Hydrogen-Bonded Helical Organic Nanotubes

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.

NDI based C2-symmetric Chiral Supramolecular Hydrogels Towards Enhanced Conductivity

To comprehend the significance of improved conductive properties in C2-symmetric hydrogels, it is vital to investigate how non-gelating achiral functional group isomers influence the conductivity of such supramolecular hydrogels, whereas understanding the major driving forces behind this regulatory process is first and foremost. Herein, we report a hydrogel system containing tryptophan-conjugated NDI as the backbone (L/D-NTrp), enabling effective supramolecular assembly with the bipyridyl functional group isomers. This co-assembly behavior results in materials with exceptional mechanical properties and high conductivities, surpassing most previously reported C2-symmetrical hydrogels, as well as the ability to form controlled morphologies. Notably, the co-hydrogels displayed an eight-fold increase in mechanical strength, making them more robust and resistant to deformation compared to the original gel. Additionally, all hydrogels exhibited favorable electrical conductivity, with the co-assembled hydrogels showcasing notable performance, making them a promising candidate for use in electronic devices and sensors. This report lays the foundation for further investigation into the properties and potential applications of L/D-NTrp compound in the range of fields, including drug delivery, tissue engineering, and electronics.

Chiral Supramolecular Polymers Assembled from Conformationally Flexible Amino-Acid-Substituted Biphenyldiimides

Hydrogen-bonded polymers are a class of highly dynamic supramolecular aggregates, whose self-assembly may be tuned by very mild external or internal stimuli. However, the rational design of chiral supramolecules remains challenging especially when flexible components are involved. The combination of the inherent weakness and dynamic nature of the intermolecular bonds that hold together such assemblies with unrestricted molecular motions introduces additional factors which may affect the self-assembly process. In this report, the self-assembly of four amino acid-derived chiral biphenyldiimides into open-chain 1D supramolecular polymers is presented. While the primary driving force, COOH···HOOC hydrogen bonding, is responsible for the polymer growth in all cases, the amino acid side chains play an important role in either stabilizing or destabilizing the assemblies obtained, as deduced from studies of the thermodynamics of the self-assembly process. Furthermore, substantial differences in the structural factors governing the polymerization process between dynamic liquid and static solid are found. This work demonstrates the potential of the rather unexplored class of diimide-based organic dyes in the formation of well-organized chiral supramolecular assemblies with tunable properties.

Ru@Carbon Nanotube Composite Microsponge: Fabrication in Supercritical CO2 for Hydrogenation of p-Chloronitrobenzene

Novel heterogeneous catalysts are needed to selectively anchor metal nanoparticles (NPs) into the internal space of carbon nanotubes (CNTs). Here, supercritical CO₂ (SC-CO₂) was used to fabricate the Ru@CNT composite microsponge via impregnation. Under SC-CO₂ conditions, the highly dispersive Ru NPs, with a uniform diameter of 3 nm, were anchored exclusively into the internal space of CNTs. The CNTs are assembled into a microsponge composite. The supercritical temperature for catalyst preparation, catalytic hydrogenation temperature, and time all have a significant impact on the catalytic activity of Ru@CNTs. The best catalytic activity was obtained at 100 °C and 8.0 MPa: this gave excellent selectivity in the hydrogenation of p-chloronitrobenzene at 100 °C. This assembly strategy assisted by SC-CO₂ will be promising for the fabrication of advanced carbon composite powder materials.

Bamboo-like π-Nanotubes with Tunable Helicity and Circularly Polarized Luminescence

We report the fabrication of an exotic bamboo-like π-nanotube via the hierarchical self-assembly of a dipeptide-substituted naphthalenediimide gelator with tunable helicity and circularly polarized luminescence (CPL). It was found that in the presence of trifluoroacetic acid (TFA) the gelator molecules self-assembled into a bamboo-like π-nanotube, which is composed of truncated nanocones and CPL active. When defining the diameter ratio of the lower to upper edge of each nanocone as a parameter to express the helicity of different nanotubes, it was found that both the helicity and CPL of these nanotubes can be adjusted by the amount of TFA. Moreover, the helicity of the nanotube can be conveyed to the achiral quantum dots (QDs) and produce a hybrid nanotube/QDs CPL active materials with adjustable dissymmetry factor. This work finds a new type self-assembled bamboo-like π-nanotube and unveils their helicity and CPL control.

Helical Nanofibers Formed by Palladium-Mediated Assembly of Organic Homochiral Macrocycles Containing Binaphthyl and Pyridyl Units

Herein, we report the synthesis and characterization of homochiral macrocycles, in which molecular rigidity, combined with the presence of multiple functional groups, allow for the assembly of helical nanostructures. 1,1'-bi-2-naphthol (Binol) units are used as robust chirality inducers, and pyridyl units embedded within the molecular frameworks allow the assembly, upon coordination with Pd(II) metal ions, of the macrocyclic building blocks. CD and NMR spectroscopies show the formation of ordered 1D assembly in solution. AFM studies indicate that the molecular systems are capable of forming nanoscale structures. The effective transfer of chiral information results in helical nanofibers, with lengths ranging from a few hundreds of nanometers to some micrometers. AFM line profiles reveal a helical longitudinal period of about 50 nm and a transverse width of 25 to 45 nm after deconvolution.

Characteristics of the pH-regulated aggregation-induced enhanced emission (AIEE) and nanostructure orchestrate via self-assembly of naphthalenediimide–tartaric acid bola-amphiphile: role in cellular uptake

A naphthalene diimide–tartaric acid conjugate was successfully synthesized, and the influence of tartaric acid on the self-assembly of the NDI–TA scaffold was explored.

A water-soluble naphthalenediimide-containing hexacationic cage

A water-soluble cage containing three naphthalenediimide (NDI) units was synthesized in a one-pot manner without chromatographic purification, during which six irreversible C-N bonds formed simultaneously via an SN2 reaction. The cage was observed to be capable of accommodating a variety π-electron rich guests in a peripheral manner in water. However, for linear guests including I3- and I2, the cage is able to form an inclusion complex. Besides, in the solid state, the cage can absorb vapor of I2.

Discrete π Stack of a Tweezer-Shaped Naphthalenediimide-Anthracene Conjugate

The design and synthesis of a tweezer-shaped naphthalenediimide (NDI)-anthracene conjugate (2NDI) are reported. In the structure of the closed form (π_NDI ⋅⋅⋅π_NDI stack) of 2NDI, which was elucidated by single-crystal XRD, the existence of C-H⋅⋅⋅O hydrogen bonding involving the nearest carbonyl oxygen atom of an NDI unit was suggested. The tunability of π_NDI ⋅⋅⋅π_NDI interactions was studied by means of UV/Vis absorption, fluorescence and NMR spectroscopy and molecular modelling. This revealed that the π_NDI ⋅⋅⋅π_NDI interactions in 2NDI affect the absorption and emission properties depending on the temperature. Furthermore, in polar solvents, 2NDI prefers the stronger π_NDI ⋅⋅⋅π_NDI stack, whereas the π_NDI ⋅⋅⋅π_NDI interaction is diminished in nonpolar solvents. Importantly, the conformational variations of 2NDI can be reversibly switched by variation in temperature, and this suggests potential application for fluorogenic molecular switches upon temperature changes.

A Naphthalene Diimide Based Macrocycle Containing Quaternary Ammonium Groups: An Electron-Deficient Host for Aromatic Carboxylate Derivatives

Naphthalene diimide (NDI) compounds are widely used as electron acceptors in various applications. Herein, we combine NDI with quaternary ammonium groups for the synthesis of a highly electron-deficient linear compound 2 and macrocycle 3. The complexation studies of the water-soluble macrocycle 3 with aromatic di- and tetra- carboxylate anions in water were done using absorption, emission, ¹ H NMR and NOESY spectroscopic titrations. The NDI incorporated macrocycle 3 showed high binding affinities towards linear aromatic tetracarboxylate anions owing to the size and charge complementarity of the host-guest complex. Macrocycle 3 binds tetracarboxylate anion much better than dicarboxylate anions. Furthermore, the macrocycle 3 is solvated differently in acetonitrile and in water or dimethyl sulfoxide, which induces changes in conformation and photophysical properties. Such electron-deficient optically active macrocycles are useful for developing useful sensor materials.

Pyrroloindole-Based Dynamic Combinatorial Chemistry

We report a new class of building blocks for Dynamic Combinatorial Chemistry (DCC) based on the pyrroloindole scaffold. The attachment of l-cysteine on the α, α′ positions of the core makes the molecule suitable for disulfide exchange in aqueous dynamic combinatorial libraries (DCLs). The synthesis of the core follows a modified version of the Knoevenagel–Hemetsberger approach. The new building block (l-PI) is fluorescent (Φ = 48%) and relatively stable towards thermal and photodegradation. The chirality of the cysteine is transferred to the electron-rich pyrroloindole core. Homo- and heterochiral DCLs of l-PI with electron-deficient l- and d-naphthalenediimide (NDI) lead to similar library distributions regardless of the enantiomer used. When no salt is present, the major component is a dimer, while dimers and tetramers are obtained at increased ionic strength.

Selectivity and bio-compatibility of self-assembled chiral flower-like and helical nanostructures

The molecular building block NDI–LCA was synthesized via substitution of NDA at the di-imide position with two lithiocholic acid moieties, resulted into chiral flower line and helical nanostructures.

Supramolecular super-helix formation via self-assembly of naphthalene diimide functionalised with bile acid derivatives

The design of chiral chromophores that lead to self-assembly of higher order helical structures is a powerful tool to understand the hierarchical helical structures of molecules of nature. In this work, we present a self-assembled helical super-structure produced via facial stacking of a bile acid bolaamphiphile derivative with a naphthalene diimide core (NDI-DCA), driven by solvophobic effects in THF–H₂O solvent mixtures. The chirality of the helical microstructure is directed by the multiple chiral centres in the precursor molecule. The chirality of the hierarchical assemblies was observed using circular dichroism (CD), Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) measurements. We propose that the NDI-DCA super-structures are formed via similar interactions and mechanisms to those observed in biological molecules such as proteins and DNA.

Steering the Self-Assembly Outcome of a Single NDI Monomer into Three Morphologically Distinct Supramolecular Assemblies, with Concomitant Change in Supramolecular Polymerization Mechanism

Noncovalent self-assembly creates an effective route to highly sophisticated supramolecular polymers with tunable properties. However, the outcome of this assembly process is highly dependent on external conditions. In this work, a monomeric naphthalene diimide (NDI), designed to allow solubility in a wide range of solvents, can assemble into three distinct noncovalent supramolecular species depending on solvent composition and temperature. Namely, while the self-assembly in chlorinated solvents yields relatively short, hydrogen-bonded nanotubes, the reduction of solvent polarity changes the assembly outcome, yielding π-π stacking polymers, which can further bundle into a more complex aggregate. The obtained polymers differ not only in their global morphology but-more strikingly-also in the thermodynamics and kinetics of their supramolecular self-assembly, involving isodesmic or two-stage cooperative assembly with kinetic hysteresis, respectively. Ultimately, three distinct assembly states can be accessed in a single experiment.

Adenosine Triphosphate Templated Self-Assembly of Cationic Porphyrin into Chiral Double Superhelices and Enzyme-Mediated Disassembly

Self-assembly of small molecules through noncovalent interactions into nanoscale architectures has been extensively studied in supramolecular chemistry. However, it is still challenging to develop a biologically inspired self-assembly system that functions in water with complex structure and dynamics by analogy with those found in nature. Here, we report a new water-soluble cationic porphyrin that undergoes adenosine triphosphate (ATP)-templated self-assembly into right-handed double-helical supramolecular structures. Direct observation of the porphyrin-ATP assembly by transmission electron microscopy has been accomplished. The assemblies consist of superhelical fibers with length greater than 1 μm and width ∼46 nm. The chiral superhelical fibers show reversible disassembly to monomers upon hydrolysis of ATP catalyzed by alkaline phosphatase (ALP), and the nanofibers can be re-formed with subsequent addition of ATP. Moreover, transient self-assembly of a chiral double helix is formed when ALP is present to consume ATP.

Organic molecular tessellations and intertwined double helices assembled by halogen bonding

Crystalline polymorphs featuring halogen-bonded single-component supramolecular polygonal tessellations, a network of 4₁- and 4₃-double helices, and intertwined 3₁ and 3₂meso-helices.

Multifunctionalized octamethoxy-[8]cycloparaphenylene: facile synthesis and analysis of novel photophysical and photoinduced electron transfer properties

A novel multifunctionalized carbon nanoring was facilely synthesized, which demonstrates an unusual hypsochromic shift in the emission spectrum with interesting photophysical properties.

Reversible Charge Trapping in Bis-Carbazole-Diimide Redox Polymers with Complete Luminescence Quenching Enabling Nondestructive Read-Out by Resonance Raman Spectroscopy

The coupling of substituted carbazole compounds through carbon-carbon bond formation upon one-electron oxidation is shown to be a highly versatile approach to the formation of redox polymer films. Although the polymerization of single carbazole units has been proposed earlier, we show that by tethering pairs of carbazoles double sequential dimerization allows for facile formation of redox polymer films with fine control over film thickness. We show that the design of the monomers and in particular the bridging units is key to polymer formation, with the diaminobenzene motif proving advantageous, in terms of the matching to the redox potentials of the monomer and polymer film and thereby avoiding limitations in film thickness (autoinsulation), but introduces unacceptable instability due to the intrinsic redox activity of this moiety. The use of a diimide protecting group both avoids complications due to p-diamino-benzene redox chemistry and provides for a redox polymer in which the photoluminescence of the bis-carbazole moiety can be switched reversibly (on/off) with redox control. The monomer design approach is versatile enabling facile incorporation of additional functional units, such as naphthalene. Here we show that a multicomponent carbazole/naphthalene containing monomer (APCNDI) can form redox polymer films showing both p- and n- conductivity under ambient conditions and allows access to five distinct redox states, and a complex electrochromic response covering the whole of the UV/vis-NIR spectral region. The highly effective quenching of the photoluminescence of both components in poly-APCNDI enables detailed characterization of the redox polymer films. The poly-APCNDI films show extensive charge trapping, which can be read out spectroscopically in the case of films and is characterized as kinetic rather than chemical in origin on the basis of UV/vis-NIR absorption and resonance Raman spectroscopic analyses. The strong resonantly enhanced Raman scattering for the various oxidized and reduced states of APCNDI enables nondestructive "read-out" of the state of the polymer, including that in which charges are trapped kinetically at the surface, making poly-APCNDI highly suitable for application as a component in organic nonvolatile memory devices.

Supramolecular Nanostructures of Chiral Perylene Diimides with Amplified Chirality for High-Performance Chiroptical Sensing

Chiral supramolecular nanostructures with optoelectronic functions are expected to play a central role in many scientific and technological fields but their practical use remains in its infancy. Here, this paper reports photoconductive chiral organic semiconductors (OSCs) based on perylene diimides with the highest electron mobility among the chiral OSCs and investigates the structure and optoelectronic properties of their homochiral and heterochiral supramolecular assemblies from bottom-up self-assembly. Owing to the well-ordered supramolecular packing, the homochiral nanomaterials exhibit superior charge transport with significantly higher photoresponsivity and dissymmetry factor compared with those of their thin film and monomeric equivalents, which enables highly selective detection of circularly polarized light, for the first time, in visible spectral range. Interestingly, the heterochiral nanostructures assembled from co-self-assembly of racemic mixtures show extraordinary chiral self-discrimination phenomenon, where opposite enantiomeric molecules are packed alternately into heterochiral architectures, leading to completely different optoelectrical performances. In addition, the crystal structures of homochiral and heterochiral nanostructures have first been studied by ab initio X-ray powder diffraction analysis. These findings give insights into the structure-chiroptical property relationships of chiral supramolecular self-assemblies and demonstrate the feasibility of supramolecular chirality for high-performance chiroptical sensing.

Self-organization of amino-acid-derived NDI assemblies into a nanofibrillar superstructure with humidity sensitive n-type semiconducting properties

The hierarchical self-assembly of l-tyrosine substituted naphthalenediimide has been explored in solution by NMR spectroscopy and in the solid-state by atomic force microscopy.

Supramolecular Helical Systems: Helical Assemblies of Small Molecules, Foldamers, and Polymers with Chiral Amplification and Their Functions

In this review, we describe the recent advances in supramolecular helical assemblies formed from chiral and achiral small molecules, oligomers (foldamers), and helical and nonhelical polymers from the viewpoints of their formations with unique chiral phenomena, such as amplification of chirality during the dynamic helically assembled processes, properties, and specific functionalities, some of which have not been observed in or achieved by biological systems. In addition, a brief historical overview of the helical assemblies of small molecules and remarkable progress in the synthesis of single-stranded and multistranded helical foldamers and polymers, their properties, structures, and functions, mainly since 2009, will also be described.

Electrically Driven White Light Emission from Intrinsic Metal-Organic Framework

Light-emitting diodes (LEDs) have drawn tremendous potential as a replacement of traditional lighting due to its low-power consumption and longer lifetime. Nowadays, the practical white LEDs (WLED) are contingent on the photon down-conversion of phosphors containing rare-earth elements, which limits its utility, energy, and cost efficiency. In order to resolve the energy crisis and to address the environmental concerns, designing a direct WLED is highly desirable and remains a challenging issue. To circumvent the existing difficulties, in this report, we have designed and demonstrated a direct WLED consisting of a strontium-based metal-organic framework (MOF), {[Sr(ntca)(H2O)2]·H2O}n (1), graphene, and inorganic semiconductors, which can generate a bright white light emission. In addition to the suitable design of a MOF structure, the demonstration of electrically driven white light emission based on a MOF is made possible by the combination of several factors including the unique properties of graphene and the appropriate band alignment between the MOF and semiconductor layer. Because electroluminescence using a MOF as an active material is very rare and intriguing and a direct WLED is also not commonly seen, our work here therefore represents a major discovery which should be very useful and timely for the development of solid-state lighting.

Highly Fluorescent Nanotubes with Tunable Diameter and Wall Thickness Self-Assembled from Asymmetric Perylene Diimides

Highly fluorescent bilayer-walled and monolayer-walled nanotubes are assembled from elaborately designed asymmetric perylene diimide (PDI) molecules. The diameter of bilayer-walled nanotubes increases with the size of the branched substituents at the meta-position of the phenyl moiety of PDI molecules, whereas that of monolayer-walled nanotubes remains unchanged regardless of the size of branched substituents.

H-bonding directed programmed supramolecular assembly of naphthalene-diimide (NDI) derivatives

In this review we have collated various supramolecular designs, all surrounding H-bonding among well-known functional groups (peptides, nucleic acids, amides, ureas, carboxylic acids, pyridine-hydroxyls, urethanes, imides and others), to dictate self-assembly of naphthalenediimide (NDI) π-systems (both small molecules and polymeric building blocks) that exhibit several exciting features including strong propensity for π-π interactions, π-acidity, excellent n-type semiconductivity, CT-complexation, ion-π interactions, ring-substitution dependent redox properties and photophysical properties. This article reveals that H-bonding can indeed serve as a very powerful and versatile tool to programmed self-assembly of a single or multiple dye system producing a wide range of tailored soft materials, including fibrillar gels, chromonic mesophases, foldamers, nanotubes, vesicles, reverse micelles and polymersomes, both in water and organic medium with distinct photophysical properties, charge transport properties, conductivity properties and functional group displays that are highly relevant in the fields of biology and organic electronics.

Effect of Amide Hydrogen Bonding Interaction on Supramolecular Self-Assembly of Naphthalene Diimide Amphiphiles with Aggregation Induced Emission

In the present work, two new naphthalene diimide (NDI) amphiphiles, NDI-N and NDI-NA, were successfully synthesized and employed to investigate their self-assembly and optical properties. For NDI-NA, which contains an amide group, aggregation-induced emission enhancement (AIEE) was demonstrated in the presence of various ratios of methylcyclohexane (MCH) in chloroform, which led to the visual color changes. This new amide-containing NDI-NA amphiphile formed nanobelt structures in chloroform/MCH (10:90, v/v) and microcup-like morphologies in chloroform/MCH (5:95, v/v). The closure of these microcups led to the formation of vesicles and microcapsules. The structural morphologies gained from the solvophobic control of NDI-NA were confirmed by various complementary techniques such as infrared spectroscopy, X-ray diffraction, and scanning and transmission electron microscopy. In the absence of the amide moiety in NDI-N, no self-assembly was observed, indicating the fundamental role of H-bonding in the self-association process.

Hierarchical self-assembly of switchable nucleolipid supramolecular gels based on environmentally-sensitive fluorescent nucleoside analogs

Exquisite recognition and folding properties have rendered nucleic acids as useful supramolecular synthons for the construction of programmable architectures. Despite their proven applications in nanotechnology, scalability and fabrication of nucleic acid nanostructures still remain a challenge. Here, we describe a novel design strategy to construct new supramolecular nucleolipid synthons by using environmentally-sensitive fluorescent nucleoside analogs, based on 5-(benzofuran-2-yl)uracil and 5-(benzo[b]thiophen-2-yl)uracil cores, as the head group and fatty acids, attached to the ribose sugar, as the lipophilic group. These modified nucleoside-lipid hybrids formed organogels driven by hierarchical structures such as fibers, twisted ribbons, helical ribbons and nanotubes, which depended on the nature of fatty acid chain and nucleobase modification. NMR, single crystal X-ray and powder X-ray diffraction studies revealed the coordinated interplay of various non-covalent interactions invoked by modified nucleobase, sugar and fatty acid chains in setting up the pathway for the gelation process. Importantly, these nucleolipid gels retained or displayed aggregation-induced enhanced emission and their gelation behavior and photophysical properties could be reversibly switched by external stimuli such as temperature, ultrasound and chemicals. Furthermore, the switchable nature of nucleolipid gels to chemical stimuli enabled the selective two channel recognition of fluoride and Hg(2+) ions through visual phase transition and fluorescence change. Fluorescent organogels exhibiting such a combination of useful features is rare, and hence, we expect that this innovative design of fluorescent nucleolipid supramolecular synthons could lead to the emergence of a new family of smart optical materials and probes.

Cooperative supramolecular polymerization of an amine-substituted naphthalene-diimide and its impact on excited state photophysical properties

A donor-acceptor-donor (D-A-D) type naphthalene-diimide (NDI-H) chromophore exhibits highly cooperative J-aggregation leading to nanotubular self-assembly and gelation in n-decane, as demonstrated by UV/Vis, FT-IR, photoluminescence and microscopy studies. Analysis of temperature-dependent UV/Vis spectra using the nucleation-elongation model and FT-IR data reveals the molecular origin of the cooperative nature of the self-assembly. The supramolecular polymerization is initiated by H-bonding up to a degree of polymerization ∼20-25, which in a subsequent elongation step promotes J-aggregation in orthogonal direction leading to possibly a sheet-like structure that eventually produces nanotubes. Time-resolved fluorescence and absorption measurements demonstrate that such a tubular assembly enables very effective delocalization of excited states resulting in a remarkably prolonged excited state lifetime.

Enabling Light Work in Helical Self-Assembly for Dynamic Amplification of Chirality with Photoreversibility

Light-driven transcription and replication are always subordinate to a delicate chirality transfer. Enabling light work in construction of the helical self-assembly with reversible chiral transformation becomes attractive. Herein we demonstrate that a helical hydrogen-bonded self-assembly is reversibly photoswitched between photochromic open and closed forms upon irradiation with alternative UV and visible light, in which molecular chirality is amplified with the formation of helixes at supramolecular level. The characteristics in these superhelixes such as left-handed or right-handed twist and helical length, height, and pitch are revealed by SEM and AFM. The helical photoswitchable nanostructure provides an easily accessible route to an unprecedented photoreversible modulation in morphology, fluorescence, and helicity, with precise assembly/disassembly architectures similar to biological systems such as protein and DNA.

Chiral nanostructuring of multivalent macrocycles in solution and on surfaces

We describe the design and synthesis of a novel functionality-rich, homochiral macrocycle, possessing the overall molecular D2 symmetry, in which multivalency is introduced into the covalent framework by means of four suitably positioned pyridine moieties. The macrocycle synthesis is carried out with functionalized, enantiopure 1,1'-binaphthyl synthons as the source of chirality by means of a room temperature esterification reaction as the cyclization procedure. Upon addition of Pd(2+), coordination of the pyridine moieties occurs both intra and intermolecularly, to afford chiral ordered mono and dimeric macrocycles or multimeric aggregates depending on the solvents and conditions used. The metal binding event takes place in combination with a significant macrocyclic conformational rearrangement detected by circular dichroism spectroscopy. When in combination with a third component (C60), the macrocycle-Pd(2+) hybrid undergoes surface-confined nanostructuring into chiral nanofibres.

A crystalline sponge based on dispersive forces suitable for X-ray structure determination of included molecular guests

A crystalline porous material showing one-dimensional (1-D) rectangular micropores (12 × 9 Å2) has been assembled from a semirigid macrocyclic tetraimine and EtOAc as the templating agent. The 1-D nature of the material is intrinsic to the conformationally rigid structure of a macrocyclic sub-unit bearing four cyclohexylidene residues. The multiple dispersive forces established among the aliphatic residues glutted the 1-D channels and provided thermal stability to the material at temperatures below 160 °C. Upon removal of the template, the structure of the empty solid exhibited permanent microporosity (SBET = 342 m2 g-1). Being a true molecular sponge, the channel framework of this material allowed the inclusion of a variety of molecular sample guests without compromising its crystalline nature. Remarkably, this crystalline material enabled the structure determination by X-ray diffraction of the included molecules. Theoretical studies demonstrated the vital role played by the dispersive forces in the overall stabilization of the crystal packing.

Anion-templated hexagonal nanotubes

Hydrogen bonding between bromide anions and a tetrahydroxytriptycene ligand was used to assemble crystalline hexagonal tubes with nanometer diameters in good yield. Use of a hexahydroxytriptycene ligand again gave hexagonal nanotubes, but containing the spontaneously-oxidised quinone-tetrahydroxy ligand. The surprisingly robust nanotubes are stable to heat, vacuum and water, and represent an unprecedented use of O-H···anion coordination to assemble complex three-dimensional structures.

A Molecular Nanotube with Three-Dimensional π-Conjugation

A π-conjugated twelve-porphyrin tube is synthesized in 32 % yield by a template-directed coupling reaction that joins together six porphyrin dimers, forming twelve new C-C bonds. The nanotube has two bound templates, enclosing an internal volume of approximately 4.5 nm3. Its UV/Vis/NIR absorption and fluorescence spectra resemble those of a previously reported six-porphyrin ring, but are red-shifted by approximately 300 cm-1, reflecting increased conjugation. Ultrafast fluorescence spectroscopy demonstrates extensive excited-state delocalization. Transfer of electronic excitation from an initially formed state polarized in the direction of the nanotube axis (z axis) to an excited state polarized in the xy plane occurs within 200 fs, resulting in a negative fluorescence anisotropy on excitation at 742 nm.

Supramolecular organic frameworks of a Schiff base showing selective guest adsorption

A relatively simple molecule,N,N′-bis(3-methoxy-4-hydroxybenzylidene)-1,4-phenylenediamine, was synthesized and found to be a suitable building block to form different types of crystalline frameworkviahydrogen bonding. The porous frameworks show potential selectivity for uptake of small guest molecules.

A Molecular Nanotube with Three-Dimensional π-Conjugation

A π-conjugated twelve-porphyrin tube is synthesized in 32 % yield by a template-directed coupling reaction that joins together six porphyrin dimers, forming twelve new C=C bonds. The nanotube has two bound templates, enclosing an internal volume of approximately 4.5 nm³. Its UV/Vis/NIR absorption and fluorescence spectra resemble those of a previously reported six-porphyrin ring, but are red-shifted by approximately 300 cm⁻¹, reflecting increased conjugation. Ultrafast fluorescence spectroscopy demonstrates extensive excited-state delocalization. Transfer of electronic excitation from an initially formed state polarized in the direction of the nanotube axis (z axis) to an excited state polarized in the xy plane occurs within 200 fs, resulting in a negative fluorescence anisotropy on excitation at 742 nm.

J-aggregation, its impact on excited state dynamics and unique solvent effects on macroscopic assembly of a core-substituted naphthalenediimide

Herein we reveal a straightforward supramolecular design for the H-bonding driven J-aggregation of an amine-substituted cNDI in aliphatic hydrocarbons. Transient absorption spectroscopy reveals sub-ps intramolecular electron transfer in isolated NDI molecules in a THF solution followed by a fast recombination process, while a remarkable extension of the excited state lifetime by more than one order of magnitude occurred in methylcyclohexane likely owing to an increased charge-separation as a result of better delocalization of the charge-separated states in J-aggregates. We also describe unique solvent-effects on the macroscopic structure and morphology. While J-aggregation with similar photophysical characteristics was noticed in all the tested aliphatic hydrocarbons, the morphology strongly depends on the "structure" of the solvents. In linear hydrocarbons (n-hexane, n-octane, n-decane or n-dodecane), formation of an entangled fibrillar network leads to macroscopic gelation while in cyclic hydrocarbons (methylcyclohexane or cyclohexane) although having a similar polarity, the cNDI exhibits nanoscale spherical particles. These unprecedented solvent effects were rationalized by establishing structure-dependent specific interactions of the solvent molecules with the cNDI which may serve as a general guideline for solvent-induced morphology-control of structurally related self-assembled materials.

Dual-tuning multidimensional superstructures based on a T-shaped molecule: vesicle, helix, membrane and nanofiber-constructed gel

Dual-tuning self-assembly of Fmoc–Gly (a T-shape molecule) supramolecular self assembly was firstly reported here.

Small bandgap naphthalene diimide copolymers for efficient inorganic–organic hybrid solar cells

The energy level control of efficient inorganic–organic hybrid solar cells induced by using a copolymer was demonstrated.