Amidofluorene-appended lower rim 1,3-diconjugate of calix[4]arene: synthesis, characterization and highly selective sensor for Cu(2.).

Rahman Hosseinzadeh,Maryam Mohadjerani,Mohammad Nemati,Reza Zadmard

doi:10.3762/bjoc.12.163

Abstract

Functionalization of calix[4]arene with amidofluorene moieties at the lower rim led to formation of the 1,3-diconjugate of calix[4]arene L as a novel fluorescent chemosensor for Cu2+. The receptor molecule L exhibited a pronounced selectivity towards Cu2+ over other mono and divalent ions. The formation of the complex between L and Cu2+ was evaluated by absorption, fluorescence and 1H NMR spectroscopy. The sensor L showed a remarkable color change from colorless to purple and a fluorescence quenching only upon interaction with Cu2+. The 1:1 stoichiometry of the obtained complex has been determined by Job’s plot. The association constant determined by fluorescence titration was found to be 1.8 × 106 M−1. The sensor showed a linear response toward Cu2+ in the concentration range from 1 to 10 µM with a detection limit of 9.6 × 10−8 M.

Highlights

Owing to the substantial role of fluorescent chemosensors in biological, environmental, and chemical processes, their design and synthesis, especially for detection of metal ions has attracted great attention in supramolecular chemistry [1,2,3,4]
In continuation of our studies on developing novel chemosensors containing fluorenyl moieties as fluorogenic group [32,33,34], we report here the design and synthesis of a new fluoreneappended 1,3-diconjugate of calix[4]arene (L), which possess distal amide groups on the lower rim of the conical framework to recognize Cu2+ with high sensitivity and specificity (Scheme 1)
Upon addition of Cu2+, at higher concentrations of L a broad signal appeared at the area of 600–800 nm which can be related to a d→d transition

Summary

Introduction

Owing to the substantial role of fluorescent chemosensors in biological, environmental, and chemical processes, their design and synthesis, especially for detection of metal ions has attracted great attention in supramolecular chemistry [1,2,3,4]. The variation of UV–vis spectra was monitored by adding 10 equivalents of different metal ions as perchlorate salts (Cu2+, Hg2+, Pb2+, Zn2+,Co2+, Ni2+, Cd2+, Ag+, Ba2+, K+, Na+ and Li+).

Results

Conclusion