MESOGENIC BEHAVIOR OF SILVER THIOLATES WITH LAYERED STRUCTURE IN THE SOLID-STATE - COVALENT SOAPS

The family of primary silver thiolate compounds AgSCnH2n+1 (n = 4, 6, 8, 10, 12, 16, and 18), which in the solid state consist of infinity 2[AgSR] layers with the R substituents extending perpendicular to both sides of a central slab of Ag and S atoms, behave as thermotropic liquid crystals. On heating they display successively lamellar (smectic A), cubic, and micellar mesophases; the range of appearance of the two former phases decreases with increasing length of R, so that for n greater-than-or-equal-to 12 only the micellar phase is observed on melting. X-ray diffraction studies on the lamellar phase for n = 6 reveal a packing rather similar to that found in the solid. For n = 18, X-ray diffraction shows that the micellar phase is a hexagonal columnar mesophase, which is understood as being the result of a rearrangement of the solid-state structure to form (AgSR)8 cyclic structures behaving as micelles.