Avoiding the Center‐Symmetry Trap: Programmed Assembly of Dipolar Precursors into Porous, Crystalline Molecular Thin Films

Nefedov, Alexei; Haldar, Ritesh; Zhao, Xu; Kühner, Hannes; Hofmann, Dennis; Goll, David; Sapotta, Benedikt; Hecht, Stefan; Krstić, Marjan; Rockstuhl, Carsten; Wenzel, Wolfgang; Bräse, Stefan; Tegeder, Petra; Zojer, Egbert; Wöll, Christof

doi:10.1002/adma.202103287

Cited by 18 publications

(38 citation statements)

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“…This approach towards directional packing of coordination networks at the solid/liquid interface on graphite surfaces has also been realized [17] . In our preliminary research, as proof‐of‐concept, the useful utility of model dipolar asymmetric‐bipyridines precursors, namely, 2,6‐dimethyl‐4,4′‐bipyridine was demonstrated to form porous crystalline thin films using programmed layer‐by‐layer (lbl) assembly [18] . The lbl technique allowed for the quasi‐epitaxial stacking of asymmetric dipolar 4,4′‐bipyridine tectons to yield porous, crystalline molecular materials that lack inversion symmetry and contain a built‐in electric field.…”

Section: Resultsmentioning

confidence: 89%

“…IR (ATR, cm À 1 ) ṽ = 3048 (vw), 2978 (m), 2928 (w), 1632 (w), 1548 (w), 1519 (w), 1473 (w), 1452 (w), 1390 (vs), 1371 (vs), 1358 (vs), 1322 (vs), 1249 (s), 1213 (m), 1163 (m), 1142 (vs), 1116 (vs), 1007 (w), 983 (w), 963 (m), 891 (m), 871 (w), 849 (vs), 734 (m), 694 (w), 674 (vs), 578 (w), 562 (w), 523 (w), 449 (w), 414 (w). MS (EI, 70 eV) m/z (%) = 234 (10), 233 (70) [M( 11 B) + H] + , 232 (18) [M( 11 B)] + , 231 (8) [M( 10 B)] + , 218 (33), 217 (8), 181 (41), 176 (8), 148 (13), 147 (100), 134 (33), 133 (37), 132 (11), 131 (43), 129 (13), 119 (8), 100 (9), 69 (78), 59 (14), 58 (13). HRMS (EI, [M] + , C 13 H 20 O 2 N 11 B) calcd.…”

Section: Additional Information On the Chemical Synthesis Is Availabl...mentioning

confidence: 99%

“…IR (ATR, cm À 1 ) ṽ = 3081, 3023, 3000, 2987, 1472, 1445, 1242 (υ-NÀ O), 1187, 1113, 1040, 864 (υ-NÀ O), 827, 667, 517, 482. MS (EI, 70 eV) m/z (%) = 131 (35) [M with 37 Cl] + , 129 (100) [M with 35 Cl] + , 102 (10), 76 (10), 73 (23), 63 (18), 62 (11). HRMS (EI, [M] + , C 5 H 4 ClNO) calcd.…”

Section: Additional Information On the Chemical Synthesis Is Availabl...mentioning

confidence: 99%

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Synthesis of Non‐centrosymmetric Dipolar 4,4′‐Bipyridines: Potential Molecular Tectons for Programmed Assembly of Supramolecular Systems

et al. 2023

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In this report, we describe a modular synthesis approach towards a new series of non‐centrosymmetric, dipolar 4,4′‐bipyridines bearing 2,6‐ and 3,5‐functionalized pyridyl moieties at the peripheries. Central to our strategy is the selective substitution on only one pyridyl motif that could contain electron‐donating (−CH3) or electron‐withdrawing (−F, −Cl, −CF3) groups which causes electronic/steric effects on one nitrogen atom in 4,4′‐bipyridines. This synthetic protocol was further applied to prepare azo‐functionalized (−N=N−) asymmetric bipyridines and non‐centrosymmetric 4,4′‐bipyridine N‐oxide scaffolds, which overcome the synthetic hurdles oxidizing 4,4′‐bipyridines to N‐monoxides selectively at only one pyridine. Compared to the conventional symmetrical bipyridines, the dipolar non‐centrosymmetric molecular tectons pave the way for the realization of non‐centrosymmetric supramolecular assemblies because of the difference in the binding energy of the pyridyl nitrogen atoms.

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Section: Resultsmentioning

confidence: 89%

Section: Additional Information On the Chemical Synthesis Is Availabl...mentioning

confidence: 99%

Section: Additional Information On the Chemical Synthesis Is Availabl...mentioning

confidence: 99%

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Synthesis of Non‐centrosymmetric Dipolar 4,4′‐Bipyridines: Potential Molecular Tectons for Programmed Assembly of Supramolecular Systems

et al. 2023

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“… 50 The key challenge for the experimental realization of such systems is that one must realize an asymmetric bonding of the linkers in order to align their dipoles (see discussion in ref ( 50 ) for details). The first successful steps in this direction have recently been made for 1,4-biphenyldicarboxylate-linked Cu-paddlewheel sheets connected by polar apical linkers, 52 but in these experiments the realized degree of dipole alignment was still rather low.…”

Section: Perspectives: Distributed Dipole Sams and Polar Linkers In C...mentioning

confidence: 99%

Concept of Embedded Dipoles as a Versatile Tool for Surface Engineering

2022

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Conspectus Controlling the physical and chemical properties of surfaces and interfaces is of fundamental relevance in various areas of physical chemistry and a key issue of modern nanotechnology. A highly promising strategy for achieving that control is the use of self-assembled monolayers (SAMs), which are ordered arrays of rodlike molecules bound to the substrate by a suitable anchoring group and carrying a functional tail group at the other end of the molecular backbone. Besides various other applications, SAMs are frequently used in organic electronics for the electrostatic engineering of interfaces by controlling the interfacial level alignment. This is usually achieved by introducing a dipolar tail group at the SAM–semiconductor interface. Such an approach, however, also changes the chemical character of that interface, for example, affecting the growth of subsequent layers. A strategy for avoiding this complication is to embed polar groups into the backbones of the SAM-forming molecules. This allows disentangling electronic interface engineering and the nucleation of further layers, such that both can be optimized independently. This novel concept was successfully demonstrated for both aliphatic and aromatic SAMs on different application-relevant substrates, such as gold, silver, and indium tin oxide. Embedding, for example, ester and pyrimidine groups in different orientations into the backbones of the SAM-forming molecules results in significant work-function changes. These can then be fine-tuned over a wide energy range by growing mixed monolayers consisting of molecules with oppositely oriented polar groups. In such systems, the variation of the work function is accompanied by pronounced shifts of the peaks in X-ray photoelectron spectra, which demonstrates that electrostatically triggered core-level shifts can be as important as the well-established chemical shifts. This illustrates the potential of X-ray photoelectron spectroscopy (XPS) as a tool for probing the local electrostatic energy within monolayers and, in systems like the ones studied here, makes XPS a powerful tool for studying the composition and morphology of binary SAMs. All these experimental observations can be rationalized through simulations, which show that the assemblies of embedded dipolar groups introduce a potential discontinuity within the monolayer, shifting the energy levels above and below the dipoles relative to each other. In molecular and monolayer electronics, embedded-dipole SAMs can be used to control transition voltages and current rectification. In devices based on organic and 2D semiconductors, such as MoS 2 , they can reduce contact resistances by several orders of magnitude without adversely affecting film growth even on flexible substrates. By varying the orientation of the embedded dipolar moieties, it is also possible to build p- and n-type organic transistors using the same electrode materials (Au). The extensions of the embedded-dipole concept from hybrid interfaces ...

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“…Predictive methods for MOF construction, design, and selection of the most prominent candidates with a desired functionality will significantly accelerate the discovery of new formulations and reduce costs (Mancuso et al, 2020). There are several free and commercial tools or molecular editors for the initial construction of a representative MOF model, e.g., Avogadro (Nefedov et al, 2021) and Materials Studio (Dassault Systèmes, 2020). Often, they require timeconsuming manual work and prior knowledge of the topological details and metal-organic interactions in MOF.…”

Section: Introductionmentioning

confidence: 99%

Automated Virtual Design of Organic Semiconductors Based on Metal-Organic Frameworks

et al. 2022

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The arrangement of organic semiconductor molecules in a material can be modulated using different supramolecular approaches, including the metal–organic framework (MOF) approach. These arrangements result in different frameworks topologies and structures. Fabrication of materials comprising optimized assemblies and functional molecules enables efficient tailoring of material properties, including electronic responses. Since semiconducting properties are sensitive to subtle changes in the nanostructure of the material, the exploitation of MOFs has promising potential in the development of new materials with designed structure and function. Based on decade-long method development, virtual design strategies have become ever more important, and such design methods profit from the availability of automated tools. Such tools enable screening of huge libraries of organic molecules in in silico models of the structure of three-dimensional nanoscale assemblies as the prerequisite to predict their functionality. In this report, we present and demonstrate the application of an automated workflow tool developed for MOFs of the primitive cubic (PCU) topology. We use pentacene-based ditopic linkers of a varied chemical composition and pillar linkers of different molecular sizes to automatically generate PCU MOFs, sample their structural dynamics at finite temperature, and predict electronic coupling matrix elements in vibrationally averaged assemblies. We demonstrate the change of the intermolecular ordering in the resulting MOFs and its impact on the semiconducting properties. This development lays the basis of an extendable framework to automatically model a wide variety of MOFs and characterize their function with respect to properties, such as conduction properties, absorption, and interaction with light. The developed workflow protocol and tools are available at https://github.com/KIT-Workflows/PCU-MOF.

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Avoiding the Center‐Symmetry Trap: Programmed Assembly of Dipolar Precursors into Porous, Crystalline Molecular Thin Films

Cited by 18 publications

References 52 publications

Synthesis of Non‐centrosymmetric Dipolar 4,4′‐Bipyridines: Potential Molecular Tectons for Programmed Assembly of Supramolecular Systems

Synthesis of Non‐centrosymmetric Dipolar 4,4′‐Bipyridines: Potential Molecular Tectons for Programmed Assembly of Supramolecular Systems

Concept of Embedded Dipoles as a Versatile Tool for Surface Engineering

Automated Virtual Design of Organic Semiconductors Based on Metal-Organic Frameworks

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