Active sites modulation with Runge–Gross theorem: CO₂ capture by porphyrinic metal–organic frameworks at excited states

Traditionally chemical modifications altering molecular skeletons (MSs) were the only solution to modulate material active sites at ground states. According to Runge–Gross theorem, the MS and the adjoint electron-configuration (MS-AEC) can be tuned at excited states (ESs), even without chemical modifications. A porphyrinic metal–organic framework PCN-222 and its metalloporphyrin homologs are used for adsorptive carbon capture both at ground states and with photoexcitation (350–780 nm). Instead of passive photothermal effects, the carbon capture performances of all the adsorbents get promotions. The dominant first ESs with long lifetimes meet the time-scale of molecular adsorption equilibrium, meanwhile tune the MS-AEC of the porphyrin ligands to generate new active sites with much more negative electrostatic-potentials, of which the distribution gradient is crucial for inducing CO₂ and can be further modulated by the central-coordinated metal cations at ground and excited states. This work demonstrates the availability of static ESs and possibility of nonchemical modifications.