Elaboration of Hydrogen-Bonded 2D Supramolecular Assemblies on Au(111) From Solutions: Toward Naphthalene Tetracarboxylic Diimide–Melamine Nanoporous Networks

Abstract

Melamine and naphthalene tetracarboxylic diimide (NTCDI) supramolecular assemblies have been elaborated by a solution-based approach on Au(111) and studied by scanning tunneling microscopy (STM). We discuss the role of π-oligomers and H-oligomers in the mechanism of the network formation. Whereas the role of the first seems negligible, thermodynamical considerations establish the key role of the H-oligomers in the network extension in relation with the solvent nature. Density functional theory (DFT) calculations on the networks support the experimental structures. We discuss the influence and advantages of the solution method on the assemblies comparatively to ultrahigh vacuum (UHV) conditions. The NTCDI−melamine network exhibits a honeycomb structure which is obtained for the first time on the Au(111) substrate. The supramolecular mixed network is remarkably robust due to the stabilization from the triple hydrogen bonds established between the neighboring NTCDI and melamine molecules.

Self-assembled π-conjugated macromolecular architectures — A soft solution process based on Schiff base coupling

“…[16,17] Scanning tunneling microscopy (STM) can potentially be used to visualize molecules with sub-molecular resolution. Molecular imaging to determine arrangements in arrays, orientations, and even inner structures of molecules has been achieved in air [18][19][20], under ultrahigh vacuum (UHV) [21][22][23] and in solutions [24][25][26][27]. In situ STM imaging is a powerful tool for the characterization of self-assembled molecular systems at solid-liquid interfaces especially for static nanostructures, dynamic formation mechanisms, and intermolecular interactions.…”

First-principles investigation of the structural and electronic properties of self-assemblies of functional molecules on graphene

“…We use the same methodology as references to build gradually the assembly of melamine [13,18], NTCDI [19] and their complexes in the absence of surface.…”

“…NTCDI molecules assembly in absence of surface was investigated before in our group [18,19]. The corresponding results have allowed designing the most stable arrangements for clusters as well as for supramolecular networks at PBE-D2 level of calculation.…”

“…The association of melamine and NTCDI has been previously investigated because of the resulting porous network which allows to receive a guest molecule inside the pores and to form a complex, for which, one can easily tune the properties through an appropriate selection of invited system [17,18,59]. In the gas phase, the interaction is characterized by the establishment of three hydrogen bonds, corresponding to an interaction energy of À0.944 eV (See Table S3), in agreement with these previous theoretical works [17,18,59].…”

“…In particular, Density Functional Theory (DFT), which has become a common technique for describing electronic systems at the atomic level, fails to describe interactions like hydrogen bonds or molecular adsorption on surface through van der Waals interactions (vdW) [17]. Fortunately, improvements have been made in the recent years to provide a better description of those interactions in the framework of DFT [12,18].…”