Anionic Chromogenic Chemosensors Highly Selective for Fluoride or Cyanide Based on 4-(4-Nitrobenzylideneamine)phenol
نویسندگان
چکیده
O composto 4-(4-nitrobenzilidenoamino)fenol foi utilizado em duas estratégias que permitem uma detecção altamente seletiva de F e CN. Primeiramente, observou-se que o composto em acetonitrila age como um quimiossensor cromogênico devido ao fato de que ânions básicos levam ao seu desprotonamento (solução incolor), resultando numa solução colorida contendo fenolato. A detecção seletiva de CN sobre F foi obtida adicionando-se 1,4% de água ao sistema: a água solvata preferencialmente o F, enquanto o CN fica relativamente livre para desprotonar o composto fenólico. Outra estratégia envolveu um ensaio de competição do fenolato e do analito pelo calix[4]pirrol em acetonitrila, um receptor altamente seletivo para F. O fenolato e o calix[4]pirrol formam um complexo por ligação de hidrogênio, com mudança na cor do meio. Dentre diversos ânions, somente o F foi capaz de restaurar a cor original correspondendo ao fenolato, pelo fato do ânion deslocá-lo do sítio de complexação.
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