Two routes of crystal engineering and elaboration of optical materials are described. The former applied to the design of organic-inorganic crystals for quadratic nonlinear optics is supported by a strategy of deliberately engineered noncentrosymmetric structures built-up from herringbone motifs of 2-amino-5-nitropyridinium chromophore. The original crystal growth of a solid solution of a member of this family is presented and discussed. The latter is a simple and generic elaboration of stable organic nanocrystals embedded in sol-gel matrices. Several molecules and characterization techniques have been involved to demonstrate the validity of this preparation.