Symmetry breaking through molecular engineering to achieve "on-off-on" nonlinear optical switch in a [SnCl 6 ] 2- framework.

The impact of molecular point groups on phase transition materials has been seldom discussed. Two organic cations with different symmetries were incorporated into a [SnCl 6 ] 2- framework. By breaking the symmetry of cations, a novel hybrid material with two successive phase transitions featuring a rare "on-off-on" nonlinear optical switch was obtained.