A new family of Na3AgSnQ4 (Q = S or Se) and Na3MIIInS4 (MII = Cd or Hg) was successfully synthesized in vacuum-sealed silica tubes for the first time. They exhibit similar isolated one-dimensional (1D) double chains {[AgSnQ4]n vs [(MII/In)S4]n} in their structures. After the detailed survey on the Inorganic Crystal Structure Database, title compounds can be described as the first discovered examples exhibiting novel 1D double-chain configurations in the known 171 (MIB and MIVA) or 48 (MIIB and MIIIA) element-based quaternary A–MIB/MIIB–MIVA/MIIIA–Q chalcogenides. In addition, their dimensionalities on the mode of connection between two anionic groups are closely related to the empirical A/(IB+IVA) and A/(IIB+IIIA) in the unit cell or the (IB+IVA)/Q and (IIB+IIIA)/Q ratios, which may produce a good way to predict and design new chalcogenides with low-dimensional structures. Photoluminescence measurement shows that Na3CdGaS4 and Na3CdInS4 display strong red emission (648 and 647 nm) at room temperature that also agrees well with the change in color from yellow to red under the irradiation of an ultraviolet lamp. Moreover, all of the title crystals exhibit a large optical anisotropy (Δn@1064 nm ≥ 0.13), and isolated 1D double chains may produce a huge effect to enhance optical anisotropy based on the first-principles calculations, which also gives us a feasible way to design new birefringent materials.
