Photocatalytic activity under visible light of five functionalized materials with an iridium(III) complex

Abstract

Photocatalysis under visible light has attracted much attention in the last years, due to theinterest in the use of the visible region of the electromagnetic spectrum for chemical reactionsunder mild conditions. It also avoids secondary reactions that can occur by using otherirradiation sources like UV light. Organometallic complexes of Ir(III) or Ru(II) are widely used asphotocatalysts due to their capacity of absorbing light in a broad region of the spectra, and theirstable and long-lived triplet emissions.[1] However, the low natural abundance of these metalsand their high price have promoted the search for ways to heterogenize the catalyticalhomogeneous processes, facilitating the photocatalyst recuperation and its reutilization inseveral catalytical cycles.[2] In addition, this fact minimizes purification steps on the obtainedproducts.In this communication, we present the use of the Iridium(III) complex[Ir(dfppy)2(dasipy)]PF6 (dasipy (4,4’-(CONH(CH2)3Si(OCH2CH3)3)2-bipyridine) (Figure 1, A) asstarting building block for the in-situ one-pot synthesis of four hybrid organometallo-silicamaterials, and the preparation of a related post-synthetic grafted silica material (Figure 1, B),obtaining discrete nanoparticles, as well as mesoporous amorphous gels. After characterizationof the materials, we have tested their photocatalytic activity using a standard isomerizationreaction (Figure 1, C), which has allowed us to study the recyclability of these materials, as wellas the influence of their textural properties in the photocatalytic activity.