A new thiacalix[4]arene-cinnamaldehyde derivative 3, which undergoes red shift in the fluorescence spectrum in the presence of Ag+ ions, has been synthesized. This emission shift is attributed to the intramolecular charge transfer process in the presence of Ag+ ions with a detection limit in the nanomolar range.
![Graphical abstract: Thiacalix[4]arene-cinnamaldehyde derivative: ICT-induced preferential nanomolar detection of Ag+ among different transition metal ions](http://hg.y866.cn/compound/lib/scimg/usr/1/C1OB06294H.jpg)
