We focused on salicylideneamine molecules, which are known to function as photomechanical crystals . Salicylideneamine molecules can be synthesized in a single step, and different compounds can be obtained by changing an amine reactant (Figure ). For molecular design, we investigated the relationship between molecular substructures and Young's modulus. Young's modulus is the most fundamental mechanical property and a parameter that influences the blocking force. Our aim here was to establish a material pool of salicylideneamine crystals with various Young's moduli and crystal sizes.