Charge Transportation in Zn(II)/Cd(II)-Based 2D MOFs of 5-Nitro-isophthalate with Isonicotinic Hydrazide

Two new families of the electro-conductive two-dimensional (2D) metal organic framework (2D MOFs) of Zn(II)/Cd(II) with the coordination of H25-NIP (5-nitro-isophthalic acid) and INH (isonicotinic hydrazide) are isolated and characterized by different physicochemical techniques. However, crystalline porous structures of {[Zn(5-NIP)(2)(INH)(2)]center dot(DMF)(H2O)(2)}(n) (1) and {[Cd(5NIP)(2)(INH)(2)]center dot(DMF)(2)(H2O)]}(n) (2) are analyzed using single-crystal X-ray diffraction techniques. Fascinatingly, the secondary building units (SBUs) of both 1 and 2 are supramolecularly aggregated arrays with interactions like hydrogen bonding and pi center dot center dot center dot pi. Moreover, the geometrical and topological analysis of 1 and 2 has been elucidated by the TOPOSPRO program package and it symbolizes dia-topology with 4-c uninodal net for 1 whereas, sql-topology with a 4-c uninodal net was exhibited for 2. Both these MOFs exhibit significant electrical conductivity with a Schottky diode nature. Out of them, 2 promotes the higher charge mobility than 1, which may be due to the larger cation size (Cd(II) (2), 0.97 angstrom > Zn(II) (1), 0.74 angstrom) and stronger pi-pi stacking (distance, 3.511(3) angstrom (2) and 3.714(4) angstrom (1)). Furthermore, the analyzed data of transit time, effective carrier mobility, diffusion length, and carrier concentration reveal that 2 is transporting charge more efficiently than 1.

Automated summary

Two new families of electro-conductive 2D metal organic frameworks (MOFs) of Zn(II)/Cd(II) with different structural topologies and electron transport capabilities have been isolated and characterized. The larger Cd(II) cation size and stronger pi-pi stacking in sample 2 may contribute to its higher charge mobility compared to sample 1.