An excellent copper selective chemosensor based on calix[4]arene framework

The article depicts a detailed study regarding copper selective chemosensing and complexation nature of 5,11,17,23-tetrakis[(N,N-diphenylamino)methyl]-25,26,27,28-tetrahydroxycalix[4]arene (PAC4). Its photophysical characteristics in various solvents of different polarities along with the influence of acid and base on its spectral properties in these solvents are also discussed. The complexation affinity of PAC4 with regard to its latent applications as Cu(II) selective colorimetric and fluorescent sensor among the selected series of various cations such as Li(I), Na(I), K(I), Rb(I), Ba(II), Sr(II), Al(III), Fe(III), Cd(II), Co(II), Hg(II), Mn(II), Ni(II), Pb(II) and Zn(II) was examined by UV–visible and fluorescence emission spectroscopy in dichloromethane:acetonitrile (DCM:MeCN) solvent system. In addition, the process of complexation has been investigated through Job's plot and it has been observed that the complex between PAC4 and Cu(II) is formed in 1:1 stoichiometric ratio. The complex formation between PAC4 and Cu(II) has also been confirmed by FT-IR spectroscopy and thermal gravimetric analysis (TGA).

Graphical abstractp-(N,N-diphenylamino)methylcalix[4]arene (PAC4) was found to be a highly Cu(II) selective and sensitive colorimetric/fluorescent sensor material. High selectivity of PAC4 may be due to its compatibility with Cu(II) in respect of size of cavity, ionic radii, nature and number of binding sites, and geometry that help in selective complexation.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Using PAC4 sensor, Cu(II) selective binding ability has been explored among series of various cations. ► PAC4 shows remarkable discernable colorimetric variations on addition of Cu(II) ions. ► TGA and FT-IR spectroscopic method also verifies the fluorescence and UV–visible spectral results.