Novel metal–organic framework linkers for light harvesting applications

Abstract

Metal–organic frameworks (MOFs) are composed of organic linkers and coordinating metals that self-assemble to form a crystalline material with tunable nanoporosity. Their synthetic modularity and inherent long-range order create opportunities for use as new functional electronic materials. Using quantum mechanical computational methodologies we propose novel conjugated organic linkers that are capable of forming the same one-dimensional infinite metal-oxide secondary building units (SBUs) as the well-known IRMOF-74. This structural arrangement allows for the formation of a continuous π–π stacking network that should enable charge transport in fashion analogous to organic semiconductors. The structural and electronic properties (fundamental and optical gaps) of the isolated proposed linkers were modeled using a non-empirically tuned long-range corrected functional that leads to significantly improved results compared with experimental benchmarks. In addition, periodic hybrid density functional calculations were employed to model the extended MOF systems. Our results demonstrate how the electronic properties of MOFs can be readily modified to have favorable orbital alignments with known electron acceptors that should facilitate charge transfer. The predicted properties are in good agreement with experiment (i.e. UV-Vis absorption spectra), demonstrating the power of this computational approach for MOF design.