Layered Insulator/Molecule/Metal Heterostructures with Molecular Functionality through Porphyrin Intercalation

Abstract

Intercalation of molecules into layered materials is actively researched in materials science, chemistry, and nanotechnology, holding promise for the synthesis of van der Waals heterostructures and encapsulated nanoreactors. However, the intercalation of organic molecules that exhibit physical or chemical functionality remains a key challenge to date. In this work, we present the synthesis of heterostructures consisting of porphines sandwiched between a Cu(111) substrate and an insulating hexagonal boron nitride ( h-BN) monolayer. We investigated the energetics of the intercalation, as well as the influence of the capping h-BN layer on the behavior of the intercalated molecules using scanning probe microscopy and density functional theory calculations. While the self-assembly of the molecules is altered upon intercalation, we show that the intrinsic functionalities, such as switching between different porphine tautomers, are preserved. Such insulator/molecule/metal structures provide opportunities to protect organic materials from deleterious effects of atmospheric environment, can be used to control chemical reactions through spatial confinement, and give access to layered materials based on the ample availability of synthesis protocols provided by organic chemistry.

Borophenes made easy

“…As expected for a large gap insulator like h BN, the atomic lattice can only be imaged under certain tip and scanning conditions, otherwise only the stripy appearance of borophene is observed (see fig. S11), i.e., the h BN cover appears “transparent” for STM ( 47 ). The orientation of the h BN on borophene is not unique but consists on a manifold of misalignments around borophene’s wavy direction ( Figs.…”

Quantitative determination of a model organic/insulator/metal interface structure

“…Scanning tunneling spectroscopy (STS) measurements on Co–P/ h -BN/Cu(111) (Fig. S2b† and ref. 56) only show Co-related states above the Fermi level on any region of the h -BN moiré, clearly refuting the idea of a charge transfer to the Co–P molecules, in agreement with a report on Co-metalated functionalized porphyrins 57.…”

Self-assembly and spectroscopic fingerprints of photoactive pyrenyl tectons on hBN/Cu(111)

“…For instance, h BN/Cu(111) [ 24 – 27 ] features a work function template with a moiré superstructure: Depending on the registry of the layer and substrate atoms, the surface is divided in areas of low and high local work function, denoted as “pores” and “wires”, respectively [ 28 – 31 ]. In recent years, our group and others used h BN/Cu(111) to guide the self-assembly of porphyrins [ 28 , 32 – 33 ], decouple perylenetetracarboxylic dianhydride (PTCDA) aggregates [ 34 ], study interfacial charge transfer in binary phthalocyanine arrays [ 35 ], probe vibronic conductance in oligophenylenes [ 36 ], and control the charge state of F 16 CoPc [ 37 ]. Studies focusing on the preparation of coordination networks [ 38 ], wires of polycyclic aromatic hydrocarbons [ 39 ], and graphene patches [ 40 – 41 ] were also performed on h BN/Cu(111).…”