Two polymeric 36-metal pure lanthanide nanosize clusters

973 Program [2011CBA00507, 2011CB932504]; National Natural Science Foundation of China [21131006]; Natural Science Foundation of Fujian ProvinceTwo rarely seen 2D coordination polymers based on huge 36-metal pure lanthanide clusters, {[Gd-36(NA)(36)(OH)(49)(O)(6)(NO3)(6)(N-3)(3)(H2O)(20)]Cl-2 center dot 28H(2)O}(n) (1) and {[Dy-36(NA)(36)(OH)(49)(O)(6)(NO3)(6)(N-3)(3-)(H2O)(20)]Cl-2 center dot 28H(2)O}(n) (2) (HNA = nicotinic acid), were synthesized and structurally characterized. The spherical Ln(36) skeleton can be viewed as the aggregation of one cyclohexane chair-like Ln(24) wheel and two identical tripod-like Ln(6) units. The coordination of the carboxylic groups of the NA ligands with the Ln(III) cations results in a square layer. Additionally, compound 1 possesses a large MCE of 39.66 J kg(-1) K-1 and compound 2 exhibits slow relaxation of the magnetization

Hydrolytic synthesis and structural characterization of lanthanide-acetylacetonato/hydroxo cluster complexes - A systematic study

Lanthanide hydroxide cluster complexes with acetylacetonate were synthesized by the hydrolysis of the corresponding hydrated lanthanide acetylacetonates in methanol in the presence of triethylamine. Polymeric lanthanide hydroxide complexes based on diamond-shaped dinuclear repeating units of [Ln(2)(CH(3)CO(3))(2)](4+) (Ln = La, Pr) and discrete complexes featuring a tetranuclear distorted cubane core of [Ln(4)(mu(3)-OH)(2)(mu(3)-OCH(3))(2)](8+) (Ln = Nd, Sm) and a nonanuclear core of [Ln(9)(mu(4)-O)(mu(4)-OH)(mu(3)-OH)(8)](16+) (Ln = Eu-Dy, Er, Yb) were obtained. The dependence of the cluster nuclearity on the identity of the lanthanide ion is rationalized in terms of the influences of a metal ion's Lewis acidity and the sterics about the Ln-OH unit on the kinetics of the assembly process that leads to a particular cluster.U.S. NSF[CHE-0238790

A dinuclear europium(III) complex with thenoyltrifluoroacetonato and 1-(2-pyridylzao)-2-naphtholato ligands and its optical properties

Dinuclear lanthanide complexes of the general for Ln(2)(TTA)(4)(PAN)(2) (Ln = Eu, Gd, Tb, Yb; TTA and monodeprotonated thenoyltrifluoroacetone and PAN 1-(2-pyridylazo)-2-naphthol, respectively) were prepared and structurally characterized. These novel complexes, representing the first examples of crystallographically characterized lanthanide-PAN complexes, each feature a dinuclear core with the metal atoms bridged by the phenolato O atoms of the chelating-bridging PAN ligands. Electronic spectroscopic and photoluminescence studies were carried out for the Eu(III) complex, and the results are consistent with ligand-mediated energy transfer and ligand-sensitized luminescence characteristic of Eu(III). The Eu(III) complex doped into a polymeric film was shown to effectively limit a nanosecond 523-nm laser pulse, and the limiting effect is rationalized in terms of reverse saturable absorption due to the strong absorption of the metal's excited triplet states that are populated by intersystem crossing. (C) 2011 Elsevier B.V. All rights reserved.US NSF[CHE-0238790]; US Army Research Office MURI through the University of Central Florida[50372-CH-MU

An organic-inorganic hybrid uranyl nicotinate molybdate polymer and its fluorescent property

A uranyl nicotinate molybdate polymer [UO2(nicot)(MoO3OH)](n) (Hnicot = nicotinic acid, NC5H4CO2H) was synthesized by the hydrothermal reaction of uranyl nitrate [UO2(NO3)(2)-6H(2)O], phosphomolybolic acid (H3PMo12O40) and nicotinic acid. Its crystal structure and fluorescent property were measured. The results show that the crystal packs in the ID chains of uranyl molybdates with strong fluorescence at the range of 470-520 nm. (c) 2007 Published by Elsevier B.V

2,5-Diketopiperazines: A Review of Source, Synthesis, Bioactivity, Structure, and MS Fragmentation

Background: 2,5-Diketopiperazines (DKPs), also called cyclic dipeptides, are the simplest peptide derivatives in nature that are formed by the condensation of two amino acids. They are an important category of bioactive substances with various structures. Objective: This review focuses on the natural sources, synthetic processes, biological properties and MS fragmentation regularity of simple DKPs, in order to provide a reference for exploring future scientific and therapeutic potentials of these compounds. Method: Pertinent information was collected and organized from several electronic scientific databases (e.g., Web of Science, China Knowledge Resource Integrated, ScienceDirect, PubMed, Wanfang Data and Google Scholar), PhD and MS dissertations. There are 107 articles published from the early 20th century to 2021 that were reviewed in this work. Results: DKPs have been obtained from a broad range of natural resources, including fungi, bacteria, plants, and animals, and have been synthesized by chemical and biological methods. DKPs have various pharmacological activities, including anticancer, antibacterial, antithrombotic, neuron protective, analgesic, and other activities. Mass spectrometry is the most common method for the structural analysis of DKPs. DKPs can be quickly screened and identified by MS according to the mass spectrum fragmentation pattern. Conclusion: As a category of relatively unexplored compounds, DKPs have been demonstrated to have various bioactivities, especially with antitumor and antibacterial activities. However, the existing research on DKPs is still in the early stage, and their application in drug development needs to be further studied

MOF-Templated Synthesis of Porous Co3O4 Concave Nanocubes with High Specific Surface Area and Their Gas Sensing Properties

National Basic Research Program of China [2011CBA00508, 2013CB933901]; National Natural Science Foundation of China [21171142, 21131005, 21333008, 21371144]; program for New Century Excellent Talents in University [NCET-11-0294]Porous metal oxides nanomaterials with controlled morphology have received great attention because of their promising applications in catalysis, energy storage and conversion, gas sensing, etc. In this paper, porous Co3O4 concave nanocubes with extremely high specific surface area (120.9 m(2).g(-1)) were synthesized simply by calcining Co-based metal organic framework (Co-MOF, ZIF-67) templates at the optimized temperature (300 degrees C), and the formation mechanism of such highly porous structures as well as the influence of the calcination temperature are well explained by taking into account thermal behavior and intrinsic structural features of the Co-MOF precursors. The gas-sensing properties of the as-synthesized porous Co3O4 concave nanocubes were systematically tested towards volatile organic compounds including ethanol, acetone, toluene, and benzene. Experimental results reveal that the porous Co3O4 concave nanocubes present the highest sensitivity to ethanol with fast response/recovery time (< 10 s) and a low detection limit (at least 10 ppm). Such outstanding gas sensing performance of the porous Co3O4 concave nanocubes benefits from their high porosity, large specific surface area, and remarkable capabilities of surface-adsorbed oxygen

MOF-Templated Synthesis of Porous Co₃O₄ Concave Nanocubes with High Specific Surface Area and Their Gas Sensing Properties

Porous metal oxides nanomaterials with controlled morphology have received great attention because of their promising applications in catalysis, energy storage and conversion, gas sensing, etc. In this paper, porous Co₃O₄ concave nanocubes with extremely high specific surface area (120.9 m²·g^‑1) were synthesized simply by calcining Co-based metal–organic framework (Co-MOF, ZIF-67) templates at the optimized temperature (300 °C), and the formation mechanism of such highly porous structures as well as the influence of the calcination temperature are well explained by taking into account thermal behavior and intrinsic structural features of the Co-MOF precursors. The gas-sensing properties of the as-synthesized porous Co₃O₄ concave nanocubes were systematically tested towards volatile organic compounds including ethanol, acetone, toluene, and benzene. Experimental results reveal that the porous Co₃O₄ concave nanocubes present the highest sensitivity to ethanol with fast response/recovery time (< 10 s) and a low detection limit (at least 10 ppm). Such outstanding gas sensing performance of the porous Co₃O₄ concave nanocubes benefits from their high porosity, large specific surface area, and remarkable capabilities of surface-adsorbed oxygen