Zn(ii)-based metal–organic framework: an exceptionally thermally stable, guest-free low dielectric material

Abstract

The synthesis of an exceptionally thermally stable, chemically stable, guest-free low-κ dielectric metal–organic coordination framework [Zn₂(Hbbim)₂(bbim)]_n (1, H₂bbim = bisbenzimidazole) was achieved under hydrothermal conditions. Structural analysis showed that compound 1 crystallizes in a triclinic space group P1 and possesses a guest-free structure. Compound 1 was found to be a low-κ dielectric material (3.05 at 1 MHz) that was extremely robust towards various solvents. The compound was exceptionally thermally stable and retained its structure at temperatures of up to 450 °C. Temperature-dependent dielectric studies revealed that 1 has a low-dielectric constant that remains stable upon increasing the temperature. This low-dielectric constant was further supported by density functional theory calculations, which showed that the dielectric property can be mainly attributed to electronic polarizability.