Abstract: A nonlinear optical material includes a noncentrosymmetric crystal of an anionic boron complex salt containing a cation and at least one organic ligand coordinated to a boron atom. The nonlinear optical crystal may consist of a compound having the formula A[BC.sub.2 ] where A is a monocation, B is boron, and C is the organic ligand, or a compound having the formula A[BC.sub.2 ].sub.2 where A is a dication, B is boron, and C is the organic ligand. The organic ligands may also be organic molecules having .alpha.-dihydroxy functionalities. Furthermore, the organic ligands may be selected from the group consisting of .alpha.-hydroxy carboxylic acids and 1,2-diols or from the group consisting of d-malic acid, d-lactic acid, d-tartaric acid, dimethyl-d-tartrate, diethyl-d-tartrate, l-malic acid, l-lactic acid, l-tartaric acid, dimethyl-l-tartrate, diethyl-l-tartrate, and ethylene glycol.