Mn–Cu Transmetalation as a Strategy for the Assembly of Decoupled Metal–Organic Networks on Sn/Cu(001) Surface Alloys

Abstract

Surface alloying of Cu(001) by Sn deposition is a finely controllable method of tuning the degree of copper reactivity in order to drive the on-surface assembly and synthesis of metal−organic coordination networks. In this work we show that the R (3 2 2) 45 × °reconstruction of the Sn/Cu(001) surface alloy acts as a weakly interacting substrate ideal for the assembly of rectangular metal−organic networks based on transition metals. As a demonstration, we have grown a twodimensional coordination network formed by manganese and TCNQ (7,7,8,8tetracyanoquinodimethane) with 1:1 stoichiometry. In contrast with the same structure grown on Au(111), the use of the Sn/Cu(001) substrate enables a commensurate structure with larger and more regular ordered domains. We show that the formation of a Cu−TCNQ coordination network and subsequent Mn−Cu transmetalation reactions are the key steps of the growth mechanism. Moreover, ab initio density-functional calculations indicate that the system studied in the present work is a unique example of a metal−organic coordination network weakly interacting with the substrate.

How the Support Defines Properties of 2D Metal–Organic Frameworks: Fe-TCNQ on Graphene versus Au(111)

“…Thus, based on the STM/DFT data, we conclude that the Fe-TCNQ is nonplanar when supported on graphene and that the nonplanarity is most likely driven by the preference of the Fe center to reside in a tetrahedral environment. We note that twisted-TCNQ models were previously proposed for some metal-TCNQ systems, , but the tilted-TCNQ structure was not reported.…”

Stabilization of high-spin Mn ions in tetra-pyrrolic configuration on copper

“…• reconstruction of the Sn/Cu(100) interface (from hereafter the 3 ̅̅̅ 2 √ ), consisting of 0.5 ML of Sn atoms embedded in the top surface layer of the Cu(100) crystal, is a robust substrate for self-assembled supramolecular structures. We have recently reported the molecular self-organization of Mn and TCNQ into a rectangular MOCN onto the 3 ̅̅̅ 2 √ , whose geometry is very similar to that observed on Au(111), but with the additional advantage of displaying long range order [27]. This organo-metallic compound, with a 1 : 1 stoichiometry ratio, displays Mn atoms in a quasi-planar tetra coordination to nitrile ligands, closely resembling that of Mn-phthalocyanine/ porphyrin.…”

Remarkably stable metal–organic frameworks on an inert substrate: M-TCNQ on graphene (M = Ni, Fe, Mn)

“…18,24,31 In some computational studies of free-standing M-TCNQ 2D MOFs, the parallel arrangement is slightly preferred, 31 but on metal-supported 2D MOFs formed by the same components the alternating structures are common. 9,11,18,19,36 One reason for this difference is the fact that TCNQ can form a strong chemical bond with the metal substrate, 22,40,41 and thus the metal substrate actively participates in the MOF formation and may significantly affect the MOF properties. 11,21 Similar effects are not expected on a graphene substrate, where strong chemical interaction with TCNQ does not take place.…”

“…Here, we present three well-defined and remarkably stable 2D MOFs supported on an inert graphene/Ir(111) substrate. As the organic linker we utilize a TCNQ molecule (7,7,8,8-tetracyanoquinodimethane), which is a strong electron acceptor and a popular choice for MOF synthesis both on-surface 7,9,[18][19][20][21][22] and in solution. 23,24 TCNQ-based 2D MOFs are also intensively studied computationally, [25][26][27][28][29][30][31] but the simulated free-standing systems are not directly comparable to metal-supported nor solution-based MOFs.…”