Synthesis, characterization and optical properties of small molecules

Abstract

Benzoselenodiazole and its derivatives have special properties to form head to head dimer via Se···N interaction in its solid state packing. The tendency to form dimers largely depends on the nonbonding interactions and the steric effect of capped rings. 4-methoxybenzene, naphthalene and 4-nitrobenzene capped benzoselenodiazoles (compounds 1-3 respectively) were synthesized and studied their photophysical as well as electrochemical properties. All the entire molecules show two absorption bands (π- π transition band and CT-band). Three molecules (1-3) show orange, yellow-green and light blue colours upon irradiation of UV light at 365 nm. Band gaps of these compounds were tuned by changing the attached group from electron donating to electron withdrawing units. Crystal structure of compounds 1 and 2 show very interesting result, both of these molecules packed in its solid state via Se···N interaction and interlock type packing. Se··· π interaction is taking the major role in the interlock type crystal packing of compound 1 in its solid state whereas Se···N, N···N and CH···π take important role for the solid state crystal packing of compound 2.