Effects of Alkyl Chain Length and N-Atom Position on Porous Supramolecular Assemblies of Luminescent Pentiptycene-Containing Mononuclear Gold(I) Acetylide-Isocyanide Complexes

Understanding the relationship between molecular and supramolecular structures is essential for molecular crystal engineering. Recently, we made an intriguing discovery involving a pentiptycene-containing mononuclear gold-(I) molecular system (1-C8) that consistently crystallizes into a porous crystalline framework and exhibits multistimuli-responsive photoluminescence properties. In this work, we modified the system by varying the alkyl chain length (1a-C n, n = 5-7, 9-12, and 16) or the N-atom position (2-C8). This allows us to pinpoint the key components that enable the porous supramolecular assembly. Our results show that C8 is the optimal alkyl chain length for effective tongue-and-groove joinery with pentiptycene U-shaped grooves, while C11 represents the longest alkyl chain capable of maintaining a porous framework. Notably, this configuration set a new porosity record (30.3%) among two-coordinate gold-(I) complexes. Another key structural requirement is that the pentiptycene group must be attached to an isocyanide ligand, rather than an acetylide ligand, to successfully form the Au4 building blocks. We also observed photoluminescence properties that are dependent on the crystal structure and responsive to photoirradiation or an aniline vapor. This work highlights the utility of shape compatibility in constructing functional porous supramolecular frameworks.