Implementation of Thermal-Triggered Binary-Ternary Switchable Memory Performance in Zn/polysulfide/organic Complex-Based Memorizers by Finely Modulating the S 6 2- Relaxation.

Polysulfide-based multilevel memorizers are promising as novel memorizers, in which the occurrence of S n 2- relaxation is key for their multilevel memory. However, the effects of crystal packing and the side group of organic ligands on S n 2- relaxation are still ambiguous. In this work, ionic [Zn(S 6 ) 2 ·Zn 2 (Bipy) 2 SO 4 ( 1 ), Zn(S 6 ) 2 ·Zn(Pmbipy) 3 ( 2 )] and neutral [ZnS 6 (Ombipy) ( 3 ), ZnS 6 (Phen) 2 ( 4 )] Zn/polysulfide/organic complexes with different packing modes and structures of organic ligands have been synthesized and were fabricated as memory devices. In both ionic and neutral Zn complexes, the S 6 2- relaxation will be blocked by steric hindrances due to the packing of counter-cations and hydrogen-bond restrictions. Consequently, only the binary memory performances can be seen in FTO/ 1 /Ag, FTO/ 2 /Ag, and FTO/ 4 /Ag, which originate from the more condensed packing of conjugated ligands upon electrical stimulus. Interestingly, FTO/ 3 /Ag illustrates the unique thermally triggered reversible binary-ternary switchable memory performance. In detail, after introducing a methyl group on the 6'-position of bipyridine in ZnS 6 (Ombipy) ( 3 ), the ring-to-chain relaxation of S 6 2- anions at room temperature will be inhibited, but it can happen at a higher temperature of 120 °C, which has been verified by elongated S-S lengths and the strengthened C-H···S hydrogen bond upon heating. The rules drawn in this work will provide a useful guide for the design of stimulus-responsive memorizers that can be applied in special industries such as automobile, oil, and gas industries.