Structurally dependent thermochromism of two iodoargentate hybrids based on the intermolecular charge transfer

• N-alkylated 3-cyano pyridinium lead to structural irregularity of iodoargentate.
• The thermochromism of 1 and 2 is attributed to intermolecular charge transfer.
• Absorption edges and thermochromic behavior of 1 and 2 are structurally dependent.

Two iodoargentates directed by N-alkylated 3-cyanopyridiniums, [(EC) (Ag2I3)]n (1) and [(PC) (Ag5I6)]n (2) (EC = N-ethyl-3-cyanopyridinium, PC = N-propyl-3-cyanopyridinium) have been solvothermally synthesized. Structural analysis reveals that the variation of N-substituents on 3-cyanopyridinium is responsible for change of the inorganic moieties (belt-like chain for 1 and columnar chain for 2) and consequent packing modes, which further results in the shift of absorption edges and different thermochromic behavior (from yellow at room temperature to almost colorless for 1 and pale yellow for 2 at liquid nitrogen temperature), as proved by UV–vis spectra.

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