Ions Conduction in pH Stable Interpenetrated-Catenated Metal-Organic Framework

The design of a rare combination of interpenetrated and catenated 3D+2D→3D MOF {[Cd₄(dim)₄(dht)₄(H₂O)₄](Sol)_x}_n (1), with a unique network and extreme pH stability, has been developed for exceptional ionic conduction across a wide range of temperature and humidity conditions. The bare pore derivative of 1 (1') features remarkable structural flexibility and large pores accessible to encapsulate molecules such as NH₃, HCl, and KOH, enabling it to function as an efficient conductor for both proton and hydroxide ions. 1' demonstrates substantial thermal-influenced proton conductivity of 4.6 × 10^-3 S cm^-1 at 80°C and 95% RH, which is significantly enhanced by the encapsulation of guest molecules, 1'@NH₃ and 1'@HCl. 1'@NH₃ exhibits a proton conductivity of 3 × 10^-2 S cm^-1 at 80°C and 95%RH, while the highly polar 1'@HCl achieves 1.21 S cm^-1 _. The 30°C (room temperature) proton conductivity of 1'@HCl is highly remarkable, reaching 6.8 × 10^-1 S cm^-1 at 95%RH, representing one of the highest values reported for MOFs to date. Similarly, 1'@KOH exhibits hydroxide ion conduction, rising from 2.8 × 10^-1 S cm^-1 at 25°C to 7.6 × 10^-1 S cm^-1 at 80°C in 95%RH, further establishing its performance as one of the highest reported so far.