Playing with Pt(II) and Zn(II) coordination to obtain luminescent metallomesogens

Blue-green luminescent terpyridine-containing Pt(II) and Zn(II) complexes are reported. Equipped by lipophilic gallate units that act as monodentate ancillary coordinating ligands and/or as anions, they display low temperature mesomorphic properties (lamello-columnar and hexagonal mesophases for Pt(II) and Zn(II) complexes, respectively). The mesomorphic properties were investigated by polarized optical microscopy, differential scanning calorimetry, thermogravimetric analysis and X-ray scattering of bulk materials and oriented thin film. The model of self-assembly into lamello-columnar phase of the Pt(II) complex has been described in details. The optical properties of the complexes were investigated in liquid and condensed liquid crystalline states highlighting the delicate balance between the role of the metal in determining the type of excited state responsible for the emission, and the role of the ancillary ligand in driving intermolecular interactions proper for mesophase formation.