^II and two Cu^I cations. The Cu cations are arranged in one‐dimensional –Cu1–Cu2–Cu3– chains along the [001] direction. Further crosslinking of these chains by HPIDC²⁻ ligands along the b axis in a –Cu2–HPIDC²⁻–Cu3–HPIDC²⁻–Cu1– sequence results in a two‐dimensional polymer in the (100) plane. The resulting (2,3)‐connected net has a (12³)₂(12)₃ topology. Powder X‐ray diffraction confirmed the phase purity for (I), and susceptibilty measurements indicated a very weak ferromagnetic behaviour. A thermogravimetric analysis shows the loss of the apical aqua ligand before decomposition of the title compound.     

Formation of lithium,sodium and potassium complexes with 1,3,5‐triamino‐1,3,5‐trideoxy‐cis‐inositol (taci)

Single crystals of (1,3‐diamino‐5‐azaniumyl‐1,3,5‐trideoxy‐cis‐inositol‐κ³O²,O⁴,O⁶)(1,3,5‐triamino‐1,3,5‐trideoxy‐cis‐inositol‐κ³O²,O⁴,O⁶)lithium(I) diiodide dihydrate, [Li(C₆H₁₆N₃O₃)(C₆H₁₅N₃O₃)]I₂·2H₂O or [Li(Htaci)(taci)]I₂·2H₂O (taci is 1,3,5‐triamino‐1,3,5‐trideoxy‐cis‐inositol), (I), bis(1,3,5‐triamino‐1,3,5‐trideoxy‐cis‐inositol‐κ³O²,O⁴,O⁶)sodium(I) iodide, [Na(C₆H₁₅N₃O₃)₂]I or [Na(taci)₂]I, (II), and bis(1,3,5‐triamino‐1,3,5‐trideoxy‐cis‐inositol‐κ³O²,O⁴,O⁶)potassium(I) iodide, [K(C₆H₁₅N₃O₃)₂]I or [K(taci)₂]I, (III), were grown by diffusion of MeOH into aqueous solutions of the complexes. The structures of the Na and K complexes are isotypic. In all three complexes, the taci ligands adopt a chair conformation with axial hydroxy groups, and the metal cations exhibit exclusive O‐atom coordination. The six O atoms of the resulting MO₆ unit define a centrosymmetric trigonal antiprism with approximate D_3d symmetry. The interligand O...O distances increase significantly in the order Li < Na < K. The structure of (I) exhibits a complex three‐dimensional network of R—NH₂—H...NH₂—R, R—O—H...NH₂—R and R—O—H...O(H)—H...NH₂—R hydrogen bonds. The structures of the Na and K complexes consist of a stack of layers, in which each taci ligand is bonded to three neighbours via pairwise O—H...NH₂ interactions between vicinal HO—CH—CH—NH₂ groups.     

One‐ and two‐dimensional CdII coordination polymers constructed from 2‐(2‐methyl‐1H‐benzimidazol‐1‐yl)acetate ligands

The one‐ and two‐dimensional polymorphic cadmium polycarboxylate coordination polymers, catena‐poly[bis[μ₂‐2‐(2‐methyl‐1H‐benzimidazol‐1‐yl)acetato‐κ³N³:O,O′]cadmium(II)], [Cd(C₁₀H₉N₂O₂)₂]_n, and poly[bis[μ₂‐2‐(2‐methyl‐1H‐benzimidazol‐1‐yl)acetato‐κ³N³:O,O′]cadmium(II)], also [Cd(C₁₀H₉N₂O₂)₂]_n, were prepared under solvothermal conditions. In each structure, each Cd^II atom is coordinated by four O atoms and two N atoms from four different ligands. In the former structure, two crystallographically independent Cd^II atoms are located on twofold symmetry axes and doubly bridged in a μ₂‐N:O,O′‐mode by the ligands into correspondingly independent chains that run in the [100] and [010] directions. Chains containing crystallographically related Cd^II atoms are linked into sheets viaπ–π stacking interactions. Sheets containing one of the distinct types of Cd^II atom are stacked perpendicular to [001] and alternate with sheets containing the other type of Cd^II atom. The second complex is a two‐dimensional homometallic Cd^II (4,4) net structure in which each Cd^II atom is singly bridged to four neighbouring Cd^II atoms by four ligands also acting in a μ₂‐N:O,O′‐mode. A square‐grid network results and the three‐dimensional supramolecular framework is completed by π–π stacking interactions between the aromatic ring systems.     

High‐Efficiency Oxygen Reduction to Hydrogen Peroxide Catalyzed by Nickel Single‐Atom Catalysts with Tetradentate N2O2 Coordination in a Three‐Phase Flow Cell

Carbon‐supported Ni^II single‐atom catalysts with a tetradentate Ni‐N₂O₂ coordination formed by a Schiff base ligand‐mediated pyrolysis strategy are presented. A Ni^II complex of the Schiff base ligand (R,R)‐(?)‐N,N′‐bis(3,5‐di‐tert‐butylsalicylidene)‐1,2‐cyclohexanediamine was adsorbed onto a carbon black support, followed by pyrolysis of the modified carbon material at 300 °C in Ar. The Ni‐N₂O₂/C catalyst showed excellent performance for the electrocatalytic reduction of O₂ to H₂O₂ through a two‐electron transfer process in alkaline conditions, with a H₂O₂ selectivity of 96 %. At a current density of 70 mA cm^?2, a H₂O₂ production rate of 5.9 mol g_cat.^?1 h^?1 was achieved using a three‐phase flow cell, with good catalyst stability maintained over 8 h of testing. The Ni‐N₂O₂/C catalyst could electrocatalytically reduce O₂ in air to H₂O₂ at a high current density, still affording a high H₂O₂ selectivity (>90 %). A precise Ni‐N₂O₂ coordination was key to the performance.     

Di‐μ‐sulfito‐bis­[(4,4′‐di­methyl‐2,2′‐bi­pyridine)­zinc(II)] dihydrate and poly­[[aqua(1,10‐phenanthroline)­zinc(II)]‐μ3‐sulfito‐zinc(II)‐μ3‐sulfito]

Two different zinc sulfite compounds have been prepared through the decomposition of pyrosulfite–­di­thionite ions in aqueous solution, viz. a dimeric complex, di‐μ‐sulfito‐κ³O,O′:O′′;κ³O:O′,O′′‐bis­[(4,4′‐di­methyl‐2,2′‐bi­pyridine‐κ²N,N′)­zinc(II)] dihydrate, [Zn₂(SO₃)₂(C₁₂H₁₂N₂)₂]·2H₂O, (I), which was solved and refined from a twinned sample, and an extended polymer, poly­[[aqua(1,10‐phenanthroline‐κ²N,N′)­zinc(II)]‐μ₃‐sulfito‐κ²O:O′:O′′‐zinc(II)‐μ₃‐sulfito‐κ³O:O:O′], [Zn₂(SO₃)₂(C₁₂H₁₀N₂)(H₂O)]_n, (II). In (I), the dinuclear Zn^II complex has a center of symmetry. The cation is five‐coordinate in a square‐pyramidal arrangement, the anion fulfilling a bridging chelating role. Compound (II) comprises two different zinc units, one being five‐coordinate (square pyramidal) and the other four‐coordinate (trigonal pyramidal), and two independent sulfite groups with different binding modes to the cationic centers.     

Two centrosymmetric dinuclear phenanthroline–copper(II) complexes with 3,5‐dichloro‐2‐hydroxybenzoic acid and 5‐chloro‐2‐hydroxybenzoic acid

The title compounds, bis(μ‐3,5‐dichloro‐2‐oxidobenzoato)‐κ³O¹,O²:O²;κ³O²:O¹,O²‐bis[(3,5‐dichloro‐2‐hydroxybenzoic acid‐κO¹)(1,10‐phenanthroline‐κ²N,N′)copper(II)], [Cu₂(C₇H₂Cl₂O₃)₂(C₇H₄Cl₂O₃)₂(C₁₂H₈N₂)₂], (I), and bis(μ‐5‐chloro‐2‐oxidobenzoato)‐κ³O¹,O²:O¹;κ³O¹:O¹,O²‐bis[(5‐chloro‐2‐hydroxybenzoic acid‐κO¹)(1,10‐phenanthroline‐κ²N,N′)copper(II)] ethanol monosolvate, [Cu₂(C₇H₃ClO₃)₂(C₇H₅ClO₃)₂(C₁₂H₈N₂)₂]·C₂H₆O, (II), contain centrosymmetric dinuclear complex molecules in which Cu²⁺ cations are surrounded by a chelating 1,10‐phenanthroline ligand, a chelating 3,5‐dichloro‐2‐oxidobenzoate or 5‐chloro‐2‐oxidobenzoate anionic ligand and a monodentate 3,5‐dichloro‐2‐hydroxybenzoic acid or 5‐chloro‐2‐hydroxybenzoic acid ligand. The chelating benzoate ligand also bridges to the other Cu²⁺ ion in the molecule, but the O atom involved in the bridge is different in the two complexes, being the phenolate O atom in (I) and a carboxylate O atom in (II). The bridge completes a 4+1+1 axially elongated tetragonal–bipyramidal arrangement about each Cu²⁺ cation. The complex molecules of both compounds are linked into one‐dimensional supramolecular chains through O—H...O hydrogen bonds.     

7‐Iodo‐8‐aza‐7‐deaza‐2′‐deoxy­adenosine and 7‐bromo‐8‐aza‐7‐deaza‐2′‐deoxyadenosine

The isomorphous structures of the title molecules, 4‐amino‐1‐(2‐deoxy‐β‐d ‐erythro‐pento­furan­osyl)‐3‐iodo‐1H‐pyrazolo‐[3,4‐d]pyrimidine, (I), C₁₀H₁₂IN₅O₃, and 4‐amino‐3‐bromo‐1‐(2‐deoxy‐β‐d ‐erythro‐pento­furan­osyl)‐1H‐pyrazolo[3,4‐d]­pyrimidine, (II), C₁₀H₁₂BrN₅O₃, have been determined. The sugar puckering of both compounds is C1′‐endo (^1′E). The N‐­glycosidic bond torsion angle χ¹ is in the high‐anti range [?73.2 (4)° for (I) and ?74.1 (4)° for (II)] and the crystal structure is stabilized by hydrogen bonds.     

catena‐Poly[[bis[aqua­(1,10‐phenanthroline)lead(II)]‐di‐μ3‐5‐carboxy‐3‐sulfonatobenzoato] dihydrate]

In the centrosymmetric title polymer, catena‐poly[[bis[aqua­(1,10‐phenanthroline‐κ²N,N′)lead(II)]‐di‐μ₃‐5‐carboxy‐3‐sulfonatobenzoato‐1:2:1′κ⁴O³:O¹,O^1′:O¹;2′:1:2κ⁴O¹:O¹,O^1′:O³] dihydrate], {[Pb(C₈H₄O₇S)(C₁₂H₈N₂)(H₂O)]·H₂O}_n, each seven‐coordinate lead(II) ion is bound by five O atoms from one water molecule and three 5‐sulfoisophthalate (sip) anions, and by two N atoms from a 1,10‐phenanthroline (phen) ligand. The sip sulfonate group is monodentate. One O atom of the sip carboxyl­ate group is chelated to one Pb²⁺ cation, with the other also bridging an adjacent Pb²⁺ cation. The carboxyl group is uncoordinated. This unusual coordination results in a chain structure along the b axis, which is linked by strong intermolecular hydrogen bonds into a three‐dimensional network.     

CdII and CoII coordination polymers constructed from benzene‐1,4‐dicarboxylic acid and 2‐(pyridin‐3‐yl)‐1H‐benzimidazole ligands

In poly[aqua(μ₃‐benzene‐1,4‐dicarboxylato‐κ⁵O¹,O^1′:O¹:O⁴,O^4′)[2‐(pyridin‐3‐yl‐κN)‐1H‐benzimidazole]cadmium(II)], [Cd(C₈H₄O₄)(C₁₂H₉N₃)(H₂O)]_n, (I), each Cd^II ion is seven‐coordinated by the pyridine N atom from a 2‐(pyridin‐3‐yl)benzimidazole (3‐PyBIm) ligand, five O atoms from three benzene‐1,4‐dicarboxylate (1,4‐bdc) ligands and one O atom from a coordinated water molecule. The complex forms an extended two‐dimensional carboxylate layer structure, which is further extended into a three‐dimensional network by hydrogen‐bonding interactions. In catena‐poly[[diaquabis[2‐(pyridin‐3‐yl‐κN)‐1H‐benzimidazole]cobalt(II)]‐μ₂‐benzene‐1,4‐dicarboxylato‐κ²O¹:O⁴], [Co(C₈H₄O₄)(C₁₂H₉N₃)₂(H₂O)₂]_n, (II), each Co^II ion is six‐coordinated by two pyridine N atoms from two 3‐PyBIm ligands, two O atoms from two 1,4‐bdc ligands and two O atoms from two coordinated water molecules. The complex forms a one‐dimensional chain‐like coordination polymer and is further assembled by hydrogen‐bonding interactions to form a three‐dimensional network.     

Neue molekulare Indium‐Zinn‐Sauerstoff‐ und Indium‐Zinn‐Natrium‐Sauerstoff‐Chlor‐Cluster

Abstract. The five‐membered heteroelement cluster THF · Cl₂In(O^tBu)₃Sn reacts with the sodium stannate [Na(O^tBu)₃Sn]₂ to produce either the new oxo‐centered alkoxo cluster ClInO[Sn(O^tBu)₂]₃ ( 1 ) (in low yield) or the heteroleptic alkoxo cluster Sn(O^tBu)₃InCl₃Na[Sn(O^tBu)₂]₂ ( 2 ). X‐ray diffraction analyses reveal that in compound 1 the polycyclic entity is made of three tin atoms which together with a central oxygen atom form a trigonal, almost planar triangle, perpendicular to which a further indium atom is connected through the oxygen atom. The metal atoms thus are arranged in a Sn₃In pyramid, the edges of which are all saturated by bridging tert‐butoxy groups. The indium atom has a further chloride ligand. Compound 2 has two trigonal bipyramids as building blocks which are fused together at a six coordinate indium atom. One of the bipyramids is of the type SnO₃In with tert‐butyl groups on the oxygen atoms, while the other has the composition InCl₃Na with chlorine atoms connecting the two metals. The sodium atom in 2 has further contacts to two plus one alkoxide groups which are part of a[Sn(O^tBu)₂]₂ dimer disposing of a Sn₂O₂ central cycle. The hetero element cluster in 2 thus combines three closed entities and its skeleton SnO₃InCl₃NaO₂Sn₂O₂ consists of three different metallic and two different non‐metallic elements.     

Topological identification of the first uninodal 8‐connected lsz MOF built from 2,2′‐difluorobiphenyl‐4,4′‐dicarboxylate pillars and cadmium(II)–triazolate layers

Using polynuclear metal clusters as nodes, many high‐symmetry high‐connectivity nets, like 8‐connnected bcu and 12‐connected fcu , have been attained in metal–organic frameworks (MOFs). However, construction of low‐symmetry high‐connected MOFs with a novel topology still remains a big challenge. For example, a uninodal 8‐connected lsz network, observed in inorganic ZrSiO₄, has not been topologically identified in MOFs. Using 2,2′‐difluorobiphenyl‐4,4′‐dicarboxylic acid (H₂L) as a new linker and 1,2,4‐triazole (Htrz) as a coligand, a novel three‐dimensional Cd^II–MOF, namely poly[tetrakis(μ₄‐2,2′‐difluorobiphenyl‐4,4′‐dicarboxylato‐κ⁵O¹,O^1′:O^1′:O⁴:O^4′)tetrakis(N,N‐dimethylformamide‐κO)tetrakis(μ₃‐1,2,4‐triazolato‐κ³N¹:N²:N⁴)hexacadmium(II)], [Cd₆(C₁₄H₆F₂O₄)₄(C₂H₂N₃)₄(C₃H₇NO)₄]_n, (I), has been prepared. Single‐crystal structure analysis indicates that six different Cd^II ions co‐exist in (I) and each Cd^II ion displays a distorted [CdO₄N₂] octahedral geometry with four equatorial O atoms and two axial N atoms. Three Cd^II ions are connected by four carboxylate groups and four trz⁻ ligands to form a linear trinuclear [Cd₃(COO)₄(trz)₄] cluster, as do the other three Cd^II ions. Two Cd₃ clusters are linked by trz⁻ ligands in a μ_1,2,4‐bridging mode to produce a two‐dimensional Cd^II–triazolate layer with (6,3) topology in the ab plane. These two‐dimensional layers are further pillared by the L²⁻ ligands along the c axis to generate a complicated three‐dimensional framework. Topologically, regarding the Cd₃ cluster as an 8‐connected node, the whole architecture of (I) is a uninodal 8‐connected lsz framework with the Schläfli symbol (4²²·6⁶). Complex (I) was further characterized by elemental analysis, IR spectroscopy, powder X‐ray diffraction, thermogravimetric analysis and a photoluminescence study. MOF (I) has a high thermal and water stability.     

Hydrolysis products of diorganotin dihalides. I. Bis[1,3‐dihydroxo‐1,1,3,3‐tetrakis(2‐methyl‐2‐phenylpropyl)­distannoxane]

In the solid state, the title compound, di‐μ‐hydroxo‐1:2κ²O;‐3:4κ²O‐dihydroxo‐1κO,4κO‐octakis(2‐methyl‐2‐phenyl­propyl)‐1κ²C,2κ²C,3κ²C,4κ²C‐di‐μ₃‐oxo‐1:2:3κ³O;2:3:4κ³O‐tetratin(IV), [Sn₄O₂(OH)₄(C₁₀H₁₃)₈], forms centrosymmetric dimeric [(Neophyl₂SnOH)(Neophyl₂SnOH)O]₂ mol­ecules (Neophyl = 2‐methyl‐2‐phenylpropyl), with an almost planar Sn–O framework that adopts a ladder‐type structure consisting of three four‐membered rings. The hydroxyl groups are shielded by the organic groups, which prevent them from further condensation and from the formation of hydrogen bonds.     

Bis[μ3‐cis‐N‐(2‐aminopropyl)‐N′‐(2‐carboxylatophenyl)oxamidato(3–)]bis(2,2′‐bipyridine)dichloridotetracopper(II) dihydrate

The title complex, bis[μ₃‐cis‐N‐(2‐aminopropyl)‐N′‐(2‐carboxylatophenyl)oxamidato(3−)]‐1:2:4κ⁷N,N′,N′′,O:O′,O′′:O′′′;2:3:4κ⁷O′′′:N,N′,N′′,O:O′,O′′‐bis(2,2′‐bipyridine)‐2κ²N,N′;4κ²N,N′‐dichlorido‐1κCl,3κCl‐tetracopper(II) dihydrate, [Cu₄(C₁₂H₁₂N₃O₄)₂Cl₂(C₁₀H₈N₂)₂]·2H₂O, consists of a neutral cyclic tetracopper(II) system having an embedded centre of inversion and two solvent water molecules. The coordination of each Cu^II atom is square‐pyramidal. The separations of Cu^II atoms bridged by cis‐N‐(2‐aminopropyl)‐N′‐(2‐carboxylatophenyl)oxamidate(3−) and carboxyl groups are 5.2096 (4) and 5.1961 (5) Å, respectively. A three‐dimensional supramolecular structure involving hydrogen bonding and aromatic stacking is observed.     

Synthesis and Conformational Analysis of 1′‐ and 3′‐Substituted 2‐Deoxy‐2‐fluoro‐D‐ribofuranosyl Nucleosides

Convergent syntheses of the 9‐(3‐X‐2,3‐dideoxy‐2‐fluoro‐β‐D ‐ribofuranosyl)adenines 5 (X=N₃) and 7 (X=NH₂), as well as of their respective α‐anomers 6 and 8 , are described, using methyl 2‐azido‐5‐O‐benzoyl‐2,3‐dideoxy‐2‐fluoro‐β‐D ‐ribofuranoside ( 4 ) as glycosylating agent. Methyl 5‐O‐benzoyl‐2,3‐dideoxy‐2,3‐difluoro‐β‐D ‐ribofuranoside ( 12 ) was prepared starting from two precursors, and coupled with silylated N⁶‐benzoyladenine to afford, after deprotection, 2′,3′‐dideoxy‐2′,3′‐difluoroadenosine ( 13 ). Condensation of 1‐O‐acetyl‐3,5‐di‐O‐benzoyl‐2‐deoxy‐2‐fluoro‐β‐D ‐ribofuranose ( 14 ) with silylated N²‐palmitoylguanine gave, after chromatographic separation and deacylation, the N⁷‐β‐anomer 17 as the main product, along with 2′‐deoxy‐2′‐fluoroguanosine ( 15 ) and its N⁹‐α‐anomer 16 in a ratio of ca. 42 : 24 : 10. An in‐depth conformational analysis of a number of 2,3‐dideoxy‐2‐fluoro‐3‐X‐D ‐ribofuranosides (X=F, N₃, NH₂, H) as well as of purine and pyrimidine 2‐deoxy‐2‐fluoro‐D ‐ribofuranosyl nucleosides was performed using the PSEUROT (version 6.3) software in combination with NMR studies.     

Ultrahigh‐Content Nitrogen‐doped Carbon Encapsulating Cobalt NPs as Catalyst for Oxidative Esterification of Furfural

It is an attractive and challenging topic to endow non‐noble metal catalysts with high efficiency via a nitrogen‐doping approach. In this study, a nitrogen‐doped carbon catalyst with high nitrogen content encapsulating cobalt NPs (CoO_x@N‐C(g)) was synthesized, and characterized in detail by XRD, HRTEM, N₂‐physisorption, ICP, CO₂‐TPD, and XPS techniques. g‐C₃N₄ nanosheets act as nitrogen source and self‐sacrificing templates, giving rise to an ultrahigh nitrogen content of 14.0 %, much higher than those using bulk g‐C₃N₄ (4.4 %) via the same synthesis procedures. As a result, CoO_x@N‐C(g) exhibited the highest performance in the oxidative esterification of biomass‐derived platform furfural to methylfuroate under base‐free conditions, achieving 95.0 % conversion and 97.1 % selectivity toward methylfuroate under 0.5 MPa O₂ at 100 °C for 6 h, far exceeding those of other cobalt‐based catalysts. The high efficiency of CoO_x@N‐C(g) was closely related to its high ratio of pyridinic nitrogen species that may act as Lewis basic sites as well as its capacity for the activation of dioxygen to superoxide radical O₂^.?.