In the case of 4PXZ-TPPQ, upon increasing the fw to 40%, a new emission band at lPL of 790 nm appears, the intensity of which increases 23-fold at fw = 80% (Figures and). When the fw > 80%, the PL intensity decreases and slightly blue-shifts to 770 nm. In both molecules, the observed AIE is attributed to the formation of aggregates, as found in their crystal structures. The red-shifted emission observed from the aggregates formed in the 80% H2O/THF mixture in both molecules likely occurs because of stronger intermolecular interactions between adjacent donor and acceptor moieties that modulate the energy of intermolecular CT states. To understand the emissive behaviour of the crystalline aggregates in THF/H2O solution (fw = 80%), we measured the PL spectra of the dried aggregates isolated from the THF/H2O solution. These spectra closely resemble those of the neat films of TPPQ, 4DMAC-TPPQ and 4PXZ-TPPQ (Figure ), indicating that the excited-state species are likely the same for both types of samples.