Modification and Restacking of Layered Terbium Hydroxide 2D Crystals

We report that 2D crystals, prepared by delamination of layered terbium hydroxide (LTbH) intercalated with dodecyl sulfate ions (DS-) in formamide, can be modified by DS- ions and further restacked to a new layer-structured compound. The modification proceeds in situ in formamide through the substitution of DS- for the hydroxyl groups, which coordinate to Tb3+ upon the delamination of the LTbH layer. With the supplementary addition of DS-, the substitution reaction progresses to a large degree of substitution, m > 2 in the chemical formula Tb-2(OH)(6-m)DSm<bold>nH</bold>2O. Since the negatively charged SO42- heads of DS- anchor to Tb3+, the alkyl chains protruding outwards convert the 2D crystal from hydrophilic to hydrophobic. The modified 2D crystals aggregate in aqueous media, restacking to the layered rare-earth compound characteristic of m greater than 2. The restacked crystals are ready to delaminate in some organic solvents owning to their structural and hydrophobic features.