Preparation of a novel organic derivative of the layered perovskite bearing HLaNb₂O₇·nH₂O interlayer surface trifluoroacetate groups

Trifluoroacetate (TFA, CF₃COO) groups have been successfully bound to the interlayer surface of a protonated form of Dion-Jacobson-type layered perovskite, HLaNb₂O₇·nH₂O (HLaNb), via a reaction between its n-propoxy derivative and trifluoroacetic acid (TFAH, CF₃COOH). The interlayer distance increases approximately to 1.8 nm upon treatment with TFAH, and varies in the range from ∼1.7 to ∼2.0 nm depending on the amount of water adsorbed in the interlayer space. The high stability of the guest species upon dispersal in organic solvents and the change in the infrared (IR) spectrum profile with respect to that of TFAH indicate that the guest species are TFA groups bound to the surface of perovskite-like slabs of HLaNb. The interlayer distance indicates that the TFA groups possess a bilayer arrangement, and a unidentate type of coordination is proposed based on consideration on the coordination geometry.