title: Surface potential switching by metal ion complexation/decomplexation using bipyridinethiolate monolayers on gold.
abstract: Surface potential switching on gold(111) surfaces is induced by complexation/decomplexation reactions of a bipyridine (BP) derivative and palladium(II) chloride, as observed by Kelvin probe force microscopy (KFM). On the basis of the theoretical predictions, a 4-(5-phenylethynyl-2,2'-bipyridine-5'-yl-ethynyl)benzenethiol (PhBP) derivative was synthesized and used as an active monolayer to catch transition metal ions. By using the microcontact printing (CP) technique, micron-size patterned PhBP monolayers, which act as effective hosts to coordinate palladium(II) chloride, were prepared on gold(111) surfaces. The KFM signal decreases by complexation of the Pd(II) chloride in PhBP monolayers and is recovered by removal of Pd ions using an ethylenediamine solution, as confirmed by X-ray photoelectron spectroscopy. This process is reversible, indicating that the surface potential switching is realized by complexation/decomplexation of Pd(II). A CP PhBP monolayer, when it detects the target palladium ion, shows sensitivity for the picomolar level detection judged from surface potential changes in KFM measurements. The dipole moment estimated by the surface potentials is much smaller than the calculated value, indicating that mechanisms for the reduction of the surface dipole moment exist in real monolayers prepared by the CP method.
authors: Nanotechnology Research Institute (NRI), National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565, Japan. tohru.nakamura@aist.go.jp
authors: Tohru
authors: T
authors: Nakamura
authors: Emiko
authors: E
authors: Koyama
authors: Yukihiro
authors: Y
authors: Shimoi
authors: Shuji
authors: S
authors: Abe
authors: Takao
authors: T
authors: Ishida
authors: Kiyomi
authors: K
authors: Tsukagoshi
authors: Wataru
authors: W
authors: Mizutani
authors: Hideo
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authors: Tokuhisa
authors: Masatoshi
authors: M
authors: Kanesato
authors: Ikuyo
authors: I
authors: Nakai
authors: Hiroshi
authors: H
authors: Kondoh
authors: Toshiaki
authors: T
authors: Ohta