Formation of Highly Ordered Molecular Porous 2D Networks from Cyano‐Functionalized Porphyrins on Cu(111)

Abstract

We investigated the adsorption of three related cyano-functionalizedt etraphenyl porphyrin derivativeso n Cu(111)b ys canningt unneling microscopy (STM) in ultrahigh vacuum (UHV) with the goalt oi dentify the role of the cyano group and the central Cu atom for the intermolecular and supramolecular arrangement. The porphyrin derivatives studied were Cu-TCNPP,C u-cisDCNPP,a nd 2H-cisDCNPP,t hat is, Cu-5,10,15,20-tetrakis-(p-cyano)-phenylporphyrin, Cumeso-cis-di(p-cyano)-phenylporphyrin and 2H-meso-cis-di(pcyano)-phenylporphyrin, respectively.S tartingf rom different structures obtained after deposition at room temperature, all three molecules form the same long-range ordered hexagonal honeycomb-type structure with triangular pores and three molecules per unit cell. For the metal-free 2H-cisDCNPP,t his occurs only after self-metalation upon heating. The structure-forming elements are pores with ad istance of 3.1 nm, formed by triangles of porphyrins fused together by cyano-Cu-cyano interactions with Cu adatoms. This finding leads us to suggest that two cyano-phenyl groups in the "cis"p ositioni st he minimum prerequisite to form ah ighly ordered 2D porous molecular pattern.T he experimental findings are supported by detailed density functional theory calculations to analyze the driving forces that lead to the formation of the porous hexagonal honeycombtype structure.

Adsorption, self-assembly and self-metalation of tetra-cyanophenyl porphyrins on semiconducting CoO(100) films

“…On the surface, this symmetry manifests itself by a dark "central line" in the molecular STM images. The appearance of the molecule is very similar to that observed on metal surfaces, where it is attributed to a saddle-shape conformation [47][48][49][50]. Hence the difference between assembly patterns A and B are simply different neighboring tautomers of 2H-TCNPP.…”

Addressing Environmental Challenges of Porphyrin Mixtures Obtained from Statistical Syntheses

“…With the successful application of our method for P1 mixtures, we wanted to explore the scope of our semi‐automated cascade; the impact on the environmental factor, as well as accompanying costs. For this purpose, we enlarged our library (Figure 6), by the synthesis of five more porphyrin mixtures ( P2 – P6 ), which comprise of commonly utilized unsymmetrical porphyrins [2,13–15,19,37–47] . The overall yields are summarized in Table 2, together with an overview on the purification parameters, obtained for all porphyrin mixtures.…”

“…For this purpose, we enlarged our library ( Figure 6), by the synthesis of five more porphyrin mixtures (P2-P6), which comprise of commonly utilized unsymmetrical porphyrins. [2,[13][14][15]19,[37][38][39][40][41][42][43][44][45][46][47] The overall yields are summarized in Table 2, together with an overview on the purification parameters, obtained for all porphyrin mixtures. Spectroscopic data of all isolated porphyrins are listed in the Supporting Information.…”

“…However, porphyrins deviating from A 4 skeleton-symmetry are often more interesting, because they offer peculiar optoelectronic properties. [12] Due to their structural features, they are interesting candidates in the construction of two-dimensional structures formed on active metal, or metal oxide surfaces, [13][14][15] or show potential as building blocks in three-dimensional framework architectures (MOFs and COFs). [16][17][18] Further, they can be utilized for the functionalization of nanomaterials, such as graphene, or other carbon nanoarchitectures.…”

Self-Assembled 2D-Coordination Kagome, Quadratic, and Close-Packed Hexagonal Lattices Formed from a Cyano-Functionalized Benzoporphyrin on Cu(111)

“…Porphyrins are omnipresent in nature. , They consist of a tetrapyrrolic macrocycle with a central cavity, which can coordinate two hydrogen atoms or a large variety of metal atoms. − Porphyrins have been shown to be versatile and stable building blocks for the construction of metal–organic coordination networks exhibiting different geometries, since their backbone can be tailored with specific functional end groups. Lately, the attachment of cyano-functionalized groups to porphyrins turned out to be particularly interesting because the partially negatively charged N atoms can interact through different bonding motifs with neighboring molecules. − In addition, benzoporphyrins have a variety of potential practical applications, such as organic near-infrared devices, − oxygen sensors, photodynamic therapy, organic thin-film transistors, − and dye-sensitized solar cells. , Despite this relevance, only very few investigations of their adsorption behavior on different metal surfaces have been reported to date. − …”