Green Synthesis of Indeno[1,2-b]quinoxalines Using ß-Cyclodextrin as Catalyst.

An efficient, mild, and green method was developed for the synthesis of indeno[1,2-b]quinoxaline derivatives via o-phenylenediamine (OPD) and 2-indanone derivatives utilizing ß-cyclodextrin (ß-CD) as the supramolecular catalyst. The reaction can be carried out in water and in a solid state at room temperature. ß-CD can also catalyze the reaction of indan-1,2-dione with OPD with a high degree of efficiency. Compared to the reported methods, this procedure is milder, simpler, and less toxic, making it an eco-friendly alternative. In addition, the ß-CD can be recovered and reused without the loss of activity.

Ultrahigh Carbon Dioxide-Selective Composite Membrane Containing a γ-CD-MOF Layer.

Mixed matrix membranes (MMMs) for CO2 separation have overcome the trade-off between gas permeability and gas selectivity to some extent. However, most MMMs still are prepared in lab- and pilot-scales since the permeability and selectivity of CO2 are not good enough to reach the economically available requirements. Moreover, the fabrication of few MMMs with good separation performance is time-consuming or need harsh conditions. In this study, a novel MOF-based composite membrane (PAN-γ-CD-MOF-PU membrane) was successfully fabricated by a facile and fast spin-coating method. In the two-step coating process, we applied a uniform selective layer of γ-cyclodextrin-MOF (γ-CD-MOF) on porous polyacrylonitrile and then coated a layer of polyurethane on the γ-CD-MOF layer. The entire membrane formation process was about 30 s. The formation of a unique γ-CD-MOF layer greatly improved the separation ability of CO2 (the CO2 permeability is 70.97 barrers; the selectivity to CO2/N2 and CO2/O2 are 253.46 and 154.28, respectively). The gas separation performance can exceed the Robeson upper limit obviously and the selectivity is better than other MOF-based composite membranes. In addition, the PAN-γ-CD-MOF-PU membrane is strong and flexible. Therefore, the PAN-γ-CD-MOF-PU membrane developed in this study has great potential in large-scale industrial separation of CO2.

Facile Fabrication of an AIE-Active Metal-Organic Framework for Sensitive Detection of Explosives in Liquid and Solid Phases.

Nowadays, the practical applications of metal-organic framework (MOF)-based fluorescence detectors are severely hindered because of the complex synthesis process of linkers or heavy metal contamination. The development of a simple, inexpensive, and environmentally friendly fluorescence sensing system remains a huge challenge. In this study, we designed and synthesized a TPE@γ-CD-MOF-K complex using the facile in situ encapsulation method. The unique pore structure of γ-CD-MOF allowed it to effectively include TPE and explosives as guests simultaneously. The TPE@γ-CD-MOF-K showed stronger fluorescence emission than TPE and sensitive fluorescence quenching activities in response to nitro-aromatic compounds in the liquid phase with detection limits as low as 3 ppm. Furthermore, TPE@γ-CD-MOF-K can also effectively detect nitro-aromatic compounds in the solid state, which is very convenient for practical detection of explosives. The unique pore structure of γ-CD-MOF-K and the interaction between K+ and nitro compounds play important roles in solid-state quenching.

Amino-Functionalized ß-Cyclodextrin to Construct Green Metal-Organic Framework Materials for CO2 Capture.

The adsorption of CO2 by conventional liquid alkanolamine adsorbents does not meet the requirements for green-friendly development in industrial applications. In this work, we constructed NH2-ß-CD-MOF for the first time through the amino-functionalization of the lowest-priced, readily available, and biocompatible ß-CD. Subsequently, the samples were characterized by single-crystal X-ray diffraction, powder X-ray diffraction, scanning electron microscopy, differential scanning calorimetry, thermogravimetric analysis, elemental analysis, and N2 adsorption/desorption. The CO2 adsorption capacity of NH2-ß-CD-MOF was found to be 12.3 cm3/g, which is 10 times that of ß-CD-MOF. In addition, NH2-ß-CD-MOF has outstanding selective adsorption of CO2/N2 (947.52) compared with the reported materials. The adsorption mechanism of CO2 was analyzed by X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. Furthermore, we have found that NH2-ß-CD-MOF has better water stability relative to ß-CD-MOF and γ-CD-MOF, and it can be recycled by an ultrasonic method.