A successive layer-by-layer assembly of supramolecular frameworks driven by a novel type of face-to-face π+–π+ interactions

The solid-state complex [PTPH3](NO3)(3)center dot 2(HNO3) (1) has been synthesized and characterized by X-ray studies, where PTPH3 is the triply protonated form of 4'-(4-pyridyl)-2,2':6',2 "-terpyridine (PTP). The solid-state structure of the complex reveals that the pi(+)-pi(+) interactions are the major driving force in the crystal packing while pi(+)-pi, pi-pi and p-anion interactions assist the overall stabilization of self-assembly. Complex 1 exhibits two different p-stack layers, where layer 1 is generated through pi(+)-pi(+) interactions and the mutual forces of pi(+)-pi(+) and pi(+)-pi form layer 2. The interaction energies of the main driving forces (pi(+)-pi(+),pi(+)-pi and pi-anion interactions) observed in the crystal structure have been calculated using dispersion-corrected density functional theory (DFT-D). An analysis of the Hirshfeld surface of complex 1 shows the intermolecular interactions involved within the crystal structure and corresponding quantitative information are presented by fingerprint plots.