Basic Aluminum Benzoate is Low-Cost, Porous, and Superhydrophobic.

Superhydrophobic materials are of tremendous application prospects, but they typically need to be prepared by relatively expensive reagents or complex treatments. Here, we report a simple aluminum-based coordination polymer [Al(OH)(ba)2] (MCF-66, Hba = benzoic acid), which can be facilely synthesized by various low-cost raw materials. For example, based on the simple acid-base reaction between Hba and Al(OH)3 (raw material costs ∼ 1 USD kg-1), MCF-66 can be synthesized in ca. 100% yield without using any solvent or additive, with water as the sole byproduct. MCF-66 consists of insufficiently packed butterfly-like chains, with hydrophobic phenyl rings exposed on the crystal surfaces, enabling superhydrophobicity. The compressed pellet showed a high water contact angle of 152°, which identified MCF-66 as a rare superhydrophobic material. Although the small discrete pores formed between the chains are just slightly larger than H2, it can deform to adsorb various small molecules and show special separation behavior for the n-C4H10/i-C4H10 mixture. MCF-66 can also be directly grown on aluminum meshes for highly efficient oil-water separation (8.8 × 103 L m-2 h-1 bar-1).