Self‐assembly of an acentric co‐crystal of a highly hyperpolarizable merocyanine dye with optimized alignment for nonlinear optics

Non‐centrosymmetric arrangement of the chromophores is a prerequisite for non‐vanishing macroscopic second‐order nonlinear optical responses. It is shown that an acentric packing of a highly polarizable merocyanine dye, with optimized orientation for frequency conversions, can be induced by hydrogen‐bond‐directed self‐assembly with appropriate phenolic derivatives. The highly polar co‐crystal is demonstrated to have potential for both second‐ and third‐order nonlinear optics applications owing to its large nonlinear response and favorable crystal properties.