Hydrogen Bonding Dependent Mesoscale Framework in Crystalline Ln(H₂O)₉(CF₃SO₃)₃

Structurally, hydrogen bonding is identified as a key factor to domain the construction of a crystallographic frame during the crystallization of the Ln­(H₂O)₉­(CF₃SO₃)₃ (Ln = La–Lu) system. In situ Raman spectroscopy is used to capture the hydrogen bonding dependent mesoscale frameworks that are formed during Ln­(H₂O)₉­(CF₃SO₃)₃ crystallization in aqueous solution by continuously collecting the spectra of structural fragments. The spectral characteristics show that the isolated Ln­(H₂O)₉³⁺ tricapped trigonal prisms cannot exist in the aqueous solution. With the concentration of aqueous solution, the hydrated Ln³⁺ and CF₃SO₃^– tend to share common H₂O molecules, and new hydrogen bonding will be built surrounding Ln³⁺. Especially, for the Nd, Eu, Yb, and Lu system, Ln­(H₂O)_n­(CF₃SO₃)₃ (n = 8–9) clusters instead of hydrated Ln³⁺ and CF₃SO₃^– are formed in the solution. Under the guiding of intermolecular hydrogen bonds, both bond lengths and bond angles of Ln–O may be regulated, leading to the initial formation of Ln­(H₂O)₆³⁺ prisms and the following Ln­(H₂O)₉³⁺ tricapped trigonal prisms. Meanwhile, the symmetry of both CF₃ and SO₃ groups decreases from C_3h to C₂ accompanied by the formation of Ln­(H₂O)₆³⁺ triprism. The present study opens up the chemical bonding behaviors of rare earth ions in aqueous solution, which provides basic data for the study of the coordination of rare earth complexes and the design of novel rare earth materials.