The polarizing power of protonating hydrogen and its influence on vibrational spectrum, NLO and biological activity in piperazinium nitrate crystal

The geometric and vibrational spectral characteristics of NO3− ions in many compounds, depend on the polarizability induced by the neighbor cation and the analysis of polarizing power of cation can be used as a novel method of deciding the band positions of different spectral modes of nitrates. The chair conformation of piperazinium, resonance structure of nitrate and hydrogen bonding in piperazinium nitrate crystal has been subjected to detailed investigation using Density Functional Theoretical (DFT) simulation. To investigate the polarizability induced on NO3−anion by protonating H+ and its influence on geometric and vibrational characteristics of NO3− in piperazinium nitrate, the correlation between the polarizing power and vibrational wavenumbers has been studied in detail for HNO3, NaNO3, KNO3 and LiNO3. The molecular docking study reveals that the protonation is found to enhance the binding affinity of piperazine towards protein.