Green and controlled synthesis of copper-based tryptophan flower-like chiral metal-organic framework for enantioselective recognition and volatile organic compound separation

This study reports the synthesis and application of a flower-like chiral metal-organic framework (CMOF) based on copper ions and tryptophan (Cu(Trp)-CMOF). The Cu(Trp)-CMOF was successfully synthesized at room temperature through a facile method with hexadecyl trimethyl ammonium bromide (CTAB) as a structure-directing agent. The material exhibits a flower-like morphology with hierarchical porosity and well-defined crystallinity in the monoclinic P2₁/c space group. Comprehensive characterization revealed that different optical configurations ((R)-type, (S)-type, and (RS)-type) could be selectively obtained by controlling the chirality of tryptophan ligands. The synthesized CMOFs demonstrated excellent performance in two key applications: colorimetric recognition of amino acid enantiomers and separation of volatile organic compounds (VOCs). When used as a chromatographic stationary phase, the CMOF significantly enhanced the separation of challenging structural isomers, particularly improving the resolution (R_S) of xylene isomers (R_S from 1.03 to 2.62) and ethyltoluene isomers (R_S from 4.83 to 9.23) compared to conventional columns. This work provides new insights into the design and application of CMOFs for chiral separation and recognition.