Synthesis, Structure, and Second-Harmonic Generation of Noncentrosymmetric Cocrystals of 2-Amino-5-nitropyridine with Achiral Benzenesulfonic Acids

Abstract

A series of noncentrosymmetric cocrystals were prepared from 2-amino-5-nitropyridine (2A5NP) and achiral benzenesulfonic acids (Ar-SO3H), which were designed for nonlinear optical materials. The cocrystals are colorless, and the melting points are fairly high, at around 200 °C. Both components are commonly crystallized in 1:1 ionic forms of 2A5NP+·Ar-SO3-. The crystal of 2A5NP and 3-methyl-4-nitrobenzenesulfonic acid belongs to chiral space group P212121, in which the 2A5NP+ cation and the anion are alternately stacked with a dihedral angle due to the large sulfonic anion to form column structures. Crystals of 2A5NP with both p-toluenesulfonic acid and p-chlorobenzenesulfonic acid are crystallized into noncentrosymmetric space group Pc and are isomorphic with each other. The 2A5NP+ cation and anion in each crystal are also alternatively stacked to form independently elongated zigzag and layer arrays in perpendicular directions. The crystal of 2A5NP and p-phenolsulfonic acid belongs to acentric space group...