Theoretical Probing of Weak Anion-Cation Interactions in Certain Pyridinium-Based Ionic Liquid Ion Pairs and the Application of Molecular Electrostatic Potential in Their Ionic Crystal Density Determination: A Comparative Study Using Density Functional Approach was written by Joseph, Aswathy;Thomas, Vibin Ipe;Zyla, Gawel;Padmanabhan, A. S.;Mathew, Suresh. And the article was included in Journal of Physical Chemistry A in 2018.Safety of 1-Butyl-4-methylpyridin-1-ium bromide This article mentions the following:
A comprehensive study on the structure, nature of interaction, and properties of six ionic pairs of 1-butylpyridinium and 1-butyl-4-methylpyridinium cations in combination with tetrafluoroborate (BF4–), chloride (Cl–), and bromide (Br–) anions have been carried out using d. functional theory (DFT). The anion-cation interaction energy (ΔEint), thermochem. values, theor. band gap, MO energy order, DFT-based chem. activity descriptors [chem. potential (μ), chem. hardness (η), and electrophilicity index (ω)], and distribution of d. of states (DOS) of these ion pairs were investigated. The ascendancy of the -CH3 substituent at the fourth position of the 1-butylpyridinium cation ring on the values of ΔEint, theor. band gap and chem. activity descriptors was evaluated. The ΔEint values were neg. for all six ion pairs and were highest for Cl– containing ion pairs. The theor. band gap value after -CH3 substitution increased from 3.78 to 3.96 eV (for Cl–) and from 2.74 to 2.88 eV (for Br–) and decreased from 4.9 to 4.89 eV (for BF4–). Ion pairs of BF4– were more susceptible to charge transfer processes as inferred from their significantly high η values and comparatively small difference in ω value after -CH3 substitution. The change in η and μ values due to the -CH3 substituent is negligibly small in all cases except for the ion pairs of Cl–. Critical-point (CP) analyses were carried out to investigate the AIM topol. parameters at the interionic bond critical points (BCPs). The RDG isosurface anal. indicated that the anion-cation interaction was dominated by strong Hcat···Xani and Ccat···Xani interactions in ion pairs of Cl– and Br– whereas a weak van der Waal’s effect dominated in ion pairs of BF4–. The mol. electrostatic potential (MESP)-based parameter ΔΔVmin measuring the anion-cation interaction strength showed a good linear correlation with ΔEint for all 1-butylpyridinium ion pairs (R2 = 0.9918). The ionic crystal d. values calculated by using DFT-based MESP showed only slight variations from exptl. reported values. In the experiment, the researchers used many compounds, for example, 1-Butyl-4-methylpyridin-1-ium bromide (cas: 65350-59-6Safety of 1-Butyl-4-methylpyridin-1-ium bromide).
1-Butyl-4-methylpyridin-1-ium bromide (cas: 65350-59-6) belongs to pyridine derivatives. Pyridine is diamagnetic and has a diamagnetic susceptibility of −48.7 × 10−6 cm3·mol−1.The molecular electric dipole moment is 2.2 debyes. The standard enthalpy of formation is 100.2 kJ·mol−1 in the liquid phase and 140.4 kJ·mol−1 in the gas phase. One of the examples of pyridines is the well-known alkaloid lithoprimidine, which is an A3 adenosine receptor antagonist and N,N-dimethylaminopyridine (DMAP) analog, commonly used in organic synthesis.Safety of 1-Butyl-4-methylpyridin-1-ium bromide