New crystal, (E)-N'-(4-(dimethylamino)benzylidene)-5-methyl-1H-pyrazole-3-carbohydrazide (3) has been synthesized and characterized by FT-IR, NMR, ESI-MS and single crystal X-ray diffraction (XRD). The optimized molecular structures of free base and cationic species of (3) in gas phase and aqueous solution, vibrational frequencies and, corresponding vibrational assignments have been investigated experimentally and theoretically by using the B3LYP/6-31G* and B3LYP/6-311thornthornG** methods. High solvation energy values are observed for both species of (3) in solution while the NBO and AIM studies support the higher stability of the cationic species in solution. The high energy values Delta E sigma/sigma* and Delta E sigma/pi* transitions, due to the planarity of both CH3 groups linked to N atom, could support the high reactivities of its free base and cationic species, as compared with naloxone, cocaine and scopolamine. Complete vibrational assignments of 105 and 108 vibration modes expected for free base and cationic species of (3) together with the corresponding harmonic force constants are here reported. In vitro antidiabetic and antioxidant activities were revealed for (3). The molecular docking studies of the title compound revealed that it may exhibit anti-diabetic activity via inhibition of a-glucosidase PDB:3A4A enzyme. (C) 2020 Published by Elsevier B.V.