Photo-induced reversible nitric oxide capture by Fe–M(CO2H)4 (M = Co, Ni, Cu) as a building block of mixed-metal BTC-based MOFs

Abstract

Metal–organic frameworks incorporating mixed-metal sites (MM-MOFs) have emerged as promising candidates in the development of sensing platforms for the detection of paramagnetic species. In this context, the present study explores the photo-induced switching behavior of mixed-metal Fe–M (M = Co, Ni, Cu) formate (Fe–M(CO₂H)₄), as an experimentally feasible strategy for the reversible capture of nitric oxide (NO). Using Fe–M(CO₂H)₄ as a building block of synthesized MOFs based on BTC (benzene-1,3,5-tricarboxylic acid), molecular simulations of NO adsorption on Fe–M(CO₂H)₄ were conducted to provide a template for evaluating the behavior of BTC-based MOFs towards NO. Accordingly, the relationship between the magnetic properties and adsorption behaviors of Fe–M(CO₂H)₄ towards NO gas molecules was evaluated before and after photoexcitation. We show that the photo-induced effect on the magnetic properties of Fe–M(CO₂H)₄ changes the interaction strength between NO and the Fe–M(CO₂H)₄ systems. NO chemisorption over Fe–Ni(CO₂H)₄ indicates that nickel-doped Fe-BTC MOFs can be efficiently applied for capturing purposes. Moreover, our calculations show a switching behavior between physisorption and chemisorption of the NO molecules over Fe–Co(CO₂H)₄, occurring through magnetic modulation under UV-Vis irradiation. As far as we know, this is the first study that proposes light-controlled reversible NO capture using MOFs. The present study provides a promising platform for reversible NO capture using MM-MOF-incorporated BTC building blocks.