Metal-Organic Frameworks for Colorimetric Sensing of VOCs

Abstract

Our research develops advanced chemical sensors using metal-organic polyhedra (MOPs) and metal-organic frameworks (MOFs), valued for their porosity and flexible design. We engineered solvatochromic and vapochromic MOPs and MOFs incorporating dicopper paddlewheel clusters and azobenzene, which change color from green to red when exposed to volatile organic compounds (VOCs). This response is quick and reversible, relying on maintaining porosity for effective diffusion. Unlike conventional sensors, our system uses a single MOF whose color change is dictated by the solvent in pretreatment, forming a versatile sensor array. The sensor enables qualitative and quantitative detection, generating unique color patterns for various analytes, and responds to humidity variations without needing high-temperature regeneration. This work highlights the potential of MOPs and MOFs in versatile colorimetric sensing applications.