Self-Assembly of Axially Functionalized Subphthalocyanines in Thin Films

The addition of trialkoxylbenzyloxyl substituents at the axial position of conformationally nonplanar SubPc promotes its solid-state self-assembly. Unlike prior SubPc derivatives, photophysical studies suggest the presence of intermolecular electronic coupling between neighboring cores of SubPc derivatives, the strength of which depends on both the electronic nature of the core - which we tune through fluorination - and the extent of van der Waals interactions originating from the alkyl side chains on the trialkoxylbenzyloxyl tail. Modulating the relative strength of core-core and van der Waals interactions introduces morphological richness and provides access to liquid crystalline hexagonal and smectic phases. When core-core interactions are strong, thin films of SubPc spontaneously adopt a highly crystalline lamellar structure in the solid state. Thin films of trialkoxylbenzyloxyl-substituted SubPcs thus support efficient energy and charge transfer given their intermolecular electronic communication and long-range order.