Synthesis and Characterization of a Luminol Based Chemiluminescent Trimeric System

Abstract

A luminol based chemiluminescent trimeric system, namely 2,3-dihydro-5,8-di(thiophen-2-yl)phthalazine-1,4-dione (T₂B-Lum), bearing thiophene rings as donor units and 2,3-dihydrophthalazine-1,4-dione as an acceptor unit was synthesized in two steps via donor-acceptor-donor approach using two different methods. It was found that T₂B-Lum emits chemiluminescent light when exposed to H₂O₂ in a basic medium, and the presence of substituents and the type of aromatic ring bearing chemiluminescent active group have a direct effect on the compound's sensitivity. Among the members of a large family of metal ions, fluorescent and chemiluminescent T₂B-Lum exhibited high sensitivity to Cu²⁺ and Fe³⁺ ions. Except for other metal cations (silver(I), cadmium(II), cobalt(II), iron(III), lithium(I), magnesium(II), manganese(II), nickel(II), zinc(II)), it has been observed that T₂B-Lum is mostly sensitive to copper(II) ions with a detection limit value of 2.2 × 10^{- 3} M. On the other hand, T₂B-Lum was also found to exhibit a high sensitivity to extremely dilute aqueous solutions (e.g., 1:50.000 dilution) of blood samples, making it a promising candidate for use in forensic applications.

Keywords: Chemiluminescence; blood detection; ion recognition; luminol; thiophene.