Intrinsic Optical Properties and Divergent Doping Effects of Manganese(II) on Luminescence for Tin(II) Phosphite Grown from a Deep-Eutectic Solvent

This is the first study on the ionothermal synthesis, intrinsic photoluminescence (PL), and dopant effects for tin­(II) phosphite, a stereochemically active 5s² lone-pair-electron-containing compound, the fundamental properties of which have rarely been explored before. In a new deep-eutectic solvent, single-phased products of SnHPO₃ (1) and Sn_1–xMn_xHPO₃ (2) have been achieved in high yield. The crystalline powder of 1 is nonenantiomorphic, with an intense second-harmonic generation comparable to that of potassium dihydrogen phosphate. Under UV excitation, it unexpectedly emits white PL, an important intrinsic property never discovered in tin­(II) oxysalts. Electron paramagnetic resonance hyperfine splitting characteristic of manganese has been detected on 2 and a three-pulse electron-spin-echo envelope modulation technique implemented to locate its corresponding location in the inorganic host. On the basis of temperature-dependent PL and lifetime measurements, the incorporated Mn²⁺ uncommonly acts as a sensitizer in enhancing white emission until extremely low temperatures, in which it would resume its normal role as an activator to give out characteristic orange light.