Synthesis, Luminescence, and Structure of a Polymorphic Polyfluorinated Diiodoplatinum(II) Diimine Complex

Area of Science:

• Inorganic Chemistry
• Materials Science
• Crystallography

Background:

• Polymorphism in metal complexes can significantly influence their physical properties, including luminescence.
• Fluorinated ligands can alter electronic properties and intermolecular interactions in organometallic compounds.
• Platinum(II) diimine complexes are known for their photophysical properties and potential applications.

Purpose of the Study:

• To synthesize and characterize a novel fluorinated platinum diiodide diimine complex.
• To investigate the occurrence and nature of polymorphism in this complex.
• To elucidate the relationship between solid-state structure and luminescence properties of different polymorphs.

Main Methods:

• Synthesis and recrystallization of the platinum complex, 55-2FH-PtI.
• X-ray diffraction analysis to determine crystalline structures of the α and β polymorphs.
• Photoluminescence spectroscopy at 77 K (glassy solution) and in the solid state.

Main Results:

• The complex PtI2(5,5'-bis(HCF2CH2OCH2)-2,2'-bpy), or 55-2FH-PtI, was synthesized and found to exhibit polymorphism.
• Two distinct polymorphs, α and β, were isolated, differing in their solid-state crystal packing and luminescence.
• The α form, with a herringbone structure, exhibited stronger emission than the β form, which showed tetrahedral distortion and quenched luminescence due to overlapping bipyridine rings.

Conclusions:

• The study demonstrates the first example of polymorphism in a substituted fluorinated diiodoplatinum diimine complex.
• Solid-state packing significantly impacts the luminescence of the α and β polymorphs, with the α form showing superior emission.
• Structural differences, including metal center distortion and intermolecular interactions, are responsible for the observed variations in photophysical behavior.