Thermally Triggered Isomerization in a Naphthalene‐Based Acylhydrazone with Solid‐State Optical Nonlinearity Response

Under the assistance of the state-of-the-art meta-dynamics simulations, in this contribution, we report a push-pull-type acylhydrazone 4(Z) ([Z)-2-(naphthalen-2-yloxy)-N'-(pyridine-2-ylmethylene)acetohydrazide] connecting an electron-donating naphthalene ether group with an accepting pyridyl unit, which could be thermally converted to its configurational isomer 4(E) ([E)-2-(naphthalen-2-yloxy)-N'-(pyridine-2-ylmethylene)acetohydrazide]. The thermally triggered Z-to-E configurational isomerization not only involves up to five chemical bonds undergoing 180 degrees rotation in the backbone of acylhydrazone, but changes the crystal packing symmetry from a centrosymmetric space group to a non-centrosymmetric one. Most impressively, the acentric crystal arrangement of 4(E) exhibits a second-harmonic generation (SHG) active response, about 2.5 times than that of KH2PO4 (KDP) standard.