Evaluation of binding selectivities of bis-crowned clefts by electrospray ionization/quadrupole ion trap mass spectrometry

✍ Scribed by Blair, Sheryl M.; Brodbelt, Jennifer S.; Reddy, G. Madhusudhan; Marchand, Alan P.

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 283 KB
• Volume: 33
• Category: Article
• ISSN: 1076-5174
• DOI: 10.1002/(sici)1096-9888(199808)33:8<721::aid-jms686>3.0.co;2-k

✦ Synopsis

Electrospray ionization (ESI) was used in conjunction with quadrupole ion trap mass spectrometry to measure metal binding selectivities of bis-crowned clefts in methanol solution. Each of the three cleft compounds contained two 15-crown-5 rings separated by di †erent quinoline spacers. Binding selectivities were compared qualitatively with previous extraction results obtained for three bis-crown clefts complexing with the alkali metals sodium, potassium and rubidium in aqueous solution. The bis-crowned cleft molecules were found to form 1 : 1 and 2 : 1 metalÈcleft complexes, and, in a few cases where larger alkali metals were involved, two cleft molecules were able to form 2 : 2 metal-cleft complexes cooperatively. The binding selectivity is greatly a †ected by the size of the alkali metal and by the Ñexibility of the quinoline bridge, factors that inÑuence the degree of electrostatic repulsion between the two crown ether rings.