Two-dimensional self-assembly of single-, poly- and co-crystals at the liquid/solid interface

Liu, Pei; Miao, Xinrui; Li, Zhuomin; Zha, Bao; Deng, Wenli

doi:10.1039/c4ce01183j

Cited by 10 publications

(8 citation statements)

References 36 publications

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“…In recent years, chirality in the field of 2D surface‐confined self‐assembly has been intensively explored with the aid of scanning tunneling microscopy (STM) . π‐Conjugated systems with substituted alkyl chains are common to be used for the purpose of exploring the mechanism of self‐assembly, on account of their capability of forming noncovalent forces, such as dipole–dipole interaction, electrostatic interaction, van der Waals interaction, hydrogen bonds, and π–π stacking . Through physical adsorption, achiral molecules can self‐assemble into chiral configurations on the achiral substrate due to the reduced freedom and constraint of the substrate lattice.…”

Section: Introductionmentioning

confidence: 99%

Exploration of Chirality and Achirality of Self‐Assembled Monolayer Formed by Unsymmetrically Substituted Fluorenone Derivative at the Liquid/Solid Interface

Miao

Dong

et al. 2017

Adv Materials Inter

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noncovalent forces, such as dipole-dipole interaction, [3] electrostatic interaction, [4] van der Waals interaction, [5] hydrogen bonds, [6] and π-π stacking. [7] Through physical adsorption, achiral molecules can self-assemble into chiral configurations on the achiral substrate due to the reduced freedom and constraint of the substrate lattice. [2d,8] Because of the rotation characteristics, porous networks show great potential in the process of chiral recognition and have received wide attentions. [9] However, nonporous networks also possess possibility of forming chiral polymorphs as long as the molecules are properly designed. Thus obtaining chirality via tiny structure modification will be a new attempt on fabricating chiral structures and will provide a new method on designing advanced functional materials in the field of surface science.Fluorenone derivatives have been reported to be used as liquid crystals. [10] Moreover, they were also good candidates for studying the self-assemblies at the liquid/highly oriented pyrolytic graphite (HOPG) interface, which have been widely explored in our group. We have previously reported that structural diversity was common to be observed and could be induced via changing the length of the alkyl chain, the concentration, and the solvent. For the bis-substituted fluorenone derivatives, molecules were arranged into a variety of nanopatterns which were regularly ordered but not chiral. [3,11] For the monosubstituted fluorenone derivatives, molecules adopted both chiral and achiral configurations and structural transition could be regulated between them. [12] Therefore, fabrication of chiral nanostructures using unsymmetrically substituted fluorenone derivatives seems to be a challenging but meaningful target. Fortunately, we realized this goal by efficient modification of the side chains.When the π-conjugated fluorenone core was substituted at the equal positions but substituted by unequal alkyl chains, chiral nanostructures were observed in its self-assembled monolayer on HOPG. The molecule we use in this study is 2-decyloxy-7-pentadecyloxy-9-fluorenone (DPF), as shown in Figure 1a. The first typical feature induced by the two different alkyl chains (C 10 H 21 and C 15 H 31 ) is that the long chains and the short chains are orderly interdigitated. As a result of this interdigitation, DPF molecules are usually notThe self-assemblies of 2-decyloxy-7-pentadecyloxy-9-fluorenone (DPF) are characterized by scanning tunneling microscopy at the liquid/solid interface. Achiral Dimer and chiral S-like structures are observed in 1-octanoic acid. The solvent molecule takes part in the self-assembly via forming COOH⋯OC and COOH⋯COOH hydrogen bonds. When 1-phenyloctane and n-tetradecane are used as the solvents, DPF self-assembles into chiral Z-like structure, which are classified into Types I-IV according to the packing styles. For the purpose of exploring the effect of solvent and the competition between these three structures, the self-assemblies of DPF in mixed solvents and ...

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Section: Introductionmentioning

confidence: 99%

Exploration of Chirality and Achirality of Self‐Assembled Monolayer Formed by Unsymmetrically Substituted Fluorenone Derivative at the Liquid/Solid Interface

Miao

Dong

et al. 2017

Adv Materials Inter

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“…Among the different dimensionalities and environments for assembly, 2D monolayer at the liquid/solid interface plays a special role . As has been widely reported, 2D self‐assembly is the result of balance between various forces, such as van der Waals, hydrogen bonding, π–π stacking, metal coordination, halogen bonds, and electrostatic interactions . Apart from these driving forces, the external conditions, for example, the solvent,[3d,10] concentration, voltage, and temperature, are considered as powerful methods to regulate the assembled patterns.…”

Section: Introductionmentioning

confidence: 99%

STM Exploration of the Diverse Polymorphs for Tri‐Substituted Anthraquinone Derivatives via Alkyl Chain Elongation

Miao

Zha

et al. 2016

Adv Materials Inter

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solvent, [ 3d,10 ] concentration, [ 5,11 ] voltage, [ 12 ] and temperature, [ 13 ] are considered as powerful methods to regulate the assembled patterns. Moreover, it is well known that in some circumstance, even tiny change of the structural units in a molecule can result in dramatic change of the nanopatterns. Hence for the alkyl chain substituted system, it is easy to change the networks by increasing or decreasing the chain length.The emergence of chain-length effect is often associated with the van der Waals interactions between the interdigitated alkyl chains and the molecule-substrate. The self-assembly of dehydrobenzo[12]annulene derivatives has been widely probed by De Feyter et al., [ 3e,14 ] and received extensive attention. By tuning the chain length, different nanostructures, i.e., honeycomb, linear, Kagomé, zigzag, polymer, etc., were obtained, and alkyl chain interdigitation was proved to act a vital function on stabilizing the networks. Furthermore, self-assembly is associated with the gain in system energy contributed from both enthalpy and entropy difference between the initial and fi nal states. [ 13b,15 ] Therefore, the appearance of structural diversity to the system as the chain length changes has direct relation with the change of Gibbs free energy. Miyake et al. systematically reported the 2D supramolecular structures of a series of N , N ′-bis( n -alkyl)-naphthalenediimides (NDIs) that the chain length spans from C 3 to C 18 . [ 16 ] They found that C 3 -and C 4 -NDIs adopted lamellar structures, C 4 -to C 12 -NDIs showed honeycomb structure, and the lamellar patterns were observed again when the chain is longer than C 12 . The drastic structural change was explained by the balance of entropy and enthalpy terms. On the whole, the self-assembly process is under both kinetic and thermodynamic control. Even though the relationship between the molecular confi gurations and the alkyl chain length has gained attention from lots of research groups and been extensively explored, it still needs further study from the viewpoint of its structural diversity, the formation mechanism, and effi cient regulation.In this contribution, we systematically investigate the formation of nanostructures of 1,2,4-tri( n -alkoxy)-9,10-anthracenedione (1,2,4-A-3OC n , Scheme 1 , synthesis is shown in Supporting Information as Figures S1 and S2) on the highly Fabrication of structural diversity in self-assembled monolayers has gained considerable attention, not only due to its signifi cance in interface science but also because of its potential application in designing nanomaterials. Here, systematical characterization of the molecular self-assembly of tri-substituted anthraquinone derivatives at the 1-octanoic acid/HOPG interface is provided. Different nanopatterns of Linear I, Butterfl y-like, and Linear II are recorded for 1,2,4-A-3OC 16 by gradually changing the solution concentration. Diverse polymorphs are also obtained by alkyl chain elongation, meaning that 1,2,4-A-3OC 15,17,18 adopt Dimer-Linear, Linear...

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“…Can the transition point be pushed to higher and lower chain lengths by changing the chain length of the solvent? While solvent dependence on physisorbed SAM morphology has been previously explored, ,− the ability to achieve solvent-independent SAM morphologies by altering the chain length of a moiety on an integral SAM component is an interesting discovery.…”

Section: Resultsmentioning

confidence: 99%

“…Two-dimensional self-organized systems have been assumed to be good models for 3D crystallization as the confinement of molecules close to interfaces allows for the experimental study of intermolecular forces . Extensive reviews on 2D self-assembly are available, covering a range of topics including solvent effects, electronic properties, chirality/odd–even effects, surface-confined supramolecular coordination chemistry, substrate effects, molecular templating, and control of structure .…”

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confidence: 99%

Two-Dimensional versus Three-Dimensional Self-Assembly of a Series of 5-Alkoxyisophthalic Acids

et al. 2018

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Physisorbed self-assembled monolayers (SAMs) have been suggested as potential models for three-dimensional (3D) crystallization. This work studies the effect of altering the chain length of 5-alkoxyisophthalic acid (C ISA) on self-assembled morphology in both two-dimensional (2D) and 3D to explore the extent comparisons can be drawn between dimensions. Previous studies of 5-alkoxyisophthalic acid at solid-liquid interfaces (2D) reported different morphologies for CISA and CISA-alkoxy chains on the one hand and CISA and CISA on the other. Independently, also in 3D a dependence of morphology on chain length has been reported, including an unexpected inclusion of a solvent in the 3D morphology of CISA, while the previous reports of 2D self-assembly were driven only by molecule-molecule and molecule-substrate interactions. However, a complete set of data for comparison has been missing. Here, we report scanning tunneling microscopy (STM) and molecular dynamics simulations performed for CISA self-assembled monolayers (SAMs) and STM imaging of CISA-CISA SAMs, to further examine self-assembly behavior in 2D. In 3D, X-ray diffraction analysis of CISA single crystals was carried out to complete the data set. With a complete set of data, it was observed that regardless of the dimension, short-chain-length C ISAs formed H-bonding-dominated structures, mid-chain-length CISAs exhibited solvent-dependent morphologies, and long-chain-length C ISAs displayed van der Waals-dominated solvent-independent structures. However, the transition point among morphologies occurred at different chain lengths in 2D and 3D regardless of the dominant interaction. The results of this study inform the design of 2D films and guide the application of knowledge from physisorbed SAMs to 3D systems, including mixed-dimensional (2D/3D) van der Waals heterostructures.

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Two-dimensional self-assembly of single-, poly- and co-crystals at the liquid/solid interface

Abstract: The observation of two polymorphs indicates that C2 cannot form single crystals because of an increase in molecular flexibility.

Cited by 10 publications

References 36 publications

Exploration of Chirality and Achirality of Self‐Assembled Monolayer Formed by Unsymmetrically Substituted Fluorenone Derivative at the Liquid/Solid Interface

Exploration of Chirality and Achirality of Self‐Assembled Monolayer Formed by Unsymmetrically Substituted Fluorenone Derivative at the Liquid/Solid Interface

STM Exploration of the Diverse Polymorphs for Tri‐Substituted Anthraquinone Derivatives via Alkyl Chain Elongation

Two-Dimensional versus Three-Dimensional Self-Assembly of a Series of 5-Alkoxyisophthalic Acids

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