Water-Stable Hydrazone-Linked Porous Organic Cages

Although porous organic cages (POCs), particularly imine-linked (C=N) ones, have advanced significantly over the last decades, the reversible nature of imine linkages makes them prone to hydrolysis and structure collapse, severely limiting their applications in moist or water conditions. Herein, seven water-stable hydrazone-linked (C=N-N) POCs are prepared through a simple coupling of the same supramolecular tetraformylresorcin[4]arene cavitand with different dihydrazide linkers. Their structures are all determined by single-crystal X-ray crystallography, demonstrating rich structural diversity from [2+4] lantern, [3+6] triangular prism, unprecedented [4+8] square prism to extra-large [6+12] octahedron. In addition, they respectively exhibit tunable window diameters and cavity volumes ranging from about 5.4 to 11.1 nm and 580 to 6800 A3. Moreover, their application in the water environment for pollutant removal was explored, indicating that they can effectively eliminate various types of contaminants from water, including radionuclides waste, toxic heavy metal ions, and organic micropollutants. This work demonstrates a convenient method for rationally constructing versatile robust POCs and presents their great application potentialities in water media.