文摘
Counterions with multiple charges have been used to organize polymethines into multichromophore salt complexes. The intramolecular Coulombic interactions between multiply charged counterions and polymethines can play a significant role in modifying intermolecular interactions (i.e., aggregation). Here, we report a detailed study of the linear and nonlinear optical properties of such complexes with dications and hexacations over a large range of molecular concentrations. Our results have demonstrated that, despite strong intramolecular interactions, the preorganization of chromophores into the multichromophore salt constructs with multiple charges can provide a steric repulsive effect that can mitigate intermolecular interactions in the solid state. This results in a more efficient translation between microscopic and macroscopic optical properties for highly polarizable polymethines, which is essential for all optical signal switching.