Perovskite-type organic-inorganic hybrid NLO switches tuned by guest cations

Three organic-inorganic hybrid analogues, ([Et-3(n-Pr)P][Mn(dca)(3)]) 1, ([Et-3(CH2CHCH2)P][Mn(dca)(3)]) 2, ([Et-3(CH2OCH3)P][Mn(dca)(3)]) 3, [dca = dicyanamide, N(CN)(2)(-)], show similar three-dimensional perovskite frameworks, in which the guest phosphonium cations occupy the cavities. Compounds 1 and 3 belong to the orthorhombic noncentrosymmetric space group P2(1)2(1)2(1) at room temperature, while compound 2 crystallizes in the monoclinic centrosymmetric space group P2(1)/c. Differential scanning calorimetry (DSC) and dielectric measurements confirmed the phase transitions in compounds 1, 2 and 3, where subtle structural distinctions of guest cations affect the crystal lattices, phase transition temperatures and physical properties. Interestingly, compounds 1 and 3 are SHG active at room temperature and can be used as NLO switches tuned by guest cations and triggered by temperature.