Mediated Electron Transfer Across Supported Bilayer Lipid Membrane with TCNQ‐Based Organometallic Compounds

Abstract

Supported bilayer lipid membrane (s-BLM) containing one-dimensional compound 1, TCNQ-based (TCNQ ¼ 7,7,8, organometallic compound {(Cu 2 (m-Cl)(m-dppm) 2 )(m 2 -TCNQ)} 1 , was prepared and characterized on the self-assembled monolayer (SAM) of 1-octadecylmercaptan (C 18 H 37 SH) deposited onto Au electrode. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) results showed that the compound 1, dotted inside s-BLM, can act as mediator for electron transfer across the membrane. Two redox peaks and the charge-transfer resistance of 400 kW were observed for compound 1 inside s-BLM. The mechanism of the electron transfer across s-BLM by TCNQ is by electron hopping while TCNQ-based organometallic compound is by conducting. Further conclusion drawn from this finding is that the TCNQ-based organometallic compound embedded inside s-BLM exhibits excellent electron transfer ability than that of free TCNQ. This opens a new path for the development of s-BLM sensor and/or biosensor by incorporation with TCNQ-based organometallic compounds. s-BLM has attracted extensive interest in recent years [5] and TCNQ as modifiers to mediate the electron transport through the s-BLM [6] has been found. Recently, electrochemical method in controlling the synthesis, morphology, and fabrication of TCNQ-based organometallic compounds has been employed [7]. However, the electrochemical property of TCNQ-based organometallic compounds inside s-BLM remains unknown. In this paper we mainly concern with electronic processes in s-BLM containing one-dimensional compound 1 {(Cu 2 (m-Cl)(m-dppm) 2 )(m 2 -TCNQ)} 1 [8]. We wonder whether the compound 1, one typical molecule of TCNQ-based organometallic compounds, dotted inside s-BLM could behave as an electronic conductor and partake in redox reactions at the membrane/solution interfaces as well as TCNQ.The electrochemical response of the free TCNQ and TCNQ-based organometallic compound in organic solution is preliminary studied. (Fig. 1b), presumably involving the electron transfer at Cu(I) centers [8]. Additionally, two reversible peaks at E red1 ¼ 0.13 V and E red2 ¼ À 0.38 V (Fig. 1c) were observed, processing at unusually high potentials, which can be attributed to the TCNQ ligand. On the other hand, free TCNQ in the solution has E red1 ¼ À 0.32 V and E red2 ¼ À 0.97 V (Fig. 1d), respectively. Thus, the compound 1 as well as TCNQ was typical electron acceptor and donor conductor, which are suitable to be dotted inside the BLM to transfer electron.With these desired properties in mind, we further explore whether the compound 1, when embedded inside the BLM, could transfer electron across the membrane and have effects on the electrical property of s-BLM. (Fig. 1). The positive shift of the peak potential for 1@LC/SAM/Au electrode can be attributed to addiShort Communication