Structural Investigation of Chemiresistive Sensing Mechanism in Redox-Active Porous Coordination Network

By changing the rate of evaporation, two kinds of crystalline films composed of redox-active porous coordination networks ( 1 and 2 ) were selectively prepared on a gold-patterned substrate using a DMF solution of 2,5,8-tri(4-pyridyl)1,3-diazaphenalene and Cd(NO 3 ) 2 . We found the highly sensitive humidity sensing ability of film 1 . Single crystal structures and infrared spectroscopic analyses before and after hydration of a single crystal of 1 revealed the sensing mechanism: exchange of nitrate ions with water on Cd atoms occurred in hydrated conditions to generate a conductive cationic network.