Thermal-Driven Formation of 2D Nanoporous Networks on Metal Surfaces

Controlling the quantum confinement of (spin-dependent) electronic states by material design opens a unique avenue to accelerate the implementation of quantum technology in next generation photonic and spintronic applications. In the nanoworld, two-dimensional porous molecular networks have emerged as highly tunable material platform for the realization of exotic quantum phases for which the nanopores can be tuned by chemical functionalization of the size and shape of the molecules. Here, we demonstrate a new approach to control the periodicity, size, and barrier width in 2D porous molecular networks on surface by tuning the balance between intermolecular and molecule–surface interactions using temperature. At 106 K, the prototypical TPT molecules form nanoporous networks with different periodicity and barrier width depending on the surface reactivity. The network structures continuously transform into a close-packed molecular structure at room temperature. This reversible structural phase transition can be attributed to an entropy-driven loss of long-range order at higher temperature coinciding with a modification of the molecular adsorption site on the surface. Our findings hence open a new way to design the quantum confinement of electrons in porous structures on surfaces by external stimuli such as temperature or laser-assisted thermal activation of the molecule–metal hybrid system.