RESUMEN
Two two-dimensional (2D) layered metal-organic frameworks (MOFs), namely, {[Yb(L)(H2O)2NO3]·2H2O}n (Yb-MOF) and [Er(L)(H2O)3Cl]n (Er-MOF) (H2L = 5-((6H-purin-6-yl)amino)isophthalic acid), were constructed by a solvothermal method and characterized. The catalytic performance study showed that the Yb-MOF could efficiently catalyze the oxidation of sulfides to sulfoxides under 15 W light-emitting diode (LED) blue light irradiation. Electron paramagnetic resonance spectroscopy and free-radical trapping experiments demonstrated that the photocatalytic reaction process involved â¢O2-, and the corresponding mechanism was proposed. Moreover, Er-MOF exhibited good catalytic efficiency and excellent substrate tolerance in the cycloaddition reaction of CO2, and the reaction conditions were mild. After 5 cycles, the catalytic activities of two MOFs did not significantly decrease, and the framework structures remained unchanged. Therefore, the Yb-MOF and Er-MOF were considered efficient and stable heterogeneous catalysts.
RESUMEN
Four Co(II)-based metal-organic frameworks (MOFs) were constructed by a mixed ligand strategy under solvothermal conditions. The controllable modification of the bridging groups in the secondary building units was realized by changing the anions in MOFs 1-3. The MOF 4 with 3D framework structure was obtained by regulating the solvent ratio following the synthesis process of MOF 3. Furthermore, the MOFs 1-4 exhibited efficient photocatalytic activity for the degradation of malachite green (MG) dye without any photosensitizer or cocatalyst under a low-energy light source, the decolorization ratio of MG all reached more than 96.0% within 60 min, and maximal degradation was obtained to be 99.4% (MOF 4). The recycling experiments showed that the degradation rate of MG was still higher than 91% after 10 cycles. In the MOF 4 as representation, the photocatalytic process was explored systematically. The possible mechanism of catalytic degradation was discussed, which proved the existence of efficient oxidation active factors (â¢O2-, â¢OH, and h+). The possible intermediates and degradation pathways were investigated based on high-performance liquid chromatography tandem mass spectrometry. Additionally, MOFs 1-4 also exhibited excellent photocatalytic activity for the degradation of methylene blue, methyl violet, rhodamine B, and basic red 9.
RESUMEN
Five new lanthanide metal-organic frameworks (Ln-MOFs), namely {[Ln(L)]·Cl}n, [Ln = Pr(1), Nd(2), Eu(3), Ho(4), Ce(5)], based on a benzimidazole carboxylic acid ligand [H2L = 2-(2-carboxyphenyl)-1H-benzo[d]imidazole-6-carboxylic acid] were synthesized by a solvothermal method. Ln-MOFs 1-5 have the same two-dimensional layered structures. Interestingly, 1-5 exhibit excellent adsorption performance to anionic dye Congo red (CR), with adsorption capacities of 2724 mg g-1, 2719 mg g-1, 2718 mg g-1, 327 mg g-1, and 2273 mg g-1, respectively. Adsorption kinetics experiments showed that this kind of adsorption belonged to chemisorption; the hydrogen bonding and π-π interactions between the 1-5 host and CR guest molecules resulted in a high adsorption capacity. Luminescence and sensing experiments showed that 5 can be considered a promising multifunctional fluorescent sensor with good reusability and a high sensitivity toward Ag+ and Hg2+ ions, with detection limits of 1.7 × 10-7 and 2.5 × 10-6 M, respectively.
RESUMEN
Three different pore sizes of oxacalix[m]arene[n]pyrimidines modified with a naphthalene substituent were synthesized and characterized by HRMS, 1H NMR, and single-crystal analysis (8OA and 8OA-N). Steady-state spectroscopy indicates these naphthalene-oxacalix[m]arenes exhibit good fluorescence properties, which isattributed to the locally excited (LE) state emission, and electrochemical results show that the photoinduced electron transfer (PET) process occurs from the naphthalene substituent to the linked pyrimidine. Nanosecond transient absorption spectra, singlet oxygen quantum yields (ΦΔ4OA-N = 45.1%, ΦΔ6OA-N = 56.6%, and ΦΔ8OA-N = 65.7%) and theoretical calculations demonstrate that the torsion angle between the donor (naphthalene) and the acceptor (pyrimidine) promotes intersystem crossing (ISC), and the lifetime of the triplet state reaches ca. 8 ms. Interestingly, all three host molecules (4OA-N, 6OA-N, and 8OA-N) showed a high affinity for fullerene C60, and significant binding constants in the range of 4.10-6.68 × 104 M-1 were obtained by fluorescence titration; in contrast, previous reports indicated that the similar oxacalix[m]arene[n]pyrimidine scaffold could not efficiently complex with C60. In the frontier molecular orbital theory calculations of the supramolecular system of 4OA-N@C 60 , the HOMO is distributed on 4OA-N and the LUMO is localized on fullerene. The calculation results further demonstrated that there are strong interactions between the host and the fullerene guest, which is consistent with the result of the experiments. The characteristic photophysical properties of these novel naphthyl-decorated oxacalix[m]arene[n]pyrimidines broaden their application field, and the stable host-guest system with fullerene can be applied to supramolecular chemistry.
RESUMEN
Six new metal-organic coordination polymers (CPs) [Ni(L)(2,5-TDC)(H2O)] n (1), [Ni(L)(1,3-BDC)(H2O)] n (2), [Ni(L)(1,4-BDC)(H2O)] n (3), [Mn(L)(2,5-TDC)(H2O)] n (4), [Mn(L)(2,6-PYDC)(H2O)] n (5) and [Mn(L)(1,4-NDC)] n (6) were achieved by reactions of the corresponding metal salt with mixed organic ligands (L = 3,6-bis(benzimidazol-1-yl)pyridazine, 2,5-H2TDC = thiophene-2,5-dicarboxylic acid, 1,3-H2BDC = isophthalic acid, 1,4-H2BDC = terephthalic acid, 2,6-H2PYDC = pyridine-2,6-dicarboxylic acid, 1,4-H2NDC = naphthalene-1,4-dicarboxylic acid) under solvothermal condition. CPs 1-6 were characterized by single-crystal X-ray diffraction, IR, TG, XRD and elemental analyses. Their structures range from the intricate 3D CPs 1, 3, 4 and 6 to the 2D coordination polymer 2 and the infinite 1D chain 5. The CPs 1-4 and 6 underlying networks were classified from the topological viewpoint, disclosing the distinct sql (in 1), pcu (in 3 and 6), new topology (in 2), and dia (in 4) topological nets. Moreover, analysis of thermal stability shows that they had good thermal stability. Finally, magnetic properties of CPs 1-6 have been studied, the results showed that complex 2 had ferromagnetic coupling and complexes 1, 3-6 were antiferromagnetic.
RESUMEN
A series of new N'-[N-(2,3,4-tri-O-acetyl-ß-d-xylopyranosyl)thiocarbamoyl]-2-[(1-aryl-1H-tetrazol-5-yl)sulfanyl]acetohydrazides 5a-5e were synthesized rapidly in high yields from 2-(1-aryl-1H-tetrazol-5-ylsulfanyl)acetohydrazides 3a-3e and 2,3,4-tri-O-acetyl-ß-d-xylopyranosyl isothiocyanate 4, then 5a-5e were converted to a series of new 5-(1-aryl-1H-tetrazol-5-ylsulfanylmethyl)-N-(2,3,4-tri-O-acetyl-ß-D-xylopyranosyl)-1,3,4-oxadiazole-2-amines 6a-6e and 5-(1-aryl-1H-tetrazol-5-ylsulfanylmethyl)-N-(2,3,4-tri-O-acetyl-ß-D-xylopyranosyl)-1,3,4-thiadiazole-2-amines 7a-7e, respectively under mercuric acetate/alcohol system or acetic anhydride/phosphoric acid system, then deacetylated in the solution of CH(3)ONa/CH(3)OH. All of the novel compounds were characterized by IR, (1)H NMR, (13)C NMR, MS and elemental analysis. The structures of compounds 2e, 3e, 5a and 5c have been determined by X-ray diffraction analysis. Some of the synthesized compounds displayed PTP1B inhibition and microorganism inhibition.
