Studies on molecular structure, spectral analysis, chemical reactivity and first hyperpolarizability of a newly synthesized 1,9-bis[(4-isonicotinoyl)-hydrazonomethyl]-5-phenyl-dipyrromethane using experimental and theoretical approaches

• FT-IR spectrum of the studied compound was recorded and compared with the theoretical result.
• To determine the hyperconjugative interactions NBO analysis was performed.
• Theoretical calculated (β0) indicates the NLO response of the investigated molecule.

The detailed spectroscopic analysis of a newly synthesized dipyrromethane derivative: 1,9-bis[(4-isonicotinoyl)-hydrazonomethyl]-5-phenyl-dipyrromethane (3) has been performed using experimental measurement and quantum chemical calculations. Calculated thermodynamic parameters (H, G, S) of all the reactants and products have been used to determine the nature of reaction of synthesis. Occurring of a 1H NMR singlet at 5.54 ppm indicates meso-proton and formation of product molecule (3). The molecular orbital coefficients and molecular plots analysis indicates the nature of electronic excitations as π → π*. Natural bond orbitals (NBOs) analysis has been carried out to investigate the intramolecular interactions within molecule and their second order stabilization energy. The primary hyperconjugative interactions n2(O23) → σ*(N21C22)/σ*(C22C24) and n2(O48) → σ*(N46C47)/σ*(C47C49) stabilize the molecule to a greater extent ∼117.75 KJ/mol. Global electrophilicity index (ω = 3.64 eV) shows that the title molecule (3) is a strong electrophile. Local reactivity descriptors: Fukui functions (fk+,fk-), local softnesses (sk+,sk-) and electrophilicity indices (ωk+,ωk-) analyses were performed to find out the reactive sites within molecule. The first hyperpolarizability (β0) has been computed and found to be 60.95 × 10−30 esu indicating synthesized molecule to be suitable for non-linear optical response.