Interaction between TEMPO Radicals and Gold Surfaces

Abstract

Organic radical molecules are, due to their relevance for spintronics and their fundamental interest, studied in mechanically controlled break junctions. It is often assumed that organic radicals are anchored to the gold electrodes by designated linker thiol groups with the radical substituents far from the electrodes. However, the interaction between a radical substituent and gold, in addition to the functional groups designed for anchoring the molecule, could influence the interaction between the whole molecule and the surface. To elucidate a possible influence, we discuss the interaction between a commonly used nitroxyl radical, (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO), with gold electrode surfaces by density functional theory methods combined with empirical dispersion corrections. Our results suggest that the interaction between TEMPO and gold is made up of two competitive and complementary contributions: direct binding between the nitroxyl and gold adatoms and dispersion interactions between bulky methyl groups and the surface (which is more pronounced for clean Au(111) surfaces but also prevents direct binding in this case). Importantly, the overall interaction is not negligible and is even comparable to some commonly used anchoring groups (e.g., amino groups). This may have consequences for interpreting the conductance and magnetoresistance data on organic radicals in molecular junctions.

Bismuth and Chlorine Dual‐Doped Perovskite Chloride as a Phase‐Structure‐Stable and Moisture‐Resistant Solid Electrolyte for Chloride Ion Batteries

“…[46] Upon charging to 2.0 V, a new N 1s peak appeared at ≈400.3 eV, which was ascribed to the oxidation of the 4-HO-TEMPO to form 4-HO-TEMPO chloride. [47,48] The subsequent discharge led to the disappearance of this new peak, thereby demonstrating the reversible reaction of the 4-HO-TEMPO cathode in the battery using the solid electrolyte. The use of the solid electrolyte also contributed to the operation and cycling of the CuCl 2 /Li electrode couple (Figure 6d,e), which could not operate in the liquid electrolyte because of the fast dissolution and subsequent reduction of CuCl 2 at the anode side (Figure S23, Supporting Information).…”

Calculation of π Using a Molecular Electron Spin Qubit Implemented by Pulsed Electron Paramagnetic Resonance

“…The use of molecular electron spins as qubits is also attracting the attention of researchers. − To control such qubits, it is proposed to use pulsed electron paramagnetic resonance (EPR). − Nowadays, there are even opportunities to address the spin center and, thus, perform operations with more than one qubit. − Approaches to characterize a molecular electron spin qubit include relevant EPR spectroscopy techniques. To estimate the coherence time of the qubit, time of transverse relaxation of magnetization ( T 2 ) or phase memory time ( T m ) could be measured .…”