Diffusion behavior of liquid state aliphatic phenothiazine compounds

Abstract

Ionic compounds are high melting compounds comprised of cations and anions held together through electrostatic interactions. When these ionic compounds contain either an organic cation or anion they tend to melt below 100 ºC and they are referred to as ionic liquids (ILs). Double salt ionic liquids (DSIL) are complex ILs with either one anion and several cations, several anions and one cation or several anions and several cations. Both the ILs and DSILs have important applications in drug design as they will keep the pharmacological properties of the constituent ions while having improved properties (such as bioavailability and aqueous solubility) when compared to the corresponding neutral precursors. Thus, by modifying the ionic composition and molar ratio, one can easily formulate new ILs and DSILs with specific purposes. One powerful technique for characterizing these liquid state compounds is diffusion-ordered spectroscopy (DOSY). When applied to ILs and DSILs, DOSY measures the self-diffusion coefficients for the constituent anion(s) and cation(s). The work presented here focuses on using DOSY to determine the diffusion behavior of several DSILs obtained by combining aliphatic phenothiazine cations (promazine, chlorpromazine or triflupromazine) with two anions, namely the ibuprofenate (a known non-steroidal anti-inflammatory drug) and docusate (a penetration enhancer) anions.