|Chemical Role of Extra-Coordination in Metal-Organic Frameworks|
: 455 : 2019.05.09 15:07
|일시 : 2019.05.08 17:00|
|소속 : DGIST 신물질과학과|
|발표자 : 정낙천|
|장소 : R404|
Open coordination sites (OCSs) in metal-organic frameworks (MOFs) often play a key role in applications such as gas sorption, molecular separation, and catalysis. To utilize the MOFs in such applications, an activation process to make the OCSs “open-state” by removing ‘coordinated solvent’ (typically the solvents used in the synthesis) is an essential step that must be performed prior to the utilization. To date, thermal activation (TA) has been popularly employed to remove the coordinated solvent molecules because this thermal process can supply the energy required for the dissociation of the solvent coordination bonds. Meanwhile, MOF-polymer mixed matrices (MMs) are a very useful platform for utilizing MOFs in applications such as molecular sorption and separation. However, the thermal deformation of polymers at high temperature during the TA process has limited the use of MOF-polymer MMs. Thus, the TA process for activating MOFs–MMs has been conducted at moderate temperature (e.g., approximately 100 C) that does not lead to the damage of polymer matrix. But the moderate temperature cannot supply a sufficient energy for full activation of OCSs in MOF–MMs.
In this presentation, we will discuss how to control the activation condition, simultaneously retaining structural integrity of MOF and MOF-polymer composite materials. As a new method, we will present “chemical activation (CA), which is performed by the treatment with a chloromethanes (CM). We found that the CA arises via (i) replacement of precoordination with CM coordination and (ii) spontaneous dissociation of CM coordination at the level of low activation energy which corresponds to room temperature.