Comparative Analysis of Theoretical and Empirical Data of Synthetic Cannabinoids

Abstract

Comparative studies of spectroscopic data of indol-3-carboxylates and indazole-3-carboxylates are reported from theoretical and empirical viewpoints. Structures of indol-3-carboxylates and indazole-3-carboxylates were modeled; quantum chemical method was employed to investigate the spectroscopic (NMR and FT-IR) properties of the structures.  The results obtained from the theoretical studies were compared to empirical results obtained for the spectroscopic properties of these compounds and level of agreement (or disagreement) between the results for the two studies are reported. The scope of the study is limited to the modeling, structural, and electronic and spectroscopic analyses of the modeled structures and comparative analysis of the theoretical data with published experimental data. The absorption transitions were calculated from the optimized geometry in the ground state (S0) using TD-B3LYP/6-31G**. The energy band gaps calculated showed that Naphthalene-1-yl 1–(5-fluoropentyl)-1H-indazole-3-carboxylate (M5) has the lowest band gap energy, which may have a substantial influence on the intramolecular charge transfer and bioactivity of the molecule. The 13C and 1HNMR chemical shifts calculated at ab initio and DFT agreed with the experimental data. DFT/6-311G** has the best correlation with fitting factor 0.9956.Thus the chemical shifts from DFT/6-311G** are very close to the experimental and can be used in the absence of experimental data. The vibrational frequency analyses by DFT/B3LYP method are in reasonable agreement with the experimental values.