Combining experimental and theoretical approaches to study the structural and spectroscopic properties of Flakka (α-pyrrolidinopentiophenone)

New Psychoactive Substances (NPS) present several identification and public health challenges. However, experimental studies with illicit substances can involve regulatory restrictions, and obtaining information about them can be time-consuming. In this scenario, in silico methods can help to monitor the emergence of new synthetic substances such as synthetic cathinones, some of the most seized NPS. Here, we study the cathinone alpha-PVP or Flakka by theoretical chemistry methods to evaluate its structure, possible conformers, and spectroscopic profile. Initially, we performed a systematic conformational analysis and an analysis based on the Boltzmann distribution. We determined the most probable experimental structure and compared it to the crystallographic structure, to verify similarity between the forms. Next, we applied the factorial design to the obtained structure so that we could decide on the most adequate computational method to obtain the spectrum in the infrared and NMR region. Then, we compared the results with experimental data available in the literature. Finally, we evaluated multivariate statistical methods to ensure that we would come to conclusions based on the responses of each step. All the steps indicated similarity between the theoretical data and the experimental results when we used the combination DFT B3LYP and the basis 6-31G**. Our results demonstrate the potential application of computer simulation in forensic chemistry and provide valuable spectroscopic and structural information about illegal substances.