Surfactant-thermal syntheses, structures, and magnetic properties of Mn-Ge-sulfides/selenides

Although either surfactants or amines have been investigated to direct the crystal growth of metal chalcogenides, the synergic effect of organic amines and surfactants to control the crystal growth has not been explored. In this report, several organic bases (hydrazine monohydrate, ethylenediamine (en), 1,2-propanediamine (1,2-dap), and 1,3-propanediamine (1,3-dap)) have been employed as structure-directing agents (SDAs) to prepare four novel chalcogenides (Mn₃Ge₂S₇(NH₃)₄ (1), [Mn(en)₂(H₂O)][Mn(en)₂MnGe₃Se₉] (2), (1,2-dapH)₂{[Mn(1,2-dap)₂]Ge₂Se₇} (3), and (1,3-dapH)(puH)MnGeSe₄(4) (pu = propyleneurea) under surfactant media (PEG-400). These as-prepared new crystalline materials provide diverse metal coordination geometries, including MnS₃N tetrahedra, MnGe₂Se₇ trimer, and MnGe₃Se₁₀ T2 cluster. Compounds 1-3 have been fully characterized by single-crystal X-ray diffraction (XRD), powder XRD, UV-vis spectra, Fourier transform infrared spectroscopy, and thermogravimetric analysis. Moreover, magnetic measurements for compound 1 showed an obvious antiferromagnetic transition at ∼9 K. Our research not only enriches the structural chemistry of the transitional-metal/14/16 chalcogenides but also allows us to better understand the synergic effect of organic amines and surfactants on the crystallization of metal chalcogenides.