Unveiling the Synthesis, Spectral Characterizations, and Electrochemical Potential of Novel (E)-Furan-2-yl Acrylohydrazides: An Exploration in Molecular Design

In this study, we present the synthesis of novel derivatives of 3-furan-2-yl acrylohydrazide using a meticulous three-step reaction sequence. The synthesis ends up in the condensation of (E)-3-(furan-2-yl) acrylohydrazine (3) with diverse benzaldehyde and acetophenone derivatives. Comprehensive characterization of the synthesized compounds was achieved through 1D NMR spectroscopic analyses (1H and 13C NMR), 2D NMR spectroscopy (HSQC, NOESY), and high-resolution mass spectrometry (HRMS). The investigation of 1H NMR data at room temperature in deuterated dimethyl sulfoxide (DMSO-d6) unveiled the existence of (E)-3-(furan-2-yl) acrylohydrazide derivatives (4a-h) in a conformational equilibrium, manifesting as a mixture of synperiplanar E (sp E) and antiperiplanar E (ap E), or synperiplanar Z (sp Z) and antiperiplanar Z (ap Z). Notably, compounds 4a and 4b predominantly adopted the sp E conformer (Ec=c sp EC=N), while compounds 4c and 4d favored the antiperiplanar conformation. For the remaining compounds (4e-h), both conformers were nearly equimolar, with a marginal preference for the anti over the syn conformer. Interestingly, compounds 4f and 4h exhibited a prevalence of the apZ conformer (Ec=c ap ZC=N), while compound 4e featured the apE conformer (Ec=c ap EC=N). UV-visible absorption spectra for the N-acylhydrazones (4a-h) indicated absorption within the 570-635 nm range. Furthermore, cyclic voltammetry results demonstrated the capacity of the synthesized (E)-3-(furan-2-yl) acrylohydrazide derivatives (4a-h) to undergo quasi-reversible oxidation and reduction processes on a platinum electrode. These findings contribute valuable insights into the conformational dynamics and electrochemical behavior of this class of compounds, holding significance for applications in diverse scientific and technological domains.