Breaking Mirror Circularly Polarized Luminescence of Chiral Metal-Organic Frameworks by High-Pressure Stimulation

Understanding high-pressure-stimulated circularly polarized luminescence (CPL) of enantiomers remains a challenging but significant task in funda-mental research and optical applications. Here, we combined in situ high-pressure photoluminescence with circularly polarized light to study how high pressure stimulated the CPL of crystalline enantio-mers. Chiral lanthanide (Ln)-tartrate (Tar) metal- organic frameworks (MOFs; Ln = Eu, Tb) were syn-thesized to study their CPL from atmospheric pres-sure to 10 GPa. Under atmospheric pressure, D- and L-Eu(Tar) showed strong and mirror CPL. CPL intensity changes, emission wavelength shifts, and signal inver-sions were induced by increasing pressure. Note that the D-Eu(Tar) enantiomer showed strong CPL with a maximal dissymmetric factor (glum) of 0.69 under 3 GPa, which is much higher than that under atmo-spheric pressure and of other reported MOF-based CPL materials. More interestingly, D- and L-Ln(Tar) enantiomers display obvious asymmetric CPL signals with increasing pressure, demonstrating that high pressure can break the mirror CPL of the MOF enantiomers. Our findings provide a critical under-standing on in situ high-pressure CPL of chiral materials and establish a new optical phenomenon where high pressure can break the mirror CPL of enantiomers.