Bidenticity-Enhanced Second Harmonic Generation from Pb Chelation in Pb₃Mg₃TeP₂O₁₄

A new ultraviolet nonlinear optical (NLO) material, Pb₃Mg₃TeP₂O₁₄ (PMTP), has been synthesized and characterized. The chiral material exhibits a large second harmonic generation (SHG) response of 13.5 × KDP (600 × α-SiO₂), and the shortest absorption edge (250 nm) of reported materials with a strong SHG response (>10 × KDP). PMTP has a three-dimensional crystal structure of corner-shared MgO₄, PO₄, and TeO₆ polyhedra, which form a [TeMg₃P₂O₁₄]_∞ framework. Electronic structure calculations revealed that the stereoactive lone pair on the Pb²⁺ cation is critical to producing the substantial NLO response and that the NLO activity is further enhanced by the presence of triply bidentate Te⁶⁺ cations found in Te–O–O–Pb rings