Compound 3 has low FQY (0.01) in THF due to high change of dipole moment upon excitation. In aggregates, the FQY for 3 increases significantly to 0.61, while for 7 decreases from 0.88 (THF) to 0.11. This suggests that AIE arising from the loss of molecular flexibility in 3 is dominant over intermolecular interactions, while ACQ observed in 7 originates from the intermolecular interactions (between dyes and in dye-water regime) in the excited state. Moreover, the crystal structure for these two molecules is very similar (see SI) suggesting similar inter-dye interaction and further supporting water influence on FQY. It is worth mentioning that the difference between energy of emission for 7 in aggregate and in THF solution is equal to 4528 cm -1 , a value comparable to the FWHM in THF across the whole series (3536 to 5910 cm -1 ) and higher than any FWHM for aggregate or solid. This makes 7 the most sensitive dye for its surrounding in the light of its FQY and λ em .