Chirality‐Dependent Solid‐State Nonlinear Optical Performance in Donor–Acceptor Bipyrimidines

The development of second‐order nonlinear optical materials requires non‐centrosymmetric organization in the solid state, which may be generated by field‐induced alignment but can also arise spontaneously through non‐centrosymmetric molecular packing. Herein, we report a series of bipyrimidine‐based chromophores with an octupolar design bearing linear alkyl chains (C6–C12), together with a chiral analog incorporating a stereogenic center. While the achiral derivatives adopt centrosymmetric packing and exhibit no second‐harmonic generation response, the introduction of molecular chirality induces non‐centrosymmetric organization, enabling intrinsic second harmonic generation in the soft material without external poling. Variation of the alkyl chain length has little impact on the nonlinear optical properties, highlighting that chirality is the key factor governing macroscopic symmetry breaking. These results establish a structure–property relationship between molecular design, macroscopic organization, and second‐harmonic generation activity, and demonstrate that chirality provides an effective strategy for the development of poling‐free nonlinear optical materials.