Mechano-induced multi-functional optical switches based on chiral cyclometalated platinum(II) complexes

•A couple of enantiomeric chiral cyclometalated platinum(II) complexes were prepared.•Mechano-induced switch of multi-functional optical properties was presented.•The switching should be attributed to the variance of molecular arrangement.

A couple of enantiomeric chiral cyclometalated platinum(II) complexes [Pt(−)-L1]Cl ((−)-1) and [Pt(+)-L1]Cl ((+)-1) [(−)-L1 = (−)-4,5-pinene-6′-phenyl-2,2′-bipyridine, (+)-L1 = (+)-4,5-pinene-6′-phenyl-2,2′-bipyridine] were obtained, studying their mechanochromic behaviors, and corresponding luminescent, chiroptical and nonlinear optical properties. Upon mechanical grinding, the crystallites of (−)-1 and (+)-1 undergo a crystal-to-amorphous and ordered-to-disorder transformation. For these grinding-induced amorphous and poorly organized aggregates, the luminescence was distinctly red-shifted (Δλem = 160 nm) compared to that of crystallites. Moreover, electronic circular dichroism signals and nonlinear optical responses became almost silent. Remarkably, the poorly organized amorphous phase can be easily restored to original crystalline state upon treatment with a few drops of dichloromethane, suggesting an excellent reversible switch.

Graphical abstractA couple of enantiomeric chiral cyclometalated platinum(II) complexes were obtained, studying their interesting mechanochromic behaviors, and corresponding luminescent, chiroptical and nonlinear optical properties.Figure optionsDownload full-size imageDownload as PowerPoint slide