RESUMEN
Chemoselective hydrogenation with high efficiency under ambient conditions remains a great challenge. Herein, an efficient photocatalyst, the 2D porphyrin metal-organic framework composite AmPy/Pd-PPF-1(Cu), featuring AmPy (1-aminopyrene) sitting axially on a paddle-wheel unit, has been rationally fabricated. The 2D AmPy/Pd-PPF-1(Cu) composite acts as a photocatalytic platform, promoting the selective hydrogenation of quinolines to tetrahydroquinolines with a yield up to 99%, in which ammonia borane serves as the hydrogen donor. The AmPy molecules coordinated on a 2D MOF not only enhance the light absorption capacity but also adjust the layer spacing without affecting the network structure of 2D Pd-PPF-1(Cu) nanosheets. Through deuterium-labeling experiments, in situ X-ray photoelectron spectroscopy, electron paramagnetic resonance studies, and density functional theory calculations, it is disclosed that Cu paddle-wheel units in 2D AmPy/Pd-PPF-1(Cu) nanosheets behave as the active site for transfer hydrogenation, and metalloporphyrin ligand and axial aminopyrene molecules can enhance the light absorption capacity and excite photogenerated electrons to Cu paddle-wheel units, assisting in photocatalysis.
RESUMEN
Ultrathin two-dimensional metal-organic framework nanosheets have emerged as a promising kind of heterogeneous catalysts. Herein, we report a series of 2D porphyrinic metal-organic framework nanosheets (X-PMOF, X=F, Cl, Br), which was prepared from the self-assembly of a halogen-based porphyrin ligand X-TCPP (X-TCPP=5-(4-halogenatedphenyl)-10,15,20-tris(4-carboxyphenyl)-porphyrin) and ZrCl4 in the presence of trifluoroacetic acid as the modulating reagent. The framework of X-PMOF possessed the ftw topology as in MOF-525. The lamellar X-PMOF nanosheets with the thickness of down to 4.5â nm were assembled and aggregated into a flower-like morphology. With the introduction of iridium(III) atoms into the porphyrin rings, the resultant X-PMOF(Ir) nanosheets were prepared by a similar method. Catalytic results show that Br-PMOF(Ir) nanosheets were efficient for CO2 reduction and aminolysis, giving rise to formamides in high yields under room temperature and atmospheric pressure, and can be recycled and reused for 3 runs. The total turnover number of Br-PMOF(Ir) after 3 runs was 1644 based on Ir. Mechanistic studies disclose that the high efficiency of Br-PMOF(Ir) nanosheets was ascribed to three factors, including the superior activation capability of iridium(III) porphyrin for Si-H bonds, more active sites on the external surfaces of Br-PMOF(Ir) nanosheets, and the defects caused by unsymmetrical porphyrin ligand that increased the framework's affinity towards CO2 .
RESUMEN
A calix[4]arene (C4A)-functionalized (phthalocyaninato)(porphyrinato) europium(iii) triple-decker compound (Pc)Eu(Pc)Eu[T(C4A)PP] (1) is firstly designed, synthesized and prepared into well-organized films using a simple solution-processing quasi-Langmuir-Shäfer (QLS) method. The QLS film of 1 on an ITO (film 1/ITO) electrode, serving as a host-guest electrochemical recognition layer, is able to establish specific responses/interactions toward organic molecules with biological and drug interest including dopamine (DA), uric acid (UA), tyrosine (Tyr), tryptophan (Trp) and Acetaminophen (APAP), depending mainly on the matching degree of molecular dimensions between the analytes and the C4A cavity in addition to their chemical nature. More significantly, the film 1/ITO electrode shows a wide linear range of electrochemical detection (from 0.1 to 100 µM) to DA and APAP, with a high sensitivity of 53.0 and 94.3 µA mM-1 and a very low detection limit of 25 and 11 nM for DA and APAP, respectively, representing the best result among the nonenzymatic organic semiconductor-based biosensors. In particular, the film 1/ITO electrode exhibits excellent stability, reproducibility, high selectivity, and anti-interference nature for the detection of both DA and APAP, indicating the great potential of calix[n]arene macrocycle-modified tetrapyrrole rare earth sandwich compounds in the field of ultrasensitive and specific nonenzymatic sensors.