posted on 2000-03-04, 00:00authored byMelinda H. Keefe, Robert V. Slone, Joseph T. Hupp, Kenneth F. Czaplewski, Randall Q. Snurr, Charlotte L. Stern
Mesoporous thin films of rhenium-based “molecular squares”, [Re(CO)3Cl(L)]4 (L = pyrazine, 4,4‘-
bipyridine), have been utilized as sensors for volatile organic compounds (VOCs). The sensing was conducted
using a quartz crystal microbalance with the target compounds present in the gas phase at concentrations
ranging from 0.05 to 1 mM. Quartz crystal microbalance studies with these materials allowed for distinction
between the following VOCs: (1) small aromatic versus aliphatic molecules of almost identical size and
volatility and (2) an array of benzene molecules derivatized with electron donating/withdrawing substituents.
The experiments suggest that the mesoporous host materials interact with VOC guest molecules through
both van der Waals and weak charge-transfer interactions. In addition, size selectivity is shown by exposure
of the molecular squares to cyclic ethers of differing size.