The shortcoming of pure activated carbons is that chemicals with weak intermolecular forces typically have weak physical interactions with the carbon surface and therefore require chemical reactivity for removal. Thus, early gas masks were large, bulky, and burdensome to ensure proper protection for the user. Over the past century, the gas mask has changed substantially many times focused on the purported threat of the day. To properly afford broad spectrum protection, activated carbons must be impregnated with a variety of compounds capable of both acidic and basic chemistries. Due to the proximity of complementary functionalities within the pores of carbons, these chemical groups will inherently interact with one another over time, reducing the efficacy of the material. Instead, covalently anchoring functional groups to the substrate may be advantageous, a property that can be imparted through crystal design of materials, such as metal-organic frameworks (MOF).