Synthesis, conformational, spectroscopic and chemical reactivity analysis of 2-cyano-3-(1H-pyrrol-2-yl)acrylohydrazide using experimental and quantum chemical approaches

• FT-IR spectrum of 2CPA was recorded and evaluated.
• The electronic descriptors have been used to explain chemical reactivity.
• The calculated β0 value indicates its use for NLO applications.
• Electronic transitions have been predicted using TD-DFT/6-311++G(d,p) method.

This paper describes the synthesis, spectroscopic (1H and 13C NMR, UV–Visible, FT-IR and ESI Mass), conformational analysis, chemical reactivity and non-linear optical (NLO) properties of newly synthesized pyrrole derivative 2-cyano-3-(1H-pyrrol-2-yl)acrylohydrazide (2CPA) C8H8N4O using experimental and quantum chemical techniques. The presence of signal at δ 8.010 ppm due to vinyl proton as well as NH and NH2 protons signals at 11.054 and 2.499 ppm in experimental 1H NMR spectrum indicate that 2CPA contain CHCCN and NHNH2 frame. The combined experimental and theoretical symmetric (3194 cm−1) and asymmetric (3221 cm−1) stretching wavenumber analysis confirms free NH2 group in the solid phase FT-IR spectrum of the synthesized compound. The interaction energies of dimer formation using density functional theory (DFT) and Quantum theory of Atoms in Molecules (QTAIM) calculations are found to be 20.210, 19.683 kcal/mol, respectively. The maximum values of the electrophilic reactivity descriptors at C6 indicate that this site is more prone to nucleophilic attack and favoring the formation of heterocyclic derivatives. A natural bond orbital (NBOs) analysis has been carried out to investigate intramolecular charge transfer, conjugative and hyperconjugative interactions within molecule. The calculated first hyperpolarizability (β0) of 2CPA, indicates that investigated molecule will show non-linear optical response and might be used as non-linear optical (NLO) material.

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