Red to Green Switch Driven by Order in an Ionic Ir^III Liquid‐Crystalline Complex

Abstract

New cationic IrIII materials of general formula [Ir(ppy)2(Cn‐bpy)]PF6 {H(ppy) = 2‐phenylpyridine; Cn‐bpy = 3,4,5‐R‐4,4′‐benzoyloxymethyl‐2,2′‐bipyridine; n = 8, R = OC8H17; n = 0, R = H} were synthesised and fully characterised. Both complexes show high phosphorescence quantum yields in their condensed phases. Moreover, the introduction of long alkoxy chains on the bipyridne ligand in [Ir(ppy)2(C8‐bpy)]PF6 (1) has induced mesomorphism, and consequently a dynamic functional material with properties modulated by external stimuli has been obtained. Starting from the isotropic phase, on slow cooling a crystalline phase characterised by a bright green emission is obtained. However, on fast cooling a kinetically favoured columnar hexagonal mesophase is preferentially formed, which is stable down to room temperature. In this phase, the high luminescence is still maintained, even if a switch to yellow emission colour is observed. Moreover, through spin coating of solutions of 1, it has been possible to obtain its amorphous thin film to accomplish a further shift of the emission wavelength in the orange‐red spectral range. A fully reversible colour tuning process by surface stress and heating from the orange‐red film to the green crystalline phase, indicative of a mechanochromic behaviour, is also achieved.

Aggregation induced colour change for phosphorescent iridium(iii) complex-based anionic surfactants

“…Most of the reported molecular systems deal with positively charged luminescent ruthenium(II) and platinum(II) complexes and neutral either linear or branched long alkyl chains, acting as polar head and apolar tail, respectively. 9 and Bruce et al 10 reported the first examples of self-assembling, both neutral and charged core, luminescent iridium(III)-based complexes, functionalized with neutral alkyl chains in order to induce liquid crystalline properties. 9 and Bruce et al 10 reported the first examples of self-assembling, both neutral and charged core, luminescent iridium(III)-based complexes, functionalized with neutral alkyl chains in order to induce liquid crystalline properties.…”

Blue and Green Phosphorescent Liquid‐Crystalline Iridium Complexes with High Hole Mobility

“…As aresult, only very few iridium-basedl uminescent metallomesogens have been reportedt od ate, and all emit in the yellow/orange region of the electronic spectrum. [18][19][20] Herein, am odular approach to thed esign of mesomorphic phosphorescent iridium complexes is demonstrated,astrategy allowing the quasi-independente ngineering of both the photophysical anda ggregation properties of the complexes. To achieve this, we grafteds trongly mesogenic groups [21][22][23][24][25] onto the non-chromophoric acetylacetonate (acac) ancillary ligand of [Ir(C^N) 2 (acac)] complexes.…”

Memory chromic polyurethane with tetraphenylethylene

“…Chromic materials, which show emission color or intensity change induced by external stimulus including: temperature, solvent, light, electro‐bean, pressure, and humidity, have aroused interest in recent years due to their potential applications in both low and high technology areas . Taking the advantage of high Φ F value in the solid state, aggregation induced emission (AIE)‐active molecules are thus considered as promising candidates for such applications.…”