Sintesi tramite click chemistry di 1,2,3-triazoli derivati dal [1] benzotieno[3,2-b][1] benzotiofene: sensing di ioni metallici, solvatocromismo ed emissione indotta da aggregazione

Abstract [1]benzothieno[3,2-b][1]benzothiophene (BTBT) is one of the most promising low molecular weight organic semiconductors of the last decade. Soluble derivatives of this semiconductor can be synthesized by Friedel-Crafts acylation, and some examples have been reported in the context of cross-coupling functionalization from its brominated derivatives. This thesis focuses on the functionalization of the conjugated nucleus of BTBT by azide-alkyne cycloaddition catalyzed by Cu(I) (CuAAC). The validity of this approach has been demonstrated by the synthesis of derivatives from 2-azide-BTBT and commercial alkynes. During the research we saw the advantage of working with alkyl substituted BTBT derivatives, as they have a greater solubility. The azides were obtained in high yields from commercial BTBT or 2-alkyl-BTBT through a 4 steps procedure: nitration, reduction, diazonium salt formation and nucleophilic substitution with sodium azide. Synthesized azides react with several commercial terminal. Reactions proceed with high yields and their products can be easily isolated by recrystallization and column chromatography. The products were characterized by NMR, IR and MS. UV-Vis absorption and emission studies have also been conducted and have shown that optical properties and aggregation can be modulated by CuAAC functionalization. Two of the synthesized derivatives have been used in specific applications: 1. The derivative bearing a pyridine ring has been studied for the sensing of metal ions. Absorption and emission studies have been conducted in acetonitrile/water mixtures that demonstrate that this derivative can be used for sensing Zn2+ ions. In this case the triazole ring is not a mere spectator but it participates actively in the metal’s coordination. 2. The derivative bearing an aniline shows instead, a solvent-dependent fluorescence, which has been deepened.