RESUMEN
A new π-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) {Zn2(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.
RESUMEN
A porous covalent triazine framework (CTF) consisting of both an electron-deficient central triazine core and electron-rich aromatic building blocks is reported. Taking advantage of the dual nature of the pore surface, bimodal functionality has been achieved. The electron deficiency in the central core has been utilized to address one of the pertinent problems in chemical industries, namely separation of benzene from its cyclic saturated congener, that is, cyclohexane. Also, by virtue of the electron-rich aromatic rings with Lewis basic sites, aqueous-phase chemical sensing of a nitroaromatic compound of highly explosive nature (2,4,6-trinitrophenol; TNP) has been achieved. The present compound supersedes the performance of previously reported COFs in both the aspects. Notably, this reports the first example of pore-surface engineering leading to bimodal functionality in CTFs.