Abstract
In this study, we report thermodynamic and kinetic strategies for arranging three types of Ca-Tb heterotetranuclear cores in a square configuration sandwiched by thiacalix[4]arene-p-tetrasulfonate (TCAS) ligands in aqueous solutions. In the thermodynamic strategy, the components were mixed under optimum pH conditions to afford a complex with a desired ratio of Ca:Tb:TCAS. In the kinetic strategy, the Ca(1)Tb(3)TCAS(2) complex was formed via mixing kinetically stable Tb(3)TCAS(2) with Ca(2+). Interestingly, the resulting complexes (Ca (x) Tb(4-x) TCAS(2), x = 1-3) exhibited Tb-centered luminescence upon excitation of the TCAS center with a high quvdantum yield (ϕ = 0.11-0.14) and a long luminescence lifetime (approximately 1.2 ms). The thermodynamic strategy can be applied to Sr(2+) instead of Ca(2+), but it is not suitable for first transition metal ions. However, the kinetic strategy is versatile and can be applied to first transition metal ions to afford M(1)Tb(3)TCAS(2) (M = Sr(2+), Mn(2+), Fe(2+), Co(2+), Ni(2+), Cu(2+), Zn(2+)).