Engineered Bifunctional Luminescent Pillared-Layer Frameworks for Adsorption of CO2 and Sensitive Detection of Nitrobenzene in Aqueous Media

Through a dual-ligand synthetic approach, five isoreticular primitive cubic (pcu)-type pillared-layer metal–organic frameworks (MOFs), [Zn₂(dicarboxylate)₂(NI-bpy-44)] ⋅ x DMF ⋅ y H₂O, in which dicarboxylate=1,4-bdc ( 1 ), Br-1,4-bdc ( 2 ), NH₂-1,4-bdc ( 3 ), 2,6-ndc ( 4 ), and bpdc ( 5 ), have been engineered. MOFs 1 – 5 feature twofold degrees of interpenetration and have open pores of 27.0, 33.6, 36.8, 52.5, and 62.1 %, respectively. Nitrogen adsorption isotherms of activated MOFs 1′ – 5′ at 77 K all displayed type I adsorption behavior, suggesting their microporous nature. Although 1′ and 3′ – 5′ exhibited type I adsorption isotherms of CO₂ at 195 K, MOF 2′ showed a two-step gate-opening sorption isotherm of CO₂. Furthermore, MOF 3′ also had a significant influence of amine functions on CO₂ uptake at high temperature due to the CO₂–framework interactions. MOFs 1 – 5 revealed solvent-dependent fluorescence properties; their strong blue-light emissions in aqueous suspensions were efficiently quenched by trace amounts of nitrobenzene (NB), with limits of detection of 4.54, 5.73, 1.88, 2.30, and 2.26 μm , respectively, and Stern–Volmer quenching constants (K_sv) of 2.93×10³, 1.79×10³, 3.78×10³, 4.04×10³, and 3.21×10³ m ⁻¹, respectively. Of particular note, the NB-included framework, NB@ 3 , provided direct evidence of the binding sites, which showed strong host–guest π–π and hydrogen-bonding interactions beneficial for donor–acceptor electron transfer and resulting in fluorescence quenching.     

The synthesis,structure, magnetic and luminescent properties of a new tetranuclear dysprosium (III) cluster

The synthesis and characterization of [Dy₄(dhampH₃)₄(NO₃)₂](NO₃)₂ (1), a new tetranuclear dysprosium (III) complex, is described. The compound was characterized by its X-ray structure, magnetic properties as well as the luminescent spectra. The compound crystallizes in a P1? space group with a zig-zag linear form of geometry. The ac magnetic susceptibilities of the molecule indicate that it is a magnetic molecule with a slow magnetization relaxation. The molecule also exhibits an emission spectrum that was confirmed to be ligand based. These results indicate that this molecule has both a slow magnetization relaxation (that could be potentially a SMM) and luminescent properties.     

STEREOSELECTIVE SYNTHESIS OF MONOFLUORO-OLEFINS FROM DIISOPROPYL (CARBOETHOXYFLUORO-METHYL)PHOSPHONATE

Abstract

Treatment of ethyl oxalyl chloride or methyl oxalyl chloride with lithium diisopropyl(carboethoxyfluoromethyl)phosphonate[(i-PrO)₂P(O)CFCO₂Et]^?Li⁺ 2 followed by in siru nucle-ophilic addition with methylmagnesium iodide or vinyl magnesium bromide affords with exclusive E-stereoselectivity formation of diethyl-2-fluoro-3-methyl fumarate (CH₃)(C0₂Et)C[dbnd]CFCO₂Et 4 or 75% of the E-isomer of a-fluoro-P-vinyl-a,P-unsaturated diester (E,Z)-(CH₂[dbnd]CH)(CO₂C₂H₅)C[dbnd]CFCO₂Et 5, respectively. However, direct reaction of ethyl pyruvate with 2 gives the fluoro-olefin (CH₃)(CO₂Et)C[dbnd]CFCO₂Et 4 with 79% E-stere-oselectivity. The E/Zratio of (CH₂[dbnd]CH)(CO₂Et)C[dbnd]CFCO₂Et 5 depends on the HMFT or DMPU cosolvents present in the reaction mixture.     

Using cone calorimeter data for the prediction of upward flame spread rate

In a cone calorimeter, the specimen receives uniformly distributed irradiance from the cone heater. Producing a heating environment simulating the heating intensity in real fires, this apparatus consequently is capable of providing information of materials relevant to their fire performance. Several previous upward flame spread models utilized the data as input with an assumption of uniformly distributed heat fluxes. Satisfactory flame spread rates were predicted. However, the heat flux in the heating region in upward flame spread is not uniform. This study introduces an alternative protocol of the cone calorimeter and a sample holder by which the following differences were made, including specimen turned 42° before ignition, lower ignition source before ignition, heater removed after ignition, and specimen moved back to vertical orientation after ignition. The heating environment is more consistent to real wall fire conditions. In addition, the prediction of flame spread rate using the alternative test protocol is closer to the measured flame spread rate than standard test methods.     

反应修饰剂ZnSO4和预处理对苯选择加氢制环己烯Ru-Zn催化剂性能的影响

共沉淀法制备了Ru-Zn催化剂,考察了反应修饰剂ZnSO₄和预处理对苯选择加氢制环己烯Ru-Zn催化剂性能的影响。结果表明,反应修饰剂ZnSO₄可以与Ru-Zn催化剂中助剂ZnO反应生成（Zn（OH）₂）₃（ZnSO₄）（H₂O）盐。随反应修饰剂ZnSO₄浓度增加,（Zn（OH）₂）₃（ZnSO₄）（H₂O）盐量的逐渐增加,Ru-Zn催化剂活性逐渐降低,环己烯选择性逐渐升高。因为（Zn（OH）₂）₃（ZnSO₄）（H₂O）盐中的Zn²⁺可以使Ru变为有利环己烯生成的缺电子的Ru^δ+物种,而且还可以占据不适宜环己烯生成的强Ru活性位。但当反应修饰剂ZnSO₄浓度高于0.41 mol·L^-1后,继续增加ZnSO₄浓度,由于Zn²⁺水解浆液酸性太强,可以溶解部分（Zn（OH）₂）₃（ZnSO₄）（H₂O）盐,Ru-Zn催化剂活性升高,环己烯选择性降低。但环己烯选择性却略微降低,这是由于ZnSO₄溶液中大量的Zn²⁺可以与生成的环己烯形成配合物,稳定生成的环己烯,抑制生成的环己烯再吸附到催化剂表面并加氢生成环己烷。在ZnSO₄最佳浓度0.61 mol·L^-1下对Ru-Zn催化剂预处理15 h,Ru-Zn催化剂中助剂ZnO可以与ZnSO₄完全反应生成（Zn（OH）₂）₃（ZnSO₄）（H₂O）盐,在该催化剂上25 min苯转化68.2%时环己烯选择性和收率分别为80.2%和54.7%。而且该催化剂具有良好的稳定性和重复使用性能。     

Synthesis,Crystal Structure,Photophysical and Electrochemical Properties of rac‐6,13‐Dihydro‐6,13‐methanopentacene

The title compound, rac‐6,13‐dihydro‐6,13‐methanopentacene ( 1 ), has been synthesized and characterized by elemental analysis, FT‐IR, ¹H NMR, UV‐Vis, HRMS spectra, cyclic voltammetry and single‐crystal X‐ray diffraction. The crystal belongs to orthorhombic, space group P2₁2₁2₁, with Z = 4 and cell dimensions a = 6.0185(4), b = 8.1914(6), c = 31.4080(19) Å. In the crystal structure, two types of intermolecular C–H···π hydrogen bonds are observed, and further stabilize the crystal structure. Its photophysical and electrochemical properties and complementary density functional theory (DFT) calculations are reported.     

Determination of 129I in cement-solidified radwastes using neutron activation

The purpose of this study is to develop a neutron activation method to determine trace amounts of ¹²⁹I in cement-solidified radwastes. The radwaste samples were alkaline fused using KOH and then ¹²⁹I and iodine carrier were chemically separated by solvent extraction before and after neutron irradiation. Both stable iodine (¹²⁷I) and ¹²⁹I can be activated by neutrons through ¹²⁷I (n, 2n) ¹²⁶I and ¹²⁹I (n, γ) ¹³⁰I reactions; their activated radionuclides were counted together with a high-purity germanium detector. The chemical recovery yields ranged from 30 to 60 %, and it was found that more than 99.9 % of interfering radionuclides can be removed using solvent extraction after neutron irradiation. The minimum detectable amounts can be lowered to less than 1 mBq g^?1, which is superior to low energy γ-ray spectrometry by a factor of >10², on average. The established technique can be applied to re-evaluation of ¹²⁹I content in radwastes that can be re-classified to lower classes, and the cost for designing a final disposal facility can be significantly reduced.     

Fused-ring and linking group effects of proton donors and acceptors on simple H-bonded liquid crystals

Two fused-ring structures, 6-decyloxy-2-naphthoic acid C₁₀ONA (3) and 6-dodecyloxyisoquinoline IS (8), were synthesized and utilized as proton donor and acceptor moieties to construct a series of simple mesogenic supramolecules. The other complementary hydrogen-bonded (H-bonded) moieties are benzoic acids, thiophenecarboxylic acid and pyridines containing different alkyl chain lengths connected by ether and ester linkages, i.e. 4-alkoxybenzoic acid C _n OBA (1), terephthalic acid monoalkyl ester C _n COOBA (2), 2,5-thiophenedicarboxylic acid monodecyl ester C₁₀COOTHA (4), 4-alkoxypyridine C _n OP (6) and isonicotinic acid alkyl ester C _n COOP (7). Several series of simple mesogenic supramolecular dimers were constructed from 1:1 molar ratios of proton donors (C _n OBA, C _n COOBA, C₁₀ONA and C₁₀COOTHA) and proton acceptors (IS, C _n OP and C _n COOP), though the proton acceptor C _n COOP induced phase separation in all complexes. In order to investigate their fused-ring and linking group effects on the mesogenic properties of the H-bonded complexes, analogous simple supramolecular structures are compared. Supramolecular architecture and the distinct mesomorphism of these simple H-bonded liquid crystalline materials were confirmed by polarizing optical microscopy, DSC and powder X-ray diffraction experiments.