Two new complexes of Ir(I) using diphosphine and diphosphinite calix[4]arene ligands have been prepared and characterized. The luminescent lowest energy excited MLCT state (metal-to-ligand charge transfer) has been addressed theoretically by extended Huckel molecular orbital calculations (EHMO), and a Franck-Condon analysis on the absorption spectra using the time dependent Heller's theory, has been made. The perturbation of τ e of the two complexes in ethanol at 77 K by the addition of substrates (UO 2 2 + , Li + , Na + ), is investigated. The amplitude in τ e change with additions of substrates varies as UO 2 2 + > Li + > Na + .