Cyclometalated Pt(II)-terpyridine metallomesogen. What is visible or invisible that is a matter of molecular packing and orientation

An anisotropic light emitting metallomesogen (PtM) consisting of a cyclometalated platinum(II)–terpyridine (Pt(II)–tpy) chromophore and a flexible dendron is newly synthesized as a thermal-induced and polarization-induced solid-state luminescence switching material. The self-assembled PtM is uniaxially aligned by mechanical shearing within the mesophase resulting in high optical anisotropy with chromophores. The shear-induced metastable PtM crystal exhibits emission change depending on the polarization direction and thermally triggered reversible emission quenching-recovery characteristic. In order to precisely control the optical feature of the PtM, the self-assembled supramolecular structure and thermal-sensitive photophysical properties are characterized. Based on the multiresponsive luminescence switching system of PtM, a multiplexed optical code is encrypted with a simple coating and its feasibility for optical anticounterfeiting applications is demonstrated.