Biomimetic Metal–Organic Nanotubular Host for Straight-Chain Fatty Acids Recognition

Subtle structural variations among fatty acids significantly influence their biological roles and health effects. However, molecular recognition of their long, flexible, and chemically inert hydrocarbon chains remains a challenge. Inspired by natural fatty acid-binding proteins (FABPs), we designed and synthesized nanotubular metallo-cavitands, termed metal-organic pillars, through the coordination-driven assembly of pillararene-derived ligands with Ag(I) salts. These biomimetic hosts feature continuous interior channels exceeding 2.6 nm, selectively binding long-chain fatty acids through precise size and shape complementarity. Saturated and <i>trans</i> fatty acids, with linear conformations, are effectively encapsulated and stabilized by C-H···π and van der Waals interactions. In contrast, coiled <i>cis</i>-polyunsaturated fatty acids, such as docosahexaenoic acid (DHA), cannot be accommodated due to structural incompatibility. This work highlights the ability of artificial receptors to emulate the recognition capabilities of natural proteins, enabling the targeting of "bad" fatty acids associated with adverse health effects.