Three Alumino/Galloborate Frameworks Templated by Organic Amines: Syntheses, Structures, and Nonlinear Optical Properties

A series of alumino/galloborates, including (H₃APEA)₆[Al-B₅O₁₀]₉·12H₂O (1, APEA = N,N′-bis(3-aminopropyl)ethylenedi-amine), (HDETA)₂(H₂DETA)₂[AlB₅O₁₀]₃ (2, DETA = diethylenetriamine), and (H₂EDAP)[GaB₅O₁₀]·H₂O (3, EDAP = N-ethyl-diaminopropane), was solvothermally synthesized and characterized in solid-state by powder X-ray diffraction, Fourier transform infrared spectroscopy, UV-vis spectroscopy, and single-crystal X-ray diffraction. All of them feature the [MB₅O₁₀]_n ^2n- (M = Al or Ga) frameworks, charge-balanced by the long chain-like amine cations. Three frameworks exhibit different interlinkage modes of {MB₅O₁₀} layers, resulting in channels varying in size and shape. The flexibility of long chain-like amine cations as well as their significant structure-directing functions in forming these crystalline products is also discussed in detail. Powder second-harmonic generation measurements showed that all three compounds present a nonlinear optical property, and compound 2 exhibits type I phase-matchable optical nonlinearity.