Nanovesicular MOF with Omniphilic Porosity: Bimodal Functionality for White-Light Emission and Photocatalysis by Dye Encapsulation

A new pi-chromophoric and asymmetric bola-amphiphilic oligo-(p-phenylene ethynylene)-based tetracarboxylate (OPE-TC1) linker was designed, synthesized, and self-assembled with Zn(OAc)(2). The resulting nanoscale metal-organic framework (MOF) {Zn-2(OPE-TC1)}(n) (NMOF-1) showed a vesicular morphology and permanent porosity with omniphilic pore surface. NMOF-1 showed cyan emission with high quantum efficiency (49%). The omniphilicity of the pore was utilized to incorporate ambipolar dye sulforhodamine G (SRG) to tune the band gap as well as to get pure white-light emission. Furthermore, the polar pore surface of NMOF-1 allowed facile diffusion of the substrate for efficient photocatalytic activity. The dye-encapsulated framework further showed enhanced dihydrogen production by 1.75-fold compared to that from the as-synthesized NMOF-1 because of the modulated band gap and high excited state lifetime. As a control experiment, we have synthesized a MOF (MOF-OMe) with an OPE-TC2 linker having -OMe functional groups that did not show nanoscale architecture. This suggested the important role of unsymmetrical bola-amphiphilicity in nanostructuring. This rational design of a chromophoric linker resulted in a nanoscale MOF with omniphilic porosity to achieve bimodal functionality in clean energy applications.