Deposition of Tetracoordinate Co(II) Complex with Chalcone Ligands on Graphene

Abstract

Studying the properties of complex molecules on surfaces is still mostly an unexplored research area because the deposition of the metal complexes has many pitfalls. Herein, we probed the possibility to produce surface hybrids by depositing a Co(II)-based complex with chalcone ligands on chemical vapor deposition (CVD)-grown graphene by a wet-chemistry approach and by thermal sublimation under high vacuum. Samples were characterized by high-frequency electron spin resonance (HF-ESR), XPS, Raman spectroscopy, atomic force microscopy (AFM), and optical microscopy, supported with density functional theory (DFT) and complete active space self-consistent field (CASSCF)/N-electron valence second-order perturbation theory (NEVPT2) calculations. This compound’s rationale is its structure, with several aromatic rings for weak binding and possible favorable π–π stacking onto graphene. In contrast to expectations, we observed the formation of nanodroplets on graphene for a drop-cast sample and microcrystallites localized at grain boundaries and defects after thermal sublimation.

Raman spectroscopy of few-layers TaS$_2$ and Mo-doped TaS$_2$ with enhanced superconductivity

“…The positions of these peaks, which dominate the spectra for the thinnest samples, is fixed for all samples measured, and matches the peaks found in measurements of the substrate alone under the same measurement conditions. These substrate peaks match the ones reported by previous works in SiO 2 /Si: the one at 300 cm −1 is reported to be originated in the Si, and the one at 428 cm −1 has been reported to come from amorphous SiO 2 on SiO 2 /Si substrates [44,45]. As mentioned, the Raman signal for the thinnest samples is dominated by the substrate peaks, which almost overlap the weak E 1 2g and A 1g sample modes.…”

Pentacoordinate cobalt(ii) single ion magnets with pendant alkyl chains: shall we go for chloride or bromide?

“…22 In this regard, only a couple of studies report on 3 d transition metal complexes (and of them even fewer on Co( ii ) mononuclear complexes) where inherent magnetic properties of a SIM were preserved after attachment to substrate or even tuned up. 23,24 A crucial point herein is a deep understanding of the anchoring of SIM molecules since their exposed surfaces offer many application possibilities but also bring many challenges, as these molecules can become redox unstable and decompose. There are two main routes to produce nanostructured magnetic surfaces – either by the thermal sublimation of SIM molecules under vacuum 24–26 or via a wet-chemistry protocol from solutions.…”

“…23,24 A crucial point herein is a deep understanding of the anchoring of SIM molecules since their exposed surfaces offer many application possibilities but also bring many challenges, as these molecules can become redox unstable and decompose. There are two main routes to produce nanostructured magnetic surfaces – either by the thermal sublimation of SIM molecules under vacuum 24–26 or via a wet-chemistry protocol from solutions. 27,28 Despite an earlier approach allowing precise surface functionalization in a well-defined and pure manner, the process often requires sufficient thermal stability and neutral molecules.…”

Thickness-dependent magneto-transport of Bi2Se3/SiO2 topological insulator thin films

“…These modes are the intrinsic modes of bismuth selenide, which ensure impurity-free deposition. Moreover, there is a Raman peak at 520 cm -1 due to SiO2 [23], as shown in the inset of fig. 1(b).…”