Cryptand spirobenzopyrans

Cryptand and Bibrachial Lariat Type Crowned Spirobenzopyrans as... 

Isomerization of cryptand-containing spirobenzopyran 63 (Scheme 3) to the open-colored merocyanine 63 in the presence of Srl2 has been studied by H NMR spectroscopy at 500 MHz. In several deuterated solvents (e.g. CDC13, CD3CN, DMSO-d6) the H NMR signals of 63 were considerably broadened at room temperature. High-temperature NMR (85 °C) in DMSO-d6 succeeded in resolv-... 

In this section, the sensing properties of the cryptand and bibrachial lariat-type crowned spirobenzopyrans were presented. In the spirobenzopyrans, coloration was efficiently induced in the presence of the alkaline earth metal cations. The cryptand and bibrachial lariat-type crowned spirobenzopyrans represent highly sensitive and selective chemosensors for alkaline earth metal cations. 

Inouye et al. have designed a sensitive and selective cryptand-type crown spirobenzopyran sensor for alkaline-earth metal cations (Figure 92) [119]. Upon metal ion complexation, the spirocycle opens up, resulting in a large increase in the absorption in the visible range. For n = 1 and 2 the selectivity orders were found to be Ca " " > Mg " " > Sr " " and > Ba > Ca " ", respectively. 

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