Baris Yucel

Multichromic, ferrocene clicked poly(2,5-dithienylpyrrole)s

Herein, we report the synthesis of a novel, click functionalized 2,5-dithienylpyrrole (SNS-Fc) for the first time. Ferrocene was employed as an anchored unit because of its well-known physical and redox properties. SNS-Fc was electrochemically polymerized and electrochromic properties of the resulting polymer were investigated in detail. In addition, electrochemical copolymerization of SNS-Fc in the presence of 3,4-ethylenedioxythiophene was performed. The resulting copolymer displayed multichromic behavior ranging between orange, yellow, green and blue in different redox states. Cyclic voltammetry studies of both polymers revealed two reversible waves related to the polymer backbone and Fe II/III redox couples, while showing the typical characteristic of surface-confined structures. Our studies have shown that the redox behavior, band gap and color of poly(2,5-dithienylpyrrole) derivatives are highly dependent on anchored unit (ferrocene) and copolymerization.

Colour-responsive fluorescent oxy radical sensors

A series of fluorene-fused benzoquinones (Q1-Q5) were prepared by thermolysis of 4-fluorenyl-4-hydroxycyclobutenones. Red fluorescence observed for Q2 is switched by reduction to blue fluorescence by formation of the hydroquinone. Reaction with hydrogen peroxide restores the original fluorescence colour. The potential use of compound Q2 as a reactive oxygen species detector is discussed.

A Novel Ferrocenyl Naphthoquinone Fused Crown Ether as a Multisensor for Water Determination in Acetonitrile and Selective Cation Binding

A multisensor which is based on a novel multifunctional triad molecule, ferrocenyl naphthoquinone fused crown ether (Fc-cnq) bearing ferrocene, quinone, and crown ether functional groups together, was synthesized and characterized in this study. Sensing performance of a trace amount of water and the selective cation binding capabilities of this multisensor were carried out by the electrochemical, spectroelectrochemical, and spectrophotometric titration techniques in acetonitrile (CH3CN). It was shown that the potential separation (E((Fc))1/2 - E((2))1/2) between the second reduction of naphthoquinone and the oxidation processes of ferrocene in the triad molecule Fc-cnq was proportional to the amount of water due to the hydrogen-bonding interactions between water and the doubly reduced species (Fc-cnq(2-)). This property enabled Fc-cnq to detect the trace amount of water in CH3CN. The half-wave potential (E((Fc))1/2) of the ferrocene in Fc-cnq was used as an internal reference potential, and it defined the accuracy of the detection. In addition, by using the UV-vis spectrophotometric titration technique in CH3CN, it was also shown that the Fc-cnq multisensor could bind Ba(2+) and Ca(2+) cations selectively. We proposed that the intramolecular charge-transfer (CT) transition which occurred between the donor ferrocene and the acceptor naphthoquinone was the principle mechanism for the selective binding property of this multisensor. Quantum chemical calculations were also performed to investigate optical and electronic properties of the Fc-cnq molecule.