We proved by computational NMR data the effect of electron-withdrawing and donating substituents on -H center dot center dot center dot N- and -H center dot center dot center dot O- intramolecular hydrogen bond of the E and Z isomers in X-phenylhydrazones switches. These interactions were analyzed in detail in terms of the energetic and geometrical parameters properties. In addition, atoms in molecules (AIM) and natural bond orbital (NBO) were also employed to characterize the interactions and to examine the strengthening of the interactions. Computational results indicate an enhanced hydrogen bond for all substituted related to an unsubstituted case. There are good relationships between the NMR, AIM, NBO, energy data and Hammett constants. (C) 2017 Elsevier B.V. All rights reserved.