(C4N2H12)(NH4)2[(GeO2)3(GeO1.5F3)2]: A new layered germanate containing helical arrays of H-bond

► A new layered germanate containing helical arrays of H-bond. ► The 3,9-net sheet was constructed by propeller-like SBUs with Δ- and Λ-configuration. ► The propeller-like SBUs with same configuration linked each other to form chiral chains.