<p>We report a series of seven cationic heteroleptic copper(I) complexes of the form [Cu (P^P) (dmphen)]BF<sub>4</sub>, where dmphen is 2,9-dimethyl-1,10-phenanthroline and P^P is a diphosphine chelate, in which the effect of the bite angle of the diphosphine ligand on the photophysical properties of the complexes was studied. Several of the complexes exhibit moderately high photoluminescence quantum yields in the solid-state, with Φ<sub>PL</sub> of up to 35%, and in solution, with Φ<sub>PL</sub> of up to 98%. We were able to correlate the powder photoluminescence quantum yields with the %V<sub>bur</sub> of the P^P ligand. The most emissive complexes were used to fabricate both organic light-emitting diodes (OLEDs) and light-emitting electrochemical calls (LECs), both of which showed moderate performance. Compared to the benchmark Cu(I)-based LECs, [Cu(dnbp)(DPEPhos)]<sup>+ </sup>(EQE<sub>max</sub> = 16%), complex <b>3</b> (EQE<sub>max</sub> = 1.85%) showed much longer device lifetime (t<sub>1/2 </sub>= 1.25 h and >16.5 h for [Cu(dnbp)(DPEPhos)]<sup>+</sup> and complex <b>3</b>, respectively). The electrochemiluminescent properties of several complexes were also studied which to the best of our knowledge constitutes the first ECL study for heteroleptic copper (I) complexes. Notably, complexes exhibiting more reversible electrochemistry were associated with higher annihilation ECL as well as better performance in an LEC device.</p>
Influence of the Bite Angle of Dianionic C,N,C-Pincer Ligands on the Chemical and Photophysical Properties of Iridium(III) and Osmium(IV) Hydride Complexes
