A Rational Approach to Selective Recognition of NH4+ over K+

✍ Scribed by Jik Chin; Christian Walsdorff; Brent Stranix; Jinho Oh; Hyun Jei Chung; Su-Moon Park; Kimoon Kim

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 121 KB
• Volume: 38
• Category: Article
• ISSN: 0044-8249
• DOI: 10.1002/(sici)1521-3773(19990917)38:18<2756::aid-anie2756>3.0.co;2-6

✦ Synopsis

Over the past several decades there has been considerable interest in developing receptors for NH 4

. Such receptors are desirable as sensors in clinical analysis and in environmental chemistry. For example, concentrations of urea or creatinine in biological samples can be determined indirectly by measuring the amount of NH 4 released upon enzymecatalyzed hydrolysis of the substrates. These receptors are also useful for determining the concentrations of NH 4 or ammonia in drinking water and in the air. One of the most effective NH 4 receptors is nonactin (1), a natural antibiotic agent that is currently used commercially in ion-selective electrodes (ISE). However, a serious drawback of nonactin is that it binds only about ten times more tightly to NH 4 than to K . Similarly, crown ethers show little or no selectivity for binding NH 4 over K . Here we report a rationally designed receptor (2) that is highly selective for binding NH 4 over K .