A class of novel heterocyclic compounds 1a–1c has been designed and synthesized. And our initial discovery is that these compounds can effectively recognize HSO 4 − . With the addition of HSO 4 − , a new energy band appears at 360–390nm in the absorption spectra. The emission spectrum (λ ex =328 nm) undergoes an important change in its fluorescent effect in the presence of HSO 4 − . All available data (absorption and emission) strongly support the formation of hydrogen-bonded complexes between 1a and 1c and HSO 4 − .