Switchable Nonlinear Optical and Tunable Luminescent Properties Triggered by Multiple Phase Transitions in a Perovskite-Like Compound

A new
perovskite-like inorganic–organic hybrid compound [Et3(n-Pr)­P]­[Cd­(dca)3] (1) (where
[Et3(n-Pr)­P]+ is the propyltriethylphosphonium
cation and dca is a dicyanamide ligand) was discovered to undergo
three reversible phase transitions at 270 K (T1), 386 K (T2), and 415 K (T3), respectively. The variable-temperature single-crystal
X-ray structural analyses reveal that these sequential phase transitions
originate from the deformations of the [Cd­(dca)3]− frameworks and the concomitant reorientations of the [Et3(n-Pr)­P]+ guest cations. It is found
that 1 possesses a sensitive nonlinear optical (NLO)
switching at T2 with a large contrast
of ∼40 within a narrow temperature range of ∼7 K. Furthermore, 1 shows intriguing photoluminescence (PL) property, and the
PL intensity suffers a plunge near T3.
The multiple phase transitions, switchable NLO and tunable luminescent
properties simultaneously exist in this inorganic–organic perovskite-like
hybrid compound, suggesting its great potential application in molecular
switches and photoelectric field.