MOF-Based Adsorbents for Atmospheric Emission Control: A Review

This review focuses on the use of metal–organic frameworks (MOFs) for adsorbing gas species that are known to weaken the thermal self-regulation capacities of Earth’s atmosphere. A large section is dedicated to the adsorption of carbon dioxide, while another section is dedicated to the adsorption of other different gas typologies, whose emissions, for various reasons, represent a “wound” for Earth’s atmosphere. High emphasis is given to MOFs that have moved enough ahead in their development process to be currently considered as potentially usable in “real-world” (i.e., out-of-lab) adsorption processes. As a result, there is strong evidence of a wide gap between laboratory results and the industrial implementation of MOF-based adsorbents. Indeed, when a MOF that performs well in a specific process is commercially available in large quantities, economic observations still make designers tend toward more traditional adsorbents. Moreover, there are cases in which a specific MOF remarkably outperforms the currently employed adsorbents, but it is not industrially produced, thus strongly limiting its possibilities in large-scale use. To overcome such limitations, it is hoped that the chemical industry will be able to provide more and more mass-produced MOFs at increasingly competitive costs in the future.

An insight into clustering of halogenated anesthetics molecules in metal-organic frameworks: Evidence of adsorbate self-association in micropores

In order to better understand the adsorption of volatile halogenated anesthetics on metal organic frameworks (MOFs), sevoflurane vapor adsorption experiments were performed on commercial MOF-177 at different temperatures. Due to the surface homogeneity of such an adsorbent, arising from its almost unimodal pore size distribution and the absence of specific, coordinatively unsaturated adsorption active sites, sevoflurane adsorption isotherms exhibited a peculiar deviation from the Langmuirian behavior. Consequently, they show a "kink" at a specific pressure that increases with increasing equilibrium temperature. Successful modeling of such data by means of the Talu-Meunier equation confirmed clustering of adsorbate molecules inside adsorbent micropores, similarly to water vapor adsorption on activated carbon, which may play an important role when designing a system using MOFs as the potential adsorbents for capturing anesthetics.

Porous dipeptide crystals as volatile-drug vessels

Anesthetic vapors find temporary hospitality in porous dipeptide crystals, which behave as biologically friendly hosts and carriers.

Tunable Porous Coordination Polymers for the Capture, Recovery and Storage of Inhalation Anesthetics

The uptake of inhalation anesthetics by three topologically identical frameworks is described. The 3D network materials, which possess square channels of different dimensions, are formed from the relatively simple combination of Zn^II centres and dianionic ligands that contain a phenolate and a carboxylate group at opposite ends. All three framework materials are able to adsorb N₂ O, Xe and isoflurane. Whereas the framework with the widest channels is able to adsorb large quantities of the various guests from the gas phase, the frameworks with the narrower channels have superior binding enthalpies and exhibit higher levels of retention. The use of ligands in which substituents are bound to the aromatic rings of the bridging ligands offers great scope for tuning the adsorption properties of the framework materials.

Adsorption of fluorinated anesthetics within the pores of a molecular crystal

Commonly used inhalation anesthetics—enflurane, isoflurane, sevoflurane, halothane, and methoxyflurane—are adsorbed within the pores of a porous fluorinated molecular crystal to the tune of up to 73.4(±0.2)% by weight.