Discovery of Non-linear Optical Materials by Function-Based Screening of Multi-component Solids

Non-centrosymmetric arrangement in the solid state is a prerequisite for a molecule to exhibit second harmonic generation (SHG), yet the majority of achiral molecules crystallize in centrosymmetric lattices. Despite advances in circumventing the molecular preference for centrosymmetric structures, current screening methods of discovering SHG active materials need large quantities of parent material. Here, we present a function-based screening method that is designed to consume small quantities of parent material for screening a large pool of coformers that enhance the probability of discovering SHG active materials. With this method, similar to 30 mg of a non-linear optical (NLO) chromophore, N-(2-aminoethyl)-4-nitro-2-ansidine (1), was sufficient for screening 50 coformers, resulting in five SHG active compounds. Crystal-structure analysis revealed that non-covalent interactions influence the disposition of NLO-phore dipoles and thus affect the bulk SHG properties. Quantum chemical calculations highlighted the coformer contribution toward the second-order susceptibility coefficients, providing a deeper understanding of the structure-property relationships in these SHG materials.