Photophysical Properties of Ir(III) Complexes Immobilized in MCM-41 via Templated Synthesis

In the search for understanding and improving the luminescence of optical materials based on Ir(III) complexes, three [Ir(C^∧N)₂(dnbp)]⁺ (dnbp = 4,4'-dinonyl-2,2'-bipyridine) emitters were immobilized in MCM-41 mesoporous nanoparticles. By taking advantage of the amphiphilic nature of [Ir(C^∧N)₂(dnbp)]⁺, the complexes were mixed with an appropriate surfactant and the resulting micelles served as templates for the synthesis of mesoporous silica host materials in a one-step sol-gel route. The MCM-encapsulated [Ir(C^∧N)₂(dnbp)]⁺ complexes present intense emissions with prominent rigidochromic spectral changes that are substantially less affected by O₂ as compared to methanolic solutions, with a thousand-fold decrease in quenching rate constants. These photophysical results points to a possible suitability of Ir(III)-complex-MCM-41 host-guest systems for possible future optoelectronic devices, rigidity optical sensors, or biological markers in different colors.