Supramolecular Nanotubes Research Articles

Retraction of “Supramolecular Nanotubes Functioning as Morphology Regulators for Fluid-State Molecular Assemblies”

Retraction of “Supramolecular Nanotubes Functioning as Morphology Regulators for Fluid-State Molecular Assemblies”

RETRACTION: Supramolecular Nanotube Reactors for Production of Imine Polymers with Controlled Conformation, Size, and Chirality.

N. Kameta, W. Ding, "Supramolecular Nanotube Reactors for Production of Imine Polymers with Controlled Conformation, Size, and Chirality," Small 15, no. 19 (2019): 1900682, https://doi.org/10.1002/smll.201900682. The above article, published online on 28 March 2019 in Wiley Online Library (wileyonlinelibrary.com), has been retracted by agreement between the authors, Naohiro Kameta and Wuxiao Ding; the journal Editor-in-Chief, Neville Compton; and Wiley-VCH GmbH, Weinheim. The retraction has been agreed upon following an investigation into concerns raised by National Institute of Advanced Industrial Science and Technology (AIST), and also requested by all authors due to image falsification in electron microscopy images. The SEM and TEM images of Figure 6a, 6b-1, 6b-2, 6c-1 upper left, 6c-1 upper right, 6c-1 lower, 6c-2, 6d, 6e, and 6f, where the first author falsificated incorrect scale bars; all affecting the interpretation of the data and research results presented.

A Lanthanide-Based Supramolecular Nanotube and Its Photochemistry

Lanthanide complex including Europium ion (Eu3+) is one of the fascinating photoluminescent compound. However, most of lanthanide complexes are used as a mononuclear-based material without void space. Here, we developed lanthanide-based assemblies including a supramolecular nanotube. Their photophysical properties related to dynamic exciton was investigated.

Correction to “Selective Construction of Supramolecular Nanotube Hosts with Cationic Inner Surfaces”

Correction to “Selective Construction of Supramolecular Nanotube Hosts with Cationic Inner Surfaces”

Porous Organic Nanotubes: Chemistry of One-Dimensional Space.

ConspectusOne-dimensional organic nanotubes feature unique properties, such as confined chemical environments and transport channels, which are highly desirable for many applications. Advances in synthetic methods have enabled the creation of different types of organic nanotubes, including supramolecular, hydrogen-bonded, and carbon nanotube analogues. However, challenges associated with chemical and mechanical stability along with difficulties in controlling aspect ratios remain a significant bottleneck. The fascination with structured porous materials has paved the way for the emergence of reticular solids such as metal-organic frameworks (MOFs), covalent organic frameworks (COFs), and organic cages. Reticular materials with tubular morphology promise architectural stability with the additional benefit of permeant porosity. Despite this, the current synthetic approaches to these reticular nanotubes focus more on structural design resulting in less reliable morphological uniformity. This Account, highlights the design motivation behind various classes of organic nanotubes, emphasizing their porous interior space. We explore the strategic assembly of organic nanotubes based on their bonding characteristics, from weak supramolecular to robust covalent interactions. Special attention is given to reticular nanotubes, which have gained prominence over the past two decades due to their distinctive micro and mesoporous structures. We examine the synergy of covalent and noncovalent interactions in constructing assembly of these nanotube structures.This Account furnishes a comprehensive overview of our efforts and advancements in developing porous covalent organic nanotubes (CONTs). We describe a general synthetic approach for creating robust imine-linked nanotubes based on the reticular chemistry principles. The use of spatially oriented tetratopic triptycene-based amine and linear ditopic aldehyde building blocks facilitates one-dimensional nanotube growth. The interplay between directional covalent bonds and solvophobic interactions is crucial for forming uniform, well-defined, and high aspect ratio nanotubes. The nanotubes derive their permeant porosity and thermal and chemical stability from their covalent architecture. We also highlight the adaptability of our synthetic methodology to guide the transformation of one-dimensional nanotubes to toroidal superstructures and two-dimensional thin fabrics. Such morphological transformation can be directed by tuning the reaction time or incorporating additional intermolecular interactions to control the intertwining behavior of individual nanotubes. The cohesion of covalent and noncovalent interactions in the tubular nanostructures manifests superior viscoelastic mechanical properties in the assembled CONT fabrics. We establish a strong correlation between structural framework design and nanostructures by translating reticular synthesis to morphological space and gaining insights into the assembly processes. We anticipate that the present Account will lay the foundation for exploring new designs and chemistry of organic nanotubes for many application platforms.

Retraction of: Direct Joining of a Heterogeneous Pair of Supramolecular Nanotubes and Reaction Control of a Guest Compound by Transportation in the Nanochannels

Retraction of: Direct Joining of a Heterogeneous Pair of Supramolecular Nanotubes and Reaction Control of a Guest Compound by Transportation in the Nanochannels

Leveraging Halogen Interactions for a Supramolecular Nanotube.

We demonstrate the formation of supramolecular nanotubes from molecular triangles in a single crystal by balancing the hydrogen bonds and halogen interactions between individual macrocycles. Thereby, we template the supramolecular nanotube growth by intermolecular interactions encoded directly in the macrocycles instead of those provided by the crystallization solvent. Ultimately, we show that replacing bromines for iodines in the macrocycle is necessary to achieve this supramolecular organization by enhancing the strength of the halogen interactions and concomitant reduction of the detrimental hydrogen bonds. We investigated the nature and the interplay of the individual intermolecular interactions by analysis of the experimental single crystal data and quantum chemical calculations. This work enriches the available toolbox of supramolecular interactions and will aid and abet the development of rationally-designed materials with a long-range 1D tubular organization.

Beyond Natural Channel Proteins: Recent Advances in Fluorinated Nanochannels.

Inspired by the structures and functions of natural channel proteins that selectively permeate ions and molecules across biological membranes, synthetic molecules capable of self-assembling into supramolecular nanotubes within the hydrophobic layer of the membranes have been designed and their material permeation properties have been studied. More recently, synthetic chemists have ventured to incorporate fluorine atoms, elements rarely found in natural proteins, into the structure of synthetic channels and discovered anomalous transmembrane material permeation properties. In this Perspective, the author provides a brief overview of recent advances in the development of fluorinated nanochannels and possible directions for the future.

Retraction: A supramolecular nanotube used as a water-degradable template for the production of protein nanotubes with high thermal/chemical stabilities

Retraction of ‘A supramolecular nanotube used as a water-degradable template for the production of protein nanotubes with high thermal/chemical stabilities’ by Naohiro Kameta and Wuxiao Ding, Mater. Chem. Front., 2022, 6, 3174–3178, https://doi.org/10.1039/D2QM00661H.

Retraction: Photo-responsive hole formation in the monolayer membrane wall of a supramolecular nanotube for quick recovery of encapsulated protein.

[This retracts the article DOI: 10.1039/D2NA00035K.].

De novo fabrication of higher arene ring incorporated contorted calix[2]phyrin(2.2.1.1.1) and its F- bound complex.

The rational design and synthesis of a novel contorted calix[2]phyrin(2.2.1.1.1) structure has been achieved, utilizing a terphenyl unit as a key building component. This terphenyl unit serves as a segment of the armchair periphery in a π-extended two-dimensional architecture. The resulting molecule exhibits remarkable properties, including the ability to self-assemble into solid-state supramolecular nanotubes. Additionally, it has demonstrated an affinity for complexation with fluoride anions, highlighting its potential for applications in molecular recognition and sensor technology. The incorporation of the terphenyl unit not only enhances the structural rigidity but also contributes to the unique electronic characteristics of the calix[2]phyrin.

Solution-based Supramolecular Hierarchical Assembly of Frenkel Excitonic Nanotubes Driven by Gold Nanoparticle Formation and Temperature.

Translating nature's successful design principle of solution-based supramolecular self-assembling to broad applications─ranging from renewable energy and information technology to nanomedicine─requires a fundamental understanding of supramolecular hierarchical assembly. Though the forces behind self-assembly (e.g., hydrophobicity) are known, the specific mechanism by which monomers form the hierarchical assembly still remains an open question. A crucial step toward formulating a complete mechanism is understanding not only how the monomer's specific molecular structure but also how manifold environmental conditions impact the self-assembling process. Here, we elucidate the complex correlation between the environmental self-assembling conditions and the resulting structural properties by utilizing a well-characterized model system: well-defined supramolecular Frenkel excitonic nanotubes (NTs), self-assembled from cyanine dye molecules in aqueous solution, which further self-assemble into bundled nanotubes (b-NTs). The NTs and b-NTs inhabit distinct spectroscopic signatures, which allows the use of steady-state absorption spectroscopy to monitor the transition from NTs to b-NTs directly. Specifically, we investigate the impact of temperature (ranging from 23 °C, 55 °C, 70 °C, 85 °C, up to 100 °C) during in situ formation of gold nanoparticles to determine their role in the formation of b-NTs. The considered time regime for the self-assembling process ranges from 1 min to 8 days. With our work, we contribute to a basic understanding of how environmental conditions impact solution-based hierarchical supramolecular self-assembly in both the thermodynamic and the kinetic regime.

Theoretical investigation of tube-like supramolecular structures formed through bifurcated lithium bonds

The stability of three supramolecular naostructures, which are formed through the aggregation of identical belts of [12] arene containing p-nitrophenyllithium, 1,4-dilithiatedbenzene and 1,4-dinitrobenzene units, is investigated by density functional theory. The electrostatic potential calculations indicate the ability of these belts in forming bifurcated lithium bonds (BLBs) between the Li atoms of one belt and the oxygen atoms of the NO2 groups in the other belt, which is also confirmed by deformation density maps and quantum theory of atoms in molecules (QTAIM) analysis. Topological analysis and natural bond analysis (NBO) imply to ionic character for these BLBs with binding energies up to approximately − 60 kcal mol−1. The many-body interaction energy analysis shows the strong cooperativity belongs to the configuration with the highest symmetry (C4v) containing p-nitrophenyllithium fragments as the building unit. Therefore, it seems that this configuration could be a good candidate for designing a BLB-based supramolecular nanotube with infinite size in this study.

Self-assembly mechanisms of cyclic peptide nanotubes in the presence of water molecules; study of hydrogen bonding, aggregation and Mir-210 gene delivery

Self-assembling cyclic peptides are a type of bioinspired supramolecular building blocks. They have the ability to stack together, forming supramolecular cyclic peptide nanotubes. This stacking is driven by β-sheet-like hydrogen bonding. In general, a single hydrogen bond is not strong enough to form ordered supramolecular structures. However, when multiple hydrogen bonds are aligned and built into arrays, they exhibit increased strength and directionality. This enables the formation of well-defined and organized supramolecular structures. The continuous advancements in understanding cyclic peptides and their unique properties open new doors for their application in functional materials, ion transport channels, and drug delivery systems, including gene therapy. When it comes to gene therapy, which involves introducing genetic material into cells to treat or prevent diseases, delivery systems play a crucial role. The use of cyclic peptides in these delivery systems can enhance the stability, specificity, and cellular uptake of the therapeutic cargo, thereby improving the overall success of gene therapy treatments. Hydrogen bond formation makes the cyclic peptide nanotube more stable and has an important role in its formation. The number of hydrogen bonds between cyclic peptides is 117 on average during the simulation time of 200 ns. Also, hydrogen bonds formation between Mir-210 and cyclic peptide nanotube during the simulation time observed which is an average of 17 bonds.

Crystalline Order Propagates Across Thick Layers of Water in Solutions of Supramolecular Nanotubes.

3D crystalline order with 1 nm resolution is observed in aqueous solutions of supramolecular nanotubes containing 94 % water, at concentrations as low as 6 wt%. 50 of star-like organic ions arrange into supramolecular rings which, in turn, stack on top of each other to form long hollow tubes with 15 nm outer diameter. Cryo-TEM and X-ray diffraction show that the parallel nanotubes arrange on a perfect hexagonal lattice. Unexpectedly, fiber diffraction on sheared solutions revealed numerous hkl Bragg reflections on several layer lines indicating longitudinal interlock between the tubes and 3D crystalline order with molecular-scale details transferred across 10 nm thick layers of water. The observed high 3D order is attributed to long-range attraction between like-charged tubes and amplified charge modulation by the extremely high intra-tube correlation length.

Controlled Hierarchical Self-Assembly of Nanoparticles and Chiral Molecules into Tubular Nanocomposites.

In this work, we show how the kinetics of molecular self-assembly can be coupled with the kinetics of the colloidal self-assembly of inorganic nanoparticles, which in turn drives the formation of several distinct hierarchically assembled tubular nanocomposites with lengths over tens of micrometers. These colloidal nanoparticles primarily serve as "artificial histones," around which the as-assembled supramolecular fibrils are wound into deeply kinetically trapped single-layered nanotubes, which leads to the formation of tubular nanocomposites that are resistant to supramolecular transformation thermally. Alternatively, when these nanoparticles are aggregated prior to the event of molecular self-assembly, these as-formed nanoparticle "oligomers" would be encapsulated into the thermodynamically favored double-layer supramolecular nanotubes, which enables the non-close-packing of nanoparticles inside the nanotubes and results in the nanoparticle superlattices with an open channel. Furthermore, increasing the amounts of nanoparticles enables the assembly of nanoparticles into pseudohexagonal superlattices at the external surface in a sequential fashion, which ultimately drives the formation of triple-layered hierarchically assembled tubular nanocomposites. Importantly, the sense of helicity transfers from the supramolecular nanotubes to the pseudo nanoparticle superlattices with a chiral vector of (2, 9). Our findings represent a strategy for controlling the hierarchical assembly bridging supramolecular chemistry to the inorganic solids to realize the complexity by design.

Synthetic Factors Determining the Curvature and Nuclearity of the Giant Mn70 and Mn84 Clusters with a Torus Structure of ∼4 nm Diameter.

New members of the Mn70 and Mn84 torus-like cluster family have been prepared from a hybrid comproportionation-alcoholysis reaction of [Mn12O12(O2CR)16(H2O)4] in alcohol in the presence of R'CO2H with NnBuMnO4 or MnII salts as initiators. Reactions using MeCO2H in nPrOH or nBuOH gave [Mn70O60(O2CMe)70(OnPr)20(nPrOH)18.5(H2O)21.5] (3) and [Mn70O60(O2CMe)70(OH)3(OnBu)17(nBuOH)7.5(H2O)32.5] (4), respectively, whereas EtCO2H in nPrOH gave [Mn84O72(O2CEt)84(OnPr)24(nPrOH)16(H2O)32] (5). They consist of alternating near-linear [Mn3(μ3-O)4]+ and distorted-cubane [Mn4(μ3-O)2(μ3-OR)2]6+ units bridged by syn,syn-μ-RCO2- and μ3-O2- groups and overall are [Mn14]5 and [Mn14]6 oligomers, the repeating unit containing two Mn3 and two Mn4 units. 3/4/5 possess external diameters (including organic ligands) of 4.0/4.1/4.6 nm, respectively, and crystallize as supramolecular nanotubes but with different packing arrangements. Considering all Mn70/Mn84 tori now available, we conclude that the Mn70 vs Mn84 nuclearity is determined by the relative bulk of the carboxylates vs the alkoxides, their increasing bulk favoring Mn84 and Mn70, respectively, with carboxylates larger than acetate giving Mn84. Alternating current (ac) magnetic susceptibility studies revealed frequency-dependent χ″M signals below ∼2.4 K, indicating 3-5 to be new members of the giant [Mn14]n torus family of giant single-molecule magnets (SMMs), in which Mn84 and Mn70 are the largest homometallic Mn/O clusters and SMMs to date.

Supramolecular peptide nanotubes as artificial enzymes for catalysing ester hydrolysis.

Peptide-based artificial enzymes are attracting significant interest because of their remarkable resemblance in both composition and structure to native enzymes. Herein, we report the construction of histidine-containing cyclic peptide-based supramolecular polymeric nanotubes to function as artificial enzymes for ester hydrolysis. The optimized catalyst shows a ca. 70-fold increase in reaction rate compared to the un-catalysed reaction when using 4-nitrophenyl acetate as a model substrate. Furthermore, the amphiphilic nature of the supramolecular catalysts enables an enhanced catalytic activity towards hydrophobic substrates. By incorporating an internal hydrophobic region within the self-assembled polymeric nanotube, we achieve a 55.4-fold acceleration in hydrolysis rate towards a more hydrophobic substrate, 4-nitrophenyl butyrate. This study introduces supramolecular peptide nanotubes as an innovative class of supramolecular scaffolds for fabricating artificial enzymes with better structural and chemical stability, catalysing not only ester hydrolysis, but also a broader spectrum of catalytic reactions.

Metallogels: a novel approach for the nanostructuration of single-chain magnets.

In this study we demonstrate that single-chain magnets (SCMs) can be assembled in gel phase and transferred intact on surface. We take advantage of a family of SCMs based on TbIII ions and nitronyl-nitroxides radicals functionalized with short alkyl chains known to form crystalline supramolecular nanotubes interacting with heptane acting as crystallizing solvent. When the radicals are functionalized with long aliphatic chains a robust gel is formed with similar structural and functional properties respect to its crystalline parent. Indeed, a small-angle X-ray scattering (SAXS) study unambiguously demonstrates that the gel is made of supramolecular nanotubes: the high stability of the gel allows the determination from SAXS data of precise nanotube metrics such as diameter, helical pitch and monoclinic cell of the folded 2D crystal lattice along the tube direction. Additionally, static and dynamic magnetic investigations show the persistence of the SCM behavior in the metallogel. Last, on-surface gelation provides thick films as well as sub-monolayer deposits of supramolecular nanotubes on surface as evidenced by atomic force microscopy (AFM) observations. This paves the road toward magnetic materials and devices made of SCMs profiting of their isolation on surface as individual chains.

Efficient light harvesting in self-assembled organic luminescent nanotubes.

Luminescent organic nanotubes derived from the co-assembly of cyanostilbene (CS) based cationic supramolecular polymers and bio-polyanion heparin, a known anticoagulant, have been utilized as highly efficient FRET (fluorescence resonance energy transfer) donors in aqueous media resulting in amplified acceptor emission in the orange-red and near-infrared (NIR). Energy transfer efficiencies higher than 80% and an ultra-high antenna effect of 150 were achieved even at high donor/acceptor ratios (500 : 1-100 : 1) translating to emission quenching of several hundred donors by one acceptor. Utilizing the temperature responsiveness of the FRET process, these systems were employed as ratiometric emission thermometers in the temperature range 20-90 °C. Moreover, the energy transfer was very effective in solid and polymer films. This allowed us to generate multi-color emissions ranging from blue to red including white light in solution as well as in solid and polymer films.