The pH dependence of the chemosensor in HEPES buffer system was checked using UV–vis and fluorescence spectroscopy. Cyanide BC 11-38 was added to the buffered solution of L at different pH values. The results indicated that L binding with CN− occurred effectively in the range of pH = 2 to 13 (Fig. 8).
Fig. 8. Effect of pH on (a) the absorbance spectra (480 nm) and (b) fluorescence spectra (513 nm) of L + CN− (50 equiv.) from 2 to 13 in DMSO/H2O (6:4, v/v, containing 0.01 M HEPES) solution.Figure optionsDownload full-size imageDownload as PowerPoint slide
Fig. 9. Partial 1H NMR spectra of L (0.1 M, DMSO-d6) and in the presence of varying amounts of CN− (L, L + 0.1 equiv., L + 0.2 equiv., L + 0.5 equiv., L + 1 equiv.).Figure optionsDownload full-size imageDownload as PowerPoint slide
AcknowledgmentsFinancial supports by the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD) and the National Natural Science Foundation of China (NSFC) (grant number 30870625) are foraminifera gratefully acknowledged.