Modulating the Self-Assembly of Calix[4]azacrowns to Design Materials with Improved Emission and Stimuli-Responsive Behavior

1,3-[Ethylene-bis­(aminocarbonylmethyl)]-p-tert-butylcalix­[4]­arene is analyzed and its optical properties are investigated, showing luminescence upon aggregation at low temperature or in the solid state described as aggregation-induced blue emission. The shift of the self-assembly from nanoporous to helical framework in the crystal is associated with a remarkable blue-shift and 33-fold increase in the fluorescence intensity. The purple-blue light emission is highly efficient (ΦF ∼ 60%) and is switched to thermally activated yellow emission as a stimuli-responsive behavior of the helical assembly. The emitting material has been characterized by single crystal and powder X-ray diffraction, ATR-FTIR spectroscopy, and DSC and PLTM analysis, and its optical properties are investigated.