Synthesis,Structures, Luminescence,and Magnetic Properties of Two Three‐dimensional Lanthanide Organic Frameworks Comprising Pyrazine‐2,3‐dicarboxylic Acid

Two three‐dimensional (3D) lanthanide coordination polymers (CPs) of the general formula [Ln₂(PDOA)₃(H₂O)]_n · 2nH₂O [Ln = Gd ( 1 ), Tb ( 2 )] were synthesized by solvothermal reactions of the corresponding rare‐earth chloride and pyrazine‐2,3‐dicarboxylic acid (H₂PDOA). The CPs were structurally characterized by single‐crystal X‐ray diffraction, IR spectroscopy, thermogravimetry, and elemental analysis. CPs 1 and 2 are isostructural and crystallize in the monoclinic space group P2₁/c. The frameworks are constructed from dinuclear lanthanide building blocks in which the PDOA^2– ions adopt three coordination modes, μ₃‐kO;kO;kN,O, μ₄‐kN,O;kO;kO;kO,O, and μ₅‐kN,O;kO;kO;kO,O;kO, respectively. The Tb³⁺ polymer of 2 exhibits characteristic photoluminescence in the visible region. The magnetic properties of CP 1 were investigated by measuring the magnetic susceptibilities in the temperature range 1.8–300 K.     

2,3‐Diethoxy‐9,10‐anthraquinone

Anthraquinone derivatives form an important class of dyes and are also known for their medicinal properties. Recently, 2,3‐disubstituted anthraquinones have been shown unexpectedly to jellify various organic solvents. No information on the packing mode of these derivatives was known. Here, the first X‐ray structure of a 2,3‐disubstituted anthraquinone is reported, namely 2,3‐diethoxy‐9,10‐anthraquinone, C₁₈H₁₆O₄. The merit of this study lies in the observation of significant differences between the packing in 9,10‐anthraquinone, which displays a herring‐bone arrangement, and that in the title 2,3‐diethoxy derivative, in which the molecules lie on parallel crystallographic morror planes separated by a distance of 3.4081 (1) Å, reminiscent of the graphite layer architecture.     

N,N′‐Bis(2‐methoxy­phenyl)­naphthalene‐1,4‐dicarboxamide

The title compound, C₂₆H₂₂N₂O₄, crystallizes in an anti‐C=O orientation, with the two N‐substituted benzene rings in different conformations relative to the naphthalene ring. These conformations allow two strong N—H⋯O hydrogen bonds and one C—H⋯π inter­action to generate mol­ecular chains in the cell.     

Synthesis,Crystal Structure,and Catalytic Properties of Porous 3d‐4f Heterometallic Coordination Polymers Constructed from Pyrazine‐2,3‐dicarboxylic Acid

Reactions of pyrazine‐2,3‐dicarboxylic acid (H₂pzdc), cobalt nitrate and lanthanide (Ln) oxide under hydrothermal conditions result in four new 3d‐4f heterometal coordination polymers, namely, [Ln₂Co(pzdc)₄(H₂O)₆] · 2H₂O [Ln = La ( 1 ), Pr ( 2 ), Eu ( 3 ) and Gd ( 4 )]. All compounds were characterized by elemental analysis, infrared spectroscopy, thermal gravimetric analysis, and X‐ray diffraction. The compounds exhibit a three‐dimensional (3D) brick‐like structure with rectangular‐shaped nano‐scale channels along a axis direction, made up of wave‐like layers containing [Ln(pzdc)]⁺ units, which are connected by one‐dimensional (1D) chain of [Co(pzdc)₂]^2–. The catalytic properties of compounds 1 and 3 were investigated in the synthesis of cyanohydrins at room temperature under solventless conditions. They showed similar catalytic activities with very high conversions of benzaldehyde and high selectivity towards cyanohydrin. The control experiment without addition of the coordination polymers only reached 16 % conversion. Other aldehydes could also be converted totally under shorter reaction times also with very high selectivities for the corresponding cyanohydrins. Compound 1 could also be recycled in another catalytic cycle.     

5‐Fluoro­indoline‐2,3‐dione

In the title compound (5‐fluoro­isatin), C₈H₄FNO₂, the N atom of one mol­ecule is linked to the amido‐O atom of an adjacent mol­ecule across a center of symmetry by a cyclic hydrogen bond [N?O = 2.888 (4) Å].     

One‐step preparation of some 2‐isopropenyl‐2,3‐dihydronaphtho‐[2,3‐b]furan‐4,9‐diones

Some 2‐isopropenyl‐2,3‐dihydronaphtho[2,3‐b]furan‐4,9‐diones la‐f,b',f were prepared by one‐step cyclizations of 2‐hydroxy‐1,4‐naphthoquinones 2a‐f with 1,4‐dibromo‐2‐methyl‐2‐butene ( 3 ).     

Fragmentation pathways of 2,3‐dimethyl‐2,3‐dinitrobutane cations in the gas phase

2,3‐Dimethyl‐2,3‐dinitrobutane (DMNB) is an explosive taggant added to plastic explosives during manufacture making them more susceptible to vapour‐phase detection systems. In this study, the formation and detection of gas‐phase [M+H]⁺, [M+Li]⁺, [M+NH₄]⁺ and [M+Na]⁺ adducts of DMNB was achieved using electrospray ionisation on a triple quadrupole mass spectrometer. The [M+H]⁺ ion abundance was found to have a strong dependence on ion source temperature, decreasing markedly at source temperatures above 50°C. In contrast, the [M+Na]⁺ ion demonstrated increasing ion abundance at source temperatures up to 105°C. The relative susceptibility of DMNB adduct ions toward dissociation was investigated by collision‐induced dissociation. Probable structures of product ions and mechanisms for unimolecular dissociation have been inferred based on fragmentation patterns from tandem mass (MS/MS) spectra of source‐formed ions of normal and isotopically labelled DMNB, and quantum chemical calculations. Both thermal and collisional activation studies suggest that the [M+Na]⁺ adduct ions are significantly more stable toward dissociation than their protonated analogues and, as a consequence, the former provide attractive targets for detection by contemporary rapid screening methods such as desorption electrospray ionisation mass spectrometry. Copyright © 2009 Commonwealth of Australia. Published by John Wiley & Sons, Ltd.     

Two new isatin derivatives: 1‐benzyl‐4,5,6‐trimethoxyindoline‐2,3‐dione and 1‐benzyl‐5‐fluoroindoline‐2,3‐dione

Isatin (1H‐indole‐2,3‐dione) derivatives represent synthetically useful substrates which can be used to prepare a broad range of heterocyclic compounds. In the title compounds, C₁₈H₁₇NO₅, (I), and C₁₅H₁₀FNO₂, (II), the isatin ring systems are planar and form a dihedral angle of 73.04 (7)° in (I) and 76.82 (11)° in (II) with the benzyl groups. The bicyclic scaffolds in both compounds are almost superimposable, with an r.m.s. deviation of 0.061 Å. The crystal structures of both derivatives are stabilized by C—H...O interactions. These contacts generate an R¹₂(7) ring motif in (I) and a C(7) chain motif in (II).     

Organic Thin Film Transistors Based on 2,3‐Dimethylpentacene and 2,3‐Dimethyltetracene

2,3‐Dimethylpentacene (DMP) and 2,3‐dimethyltetracene (DMT) were synthesized, characterized and employed as the channel material in the fabrication of thin‐film transistors. The two methyl groups increase the chemical stability of the compounds versus the pristine acene analogues. The crystals maintain herringbone‐like molecular packing, whereas the weak dipole associated with the unsymmetrical molecule induces an anti‐parallel alignment among the neighbors. This structural motif favors layered film growth on SiO₂/Si surface. Thin film transistors prepared on SiO₂/Si and n‐nonyltrichlorosilane‐modified SiO₂/Si at different substrate temperatures were compared. DMP‐based transistors prepared on rubbed n‐nonyltrichlorosilane‐modified SiO₂/Si substrate gave the highest field‐effect mobility of 0.46 cm²/Vs, whereas DMT‐based transistor gave a mobility of 0.028 cm²/Vs.     

Synthesis of pyridazine derivatives through the unexpected intermediate 5‐amino‐ 4‐cyano ‐2,3‐dihydro‐furan‐2,3‐disulfonic acid disodium salt

An unexpected compound (5‐amino‐4‐cyano‐2,3‐dihydrofuran‐2,3‐disulfonic acid disodium salt, 4 ) was isolated from the reaction of glyoxale bis hydrogen sulfite disodium salt with malononitrile. Its structure was undoubtly identified through crystal structure analysis. Compound 4 was highly stable and it was isolated easily and in a very high yield. Its reactivity was studied in the reactions with some hydrazine derivatives in order to obtain different pyridazine analogs.     

2,3‐Dihydro‐3‐methyl‐2‐nitrimino‐1,3‐thiazole

The title compound {alternatively, 3‐methyl‐2‐[oxido(oxo)hydrazono]‐2,3‐dihydro‐1,3‐thiazole}, C₄H₅N₃O₂S, was obtained by methyl­ation of N‐(2‐thia­zolyl)­nitr­amine. The molecule lies on a mirror plane and the thia­zole ring is planar, regular in shape and aromatic. The S atom participates in the aromatic sextet via an electron pair on the 3p_z orbital. In the crystal, the mol­ecules are arranged in parallel layers, bound to each other by weak C—H?O and C—H?N hydrogen bonds and by S?O dipolar interactions, with an interlayer separation of 3.23 Å.     

A Pyrazine‐Based Polymer for Fast‐Charge Batteries

The lack of high‐power and stable cathodes prohibits the development of rechargeable metal (Na, Mg, Al) batteries. Herein, poly(hexaazatrinaphthalene) (PHATN), an environmentally benign, abundant and sustainable polymer, is employed as a universal cathode material for these batteries. In Na‐ion batteries (NIBs), PHATN delivers a reversible capacity of 220 mAh g^?1 at 50 mA g^?1, corresponding to the energy density of 440 Wh kg^?1, and still retains 100 mAh g^?1 at 10 Ag^?1 after 50 000 cycles, which is among the best performances in NIBs. Such an exceptional performance is also observed in more challenging Mg and Al batteries. PHATN retains reversible capacities of 110 mAh g^?1 after 200 cycles in Mg batteries and 92 mAh g^?1 after 100 cycles in Al batteries. DFT calculations, X‐ray photoelectron spectroscopy, Raman, and FTIR show that the electron‐deficient pyrazine sites in PHATN are the redox centers to reversibly react with metal ions.     

Syntheses of 2,4‐diaryl‐2,3‐dihydro‐1,5‐benzothiazepines

The condensation of α,β‐unsaturated ketones with substituted o‐aminothiophenols, obtained by reductive cleavage of the corresponding disulfides in the presence of triphenylphosphine, is an effective method for the synthesis of 2,4‐diaryl‐2,3‐dihydro‐1,5‐benzothiazepines under neutral conditions.     

catena‐Poly[[[diaquazinc]‐bis{μ‐N2,N6‐bis[(pyridin‐3‐yl)methyl]pyridine‐2,6‐dicarboxamide}] dinitrate]

In the title compound, {[Zn(C₁₉H₁₇N₅O₂)₂(H₂O)₂](NO₃)₂}_n, the Zn^II cation is located at an inversion centre within a slightly distorted octahedron, ligated by four N atoms from four N²,N⁶‐bis[(pyridin‐3‐yl)methyl]pyridine‐2,6‐dicarboxamide (L) ligands occupying a plane about the Zn^II atom with the two water O atoms perpendicular to that. In the complex molecule, the bidentate bridging L ligands display helical R and S conformers, and link the Zn^II cations into a one‐dimensional centrosymmetric double‐chain structure containing 32‐membered rings. The nitrate anions reside in these rings and are involved in multiple N—H...O hydrogen‐bond interactions. On excitation at 390 nm, the title compound displays a strong blue emission centred at 449 nm. Investigation of the thermal stability shows that the network structure is stable up to 420 K.