One-dimensional Self-assembly Research Articles

Syntheses, crystal structures and magnetic properties of [2 × 1 + 1 × 2] heterotetrametallic and [1 × 1 + 1 × 1] heterodimetallic cocrystals of copper(II) and iron(II/III)

The present work reports syntheses, crystal structures and variable-temperature magnetic properties of three copper(II)–iron(II/III) compounds [{CuIIL1}{FeIIIL1(H2O)2}](ClO4) (1), [{CuIIL1FeII(H2O)3}{CuIIL1}2](ClO4)2 (2) and [{CuIIL2FeII(H2O)3}{CuIIL2}2](ClO4)2·H2O·CH3COCH3 (3), where H2L1=N,N′-ethylenebis(3-ethoxysalicylaldimine) and H2L2=N,N′-o-phenylenebis(3-ethoxysalicylaldimine). Compounds 2 and 3 are tetrametallic [2×1+1×2] cocrystals of one diphenoxo-bridged dinuclear CuIIFeII and two mononuclear CuII moieties, while compound 1 is a dimetallic [1×1+1×1] cocrystal of one mononuclear FeIII and one mononuclear CuII moieties. The overall topology of 1 is one-dimensional. Tetrametallic (in 2 and 3) and one-dimensional (in 1) self-assemblies are generated due to weak noncovalent interactions. Variable-temperature magnetic susceptibility measurements reveal that iron(II) or iron(III) centers in 1–3 remain in high-spin state. Compounds 2 and 3 exhibit weak antiferromagnetic interaction; the J values in the dinuclear core are −22.5 and −13.7cm−1, respectively, compound 1 exhibits very weak antiferromagnetic interaction (J=−0.25cm−1) propagated through the weak noncovalent bonds.

Complete solution of the problem of one-dimensional non-covalent non-cooperative self-assembly in two-component systems

Equations for the mass conservation law and the molecular parameters observed in spectroscopic experiments have been derived for non-covalent, non-cooperative, one-dimensional self-assembly in systems containing two types of interacting molecules (hetero-association), taking into account "reflected" complexes and "edge effects."

One-dimensional self-assembly of mouse embryonic stem cells using an array of hydrogel microstrands

The ability of embryonic stem (ES) cells to self-renew indefinitely and to differentiate into multiple cell lineages holds promise for advances in modeling disease progression, screening drugs and treating diseases. To realize these potentials, it is imperative to study self-assembly in an embryonic microenvironment, as this may increase our understanding of ES cell maintenance and differentiation. In this study, we synthesized an array of one-dimensional alginate gel microstrands and aqueous microstrands through an SU-8 filter device by means of capillary action. Furthermore, we investigated self-assembly behaviors and differentiation potentials of mouse ES cells cultured in microstrands of varying diameters. We found that microstrands with an aqueous interior facilitated high density cell culture and formed compact microtissue structures, while microstrands with gelled interiors promote smaller cell aggregate structures. In particular, we noticed that ES cells collected from one-dimensional aqueous microstrands favored the differentiation towards cell lineages of endoderm and mesoderm, whereas those from gelled microstrands preferred to differentiate into ectoderm and mesoderm lineages. In addition to providing a “liquid-like” tubular microenvironment to understand one-dimensional self-assembly process of ES cells, this alginate hydrogel microstrand system also offers an alternative way to manipulate the stem cell fate-decision using bioengineered microenvironments.

Synthesis of novel gelatin/poly(acrylic acid) nanorods via the self-assembly of nanospheres

In this work, gelatin-poly(acrylic acid) (GEL-PAA) nanospheres with diameter of around 35 nm were prepared using a polymermonomer (gelatin-AA) pair reaction system. These nanospheres can self-assemble into nanorods in aqueous solution at 4 °C. Based on the observation that the intermediate state of the formation of the nanorods and the facts that the self-assembly can only occur at relatively low temperature and the gelatin molecules on the outermost layer of the GEL-PAA nanospheres can be renatured to triple helix conformation, it can be rationally inferred that the hydrogen bonding and electrostatic interactions between the gelatin molecules with the triple helix structure induce the one-dimensional self-assembly of the nanospheres into nanorods.

Construction and application of tunable one-dimensional soft supramolecular assemblies

Self-assembly of small molecules into one-dimensional soft nanostructures offers many advantages in understanding biological process and fabrication of electronically active materials. In recent decades, various one-dimensional soft nanostructures have been fabricated. The present review focuses on the following content: (1) frequently occurring forces in one-dimensional molecular self-assembly; (2) how these forces are used to construct this type of nanostructures; (3) fine-tuning one-dimensional self-assemblies by employing tools such as photo, pH, temperature, additives, and concentration; (4) some examples of the applications of one-dimensional self-assemblies in fabrication of one-dimensional hard materials are described.

Room temperature synthesis and one-dimensional self-assembly of interlaced Ni nanodiscs under magnetic field

Uniform and aligned nickel nanochains with interlaced-nanodiscs structure were first synthesized by using a template-free magnetic-field-assisted method at room temperature. The interlaced-disc nanochains were composed of nanodiscs with diameters of ∼90 nm and thicknesses of ∼10 nm. An attachment process has been proposed to explain the observed growth of the nanodiscs. With concentration of the OH− increased, the morphology of the products transforms from star- to interlaced-nanodisc-like nanochains. Systematic magnetic measurements demonstrate that the well-aligned interlaced-nanodisc-like Ni nanochains have coercivity of about 300 Oe and effective anisotropy of about five times more than the bulk value.

Basic Logical Operations Using Algorithmic Self-Assembly of DNA Molecules

In recent years, DNA self-assembly is beginning to be seen as a practical vehicle for computation. A number of research groups have begun developing nanofabrication methods based on DNA self-assembly. Since the basic logical operations based on DNA molecules could be considered as the fundamental units of DNA computer architecture, how to achieve the basic logical operations based DNA self-assembly is explored in this paper. Original intention on tiling can be applied to the assembly and realization of circuits. These procedures can be realized on the molecular scale through the medium of self-assembled DNA tiles. One layer of self-assembled DNA tiles will be used as self-assembly the program or circuit that leads to the computation of a basic Boolean expression. For this purpose, a modified triple-crossover (TX) tiles which consist of two inputs and one output are used to execute molecular logical operations. The self-assembly of designed periodic one-dimensional arrays are composed of modified triple-crossover (TX) tiles, in which the intermolecular contacts are directed by sticky ends. Here, the paper makes a further to perform a one-dimensional algorithmic self-assembly of DNA triple-crossover molecules that can be used to execute five steps of a logical (cumulative AND and OR) operations on a string of binary bits.

Extended one-dimensional self-assemblies of nanoparticles; nano-rouleaux formations

In this communication, we report the unusually extensive uni-directional self-assembly of nanoparticulate EuF(3) and discuss the origins behind such behaviour.

One-dimensional self-assembly of inorganic nanoparticles

This review is focused on the recent research progresses on one-dimensional (1-D) inorganic nanoparticle (NP) assemblies. First, we introduce some preparation methods of 1-D NP assemblies, which are the base of the investigation to 1-D NP assemblies. In the following part, we discuss the formation mechanism of 1-D NP assemblies, which is very important for us to understand the self-assembly process. We also summarize the novel properties of 1-D NP assemblies. Finally, we outlook the development of 1-D NP assemblies in the near future. We believe that the scientific and technical potentials of NP assemblies are immense, and their future is bright.

Controlled Chainlike Agglomeration of Charged Gold Nanoparticles via a Deliberate Interaction Balance

Chain-like agglomeration (one-dimensional self-assembly) of aqueous gold nanoparticles (NPs) has been experimentally and theoretically studied. It is demonstrated that the chain growth of aqueous gold NPs is mainly triggered by the anisotropic dipolar interaction due to the Au−S bonding originating from the thiol-ligand capping, plus van der Waals interaction. This anisotropic self-assembly can be endorsed by the isotropic electrostatic repulsion between the gold NPs, which can be finely tuned by the dielectric constant of the surrounding media of the NPs that is dependent on the volume ratio of water to a polar organic solvent. Adding more thiol-ligands or NaCl brings a similar effect of increasing the ionic strength of the NP suspensions, thus lowering the electrostatic repulsion between and, at a certain range, accelerating chain-like agglomeration of the NPs. The use of various thiol-ligands with different terminal groups allow involvement of other interactions, including hydrophobic interaction and h...

One-Dimensional Self-Assembly of Planar π-Conjugated Molecules: Adaptable Building Blocks for Organic Nanodevices

In general, fabrication of well-defined organic nanowires or nanobelts with controllable size and morphology is not as advanced as for their inorganic counterparts. Whereas inorganic nanowires are widely exploited in optoelectronic nanodevices, there remains considerable untapped potential in the one-dimensional (1D) organic materials. This Account describes our recent progress and discoveries in the field of 1D self-assembly of planar pi-conjugated molecules and their application in various nanodevices including the optical and electrical sensors. The Account is aimed at providing new insights into how to combine elements of molecular design and engineering with materials fabrication to achieve properties and functions that are desirable for nanoscale optoelectronic applications. The goal of our research program is to advance the knowledge and develop a deeper understanding in the frontier area of 1D organic nanomaterials, for which several basic questions will be addressed: (1) How can one control and optimize the molecular arrangement by modifying the molecular structure? (2) What processing factors affect self-assembly and the final morphology of the fabricated nanomaterials; how can these factors be controlled to achieve the desired 1D nanomaterials, for example, nanowires or nanobelts? (3) How do the optoelectronic properties (e.g., emission, exciton migration, and charge transport) of the assembled materials depend on the molecular arrangement and the intermolecular interactions? (4) How can the inherent optoelectronic properties of the nanomaterials be correlated with applications in sensing, switching, and other types of optoelectronic devices? The results presented demonstrate the feasibility of controlling the morphology and molecular organization of 1D organic nanomaterials. Two types of molecules have been employed to explore the 1D self-assembly and the application in optoelectronic sensing: one is perylene tetracarboxylic diimide (PTCDI, n-type) and the other is arylene ethynylene macrocycle (AEM, p-type). The materials described in this project are uniquely multifunctional, combining the properties of nanoporosity, efficient exciton migration and charge transport, and strong interfacial interaction with the guest (target) molecules. We see this combination as enabling a range of important technological applications that demand tightly coupled interaction between matter, photons, and charge. Such applications may include optical sensing, electrical sensing, and polarized emission. Particularly, the well-defined nanowires fabricated in this study represent unique systems for investigating the dimensional confinement of the optoelectronic properties of organic semiconductors, such as linearly polarized emission, dimensionally confined exciton migration, and optimal pi-electronic coupling (favorable for charge transport). Combination of these properties will make the 1D self-assembly ideal for many orientation-sensitive applications, such as polarized light-emitting diodes and flat panel displays.

A templating approach for monodisperse self-assembled organic nanostructures.

The precise structural control is known for self-assembly into closed spherical structures (e.g., micelles), but similar control of open structures is much more challenging. Inspired by natural tobacco mosaic virus, we present the use of a rigid-rod template to control the size of a one-dimensional self-assembly. We believe that this strategy is novel for organic self-assembly and should provide a general approach to controlling size and dimension.

Synthesis of high purity Au nanobelts via the one-dimensional self-assembly of triangular Au nanoplates

High purity (∼88%) gold nanobelts have been synthesized in the water/polyvinylpyrrolidone (PVP)/n-pentanol system created to realize the selective-adsorption of PVP on Au which directs Au to grow in belt form via the one-dimensional (1D) self-assembly of triangular Au nanoplates. These nanobelts present uniform thickness and lateral dimension, large aspect ratio up to 160, unique 60° angle end structure, and double-peak plasmon resonance property. The PVP directed 1D self-assembly method demonstrated here may provide a general route for the shape-selective synthesis of the other 1D functional nanostructures.

Low-dimensional structures on carbon-terminated W(110): from metallic nanowires to molecular chains

In recent experiments we have discovered the unique ability of the two-dimensional tungsten surface carbideW(110)/C-R(15 × 3) to support self-organization of nanostructures with an extreme variety of physical and chemical properties. The goal of the current publication is to provide a comprehensive review of our recent achievements with this system. Using the technique of scanning tunneling microscopy we have observed one-dimensional self-assembly of noble and transition metals. Experiments with fullerene molecules have shown that C60 deposited on the surface carbide self-organizes into clusters with magic numbers and at higher coverage into chains. Angular-resolved photoelectron spectroscopy has provided comprehensive information about the electronic and chemical states in the self-assembled nanostructures.

One‐dimensional self‐assembly of a rational designed β‐structure peptide

Fabricating various nanostructures based on the self-assembly of diverse biological molecules is now of great interest to the field of bionanotechnology. In this study, we report a de novo designed peptide (T1) with a preferential beta-hairpin forming property that can spontaneously assemble into nanofibrils in ultrapure water. The nanofibrils assembled by T1 could grow up to tens of microns in length with a left-handed helical twist and an average height of 4.9 +/- 0.9 nm. Moreover, protofilaments and nucleus structures both with a similar height of 1.4 +/- 0.2 nm were observed during fibrilization as well as via sonication of the mature nanofibrils. A typical conformational transition from random coil to beta-structure was observed in association with the fibrilization. Molecular modeling of T1 assemblies displayed that the beta-hairpin molecules organize in a parallel fashion in which the beta-strands align in an antiparallel fashion and each adjoining beta-strand runs left-handed twist at about 2.9 degrees with respect to the one located before it along the fibrillar axis. It also revealed that the maximum thickness of the assembly intermediate, the helical tape structure, is about 1.4 nm and four tapes can further assemble into a fibril with a diameter of about 4.1 nm. Taken together the results obtained by AFM, CD, and molecular modeling, T1 fibrilization probably undergoes a hierarchy approach, in which the aromatic stacking and the electrostatic interactions between the assembled structures are most likely the two major factors directing the one-dimensional self-assembly. Based on these studies, we propose T1 can be used as a model peptide to investigate the beta-sheet based self-assembly process and could be a potential bioorganic template to develop functional materials.

On one-dimensional self-assembly of surfactant-coated nanoparticles

Nanometer-sized metal and semiconductor particles possess novel properties. To fully realize their potential, these nanoparticles need to be fabricated into ordered arrays or predesigned structures. A promising nanoparticle fabrication method is coupled surface passivation and self-assembly of surfactant-coated nanoparticles. Due to the empirical procedure and partially satisfactory results, this method still represents a major challenge to date and its refinement can benefit from fundamental understanding. Existing evidences suggest that the self-assembly of surfactant-coated nanoparticles is induced by surfactant-modified interparticle interactions and follows an intrinsic road map such that short one-dimensional (1D) chain arrays of nanoparticles occur first as a stable intermediate before further assembly takes place to form higher dimensional close-packed superlattices. Here we report a study employing fundamental analyses and Brownian dynamics simulations to elucidate the underlying pair interaction potential that drives the nanoparticle self-assembly via 1D arrays. We find that a pair potential which has a longer-ranged repulsion and reflects the effects of surfactant chain interdigitation on the dynamics is effective in producing and stabilizing nanoparticle chain arrays. The resultant potential energy surface is isotropic for dispersed nanoparticles but becomes anisotropic to favor the growth of linear chain arrays when self-assembly starts.

One-Dimensional Self-Assembly of Alkoxy-Capped Silicon Nanoparticles

We demonstrate here a novel method for self-assembling in dimensional alignment the alkoxy-capped silicon nanoparticles synthesized through a room-temperature chemical route. The alkoxy-capped silicon nanoparticles were prepared via a reduction of silicon tetrachloride with sodium-naphthalide and subsequent surface capsulation with 1-octanol monolayers. In the present method, a sublimation process, which was employed as a final purification process for removing the residual naphthalene, influenced significantly on the final morphology of the resultant nanoparticles. Scanning transmission electron microscope (STEM) confirmed the spherical nanoparticles on a holey carbon grid after sublimation process, while only the fibril-like morphology just before sublimation process. In the former sample, the resultant particle size was measured by STEM to be about 9.5 nm +/- 3.4 nm. On the other hand, in the latter sample, the fibril-like structures were shaped by self-assembled silicon nanoparticles in dimensional alignment. The diameters and lengths of the fibril-like assemblies were approximately measured to be 10 to 20 nm and over 5 microm, respectively.

One-dimensional self-assembly of gold nanoparticles for tunable surface plasmon resonanceproperties

The localized surface plasmon resonance (LSPR) is a collective oscillation of thenanoparticle conduction electrons. LSPR excitation in silver and gold nanoparticlesproduces strong extinction and scattering spectra that in recent years have been usedfor important sensing and spectroscopy applications. Tuning the optoelectronicproperties by controlling coupled SP modes in metals is one of the major challenges inthe area of metal nanomaterials. Here we develop a simple method to fabricatelinear-chainlike aggregates of gold nanoparticles (so-called nanochains), tuning the linearoptical properties in a wide wavelength range from visible to the near infrared. Theaggregation behaviour and linear self-assembly mechanism of citrate-stabilizedgold colloids as provoked by the addition of cetyltrimethylammonium bromide(CTAB) are also analysed. The CTAB with appropriate concentration serves as the‘glue’ that can link the {100} facets of two neighbour Au NPs, which leads to ananisotropic distribution of the residual surface charge, and this extrinsic electric dipoleformation is responsible for the linear organization of the gold NPs into short chains.

One-Dimensional Chiral Self-Assembly of Pyrene Derivatives Based on Dendritic Oligopeptides

Supramolecular chiral columnar liquid crystals have been formed through one-dimensional self-assembly of pyrene-containing oligopeptides. Supramolecular chirality is further tuned by cooperation of intermolecular hydrogen bonding and electron donor-acceptor interactions. [reaction: see text]

One-dimensional assemblies of platinum nanoparticles on a graphite surface using nonionic/ionized mixed hemicylindrical micelle templates

One-dimensional (1-D) self-assemblies of Pt nanoparticles on a graphite surface have been synthesized via a template-directed sintering process of individual nanoparticles, using nonionic/cationic mixed hemicylindrical micelle templates of dodecyldimethylamine oxide surfactant at graphite/solution interfaces. The dimension and morphology of Pt nanoparticles can be widely controlled by the concentration of Pt ions equivalent to the mixing ratio of nonionic and cationic species in the surfactant micelle. This approach could be extended to fabricate a wide range of self-assembling metallic nanostructures on surfaces using various nonionic/cationic mixed micelle-like self-assemblies carrying metal ions at interfaces, while providing a fundamental insight into a 1-D self-assembly from individual nanoparticles.