Integration of Fluorescent Functionality into Pressure Amplifying Metal Organic Frameworks

The flexibility of soft porous crystals, i.e., their ability to respond to external stimuli with structural changes, is one of the most fascinating features of metal organic frameworks MOFs . In addition to breathing and swelling phenomena of flexible MOFs, negative gas adsorption NGA and pressure amplification PA are the more recent discoveries in this field initially observed in the cubic DUT 49 framework. In recent years, the structural contraction was monitored by physisorption, X ray diffraction, nuclear magnetic resonance NMR , and electron paramagnetic resonance EPR techniques, providing only limited information about the electronic structure of the ligand. In this work, we designed a new ligand with a fluorescent core in the linker backbone and synthesized three new MOFs, isoreticular to DUT 49, denoted as DUT 140 M M Cu, Co, Zn , crystallizing in the space group Fm3 amp; 773;m. DUT 140 Cu can be desolvated and is highly porous with an accessible apparent surface area of 4870 m2 g 1 and a pore volume of 2.59 cm3 g 1. Furthermore, it shows flexibility and NGA upon adsorption of subcritical gases. DUT 140 Zn , synthesized using postsynthetic metal exchange, could only be studied with guests in the pores. In addition to the investigation of the adsorption behavior of DUT 140 Cu , spectroscopic and computational methods were used to study the light absorption propertie