Fabrication of Photomagnetic Carbon Surfaces via Redox Assembly

Y.-L Song,C M Wang

doi:10.1155/2017/6058216

Abstract

3-Aminophenylboronic acid (APBA) and the complex Ru(bpy)2(phendione)2+ (bpy = 2,2′-bipyridine, phendione = 1,10-phenanthroline-5,6-dione) were found to be useful building blocks for preparing photomagnetic carbon surfaces. Scanning tunneling microscopy (STM) showed that when APBA was diazotized in acidic sodium nitrite solutions and cathodically reduced with highly ordered pyrolytic graphite (HOPG) electrodes, nanoscale films formed on the electrodes. The resulting HOPG had strong affinities for phendione and Ru(bpy)2(phendione)2+ as the electrodes were biased in the presence of them, respectively, with voltages more negative than the cathodic peak potentials for phendione/phendiol and Ru(bpy)2(phendione)2+/Ru(bpy)2(phendiol)2+ (phendiol = 1,10-phenanthroline-5,6-diol). However, if APBA was excluded, the affinities did not exist. Boronate ester formation featured prominently in these intermolecular interactions. The average increments in the HOPG surface roughness contributed by APBA and Ru(bpy)2(phendione)2+ were roughly 1 : 2, suggesting that the reaction stoichiometry between APBA and Ru(bpy)2(phendione)2+ be 1 : 1. Ru(bpy)2(phendione)2+ could also be grafted to carbon nanotubes (CNTs) under conditions similar to those for the HOPG using ascorbate as sacrificial donor. The resulting CNTs and HOPG exhibited photomagnetism when exposed to the 473 nm light. The ruthenium complex was shown to be a room-temperature photomagnetism precursor, and APBA was shown to be an effective molecular bridge for the complex and carbon substrates.

Highlights

Photosensitive nanostructures have great potential for use in a wide variety of applications, including manipulating the physiology of DNA [1], enhancing light harvesting [2], and integrating photonanoelectronics [3] and photospintronics [4]
We have recently demonstrated that ordinary multiwalled carbon nanotubes (CNTs) develop photomagnetic and photoconductive characteristics after being modified with Ru(bpy)2(phen-NH2)2+ through diazotization/denitrogenation processes [5]
The process for accomplishing this, which is shown in Scheme 1, is supported by the electrochemical impedance spectroscopic (EIS) and scanning tunneling microscopic (STM) characterizations

Summary

Introduction

Photosensitive nanostructures have great potential for use in a wide variety of applications, including manipulating the physiology of DNA [1], enhancing light harvesting [2], and integrating photonanoelectronics [3] and photospintronics [4]. We have recently demonstrated that ordinary multiwalled carbon nanotubes (CNTs) develop photomagnetic and photoconductive characteristics after being modified with Ru(bpy)2(phen-NH2)2+ (phen-NH2 = 5-amino-1,10phenanthroline) through diazotization/denitrogenation processes [5]. Further research in this area has shown that many other ruthenium complexes, such as Ru(bpy)2(phendione)2+, are effective alternatives to Ru(bpy)2(phen-NH2)2+, and that boronic acids, including APBA, can serve as surface adhesives [6]. Organic derivatives of boric acid, can form stable 5-membered cyclic dioxaborolanes or 6-membered dioxaborinanes with polyols [7] Due to this unique property, APBA has recently been identified as a surface antenna and receptor for biochemically important substances, such as glucose and dopamine [8, 9]. Scheme 1: Schematic illustration for the electrochemical attachment of APBA and Ru(bpy)2(phendione)2+ to carbon surface

Materials and Methods

Results and Discussion

Conclusions