• Oliveira, Elisabete
• Cano, Mercedes
• Campo, Jose A.
• Cuerva, Cristian
• Torres, M. Rosario
• Lodeiro, Carlos
• Ovejero, Paloma
• Santos, Sergio M.

Abstract

A new family of Pt(II) luminescent metallomesogens based on dicatenar pyridylpyrazolate ligands [Pt(pzR(n,n)py)2](R(n,n) ¼ C6H3(OCnH2n+1)2, n ¼ 4–18) has been prepared, and their mesomorphic and photophysicalproperties are described. The compounds were isolated as red (n ¼ 4–8) or yellow (n ¼ 10–18) solids atroom temperature, but the first ones were converted to yellow crystals by slow evaporation of achloroform–acetone mixed solution. All of them behave as discotic liquid crystal materials, exhibitinghexagonal columnar mesophases (Colh) in a wide range of temperatures. Photoluminescence studies inthe solid state at variable temperatures showed a high emission in the liquid crystalline phase, which wassignificantly red-shifted with respect to the yellow-green emission of the solid state. This photophysicalchange was attributed to the formation of aggregates through Pt(dz2)–Pt(dz2) interactions, thereby givingrise to the metal–metal-to-ligand charge transfers (3MMLCT) responsible for the luminescenceobserved. Taking advantage of these properties we have fabricated polymeric solid supports doped withthe platinum complex [Pt(pzR(10,10)py)2], which can be used as temperature sensors for real technologicalapplications. In addition, the Pt–bispyrazolate complexes and their corresponding pyrazole ligands havebeen proved to be useful as chemosensors towards Pd2+, Zn2+, Cd2+ and Hg2+ metal ions.

Topics

• compound
• photoluminescence
• crystalline phase
• Platinum
• evaporation
• liquid crystal