A Facile Strategy for the Construction of Purely Organic Optical Sensors Capable of Distinguishing D 2 O from H 2 O

Owing to the quite similar chemical properties of H 2 O and D 2 O, rational molecular design of D 2 O optical sensors has not been realized so far. Now purely organic chromophores bearing OH groups with appropriate p K a values are shown to display distinctly different optical responding properties toward D 2 O and H 2 O owing to the slight difference in acidity between D 2 O and H 2 O. This discovery is a new and facile strategy for the construction of D 2 O optical sensors. Through this strategy, ratiometric colorimetric D 2 O sensor of NIM‐2F and colorimetric/fluorescent dual‐channel D 2 O sensor of AF were acquired successfully. Both NIM‐2F and AF can not only qualitatively distinguish D 2 O from H 2 O by the naked eye, but also quantitatively detect the H 2 O content in D 2 O.