Intramolecular Hydrogen Bonds Enhance Disparity in Reactivity between Isomers of Photoswitchable Sorbents and CO2 : A Computational Study.

Reducing the emission of greenhouse gases, such as CO2 , requires efficient and reusable capture materials. The energy for regenerating sorbents is critical to the cost of CO2 capture. Here, we design a series of photoswitchable CO2 capture molecules by grafting Lewis bases, which can covalently bond CO2 , to azo-based backbones that can switch configurations upon light stimulation. The first-principles calculations demonstrate that intramolecular hydrogen bonds are crucial for enlarging the difference of CO2 binding strengths to the cis and trans isomers. As a result, the CO2 -sorbent interaction can be light-adjusted from strong chemical bonding in one configuration to weak bonding in the other, which may lead to a great energy reduction in sorbent regeneration.