Cascading in-situ grown UiO-66 and alternative calix[n]arenes for high-resolution isomer separation

• Flexible TBCx[n]s were cascaded with in-situ grown UiO-66 coatings successfully. • The separation performance toward various isomers was systematically evaluated. • TBCx[n]s made up for the deficiency on the separation of ethylbenzene and styrene. • UiO-66@TBCx[6] column exhibited the best separation performance with high resolution. High-resolution separation of numerous isomers is highly desirable for their high-quality analysis, yet challenging, which puts forward high requirements on the precise design of stationary phase. Herein, flexible 4- tert -butylcalix[n]arenes (TBCx[n]s) with different cavities have been intelligently integrated with in-situ grown UiO-66 coatings, to investigate their separation efficiencies for alkane and substituted benzene isomers. The modifications of UiO-66 with TBCx[n]s have made up for the deficiency of UiO-66 on the separation of ethylbenzene and styrene. The effects of TBCx[n]s on the separation performance of UiO-66@TBCx[n]s have demonstrated distinct regularities, i.e., the effects of TBCx[6] are superior to those of TBCx[8], while the TBCx[4] is the least effective. The baseline separation of all analytes has been achieved by the UiO-66@TBCx[6] column with enhanced selectivity and improved separation resolution (Rs). For the six groups of isomers that are most difficult to separate, the corresponding selectivity and Rs are greater than 1.09 and 5.48, respectively, confirming the outstanding separation performance of the UiO-66@TBCx[6] column and the feasibility of integrating soft supramolecule and rigid MOF.