A novel mixed alkali hydro-isocyanurate, KLi­(HC3N3O3)·2H2O was first prepared in AOH-BOH-H3C3N3O3 (A/B = Li/Na/K/Rb/Cs) system via a solvent-drop grinding method. KLi­(HC3N3O3)·2H2O shows a large second harmonic generation response (5.3 × KH2PO4) with an ultraviolet cutoff edge of 237 nm. More importantly, the bulk single crystal can be readily grown through water solution technique. Characterization of these crystals indicates that KLi­(HC3N3O3)·2H2O has a high laser damage threshold (LDT) (4.76 GW/cm2) and exhibits a large birefringence (Δn = 0.186@514 nm), which reduces Type I phase-matching to 246 nm.

The combination of Pb(2+) cations with lone-pair electrons and F(-) anions with the largest electronegativity into the carbonate generates a new nonlinear optical material, CsPbCO3F, with the largest powder second-harmonic generation (SHG) response among carbonates of about 13.4 times that of KDP (KH2PO4), and transparency over the near-UV to middle-IR region. The optical characterization of the compound indicates that it is phase matchable. Its crystal structure exhibits the stacking of [CsF]∞ and [Pb(CO3)]∞ layers, and the coplanar alignment of [CO3] triangles which are oriented in the same direction. Yet the Pb(2+) cation has an inert or nonstereoactive lone-pair, as indicated by its more spherical shape. Theoretical calculations confirm that the extremely large SHG efficiency indeed originates from enhancement via p-π interaction between Pb(2+) and [CO3](2-) within the [Pb(CO3)] layers.

A meticulously designed, polar, non-centrosymmetric lead borate chloride, Pb2 BO3 Cl, was synthesized using KBe2 BO3 F2 (KBBF) as a model. Single-crystal X-ray diffraction revealed that the structure of Pb2 BO3 Cl consists of cationic [Pb2 (BO3 )](+) honeycomb layers and Cl(-) anions. Powder second harmonic generation (SHG) measurements on graded polycrystalline Pb2 BO3 Cl indicated that the title compound is phase-matchable (type I) and exhibits a remarkably strong SHG response, which is approximately nine times stronger than that of potassium dihydrogen phosphate, and the largest efficiency observed in materials with structures similar to KBBF. Further characterization suggested that the compound melts congruently at high temperature and has a wide transparency window from the near-UV to the mid-IR region.