Synthesis and binding properties of ditopic receptors based on hexahomotriazacalix[3]arene and electrochemically active dendrimers

Abstract

Hexahomotriaza-p-chlorocalix[3]arene (L1) was successfully by synthesized and functionalized to provide two novel heteroditopic sensors. From complexation studies, the hexahomotriaza-p-chlorocalix[3]arene could be used as a selective chromogenic sensor for F[superscript -] and H[subscript 2]PO[subscript 4][superscript -]. The partial-cone hexahomotriaza-p-chlorocalix[3]-trinaphthylamide (L2) synthesized from both cone and partial cone triester derivatives exhibited a selective fluorescent sensor for Cd[superscript 2+], Pb[superscript 2+] and F[superscript -]. Hexahomotriaza-p-chlorocalix[3]-cryptand (L3) which is fixed in cone conformation and possesses a close well-defined cavity showed a high selectivity for Cl[superscript -] ion. Tuning this ligand by complexing with Zn[superscript 2+] on hexahomotriaza-p-chlorocalix[3]arene framework, its anion binding selectivity changed to Br[superscript -] ion. Moreover, a new class of chemosensor recognition elements based on conjugated polymer network ultra-thin films from electrochemical cross-linking of hexahomotriaza-p-chlorocalix[3]arene-carbazole (L4) was successfully realized. Its demonstrated high selectivity and sensitivity towards Zn[superscript 2+] was observed. A self-assembly between polyamidoamine (PAMAM) dendrimer and dendron surfmers (G[subscript 0]COOH, G[subscript 1]COOH and G[subscript 1]COOH) was prepared through an efficient supramolecular interaction. The electrochemical cross-linking of dendrimer complexes (PAMAM-G[subscript 1]COOH) provided thin films which have a ring-like or donut structure most likely composed of the PAMAM-core and dendron-carbazole shell. In addition, [pi]-conjugated dendrimer-protected gold nanoparticles in a stable colloidal form have been successfully prepared via simultaneous reduction of AuCl[subscript 3] with terthiophene (PT) and carbazole (PC) peripheral functionalized PAMAM dendrimers.