Evaluating Iodine Uptake in a Crystalline Sponge Using Dynamic X-ray Crystallography

The uptake of gaseous iodine into the crystalline sponge material [(ZnI2)3(tpt)2]·0.7triphenylene·0.3PhNO2·0.7C6H12 1 (tpt = 2,4,6-tris(4-pyridyl)-1,3,5-triazine) has been monitored by dynamic X-ray diffraction and thermogravimetric analysis. The X-ray analyses have enabled the location, quantity, uptake rate, and subsequent chemistry of the iodine upon inclusion into the pores to be determined. An uptake of 6.0 wt % (0.43 I2 per formula unit) was observed crystallographically over a period of 90 min before crystal degradation occurred. The included iodine molecules interact with the iodine atoms of the ZnI2 nodes at three different sites, forming coordinated I3– ions. The results contrast to recent observations on [(ZnI2)3(tpt)2] without the triphenylene guests which show the presence of I42– ions with low quantities of absorbed iodine.