RESUMO
Increased gas adsorption in a series of post-synthetically modified metal-organic frameworks (MOFs) of the type HKUST-1 was achieved by the partial cation exchange process. Manipulation of post-synthetic conditions demonstrates high tunability in the site substitution and gas adsorption properties during the dynamic equilibrium process. In this work, post-synthetic modification of Cu3(BTC)2 is carried on by exposure to TM2+ solutions (TM = Mn, Fe, Co, Ni) at different time intervals. The crystal structure, composition, and morphology were studied by powder X-ray diffraction, Fourier-transform infrared spectroscopy, inductively coupled plasma optical emission spectroscopy, and scanning electron microscopy. Structural analysis supports the retention of the crystal structure and partial substitution of the Cu metal nodes within the framework. A linear increase in the transmetalation process is observed with Fe and Co with a maximum percentage of 39 and 18%, respectively. Conversely, relatively low cation exchange is observed with Mn having a maximum percentage of 2.40% and Ni with only 2.02%. Gas adsorption measurements and surface area analysis were determined for each species. Interestingly, (Cu/Mn)3(BTC)2 revealed the highest CO2 adsorption capacity of 5.47 mmol/g, compared to 3.08 mmol/g for Cu3(BTC)2. The overall increased gas adsorption can be attributed to the formation of defects in the crystal structure during the cation exchange process. These results demonstrate the outstanding potential of post-synthetic ion exchange as a general approach to fine-tuning the physical properties of existing MOF architectures.
RESUMO
Nowadays, massive segmental bone defects represent a surgical challenge for trauma surgeons. Most of these injuries appear in the context of high-energy trauma, not only significantly affecting the bones, but also involving severe injuries of the adjacent soft tissues. For these reasons, their treatment requires complex reconstruction surgeries. There are multiple techniques to treat bone defects, bone transport being one of the most widely used. Historically, external fixators (monolateral and circular) have been and still are the gold standard for performing this technique, although they are not exempt from complications. By means of specific intramedullary nails for bone transport, it is possible to minimize the complications of external fixation, allowing large tibial bone defects to be treated through distraction osteogenesis (all-internal system), which is favoured by early weight bearing.