An Adaptable Water-Soluble Molecular Boat for Selective Separation of Phenanthrene from Isomeric Anthracene

Abstract

Anthracene crude oil is a common source of phenanthrene for its industrial use. The isolation of phenanthrene from this source is a challenging task due to very similar physical properties to its isomer anthracene. We report here a water-soluble Pd­(II) molecular boat (MB1) with unusual structural topology that was obtained by assembling a flexible tetrapyridyl donor (L) with a cis-Pd­(II) acceptor. The flexible backbone of the boat enabled it to breathe in the presence of a guest optimizing the fit within the cavity. The boat binds phenanthrene more strongly than anthracene, which enabled separation of phenanthrene with an >98% purity from an equimolar mixture of the two isomers using MB1 as an extracting agent. MB1 represents a unique example of a coordination receptor suitable for selective aqueous extraction of phenanthrene from anthracene with reusability of several cycles.

Bifunctional {Pb10K2}–Organic Framework for High Catalytic Activity in Cycloaddition of CO2 with Epoxides and Knoevenagel Condensation

“…Furthermore, it is worth emphasizing that the inner wall of voids is characterized by exposed open Pb 2+ sites, protruding K + ions, μ 2 -OH groups, and uncoordinated N pyridine atoms. In addition, it is worth emphasizing that all Pb­(II) ions exhibit distorted semidirected geometries with stereochemically active lone pair electrons (Figures and S1), which is more conducive to the polarization of guest molecules. − …”

Fluorine-Functionalized NbO-Type {Cu2}-Organic Framework: Enhanced Catalytic Performance on the Cycloaddition Reaction of CO2 with Epoxides and Deacetalization-Knoevenagel Condensation

“…At present, the rapid increase of the concentrations of carbon dioxide (CO 2 ) has resulted in more and more serious environmental problems, such as global warming, rising sea level, and deterioration of the ecological environment. − Although the CO 2 emission mitigation with new energy and energy storage as the core provides a feasible method for decarbonization of the energy system, for the sake of energy safety, fossil energy will still exist in the energy structure in a certain proportion for a long time, and its corresponding total CO 2 emission will exceed the capacity of natural carbon sink. Therefore, it is certainly worth developing carbon capture, utilization, and storage technology to treat the waste gas of CO 2 discharged in the industrial production. − For now, the chemical conversion of CO 2 into high value-added chemicals is one of the most attractive and effective strategies to reduce the content of CO 2 , which illustrates that it is still of great practical significance to develop heterogeneous catalytic systems with high stability and high catalytic activity. − MOFs, as heterogeneous catalysts, have shown promising application prospects in the thermal catalytic conversion of CO 2 because of the following advantages: (i) porous structure can shorten the transmission distance between the substrate and the reaction center by enriching the substrate around the catalytic site, so as to improve the reaction rate; (ii) specific pores and highly dispersed catalytic sites are conducive to the highly selective catalytic reaction; and (iii) easy separation and recyclability can greatly reduce the reaction cost. − However, reported MOF-based catalysts also have some disadvantages, such as poor stability and the limitation of their microporosity on the mass transfer in the reaction. Therefore, in order to realize efficient CO 2 catalytic conversion of MOFs under mild conditions, it is of great significance to optimize their structures in the aspects of stability, active sites, and unobstructed void volumes.…”

Nanocage-Based Tb3+-Organic Framework for Efficiently Catalyzing the Cycloaddition Reaction of CO2 with Epoxides and Knoevenagel Condensation

“…After chelating a metal ion, other carboxyl groups of H 5 BDCP will grab other metal ions to result in binuclear or multinuclear metal-cluster nodes. 27,28 By employing the solvothermal reaction condition, a highly robust nanoporous framework of {[Tb 4 (BDCP) 2 (μ 2 −OH) 2 ]•3DMF• 5H 2 O} n (NUC-58) consisting of scarcely reported coplanar [Tb 4 (μ 2 −OH) 2 (CO 2 ) 8 ] cluster was obtained. Due to the structural stability, a well-developed nanopore structure, a high specific surface area, and coexisting acid−base sites, the activated framework of NUC-58a displayed excellent catalytic performances on the cycloaddition reactions of epoxides with CO 2 under mild conditions and on the Knoevenagel condensation reactions of aldehyde and malononitrile.…”

“…According to previous cognition, the reason that H 5 BDCP can easily induce metal ions to form metal-cluster nodes should be attributed to the fact that two α-carboxyl groups located on the two benzene rings at the 2,6-position of pyridine are strongly affected by the lone electron pair of N pyridine atoms and tend to chelate the metal with stronger Lewis acidity. After chelating a metal ion, other carboxyl groups of H 5 BDCP will grab other metal ions to result in binuclear or multinuclear metal-cluster nodes. , By employing the solvothermal reaction condition, a highly robust nanoporous framework of {[Tb 4 (BDCP) 2 (μ 2 –OH) 2 ]·3DMF·5H 2 O} n ( NUC-58 ) consisting of scarcely reported coplanar [Tb 4 (μ 2 –OH) 2 (CO 2 ) 8 ] cluster was obtained. Due to the structural stability, a well-developed nanopore structure, a high specific surface area, and coexisting acid–base sites, the activated framework of NUC-58a displayed excellent catalytic performances on the cycloaddition reactions of epoxides with CO 2 under mild conditions and on the Knoevenagel condensation reactions of aldehyde and malononitrile.…”