- Zn- and Cd-based Coordination Polymers Offering H-Bonding Cavities: Highly Selective Sensing of S2O7 2? and Fe3+ Ions
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We present two ZnII- and CdII-based coordination polymers (CPs), L-Zn and L-Cd, offering H-bonding-based cavities of varying dimensions. Both CPs were used for the highly selective detection of S2O7 2? and Fe3+ ions where H-bonding based cavities played an important role. Fluorescence quenching, competitive binding studies and binding parameters substantiated significant recognition of S2O7 2? and Fe3+ ions by both CPs.
- Kumar, Gulshan,Pachisia, Sanya,Kumar, Pramod,Kumar, Vijay,Gupta, Rajeev
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- Synthesis and catalytic activities of a Zn(ii) based metallomacrocycle and a metal-organic framework towards one-pot deacetalization-Knoevenagel tandem reactions under different strategies: A comparative study
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Solvothermal reactions between a pyridine based amide functionalized dicarboxylic acid, 4,4′-{(pyridine-2,6-dicarbonyl)bis(azanediyl)}dibenzoic acid (H2L), and zinc(ii) nitrate in the absence and presence of a base produced the binuclear metallomacrocyclic compound [Zn2(L)2(H2O)4]·2(H2O)·6(DMF) (1) and the metallomacrocyclic based two dimensional MOF [Zn5(L)4(OH)2(H2O)4]n·8n(DMF)·4n(H2O) (2), respectively. Compound 1 bears two tetrahedral Zn(ii) centres, whereas the 2D framework 2 includes a penta-nuclear Zn(ii) cluster as a secondary building block unit, with two of the metal cations assuming a tetrahedral type geometry and the remaining three an octahedral type geometry. The topological analyses reveal that compound 1 has a 2-connected uninodal net and framework 2 has a 2, 8-connected binodal net. These compounds heterogeneously catalyse the tandem deacetalization-Knoevenagel condensation reactions carried out under conventional heating, microwave irradiation or ultrasonic irradiation. Comparative studies show that ultrasonic irradiation (final product yield of 99percent after 2 h of reaction time) provides the most favourable method (e.g., microwave irradiation leads to a final product yield of 91percent after 3 h of reaction time). Moreover, the catalysts can be reused at least for five consecutive cycles without losing activity significantly.
- Guedes Da Silva, M. Fátima C.,Karmakar, Anirban,Pombeiro, Armando J. L.,Rúbio, Guilherme M. D. M.,Soliman, Mohamed M. A.
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p. 8075 - 8085
(2020/07/10)
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- Preparation of core-shell coordination molecular assemblies via the enrichment of structure-directing codes of bridging ligands and metathesis of metal units
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A series of molybdenum- and copper-based MOPs were synthesized through coordination-driven process of a bridging ligand (3,3′-PDBAD, L1) and dimetal paddlewheel clusters. Three conformers of the ligand exist with an ideal bridging angle between the two carboxylate groups of 0° (H2α-L1), 120°(H2β-L1), and of 90°(H2γ-L1), respectively. At ambient or lower temperature, H2L1 and Mo2(OAc)4 or Cu2(OAc)4 were crystallized into a molecular square with γ-L1 and Mo2/Cu2 units. With proper temperature elevation, not only the molecular square with γ-L1 but also a lantern-shaped cage with α-L1 formed simultaneously. Similar to how Watson-Crick pairs stabilize the helical structure of duplex DNA, the core-shell molecular assembly possesses favorable H-bonding interaction sites. This is dictated by the ligand conformation in the shell, coding for the formation and providing stabilization of the central lantern shaped core, which was not observed without this complementary interaction. On the basis of the crystallographic implications, a heterobimetallic cage was obtained through a postsynthetic metal ion metathesis, showing different reactivity of coordination bonds in the core and shell. As an innovative synthetic strategy, the site-selective metathesis broadens the structural diversity and properties of coordination assemblies.
- Park, Jinhee,Chen, Ying-Pin,Perry, Zachary,Li, Jian-Rong,Zhou, Hong-Cai
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supporting information
p. 16895 - 16901
(2015/02/05)
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