Session: Physical Chemistry Poster:

Advent of conductive two-dimensional (2D) layered MOFs opened a new branch of potential applications for porous materials. Because of extended π-conjugation on all layers, charge transport has two possible paths, intra-layer due to conjugation of metal d orbitals and organic linker π orbitals and inter-layer due to π-π interactions in the stacking direction. However, tuning electronic properties for specific application can be challenging due to our limited knowledge of high flexibility and dynamics of 2D MOFs. To examine the relationship between flexibility and charge mobility, and also provide a guideline for tuning band gap openings of 2D MOFs, here, we focus on Ni₃(HITP)₂, HITP=2,3,6,7,10,11–hexaiminotriphenylene, which is at the center of debate over the semiconducting or metallic nature of 2D MOFs. Using ab initio molecular dynamics (AIMD) we show a range of different structural dynamics in 2D MOFs which affect the electrical conductivity drastically rendering the electronic band structure calculations on pristine structures, optimized at 0 K, irrelevant. Due to these motions, bands of equilibrated systems at 293 K start to open around Fermi level and the gaps in intar-layer CT region reach around 50 to 200 meV. Our analysis clearly show that thermally-induced deformation are allowed to happen and further affect the conductivity of the materials, revealing the relationship between structure deformations and electronic properties.

Zeyu Zhang

PhD Candidate

Appearances