MOFs Detect Alkanes

MOFs Detect Alkanes


Alkanes are not easy to detect with simple, inexpensive methods, such as colorimetric changes, due to their lack of functional groups. However, they are widely used and a method of detecting them with the naked eye could be useful.

Yohei Takashima, Kensuke Akamatsu, and colleagues, Konan University, Kobe, Japan, have developed a simple system that can recognize alkanes and changes its color from white to pink in their presence. The team synthesized two types of the metal-organic framework (MOF) UiO-66, which contains Zr6O4(OH)4 and 1,4-benzenedicarboxylate: one under typical conditions and one with the addition of hypochloric acid, which introduces defects into the framework.

The MOF was combined with 7-azaindole, which can coordinate to defect sites in the framework’s pores, where it forms a charge-transfer complex with zirconium and causes a change in light absorption. 7-azaindole strongly interacts with polar solvents and remains in solution. However, in hydrophobic solvents such as alkanes, it enters the MOF’s pores and coordinates to defect sites, leading to a detectable color change. This mechanism was corroborated by the fact that the colorimetric change is stronger in the UiO-66 sample with a higher number of defect sites. According to the researchers, this system could be especially interesting for monitoring the leakage of alkanes in petroleum plants.


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