POTENTIOMETRIC, ENANTIOSELECTIVE SENSORS FOR ALKYL AND ARYL AMMONIUM-IONS OF PHARMACEUTICAL SIGNIFICANCE, BASED ON LIPOPHILIC CYCLODEXTRINS

Lipophilic alpha, beta and gamma cyclodextrins (CDs) have been systema tically analysed in order to establish their selective binding to oniu m ions. They have been identified as excellent ionophores for a range of ions of vital importance in clinical, pharmaceutical and forensic a nalysis. From the results obtained we found the following. A peroctyla ted cyclodextrin provides a size-selective cavity for the binding and detection of onium ions. Potentiometric alpha, beta and gamma cyclodex trin-based electrodes selectively sense NH4+, NMe(4)(+) and NEt(4)(+) ions respectively. These experiments were performed in order to enable us to understand the nature of analyte recognition by the lipophilic cyclodextrins. Peroctylated alpha CD is a suitable ionophore for dopam ine hydrochloride, - log [C] = 5.4, - log K = 2.0 (in serum level of N a+, K+, Ca2+) whereas peroctylated and 2,6 didodecyl beta CD sense ace tylcholine chloride, - log[C] = 5.0, - log K = 4.2 (in serum level of Na+, K+, Ca2+) and creatinine hydrochloride, - log K = 2.7 (in serum l evel of Na+, K+, Ca2+), respectively. The 2,6 didodecyl beta CD respon ds to more bulky aryl ammonium ions such as the anaesthetics procaine, prilocaine and lignocaine hydrochlorides, - log K = 4.2 (in serum lev el of Na+, K+, Ca2+). Partially octylated alpha CD has been identified as an enantioselective sensor for ephedrine hydrochloride, - log K = 4.5 (in serum level of Na+, K+, Ca2+), - log K-+/-(pot) = 2.6, and rel ated compounds such as amphetamine hydrochloride. The 2,6 didodecyl be ta CD is enantioselective for propranalol hydrochloride, - log K = 4.2 (in serum level of Na+, K+, Ca2+), - log K-+/-(pot) = 2.7. Complexati on has also been studied by electrospray mass spectrometry (ESMS).