Electrochemiluminescence of iridium(iii)/ruthenium(ii) complexes with naphthyl tags in solutions and host-guest thin films

Herein we report electrochemiluminescence (ECL) generation from three new iridium(iii)/ruthenium(ii) (Ir(iii)/Ru(ii)) complexes with naphthyl (nap) tags in solutions and host-guest thin films. In comparison with its parent structure, the addition of a nap tag to [4-(2-naphthalenyl)-1,10-phenanthroline]bis(2,2'-bipyridine)ruthenium(ii) results in a 6.1-fold enhancement in the ECL efficiency. Moreover, the nap tag enables the non-covalent immobilization of Ir(iii)/Ru(ii) complexes via host-guest interactions. Therefore, a molecular thin film was constructed by hydrophobic effects between the cavity of beta-cyclodextrin and the nap tags, which emits stable and strong ECL emission in the presence of tri-n-propylamine (TPrA). These results give a mechanistic insight into ECL generation from (Ir(iii)/Ru(ii)) complexes with host-guest recognition tags and may help in the development of host-guest thin film-based ECL sensors.