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Supramolecular nanogels are an emerging class of polymer nanocarriers for intracellular delivery, due to their straightforward preparation, biocompatibility, and capability to spontaneously encapsulate biologically active components such as DNA. A completely biodegradable three‐component cationic supramolecular nanogel was designed exploiting the multivalent host‐guest interaction of cyclodextrin and adamantane attached to a polypeptide backbone. While cyclodextrin was conjugated to linear poly‐L‐lysine, adamantane was grafted to linear as well as star shaped poly‐L‐lysine. Size control of nanogels was obtained with the increase in the length of the host and guest polymer. Moreover, smaller nanogels were obtained using the star shaped polymers because of the compact nature of star polymers compared to linear polymers. Nanogels were loaded with anionic model cargoes, pyranine and carboxyfluorescein, and their enzyme responsive release was studied using protease trypsin. Confocal microscopy revealed successful transfection of mammalian HeLa cells and intracellular release of pyranine and plasmid DNA, as quantified using a luciferase assay, showing that supramolecular polypeptide nanogels have significant potential in gene therapy applications., Wrapped in a peptide box: Supramolecular nanogels self‐assembled from poly‐L‐lysine (PLL) modified with host and guest units can entrap molecular cargo such as DNA and deliver it into cells for transfection. The PLL is made by N‐carboxyanhydride polymerization and equipped with cyclodextrin and adamantane groups. The size of the nanogel can be tuned by the length of the PLL and smaller nanogels are better transfection agents.

Atropisomerism is a fundamental feature of substituted biaryls resulting from rotation around the biaryl axis. Different stereoisomers are formed due to restricted rotation about the single bond, a situation often found in substituted porphyrins. Previously NMR determination of porphyrin atropisomers proved difficult, if not almost impossible to accomplish, due to low resolution or unresolvable resonance signals that predominantly overlapped. Here, we shed some light on this fundamental issue found in porphyrinoid stereochemistry. Using benzenesulfonic acid (BSA) for host‐guest interactions and performing 1D, 2D NMR spectroscopic analyses, we were able to characterize all four rotamers of the nonplanar 5,10,15,20‐tetrakis(2‐aminophenyl)‐2,3,7,8,12,13,17,18‐octaethylporphyirin as restricted H‐bonding complexes. Additionally, X‐ray structural analysis was used to investigate aspects of the weak host–guest interactions. A detailed assignment of the chemical signals suggests charge‐assisted complexation as a key to unravel the atropisomeric enigma. From a method development perspective, symmetry operations unique to porphyrin atropisomers offer an essential handle to accurately identify the rotamers using NMR techniques only., Porphyrin atropisomers: Upon full assignment of all NMR signals symmetry elements were found to play a crucial part in the atropisomeric characteristics. A detailed study on nonplanar porphyrin atropisomers highlights new means to detect and identify individual rotamers in solution while X‐ray crystallographic analyses identified new supramolecular binding modes and specified aspects of weak interactions.

H‐bond donor catalysts able to modulate the reactivity of ionic substrates for asymmetric reactions have gained great attention in the past years, leading to the development of cooperative multidentate H‐bonding supramolecular structures. However, there is still a lack of understanding of the forces driving the ion recognition and catalytic performance of these systems. Herein, insight into the cooperativity nature, anion binding strength, and folding mechanism of a model chiral triazole catalyst is presented. Our combined experimental and computational study revealed that multi‐interaction catalysts exhibiting weak binding energies (≈3–4 kcal mol−1) can effectively recognize ionic substrates and induce chirality, while strong dependencies on the temperature and solvent were quantified. These results are key for the future design of catalysts with optimal anion binding strength and catalytic activity in target reactions., Brought into the fold! Fundamental insight into the folding mechanism, cooperativity nature and anion binding strength requirements in supramolecular anion‐binding catalysis is presented. This is afforded by a combined experimental and computational study with a prototypical foldameric triazole‐based chiral anion‐binding catalytic system, implying multi‐recognition sites to the ionic substrate units and weak binding energies as success factors.

Squaraine dyes are well known for their strong absorption in the visible regime. Reports on chiral squaraine dyes are, however, scarce. To address this gap, we here report two novel chiral squaraine dyes and their achiral counterparts. The presented dyes are aggregated in solution and in thin films. A detailed chiroptical study shows that thin films formed by co‐assembling the chiral dye with its achiral counterpart exhibit exceptional photophysical properties. The circular dichroism (CD) of the co‐assembled structures reaches a maximum when just 25 % of the chiral dye are present in the mixture. The solid structures with the highest relative CD effect are achieved when the chiral dye is used solely as a director, rather than the structural component. The chiroptical data are further supported by selected spin‐filtering measurements using mc‐AFM. These findings provide a promising platform for investigating the relationship between the dissymmetry of a supramolecular structure and emerging material properties rather than a comparison between a chiral molecular structure and an achiral counterpart., Helicity control: An unexpected outcome of the co‐assembly of achiral squaraine dye a‐SQ‐1 with its chiral counterpart S ‐SQ‐1 is reported. A maximum in optical activity is observed in the supramolecular aggregates of a 3:1 mixture with a‐SQ‐1 as the major component. Intriguingly, the highest spin‐selective electron transport is observed for this mixing ratio as well, illustrating the direct relationship between optical activity and spin‐selective electron transport.

Owing to the electron‐donating and ‐accepting nature of corroles (Corr) and phthalocyanines (Pc), respectively, we designed and developed two novel covalently linked Corr‐Pc conjugates. The synthetic route allows the preparation of the target conjugates in satisfying yields. Comprehensive steady‐state absorption, fluorescence, and electrochemical assays enabled insights into energy and electron‐transfer processes upon photoexcitation. Coordinating a pyridine‐appended subphthalocyanine (SubPc) to the Pc of the conjugate sets up the ways and means to realize the first example of an array composed by three different porphyrinoids, which drives a cascade of energy and charge‐transfer processes. Importantly, the SubPc assists in stabilizing the charge‐separated state, that is, one‐electron oxidized Corr and the one electron‐reduced Pc, upon photoexcitation by means of a reductive charge transfer to the SubPc. To the best of our knowledge, this is the first case of an intramolecular oxidation of a Corr within electron‐donor–acceptor conjugates by means of just photoexcitation. Moreover, the combination of Corr, Pc, and SubPc guarantees panchromatic absorption across the visible range of the solar spectrum, with the SubPc covering the „green gap“ that usually affects porphyrinoids., Cascades: The preparation of two covalently linked corrole‐Zn phthalocyanine dyads is reported. The coordination of a pyridine‐appended perfluorinated subphthalocyanine to the zinc phthalocyanine leads to the formation of supramolecular triads. Corrole acts as electron donor upon photoexcitation, with subphthalocyanine as the final acceptor. These cascade‐like charge phenomena make these triads promising materials in molecular photovoltaics (see figure).

We investigated the adsorption of three related cyano‐functionalized tetraphenyl porphyrin derivatives on Cu(111) by scanning tunneling microscopy (STM) in ultra‐high vacuum (UHV) with the goal to identify the role of the cyano group and the central Cu atom for the intermolecular and supramolecular arrangement. The porphyrin derivatives studied were Cu‐TCNPP, Cu‐cisDCNPP, and 2H‐cisDCNPP, that is, Cu‐5,10,15,20‐tetrakis‐(p‐cyano)‐phenylporphyrin, Cu‐meso‐cis‐di(p‐cyano)‐phenylporphyrin and 2H‐meso‐cis‐di(p‐cyano)‐phenylporphyrin, respectively. Starting from different structures obtained after deposition at room temperature, all three molecules form the same long‐range ordered hexagonal honeycomb‐type structure with triangular pores and three molecules per unit cell. For the metal‐free 2H‐cisDCNPP, this occurs only after self‐metalation upon heating. The structure‐forming elements are pores with a distance of 3.1 nm, formed by triangles of porphyrins fused together by cyano‐Cu‐cyano interactions with Cu adatoms. This finding leads us to suggest that two cyano‐phenyl groups in the “cis” position is the minimum prerequisite to form a highly ordered 2D porous molecular pattern. The experimental findings are supported by detailed density functional theory calculations to analyze the driving forces that lead to the formation of the porous hexagonal honeycomb‐type structure., Snowflake‐shaped porphyrins: Twelve doubly cyano‐functionalized Cu‐tetraphenylporphyrins form a snowflake‐like structure around a macropore, as observed by scanning tunneling microscopy at room temperature.

The synthesis of tetramethoxyresorcinarene podands bearing p‐toluene arms connected by ‐SO3‐ (1) and ‐CH2O‐ (2) linkers is presented herein. In the solid state, the resorcinarene podand 1 forms an intramolecular self‐inclusion complex with the pendant p‐toluene group of a podand arm, whereas the resorcinarene podand 2 does not show self‐inclusion. The conformations of the flexible resorcinarene podands in solution were investigated by variable‐temperature experiments using 1D and 2D NMR spectroscopic techniques as well as by computational methods, including a conformational search and subsequent DFT optimisation of representative structures. The 1H NMR spectra of 1 and 2 at room temperature show a single set of proton signals that are in agreement with C 4v symmetry. At low temperatures, the molecules exist as a mixture of boat conformations featuring slow exchange on the NMR timescale. Energy barriers (ΔG ≠ 298) of 55.5 and 52.0 kJ mol−1 were calculated for the boat‐to‐boat exchange of 1 and 2, respectively. The results of the ROESY experiments performed at 193 K and computational modelling suggest that in solution the resorcinarene podand 1 adopts a similar conformation to that present in its crystal structure, whereas podand 2 populates a more versatile range of conformations in solution., Self‐inclusion: An intramolecular self‐inclusion complex of a flexible resorcinarene podand stabilised by weak C−H⋅⋅⋅O interactions has been observed in both the crystal structure and in solution (see figure). The solid‐state conformation was determined by XRD and the conformation in solution was investigated by NMR and computational methods, with good agreement observed between the different techniques.

The design and synthesis of air‐stable and conveniently crystallizable RhIII‐cyclopentadienyl catalysts substituted with a urea moiety, which are able to accelerate the C−H olefination of benzoic acid derivatives, is reported. Through kinetic studies and NMR titration experiments, the catalysts’ substrate recognition ability mediated by hydrogen bonding was identified to be the reason for this effect. Introduction of pyridone‐phosphine ligands capable of forming additional H‐bond interactions increased the catalytic performance even further. By unveiling a proportionality between reaction rate and relative complex formation enthalpy the hypothesis of a supramolecular catalyst preformation was supported. Its application to a variety of substrates proved the catalyst system's advantages, generally increasing the yields when compared to the results obtained with widely used [RhCp*Cl2]2., Supramolecular chemistry: The design and synthesis of urea‐substituted RhIII‐cyclopentadienyl catalysts, which accelerate the C−H olefination of benzoic acid derivatives, is reported. The catalysts’ substrate recognition ability mediated by H‐bonding is identified to be the reason for this effect. Its application to a variety of substrates proves the catalyst system's advantages compared to the results obtained with widely used [RhCp*Cl2]2.

The supramolecular polymerization of an acid‐sensitive pyridyl‐based ligand (L1) bearing a photoresponsive azobenzene moiety was elucidated by mechanistic studies. Addition of trifluoroacetic acid (TFA) led to the transformation of the antiparallel H‐bonded fibers of L1 in methylcyclohexane into superhelical braid‐like fibers stabilized by H‐bonding of parallel‐stacked monomer units. Interestingly, L1 dimers held together by unconventional pyridine–TFA N⋅⋅⋅H⋅⋅⋅O bridges represent the main structural elements of the assembly. UV‐light irradiation caused a strain‐driven disassembly and subsequent aggregate reconstruction, which ultimately led to short fibers. The results allowed to understand the mechanism of mutual influence of acid and light stimuli on supramolecular polymerization processes, thus opening up new possibilities to design advanced stimuli‐triggered supramolecular systems., A look into the self‐assembly: Detailed mechanistic insights into the supramolecular polymerization of an acid‐sensitive photoresponsive pyridyl‐based ligand are reported. Addition of acid (TFA) caused the transformation of long twisted fibers into superhelical braid‐like assemblies stabilized by aromatic, H‐bonding, and van der Waals interactions through a dimerization event involving two unconventional pyridine–TFA N⋅⋅⋅H⋅⋅⋅O bridges. Photoirradiation led to a strain‐driven disassembly of the superhelical fibers and subsequent attenuated growth into short fibers after reconstruction.

Versatile photoresponsive gels based on tripodal low molecular weight gelators (LMWGs) are reported. A cyclohexane‐1,3,5‐tricarboxamide (CTA) core provides face‐to‐face hydrogen bonding and a planar conformation, inducing the self‐assembly of supramolecular polymers. The CTA core was substituted with three arylazopyrazole (AAP) arms. AAP is a molecular photoswitch that isomerizes reversibly under alternating UV and green light irradiation. The E isomer of AAP is planar, favoring the self‐assembly, whereas the Z isomer has a twisted structure, leading to a disassembly of the supramolecular polymers. By using tailor‐made molecular design of the tripodal gelator, light‐responsive organogels and hydrogels were obtained. Additionally, in the case of the hydrogels, AAP was coupled to the core through hydrazones, so that the hydrogelator and, hence, the photoresponsive hydrogel could also be assembled and disassembled by using dynamic covalent chemistry.

We disclose the results of our investigations on the influence that the insertion method of aryl-extended calix[4]pyrrole into liposomal membranes exerts on their properties as anion carriers. We use the standard HPTS assay to assess the transport properties of the carriers. We show that the post-insertion of the carrier, as DMSO solution, assigns better transport activities to the “two-wall” a,a-aryl-extended calix[4]pyrrole 1 compared to the “four-wall” a,a,a,acounterpart 2. Notably, opposite results were obtained when the carriers were pre-inserted into the liposomal membranes. We assign this difference to an improved incorporation of carrier 2 into the membrane when delivered by the pre-insertion method. On the other hand, carrier 1 shows comparable levels of transport independently of the method used for its incorporation. Thus, an accurate comparison of the chloride transport activities featured by these two carriers demands their pre-incorporation in the liposomal membranes. In contrast, using the lucigenin assay with the pre-insertion method both carriers displayed similar transport efficiencies.

The cellular uptake of self‐assembled biological and synthetic matter results from their multicomponent properties. However, the interplay of the building block composition of self‐assembled materials and uptake mechanisms urgently requires addressing. It is shown here that supramolecular polymers that self‐assemble in aqueous media, are a modular and controllable platform to modulate cellular delivery by the introduction of small ligands or cationic moieties, with concomitantly different cellular uptake kinetics and valence dependence. A library of supramolecular copolymers revealed stringent mutually exclusive uptake behavior in which either of the uptake pathways dominated, with sharp compositional transition. Supramolecular biomaterial engineering thus provides for adaptive platforms with great potential for efficient tuning of multivalent and multicomponent systems interfacing with biological matter.

none 8 si VIP paper, featured in front cover (DOI: 10.1002/chem.201605975) The formation of distinct supramolecular assemblies, including a metastable species, is revealed for a lipophilic guanosine (G) derivative in solution and in the solid state. Structurally different G-quartet-based assemblies are formed in chloroform depending on the nature of the cation, anion and the salt concentration, as characterized by circular dichroism and time course diffusion-ordered NMR spectroscopy data. Intriguingly, even the presence of potassium ions that stabilize G-quartets in chloroform was insufficient to exclusively retain such assemblies in the solid state, leading to the formation of mixed quartet and ribbon-like assemblies as revealed by fast magic-angle spinning (MAS) NMR spectroscopy. Distinct N−H⋅⋅⋅N and N−H⋅⋅⋅O intermolecular hydrogen bonding interactions drive quartet and ribbon-like self-assembly resulting in markedly different 2D 1H solid-state NMR spectra, thus facilitating a direct identification of mixed assemblies. A dissolution NMR experiment confirmed that the quartet and ribbon interconversion is reversible–further demonstrating the changes that occur in the self-assembly process of a lipophilic nucleoside upon a solid-state to solution-state transition and vice versa. A systematic study for complexation with different cations (K+, Sr2+) and anions (picrate, ethanoate and iodide) emphasizes that the existence of a stable solution or solid-state structure may not reflect the stability of the same supramolecular entity in another phase. Reddy, G. N. Manjunatha; Huqi, Aida; Iuga, Dinu; Sakurai, Satoshi; Marsh, Andrew; Davis, Jeffery T.; Masiero, Stefano; Brown, Steven P Reddy, G. N. Manjunatha; Huqi, Aida; Iuga, Dinu; Sakurai, Satoshi; Marsh, Andrew; Davis, Jeffery T.; Masiero, Stefano; Brown, Steven P

Chemistry - a European journal 24(10), 2503 - 2508 (2018). doi:10.1002/chem.201705883, Pentaphosphaferrocene $\mathrm{[Cp*Fe(η^5-P5)]}$ (1 a) represents an excellent building block for the template-directed synthesis of spherical supramolecules. Here, the self-assembly of 1 a with $\mathrm{Cu^I}$ and $\mathrm{Cu^{II}}$ halides in the presence of the template complexes $\mathrm{[FeCp_{2}][PF_{6}], [CoCp_{2}][PF6]}$ and $\mathrm{[CoCp_2]}$ is reported, testifying to the redox behavior of the formed supramolecules. The oxidation or reduction capacity of these reactive complexes does not inhibit their template impact and, for the first time, the cationic metallocene $\mathrm{[CoCp_{2}]^+}$ is enclosed in unprecedented anionic organometallic hosts. Furthermore, the large variety of structural motifs, as icosahedral, trigonal antiprismatic, cuboidal and tetragonal antiprismatic arrangements of 1 a units are realized in the supramolecules $\mathrm{[FeCp_2]@[{1 a}_{12}(CuBr)_{17.3}] (3), [CoCp_{2}]^{+}_{3}{[CoCp_{2}]^{+}@[{1 a}_{8}Cu_{24.25}Br_{28.25}(CH_{3}CN)_{6}]^{4−}} (4), {[Cp_{2}Co]^{+}@[{1 a}_{8}(CuI)_{28} (CH_{3}CN)_{9.8}]}{[Cp_{2}Co]^{+}@[{1 a)}_{8}Cu_{24.4}I_{26.4}(CH_{3}CN)_{8}]^{2−}} (5), and [{1 a}_{3}{(1 a)_{2}NH}_{3}Cu_{16}I_{10}(CH_{3}CN)_{7}] (6)}$, respectively., Published by Wiley-VCH, Weinheim

The cavity of an M8L12 cubic coordination cage can accommodate a cluster of ten water molecules in which the average number of hydrogen bonds per water molecule is 0.5 H‐bonds less than it would be in the bulk solution. The presence of these “hydrogen‐bond frustrated” or “high‐energy” water molecules in the cavity results in the hydrophobic effect associated with guest binding being predominantly enthalpy‐based, as these water molecules can improve their hydrogen‐bonding environment on release. This contrasts with the classical form of the hydrophobic effect in which the favourable entropy change associated with release of ordered molecules from hydrophobic surfaces dominates. For several guests Van't Hoff plots showed that the free energy of binding in water is primarily enthalpy driven. For five homologous pairs of guests related by the presence or absence of a CH2 group, the incremental changes to ΔH and TΔS for guest binding—that is, ΔΔH and TΔΔS, the difference in contributions arising from the CH2 group—are consistently 5(±1) kJ mol−1 for ΔΔH and 0(±1) kJ mol−1 for TΔΔS. This systematic dominance of ΔH in the binding of hydrophobic guests is consistent with the view that guest binding is dominated by release of “high energy” water molecules into a more favourable solvation environment, as has been demonstrated recently for some members of the cucurbituril family.

Anion receptors can be used to transport ions across lipid bilayers, which has potential for therapeutic applications. Synthetic bicarbonate transporters are of particular interest, as defects in transmembrane transport of bicarbonate are associated with various diseases. However, no convenient method exists to directly observe bicarbonate transport and study the mechanisms involved. Here, an assay is presented that allows the kinetics of bicarbonate transport into liposomes to be monitored directly and with great sensitivity. The assay utilises an encapsulated europium(III) complex, which exhibits a large increase in emission intensity upon binding bicarbonate. Mechanisms involving CO2 diffusion and the dissipation of a pH gradient are shown to be able to lead to an increase in bicarbonate concentration within liposomes, without transport of the anion occurring at all. By distinguishing these alternative mechanisms from actual bicarbonate transport, this assay will inform the future development of bicarbonate transporters., A new assay to study bicarbonate transport is reported, which is based on a europium complex that is encapsulated inside liposomes and reports changes in the intravesicular concentration of bicarbonate in a direct and highly sensitive way. This assay was used to reveal that synthetic anion transporters can act via different mechanisms: 1) actual transport of HCO3 − anions; 2) CO2 diffusion coupled to dissipation of the resulting transmembrane pH gradient.

In this study unprecedented regio-selectivity to the branched aldehyde product in hydroformylation of propene is attained upon embedding a rhodium complex in a supramolecular assembly, L2, formed by coordination-driven self-assembly of tris-(meta-pyridyl)-phosphine and zinc(II) porpholactones. The design of the new capsule is based on the ligand-template approach, in which the ligand acts as a template for the capsule formation. Previously we have reported the first generation capsule L1, in which zinc(II) porphyrin units were utilized instead of porpholactones. Binding studies demonstrate that the association constant for the formation of the second generation capsule L2 is nearly an order of magnitude higher than for L1. This strengthened binding keeps the new capsule L2 intact in polar and industrially interesting solvents. As a consequence, the unprecedented regioselectivity for branched aldehyde products can be retained in polar and coordinating solvents when using the second-generation assembly.

Herein, the synthesis of fullerene derivatives with adjustable polarities and lyotropic aggregation properties is reported. The polarity range spans from superhydrophobic to hydrophilic, while simultaneously providing a further reactive position with a view to graft them onto other materials. The synthetic strategy relies on a selective protection with an isoxazoline moiety. The remaining octahedral positions were further functionalized with the desired groups to tune their solubility, yielding mixed [5:1] hexakisadducts. The subsequent deprotection by clean photolytic reaction led to fullerene pentakisadducts with an incomplete octahedral addition pattern, which are useful forerunners for the synthesis of building blocks. Their hydrophobic/hydrophilic behavior has been characterized both in solution and surface through octanol/water partition coefficients (log P) and contact angle measurements. Furthermore, these derivatives can form supramolecular constructions which have been studied by dynamic light scattering (DLS) and cryo‐TEM.

A chiral perylene diimide building block has been prepared based on an amine derivative of the amino acid l‐phenylalanine. Detailed studies were carried out into the self‐assembly behaviour of the material in solution and the solid state using UV/Vis, circular dichroism (CD) and fluorescence spectroscopy. For the charged building block BTPPP, the molecular chirality of the side chains is translated into the chiral supramolecular structure in the form of right‐handed helical aggregates in aqueous solution. Temperature‐dependent UV/Vis studies of BTPPP in aqueous solution showed that the self‐assembly behaviour of this dye can be well described by an isodesmic model in which aggregation occurs to generate short stacks in a reversible manner. Wide‐angle X‐ray diffraction studies (WXRD) revealed that this material self‐organises into aggregates with π–π stacking distances typical for π‐conjugated materials. TEM investigations revealed the formation of self‐assembled structures of low order and with no expression of chirality evident. Differential scanning calorimetry (DSC) and polarised optical microscopy (POM) were used to investigate the mesophase properties. Optical textures representative of columnar liquid–crystalline phases were observed for solvent‐annealed samples of BTPPP. The high solubility, tunable self‐assembly and chiral ordering of these materials demonstrate their potential as new molecular building blocks for use in the construction of chiro‐optical structures and devices.

A series of novel functionalised dumbbell‐shaped bifullerenes in which two [5.0] pentakis‐adducts of C60 are covalently connected by cyclic bismalonates were synthesised. These dimeric compounds, carrying various combinations of hydrophilic and hydrophobic addends, self‐assemble in aqueous solution towards supramolecular architectures of different structural complexity as observed by cryogenic transmission electron microscopy (cryo‐TEM). The detailed analysis of the image data revealed an unprecedented hierarchical aggregation behaviour. Whereas completely hydrophilic substituted bifullerenes formed profoundly monodisperse populations of small oligomeric elementary micelles consisting of only three or four bifullerene molecules in a supposedly bent conformation, their amphiphilic equivalents underwent a hierarchical two‐step assembly process towards larger spherical and even rod‐like structures. The data suggest that the hierarchical assembly process is driven by hydrophobic interactions of preformed tetrameric elementary micelles.

A self‐sorting network comprising six different hydrogen bonding‐motifs is presented. Detailed analysis of the pairwise molecular recognition behavior of each hydrogen‐bonding motif by NMR spectroscopy, single‐crystal studies, and DFT allowed the construction of cascades exploiting integrative and non‐integrative narcissistic and social self‐sorted product distributions. Multiple distinct pathways within the network could be created depending on the presence or absence of different components. More information can be found in the Full Paper by C. Fonseca Guerra, A. J. Wilson, et al. on page 785-795.

(Figure Presented). Methylene-bridged calix[4]arenes have emerged as extremely versatile ligand supports in the formation of new polymetallic clusters possessing fascinating magnetic properties. Metal ion binding rules established for this building block allow one to partially rationalise the complex assembly process. The ability to covalently link calix[4]arenes at the methylene bridge provides significantly improved control over the introduction of different metal centres to resulting cluster motifs. Clusters assembled from bis-calix[4]-arenes and transition metal ions or 3d-4 f combinations display characteristic features of the analogous calix[4]arene supported clusters, thereby demonstrating an enhanced and rational approach towards the targeted synthesis of complex and challenging structures.

Vernier templating exploits a mismatch between the number of binding sites in a template and a reactant to direct the formation of a product that is large enough to bind several template units. Here, we present a detailed study of the Vernier-templated synthesis of a 12-porphyrin nanoring. NMR and small-angle X-ray scattering (SAXS) analyses show that Vernier complexes are formed as intermediates in the cyclo-oligomerization reaction. UV/Vis/NIR titrations show that the three-component assembly of the 12-porphyrin nanoring figure-of-eight template complex displays high allosteric cooperativity and chelate cooperativity. This nanoring–template 1:2 complex is among the largest synthetic molecules to have been characterized by single-crystal analysis. It crystallizes as a racemate, with an angle of 27° between the planes of the two template units. The crystal structure reveals many unexpected intramolecular C[BOND]H⋅⋅⋅N contacts involving the tert-butyl side chains. Scanning tunneling microscopy (STM) experiments show that molecules of the 12-porphyrin template complex can remain intact on the gold surface, although the majority of the material unfolds into the free nanoring during electrospray deposition.

Statistical copolymerization plays a key role in many biological and technological processes; however, mechanistic understanding of the formation of analogous supramolecular counterparts remains limited. Herein, we report detailed insights into the supramolecular co‐assembly of two π‐conjugated PdII and PtII complexes, which in isolation self‐assemble into flexible fibers and nanodisks, respectively. An efficient single‐step co‐assembly into only one type of nanostructure (fibers or nanodisks) takes place if any of the components is in excess. In contrast, equimolar mixtures lead to PdII‐rich fiber‐like co‐assemblies by a statistical co‐nucleation event along with a residual amount of self‐sorted nanodisks in a stepwise manner., Go nano! Mechanistic insights into the supramolecular co‐assembly of two structurally related π‐conjugated PdII and PtII complexes are reported. While the final nanostructure morphology upon co‐assembly (fibers or nanodisks; see figure) is dictated by the component that is present in excess, equimolar mixtures lead to PdII‐rich co‐assembled fibers by a co‐nucleation event along with a residual amount of self‐sorted nanodisks in a stepwise manner.

EPR spectroscopic evidence for intramolecular electron transfer in anionic N-substituted naphthalimides to yield persistent diradical anions and intermolecular electron transfer from a variety of carbanions to 6-bromo-N-phenyl-naphthalimide to yield persistent radical-radical anion pairs was recently claimed in two papers by Zhang et al. In this comment, it is shown that the EPR spectra published in both papers do not agree with the proposed triplet-state species. Rather, the spectra are due to various doublet-state radicals, deriving from minor side reactions. The misinterpretations invalidate the general conclusions of the papers.

Supramolecular forces govern self-assembly and further deter- mine the final morphologies of self-as- semblies. However, how they control the morphology remains hitherto large- ly unknown. In this paper, we have dis- covered that the self-assembled nano- structures of rigid organic semiconduc- tor chromophores can be finely con- trolled by the secondary forces by fine- tuning the surrounding environments. In particular, we used water/methanol/ hydrochloric acid to tune the environ- ment and observed five different phases that resulted from versatile mo- lecular self-assemblies. The representa- tive self-assembled nanostructures were nanotapes, nanoparticles and their 1D assemblies, rigid microplates, soft nanoplates, and hollow nano- spheres and their 1D assemblies, re- spectively. The specific nanostructure formation is governed by the water fraction, Rw, and the concentration of hydrochloric acid, (HCl). For instance, nanotapes formed at low (HCl) and Rw values, whereas hollow nanospheres formed when either the HCl concentra- tion is high, or the water fraction is low, or both. The significance of this paper is that it provides a useful phase diagram by using Rw and (HCl) as two variables. Such a self-assembly phase diagram maps out the fine control that the secondary forces have on the self- assembled morphology, and thus allows one to guide the formation toward a desired nanostructure self-assembled from rigid organic semiconductor chro- mophores by simply adjusting the two key parameters of Rw and (HCl).

Supramolecular structures of organic molecules on planar nanocarbon surfaces, such as highly oriented pyrolytic graphite (HOPG), have been extensively studied and the factors that control them are generally well-established. In contrast, the properties of supramolecular structures on curved nanocarbon surfaces like carbon nanotubes remain challenging to predict and/or to understand. This paper reports an investigation into the first study of the supramolecular structures of 5,15-bisdodecylporphyrin (C12P) on chiral, concentrated single-walled carbon nanotubes (SWNTs; with right-handed helix P- and left-handed helix M-) surfaces using STM. Furthermore, the study is the first of its kind to experimentally assign the absolute-handedness chirality of SWNTs, as well as to understand their effect on the supramolecular structures of organic molecules on their surfaces. Interestingly, these SWNT enantiomers resulted in supramolecular structures of opposite chirality based on the handedness chirality. With molecular modelling, we predicted the absolute-handedness chirality of SWNTs, before demonstrating this experimentally.

With the rapid progress in the development of supramolecular soft materials, examples of low-molecular- weight gelators (LMWGs) with the ability to immobilise both water and organic solvents by the same structural scaffold are very limited. In this paper, we report the development of pyrene-containing peptide-based ambidextrous gelators (AGs) with the ability to efficiently gelate both organic and aqueous solvents. The organo- and hydrogelation efficien- cies of these gelators are in the range 0.7-1.1 % w/v in vari- ous organic solvents and 0.5-5 % w/v in water at certain acidic pH values (pH 2.0-4.0). Moreover, for the first time, AGs have been utilised to prepare single-walled carbon- nanotube (SWNT)-included soft nanocomposites in both hydro- and organogel matrices. The influence of different non-covalent interactions such as hydrogen bonding, hydro- phobic, p-p and van der Waals interactions in self-assem- bled gelation has been studied in detail by circular dichro- ism, FTIR, variable-temperature NMR, 2D NOESY and lumi- nescence spectroscopy. Interestingly, the presence of the pyrene moiety in the structure rendered these AGs intrinsi- cally fluorescent, which was quenched upon successful inte- gration of the SWNTs within the gel. The prepared hydro- and organogels along with their SWNT-integrated nanocom- posites are thermoreversible in nature. The supramolecular morphologies of the dried gels and SWNT-gel nanocom- posites have been studied by transmission electron micros- copy, fluorescence microscopy and polarising optical micros- copy, which confirmed the presence of three-dimensional self-assembled fibrillar networks (SAFINs) as well as the inte- grated SWNTs. Importantly, rheological studies revealed that the inclusion of SWNTs within the ambidextrous gels im- proved the mechanical rigidity of the resulting soft nano- composites up to 3.8-fold relative to the native gels.

Linear arrays of hydrogen bonds are useful for the reversible assembly of "stimuli-responsive" supramolecular materials. There is thus an ongoing requirement for easy-to-synthesise motifs that are capable of presenting hydrogen-bonding functionality in a predictable manner, such that high-affinity and high-fidelity recognition occurs. The design of linear arrays is made challenging as a consequence of their ability to adopt multiple conformational and tautomeric configurations; with each additional hydrogen-bonding heteroatom added to an array, the available tautomeric and conformational space increases and it can be difficult to anticipate where unproductive conformers/tautomers will arise. This paper describes a detailed study on the complementary ureidoimidazole donor-donor-acceptor (DDA) array (1) and amidoisocytosine donor-acceptor-acceptor (DAA) array (2). A specific feature of 1 is that two degenerate, intramolecular hydrogen-bonded conformations are postulated, both of which present a DDA array that is complementary to appropriate DAA partners. 1D and 2D (1)H NMR spectroscopy, isothermal titration calorimetry, and ab initio structure calculations confirm 1 interacts with 2 (K(a) ≈ 33,000 M(-1) in CDCl(3)) in a conformer-independent fashion driven by enthalpy. Comparison of the binding behaviour of 1 with hexylamidocytosine (4) and amidonaphthyridine (5) provides insight on the role that intramolecular hydrogen-bonding plays in mediating affinity towards DAA partners.

The syntheses, structures, and characterization of six Ln 3+ ―Cu 2+ ― glycine (Hgly) coordination polymers are described in this paper. They represent three types of structures. Type I (Ln = La (1), Pr (2), and Sm (3)) is a 1D catenarian polymer comprising [Ln 2 ] nodes bridged by four cis-Cu-(gly) 2 linkers. Type II (Ln = Eu (4) and Dy (5)) is a 2D open framework with a 4 4 -net, composed of novel [Ln 6 Cu 22 ] cluster nodes linked by trans-Cu(gly) 2 linkers. Furthermore, the inner structures of the [Ln 6 Cu 22 ] nodes, and the connection mode between the nodes and linkers are slightly different for 4 and 5. Type III (Ln=Er (6)) is a 3D open framework with a novel 3 6 ·4 18 ·5 3 ·6 topology, made up of [Er 6 Cu 24 ] cluster nodes and trans-Cu(gly) 2 linkers. The rich variety of the resulting structures owes itself mainly to the interselection between the dynamic control of metalloligands and cationic components. A transition from frequency dependence to frequency independence is observed in the field-induced magnetization lag for 1―3. The frequency dependence at low temperatures may come from the antiferromagnetic Cu—Cu interaction through the [Ln 2 ] nodes, whereas the frequency independence may be due to the disappearance of the antiferromagnetic Cu—Cu interaction at high temperatures.

This paper describes novel host-guest systems comprising viologen cations (guests) and the derivatives of bis-para-phenylene-34-crown-10 (hosts) with anionic groups COO(-) or SO(3)(-). The structure of the resulting charge-compensated host-guest complexes, their association constants and their electrochemical behaviour have been studied. In the solid state, the viologen cations thread the negatively charged crown ethers forming electroneutral zwitterion-like [2]pseudorotaxane salts; in solution this threaded geometry is preserved. The association constants of [2]pseudorotaxane salts incorporating the 1,1'-diethylviologen moiety in solution are significantly higher than those of previously reported analogues. The extrapolated association free energies in non-aqueous media exceed -40 kJ mol(-1) at 25 degrees C. This significant increase of the interaction free energy makes these compounds stable even in aqueous solutions. The association constants of [2]pseudorotaxane salts incorporating sterically more hindered 1,1'-diethyl-3,3'-dimethylviologen moieties are significantly lower. Structurally related [2]rotaxane salts, in which the oppositely charged ionic components are mechanically interlocked, have been prepared in good yields. It has been shown that [2]rotaxane salts incorporating anti-isomers of bisfunctionalised crown ethers are cycloenantiomeric. In both [2]pseudorotaxane and [2]rotaxane salts, the electrostatic interactions between the viologen moieties and the negatively charged crown ethers lead to very significant negative shifts of viologen reduction potentials up to 450 mV. The findings of the present study are valuable for the design of nanoscale molecular electronic devices.

This paper describes the synthesis and electrochemistry of biferrocenyl-terminated dendrimers and their beta-cyclodextrin (beta-CD) inclusion complexes in aqueous solution and at surfaces. Three generations of poly(propylene imine) (PPI) dendrimers, decorated with 4, 8, and 16 biferrocenyl (BFc) units, respectively, were synthesized. A water-soluble BFc derivative forms stable inclusion complexes with beta-CD. The intrinsic binding constant is K(i)=2.5 x 10(4) M(-1). The BFc dendrimers were solubilized in water by complexation of the end groups with beta-CD, resulting in large water-soluble supramolecular assemblies. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) showed that all the end groups are complexed to beta-CD. Adsorption of the dendrimers at self-assembled monolayers (SAMs) of heptathioether-functionalized beta-CD on gold ("molecular printboards") resulted in stable monolayers of the dendrimers due to the formation of multivalent host-guest interactions between the BFc end groups of the dendrimers and the immobilized beta-CD molecules. The number of interacting end groups is 3, 4, and 4 for dendrimer generations 1, 2, and 3, respectively. The complexation of BFc to beta-CD is sensitive to the oxidation state of the BFc unit. Oxidation of neutral BFc-Fe(2) ((II,II)) to the cationic, mixed-valence biferrocenium BFc-Fe(2) ((II,III)+) resulted in dissociation of the host-guest complexes. Scan-rate-dependent CV and DPV analyses of the dendrimer-beta-CD assemblies immobilized at the beta-CD host surface and in solution revealed that the dendrimers are oxidized in three steps. First, the surface-beta-CD-bound BFc moieties are oxidized to the mixed-valence state, Fe(2) ((II,III)+), followed by the oxidation of the non-surface-interacting BFc groups to the Fe(2) ((II,III)+) state. The third step involves the oxidation of all the BFc moieties to the Fe(2) ((III,III)2+) state.

The self-assembly of diaminododecane solubilised by four different stereoisomeric dendritic peptides to form gel-phase materials in toluene was investigated. The second generation dendritic peptides were based on D- and L-lysine building blocks, and each contained three chiral centres. By designing dendritic peptides in which the configurations of the chiral centres were modified, and applying them as gelator units, the assembly of stereoisomers could be investigated. In all cases, the self-assembly of gelator units resulted in macroscopic gelation. However, the degree of structuring was modulated by the stereoisomers employed, an effect which changed the morphology and macroscopic behavior of the self-assembled state. Enantiomeric (L,L,L or D,D,D) gelator units formed fibrous molecular assemblies, whilst the racemic gel (50 % L,L,L : 50 % D,D,D) formed a flat structure with a "woven" appearance. Gelator units based on L,D,D or D,L,L dendritic peptides also formed fibrous assemblies, but small-angle X-ray scattering indicated significant morphological differences were caused by the switch in chirality. Furthermore, the macroscopic stability of the gel was diminished when these peptides were compared with their L,L,L or D,D,D analogues. In this paper it is clearly shown that individual stereocentres, on the molecular level, are directly related to the helicity within the fibre. It is argued that the chirality controls the pattern of hydrogen bonding within the assembly, and hence determines the extent of fibre formation and the macroscopic gel strength.

The acceptor capabilities of "organic" halogen, CX (X=F, Cl, Br, I), with respect to hydrogen bonding are controversial, and unactivated organic chlorine is generally deemed to be a poor acceptor. Hydrogen bridges of the type O--H...Cl--C are uncommon and occur mainly in an intramolecular situation when the donor group is sterically hindered, so that the formation of intermolecular interactions is difficult. In this paper, intramolecular O--H...Cl--C interactions in a series of chloro-substituted gem-alkynols are studied. We describe various features of this interaction using crystallographic, spectroscopic and computational methods. The O--H...Cl--C interaction occurs in five of the six compounds under consideration here (CDDA, 14DDDA, 15DDDA, 18DDDA, 15MKA). Solution (1)H NMR spectroscopy shows that the interaction is intramolecular and that it is a true hydrogen bond. DFT calculations give a stabilisation energy around 4.0 kcal mol(-1). In the crystal structures of the compounds studied, the intramolecular O--H...Cl--C interactions fit into the overall scheme of cooperative interactions. These structures may be derived from that of the unsubstituted compound DDA by means of synthon exchange and the O--H...Cl--C interaction fares surprisingly well in the presence of competing stronger acceptors. The crystal structures show an unusual degree of modularity for compounds that generally form interactions that are weak and variable. It is noteworthy that the so-called "weak" acceptor, organic chlorine, is able to sustain a good intramolecular hydrogen bridge that is of an attractive and stabilizing nature and which is of potential importance in crystal engineering and supramolecular chemistry.

Semisynthetic DNA-protein conjugates are versatile molecular tools useful, for instance, in the self-assembly of high-affinity reagents for immunological detection assays, the fabrication of highly functionalized laterally microstructured biochips, and the biomimetic "bottom-up" synthesis of nanostructured supramolecular devices. This concept paper summarizes the current state-of-the-art concerning the synthesis, characterization, and applications of such hybrid molecules, and also draws perspectives on future developments.

The cover picture shows how trimeric perfluoro-ortho-phenylene mercury (center), one of the simplest trifunctional Lewis acidic hosts, interacts with organic molecules to afford various adducts. The planarity of this trinuclear complex as well as its overall polarizability compounded with relativistic effects at mercury permits the occurrence of noncovalent interactions and accounts for the tendency of this compound to form cofacial dimers as observed in the structure of the acetone adduct (top left). With a triply coordinated acetone molecule, the structure of this adduct also substantiates the cooperative effects that arise from the proximity and accessibility of the mercury centers. The complexation of arenes, such as benzene (bottom left) and naphthalene (bottom right), also occurs and leads to the formation of binary stacks in which the arene establishes multiple linkages with the mercury centers of the trifunctional Lewis acids. In addition to displaying unusual coordination environment, the arene units present in those stacks exhibit remarkable phosphorescent properties. For more details, see the paper by F. P. Gabbai, R. E. Taylor, and M. R. Haneline on p. 5188 ff.

In this paper we report the development of a family of polymerizable urea derivatives that are gelators for organic solvents. The design involves amino-acid-based urea derivatives containing methacrylate functional groups. Several of the bis-ureas show excellent gelation properties in a variety of organic solvents at very low concentrations (1.5 mM). The self-assembling properties of these compounds were studied by X-ray powder diffraction, optical microscopy, and electronic microscopy. The molecules self-assemble into fibrous aggregates as indicated by scanning electron microscopy. Depending on the nature of the monomeric unit, the structure of the aggregates ranges from small to large fibers and planar sheets. In polar solvents, the molecules exhibit multilamellar packing modes. The organogels can be polymerized by photoirradiation leading to significant increases in stability as indicated by changes in phase-transition temperature. The morphology of the aggregates was seen to maintain a similar structure both before and after irradiation. This method provides a novel type of polymer with designed self-assembling architecture and also affords to a route to stabilized polymer gels.