Effect of substituents in tuning the inter- and intra-molecular interactions in the dinuclear Pt(II) complexes

Abstract

Substituents play a vital role in the formation of inter- and intra-molecular interactions in the Pt(II) complexes, especially Pt···Pt interactions have a tendency to tune the emission wavelength and the efficiency which has the potential applications in the field of organic light-emitting diodes (OLEDs). In this regard, the pyridazine-based bidentate ligands L1 (-CH3) and L2 (-CF3) are designed and synthesized. Subsequently, the ligands are carefully utilized for the preparation of dinuclear Pt(II) complexes 1 and 2. Complexes were analyzed by various analytical and spectroscopic studies and further confirmed by single crystal X-ray studies, which revealed both complexes show much shortened intra-molecular Pt···Pt distance (2.903 Å in 1 and 2.883 Å in 2) which helps to tune the emission towards the NIR region (up to 850 nm). Further, both complexes show various intermolecular interactions which lead to the formation of a multi-dimensional framework. Complexes 1 and 2 show strong emission at 705 nm and 725 nm, respectively, and further, DFT and TD-DFT studies were performed which confirms that complexes 1 and 2 show strong MMLCT character.