Structures and Properties of Two Pillared-layer Mn(Ⅱ) MOFs with 5-Ethyl-pyridine-2,3-dicarboxylate

The reaction of Mn(OAc)2·4 H2 O, 5-ethyl-pyridine-2,3-dicarboxylic acid(H2 epda) and 4,4?-bipyridine(4,4?-bipy)/4,4?-bis(imidazolyl)biphenyl)(bibp) under hydrothermal conditions produced two new manganese(Ⅱ) MOFs [Mn(epda)(4,4?-bipy)1/2](1) and [Mn(epda)(bibp)1/2](2), which were characterized by elemental analysis, infrared spectroscopy, thermogravimetric analyses, and single-crystal X-ray diffraction. The structures of complexes 1 and 2 are similar. In 1, the adjacent Mn(Ⅱ) ions are connected by epda dianion to generate a 2 D(4,4) grid layer, and such 2 D layers are further connected via bibp ligand to form another layer, forming a 2 D pillared-layer. Topologically, the Mn atoms as the node are bridged by the edpa anions and bibp ligands to form a uninodal 5-connected network topology. The magnetic properties of 1 and 2 have also been-investigated, and the exchange interctions were –1.39 and –1.05 cm1, respectively. According to the crystal structures, compounds 1 and 2 were carried out by using hybrid DFT methods at the B3 LYP/6-31 G(d) level. The DFT-BS approach was applied to study the magnetic coupling behaviors for 1 and 2. The result reveals that the calculated exchange coupling constants J were in good agreement with the experimental data.

A Synthesis Method of Diethyl 5-Ethylpyridine-2,3-Dicarboxylate

[Objective]This paper was to synthesize the intermediate diethyl 5-ethylpyridine-2,3-dicarboxylate of imazethapyr using 5-ethyl-2,3-pyridinedicarboxylic acid as the raw material.[Method]Diethyl 5-ethylpyridine-2,3-dicarboxylate was successfully synthesized via direct esterification and indirect esterification.[Result]The structure of intermediate was confirmed by LC and1 H NMR.[Conclusion]The intermediate yield of the two methods was both above 89%.Imazethapyr was prepared from the intermediate and the purity reached 99%.

The mechanism of unexpected reduction of dimethyl pyridine-2,3-dicarboxylate to l,2,3,4-tetrahydrofuro[3,4-b]-pyridin-5(7H)-one with sodium borohydride

An unexpected reduction of dimethyl pyridine-2,3-dicarboxylate to 1,2,3,4-tetrahydrofuro[3,4-b]pyridin-5（7H）-one with sodium borohydride in ethanol and tetrahydrofuran, respectively, is described, a hypothetic mechanism for the unusual reductive product is proposed.

Two Pillared-layer Co(Ⅱ) Metalorganic Frameworks Displaying Pore Modulation by Rodlike Ligands

Two novel compounds, {[Co2（epda）2（4,4＇-bpy）（H20）z]＇3H20}n 1 and {[Co2（epda）2（bpe）（HzO）z]＇3HzO}n 2 （H2epda = 5-ethyl-pyridine-2,3-dicarboxylic acid, 4,4＇-bpy = 4,4＇-bipyridine and bpe = 1,2-di（4-pyridyl）ethylene） were solvothermally synthesized and charac- terized by elemental analysis, IR spectroscopy, thermogravimetric analysis （TGA）, and single- crystal X-ray diffraction. Complex 1 is ofmonoclinic system, space group P21/c with a = 13.344（5）, b = 14.724（5）, c = 8.267（3） A, fl = 105.840（4）~, V= 1562.5（10） A3, Dc = 1.480 g/cm3, Mr = 375.19, Z = 4, F（000） = 712, gl = 1.121 mm-1, the final R = 0.0512 and wR = 0.1260 for 2890 observed reflections with I 〉 2σ（I）. 2 belongs to the monoclinic system, space group P21/c with a = 14.224（4）, b = 14.726（4）, c = 8.287（2） A,β = 99.696（4）°, V= 1711.1（9） A3, Dc = 1.402 g/cm3, Mr = 388.21, Z = 4, F（000） = 740, kt = 1.027 mm-1, the final R = 0.0354 and wR = 0.0862 for 12237 observed reflections with I 〉 2a（/）. Both complexes present intimately related structures featuring infinite Co-carboxylate layers of [Con（epda）（H20）]n pillared by 4,4＇-bpy （or bpe） molecule to produce the microporous frameworks, Unambiguously indicating that pore dimensions of the framework are regulated by the N,N＇-donor pillars.

Aqueous Diels-Alder Reactions of Cyclopentadicnc with Symmetric Diester of Fumarate or Maleate

Symmetric, diesters of cis- or trans- bicyclo[2,2,1]hept-5-ene-2,3-dicarboxylate were prepared by aqueous Diels-Alder reaction of cyclopentadiene with symmetric diester of fumarate or maleate.