Thionine Self-Assembled Structures on Graphene: Formation, Organization, and Doping

Abstract

The association of organic molecules with two-dimensional (2D) materials, creating hybrid systems with mutual influences, constitutes an important testbed for both basic science self-assembly studies and perspective applications. Following this concept, in this work, we show a rich phenomenology that is involved in the interaction of thionine with graphene, leading to a hybrid material formed by well-organized self-assembled structures atop graphene. This composite system is investigated by atomic force microscopy, electric transport measurements, Raman spectroscopy, and first principles calculations, which show (1) an interesting time evolution of thionine self-assembled structures atop graphene; (2) a highly oriented final molecular assembly (in accordance with the underlying graphene surface symmetry); and (3) a strong n-type doping effect introduced in graphene by thionine. The nature of the thionine-substrate interaction is further analyzed in experiments using mica as a polar substrate. The present results may help pave the way to achieve tailored 2D material hybrid devices via properly chosen molecular self-assembly processes.

Real-time PCR for direct aptamer quantification on functionalized graphene surfaces

“…Thionine has a planar aromatic structure that allows strong interaction with the surface of graphene sheets through synergistic non-covalent charge-transfer and π-stacking 33 , leaving a large amount of hydrophilic amino groups (NH 2 ) available for interaction with other molecules. In a recent work 34 , we have demonstrated that, contrary to what was previously believed, thionine molecules do not lie flat on the graphene but are vertically attached to the surface. In this same work, we also demonstrated that the thionine bounded onto the graphene surface undergoes a structural transition, driven by the amount of surface coverage, were a preferential alignment of domains along graphene crystallographic directions takes place.…”

Poly(Thionine)-Modified Screen-Printed Electrodes for CA 19-9 Detection and Its Properties in Raman Spectroscopy

“…By evaluating the Raman spectra of the same carbon electrode modified with TH, one may determine if it is present and if TH interaction with carbon is covalent or noncovalent in nature. This was carried out by observing the D band (1360 cm −1 ) and following the alterations that may appear [25], as shown in Figure S2. The spectra of TH casted on carbon electrode is shown in Figure 4b.…”

“…It has received considerable attention as a polymeric film for sensing purposes, yielding improved sensitivity and lower limits of detection [1]. Thionine (TH) is its monomeric species, which is a redox dye that has been extensively studied (de Sousa et al, 2018). PTH-modified electrodes have been prepared in a simple way by cyclic voltammetry (CV) having a solution of TH under a potential sweep in the range from −0.4 to +0.4 V [10]; the specific potential range of interest depends on the electrical features of the receptor substrate.…”

Surface Engineering of Graphite and Graphene by Viologen Self-Assembling: From Global to Local Architectures

“…Surface modification via molecular self-assemblies is considered a potentially useful technique for tuning the electronic properties of graphene layers. − Due to its delocalized π electrons, graphene is highly susceptible to adsorbates on the surface. Therefore, organic molecules with the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) at a suitable position with respect to the Fermi level of graphene have been employed to dope graphene. − …”