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A Chiral‐at‐Al aluminate can be prepared by the stepwise reaction of two different alcohols with the aluminate anion [EtAl(6‐Me‐2‐py)3]−. The method can also be used to prepare chiral‐at‐ligand aluminates and for the introduction of 3‐py and 4‐py functionalities into the aluminate framework through the selective and controlled substitution of one or two pyridine arms, thereby giving entry to new supramolecular chemistry. The cover represents the formation of such a rare example of a chiral‐at‐aluminum aluminate and it is also a tribute to the oneiric worlds of surrealist painter René Magritte. More information can be found in the Full Paper by R. García‐Rodríguez et al. on page 17019. [ABSTRACT FROM AUTHOR]

From the reaction of manganese halides with the chiral Schiff bases obtained by condensation of o‐vanillin and (R)‐ or (S)‐phenylglycinol, 11 complexes based on pentanuclear cages with trigonal bipyramidal [MnIIMnIII3M′] (M′=NaI, CaII, MnII) or enneanuclear [MnIIMnIII6NaI2] cores were synthesized. Structural, supramolecular chirality, and optical properties were explored. The magnetic properties of related systems were reviewed, and the magnetic response of the new systems was rationalized to the bond parameters. Mirror, mirror: A family of chiral clusters with [MnIIMnIII3M′] or [MnIIMnIII6NaI2] cores (see figure) was obtained from enantiomerically pure Schiff bases. Structural characteristics, optical properties, and magnetic response were studied for these complexes. [ABSTRACT FROM AUTHOR]

A new family of homochiral silver complexes based on carbophilic interactions with ortho-phenylene ethynylene (o-OPE) scaffolds containing up to two silver atoms are described. These compounds represent a unique class of complexes with chirality at the metal. Chiral induction is based on the inclusion of chiral sulfoxides, which allow efficient transfer of chirality to the helically folded o-OPE, leading to circularly polarized luminescence (CPL)- and vibrational circular dichroism (VCD)-active compounds. In the presence of silver(I) cations, carbophilic interactions dominate, which promote helical structures with a defined helicity. This is one of the very scarce examples of the use of such interactions in the attractive field of abiotic foldamers. The switching event has been extensively studied by using different chiroptical techniques, including circular dichroism, CPL, and VCD, and represents one of the few CPL switches described in the literature. [ABSTRACT FROM AUTHOR]

Supramolecular chirality in a binary mixture of achiral bent-core (BC) and achiral rodlike mesogens was observed. Three different nanosegregated mesophases were determined in the binary system, and meaningful changes in circular dichroism (CD) were detected near the phase-transition temperatures of the rodlike mesogens. The highest CD intensity in the binary system was noted in the nanosegregated mesophase, in which the BC mesogens were in the helical nanofilament (HNF) phase and the rodlike mesogens were in the smectic A phase. The supramolecular chirality in the binary mixture was attributed to the self-assembled hierarchical chiral superstructures. Based on the experimental results, plausible scenarios for the chiral superstructures of the rodlike molecules embedded in the HNF networks are suggested. In addition, a system comprising BC and rodlike molecules doped with a photoresponsive compound exhibited remarkable photoswitching of CD intensity. According to the isothermal photoinduced phase transition of the embedded molecules in BC molecular HNFs, the observed CD intensities can be dynamically and reversibly modulated. Such a material with easily controllable functionality is of considerable interest in the field of materials science. [ABSTRACT FROM AUTHOR]

Invited for the cover of this issue is the group of Mikiji Miyata at Osaka University. The image depicts the concept of supramolecular hidden chirality of hydrogen-bonded networks characterized by advanced graph set analysis. Read the full text of the article at . [ABSTRACT FROM AUTHOR]

Coordination chemistry is a powerful method to synthesize supramolecular cages with distinct features that suit specific applications. This work demonstrates the synthesis of discrete, homochiral FeII2L3 cages via chirality‐driven self‐assembly. Specifically, the installation of chirality – at both the vertices and ligand backbones – allows the formation of discrete, homochiral FeII2L3 cages of different sizes via stereochemical control of the iron(II) centers. We observed that larger cages require multiple chiral centra (chiral ligands and vertices). In contrast, the formation of smaller cages is stereoselective with solely chiral ligands. The latter cages can also be formed from two chiral subcomponents, but only when they have matching chirality. Single‐crystal X‐ray diffraction of these smaller FeII2L3 cages revealed several non‐covalent interactions as a driving force for narcissistic chiral self‐sorting. This expected behavior was confirmed utilizing the shorter ligands in racemic form, yielding discrete, homochiral FeII2L3 cages formed in enantiomeric pairs. [ABSTRACT FROM AUTHOR]

The syntheses of two novel mechanically chiral rotaxanes containing urea and squaramide motifs (in yields of 33 % and 22 %, respectively) are presented. 1H NMR spectroscopic titrations reveal shuttling of the macrocycle – detectable by modulation of the expression of mechanical chirality in the NMR spectrum – is possible through the addition of achiral chloride anions, a process which is reversed by the addition of sodium cations. [ABSTRACT FROM AUTHOR]

Stabilization of chiral propeller conformations in triaryl compounds is challenging due to generally low racemization barriers. Nonetheless, it was recently found that chiral conformational preferences can be induced to triaryl boranes by incorporating point‐chiral alkylether chains to the aryl blades and subsequently locking the structure with ammonia. A four‐point interaction, meaning that the cooperative effects of Lewis‐adduct formation and three hydrogen bonds, was proposed as stabilizing mechanism. Herein, it was shown that three such strong interactions suffice to introduce a preferential propeller handedness. Although DFT calculations predict no noteworthy preferences for either P‐ or M‐chiral propellers for some of the investigated triarylborane–amine adducts that were prepared with chiral primary amines, vibrational circular dichroism (VCD) spectroscopic characterizations revealed that there is indeed a measurable excess of one propeller handedness. Furthermore, the steric demand of the amine was found to play a key role in the induction process and especially in preventing blade rotations. [ABSTRACT FROM AUTHOR]

A highly accurate and reliable screening method for enantiomeric excess of amine derivatives in the presence of water is reported. The fluorescence-based screening system has been realized by self-assembly of chiral diol-type dyes (BINOL, VANOL and VAPOL), 2-formylphenylboronic acid, and chiral amines forming iminoboronate esters. The structure and chirality of the amine analytes determine the stability of the diastereomeric iminoboronate esters, which in turn display differential fluorescence. The fluorescence signal reflects the enantiomeric purity of the chiral amines and was utilized in high-throughput arrays. The arrays were able to recognize enantiomeric excess of amines, amino esters, and amino alcohols. In addition to qualitative analysis, quantitative experiments were successfully performed. Studies of the role of additives such as water or citrate were carried out to gain insight into the stability of the iminoboronate esters. It is shown that the above additives destabilize less stable esters while the stable esters remain unchanged. Thus, the presence of water and citrate leads to increased difference between the diastereomeric iminoboronates and contributes to the enantiodiscrimination of the chiral amines. [ABSTRACT FROM AUTHOR]

Chiral head groups have been introduced into water-soluble hydroxyl-terminated nonionic amphiphiles and the impact of the head group stereochemistry on the supramolecular ultrastructures has been studied. Enantiomeric isomers were compared with the achiral meso form and the racemic mixture by means of cryogenic transmission electron microscopy and circular dichroism spectroscopy. Structurally, all amphiphiles are composed of the first-generation hydrophilic polyglycerol head group coupled to a single hydrophobic hexadecyl chain through an amide linkage and diaromatic spacer. The enantiomers aggregate to form twisted ribbons with uniform handedness, whereas the meso stereoisomer and racemic mixture produce elongated assemblies, namely, tubules and platelets, but without a chiral ultrastructure. Simulations on the molecular packing geometries of the stereoisomers indicate different preferential assembly routes that explain the individual supramolecular aggregation behavior. [ABSTRACT FROM AUTHOR]

Molecular capsules composed of amino acid or peptide derivatives connected to resorcin[4]arene scaffolds through acylhydrazone linkers have been synthesized using dynamic covalent chemistry (DCC) and hydrogen-bond-based self-assembly. The dynamic character of the linkers and the preference of the peptides towards self-assembly into β-barrel-type motifs lead to the spontaneous amplification of formation of homochiral capsules from mixtures of different substrates. The capsules have cavities of around 800 Å3 and exhibit good kinetic stability. Although they retain their dynamic character, which allows processes such as chiral self-sorting and chiral self-assembly to operate with high fidelity, guest complexation is hindered in solution. However, the quantitative complexation of even very large guests, such as fullerene C60 or C70, is possible through the utilization of reversible covalent bonds or the application of mechanochemical methods. The NMR spectra show the influence of the chiral environment on the symmetry of the fullerene molecules, which results in the differentiation of diastereotopic carbon atoms for C70, and the X-ray structures provide unique information on the modes of peptide-fullerene interactions. [ABSTRACT FROM AUTHOR]

Keywords: chirality switching; pillar[n]arenes; solvent mixing; supramolecular chemistry; temperature effects Solvent mixing drastically varied the inversion temperature of MUJs, and the temperature-driven chirality switching direction could be critically controlled by mixing the ratios of two solvents. Solvent mixing drastically varied the inversion temperature of MUJs, and the temperature-driven chirality switching direction could be critically controlled by mixing the ratios of two solvents. [Extracted from the article]

Heterometal arrays in molecular aggregations were obtained by the spontaneous and ultrasound-induced gelation of organic liquids containing the chiral, clothespin-shaped trans-bis(salicylaldiminato) d8 transition-metal complexes 1. Heterometallic mixtures of complexes 1 a (Pd) and 1 b (Pt) underwent strict heterochiral aggregation entirely due to the organic shell structure of the clothespin shape, with no effect of the metal cores. This phenomenon provides an unprecedented means of generating highly controlled heterometallic arrangements such as alternating sequences [(+)-Pd(−)-Pt(+)-Pd(−)-Pt ⋅⋅⋅] as well as a variety of single metal-enriched arrays (e.g., [(+)-Pt(−)-Pd(+)-Pd(−)-Pd(+)-Pd(−)-Pd ⋅⋅⋅] and [(+)-Pd(−)-Pt(+)-Pt(−)-Pt(+)-Pt(−)-Pt ⋅⋅⋅]) upon the introduction of an optically active masquerading unit with a different metal core in the heterochiral single-metal sequence. The present method can be applied to form various new aggregates with optically active Pd and Pt units, to allow 1) tuning of the gelation ultrasound sensitivity based on the different hearing abilities of the metal units; 2) aggregation-induced chirality transfer between heterometallic species; and 3) aggregation-induced chirality enhancement. A mechanistic rationale is proposed for these molecular aggregations based on the molecular structures of the units and the morphologies of the aggregates. [ABSTRACT FROM AUTHOR]

Advanced graph set analysis has been proposed by incorporating a concept of symmetry into conventional graph set analysis. Based on the advanced graph set analysis, handedness determinations were demonstrated on supramolecular hidden chirality of three types of hydrogen‐bonded networks, 0D‐cubic, 1D‐ladder, and 2D‐sheet networks, by characterizing the symmetric properties of their component ring‐type hydrogen‐bonded networks formed by primary ammonium carboxylates. For more details see the Full Paper by I. Hisaki, M. Miyata et al. on page 2478 ff. [ABSTRACT FROM AUTHOR]

Although chiral nanostructures have been fabricated at various structural levels, the transfer and amplification of chirality from molecules to supramolecular self‐assemblies are still puzzling, especially for heterochiral molecules. Herein, four series of C2‐symmetrical dipeptide‐based derivatives bearing various amino acid sequences and different chiralities are designed and synthesized. The transcription and amplification of molecular chirality to supramolecular assemblies are achieved. The results show that supramolecular chirality is only determined by the amino acid adjacent to the benzene core, irrespective of the absolute configuration of the C‐terminal amino acid. In addition, molecular chirality also has a significant influence on the gelation behavior. For the diphenylalanine‐based gelators, the homochiral gelators can be gelled through a conventional heating–cooling process, whereas heterochiral gelators form translucent stable gels under sonication. The racemic gels possess higher mechanical properties than those of the pure enantiomers. All of these results contribute to an increasing knowledge over control of the generation of specific chiral supramolecular structures and the development of new optimized strategies to achieve functional supramolecular organogels through heterochiral and racemic systems. [ABSTRACT FROM AUTHOR]

The reaction in basic media of manganese chloride with Schiff bases derived from the condensation of o‐vanillin with different chiral/racemic aminoalcohols yielded in a family of complexes in which the nuclearity, symmetry and magnetic behavior is controlled by changing the position of the chiral carbon. Chiral and racemic clusters with [MnIII6MnIINaI], [MnIII6MnII2NaI2] and [MnIII3MnIINaI] metallic core have been structurally and magnetically characterized. The racemic clusters with an odd number of chiral ligands exhibit the anomalous mixing of ligands with different conformation. Related racemic compounds have been reviewed. [ABSTRACT FROM AUTHOR]

The syntheses of novel amphiphilic 5,5′,6,6′‐tetrachlorobenzimidacarbocyanine (TBC) dye derivatives with aminopropanediol head groups, which only differ in stereochemistry (chiral enantiomers, meso form and conformer), are reported. For the achiral meso form, a new synthetic route towards asymmetric cyanine dyes was established. All compounds form J aggregates in water, the optical properties of which were characterised by means of spectroscopic methods. The supramolecular structure of the aggregates is investigated by means of cryo‐transmission electron microscopy, cryo‐electron tomography and AFM, revealing extended sheet‐like aggregates for chiral enantiomers and nanotubes for the mesomer, respectively, whereas the conformer forms predominately needle‐like crystals. The experiments demonstrate that the aggregation behaviour of compounds can be controlled solely by head group stereochemistry, which in the case of enantiomers enables the formation of extended hydrogen‐bond chains by the hydroxyl functionalities. In case of the achiral meso form, however, such chains turned out to be sterically excluded. [ABSTRACT FROM AUTHOR]

A chiral, octahedral M12L12 cage, which is charge neutral and contains an internal void of about 2000 Å3, is reported. The cage was synthesised as an enantiopure complex by virtue of amino‐acid‐based dicarboxylate ligands, which assemble around copper paddlewheels at the vertices of the octahedron. The cage persists in solution with retention of the fluorescence properties of the parent acid. The solid‐state structure contains large pores both within and between the cages, and displays permanent porosity for the sorption of gases with retention of crystallinity. Initial tests show some enantioselectivity of the cage towards guests in solution. [ABSTRACT FROM AUTHOR]

Directional self‐assembly of uncharged molecules in water is a major challenge in supramolecular chemistry. Herein, it is demonstrated that peptide‐based cavitands wrap around a hydrophobic core (fullerene C60) by a combination of the hydrophobic effect and hydrogen‐bonding interactions to form highly ordered three‐component complexes in water that resemble the molten‐globule stage of protein folding. The complexes were characterized by DOSY NMR spectroscopy, small‐angle X‐ray scattering, and circular dichroism, and their structures were confirmed by X‐ray crystallography. Enhancement of the CD signals by nearly one order of magnitude and increased hydrolytic stability of hydrazone bonds of the complexes relative to the nonassembled species were observed. In contrast, DMSO and DMSO/water mixtures were found to be highly disintegrative for these complexes. Interestingly, some cavitands can only be synthesized in the presence of the hydrophobic template followed by disassembly of the complexes. Highly competitive: Directional self‐assembly of uncharged molecules in water is a major challenge in supramolecular chemistry. In this work, a combination of hydrogen bonding and the hydrophobic effect allows peptide‐based cavitands to wrap around a C60 fullerene core to form well‐ordered noncovalent chiral assemblies in a highly competitive environment involving intermolecular and intramolecular interactions with water and charged substituents, respectively. [ABSTRACT FROM AUTHOR]

Postfunctionalization of the aluminate anion [EtAl(6‐Me‐2‐py)3]− (1) (2‐py=2‐pyridyl) with alkoxide ligands can be achieved by the selective reactions of the lithium salt 1 Li with alcohols in the appropriate stoichiometry. This method can be used to introduce 3‐ and 4‐py functionality in the form of 3‐ and 4‐alkoxymethylpyridyl groups, while maintaining the integrity of the aluminate framework, thereby giving entry to new supramolecular chemistry. Chirality can be introduced either by using a chiral alcohol as a reactant or by the stepwise reaction of 1 Li with two different nonchiral alcohols. The latter route has allowed the synthesis of a rare example of a chiral‐at‐aluminium aluminate. Deconstructing the scorpionate: Postfunctionalization of the aluminate anion [EtAl(6‐Me‐2‐py)3]− (2‐py=2‐pyridyl) with alkoxide ligands can be used to incorporate different functionalities (see figure), introducing supramolecular chemistry and chirality, either at the ligand or at the Al centre. [ABSTRACT FROM AUTHOR]

Synthesis of the first enantiomerically pure chiral bambusurils is reported. The bambusurils were prepared on the gram scale without using any chromatography techniques. The bambusurils formed supramolecular complexes with all tested chiral carboxylates including amino acids and drug molecules with the enantioselectivity ranging from 1.1 to 3.2. Macrocyclization of glycoluril diastereomers leads to enantiomerically pure chiral bambusurils with the ability to recognize biologically relevant carboxylate anions. [ABSTRACT FROM AUTHOR]

Supramolecular chirality was observed in a charge-transfer (CT) complex formed by self-assembly of β-cyclodextrin-linked pyrene and adamantane-linked pyromellitic diimide in water. In the complex, the pyrene-pyromellitic diimide CT interaction is reinforced several-fold by the strong β-cyclodextrin-adamantane inclusion binding interaction, as confirmed by 1H NMR, absorption, fluorescence and isothermal titration calorimetry studies. The CT complex exhibited high stability, as inferred from the temperature-dependent absorption and NMR studies. The CT absorption band exhibited a positive Cotton effect indicative of supramolecular chirality for the complex. Twisted fibres were observed in TEM, AFM, and SEM experiments. A mechanism involving synergistic binding interactions leading to 2D sheets, followed by twisting of the sheet, is proposed for the formation of twisted fibres. This system offers a chance to investigate a combination of supramolecular CT and supramolecular chirality and explore their synergistic effects. [ABSTRACT FROM AUTHOR]

Recognition of enantiomers of chiral acids by anion-π or lone pair-π interactions has not yet been investigated but is a significant and attractive challenge. This study reports an optically active polymer-based supramolecular system with capabilities of discriminating enantiomers of various chiral acids. The polymer featuring alternate π-acidic naphthalenediimides (NDIs) and methyl l-phenylalaninates in the backbone exhibits an unprecedented slow self-assembly process that is susceptible to perturbation by various chiral acids. Thus, the combination of anion-π or lone pair-π interactions and sensitivity of the polymeric self-assembly process to external chiral species endows the system with recognition capabilities. This is the first time that anion-π or lone pair-π interactions have been applied in the recognition of enantiomers of various chiral acids with a single system. The results shed light on new strategies for material design by integrating π-acidic aromatic systems and chiral building blocks to afford relevant advanced functions. [ABSTRACT FROM AUTHOR]

Chiral helical structures have attracted increasing attention in the field of supramolecular assembly because of their critical roles in life and material sciences. In this research, the achiral amphiphile 1-[11-(2-anthracenylmethoxy)-11-oxoundecyl]pyridinium bromide ( 2-APB), in which the hydrophobic anthracene and the hydrophilic pyridinium units are linked by alkyl chains, was found to form chiral supramolecular assemblies in a cooperative manner in the presence of iodide anion. Moreover, these assemblies show left (L)- or right (R)-handedness randomly, independent of the assembly conditions. By using the same method, 2-APB could assemble together with other pseudo-halogen anions (OCN−, SCN−, SeCN−) that have similar anionic radius as iodide to form chiral structures. This work illustrates a simple and rational design that can be used to fabricate supramolecular chiral structures from achiral molecules. [ABSTRACT FROM AUTHOR]

Enantiopure alleno-acetylenic ligands, containing two chiral allene moieties, assemble diastereoselectively with zinc(II) ions to form trinuclear triple-stranded helicates, featuring two internal cavity binding sites ('helicages'). The addition of cycloalkanes or heteroalicycles results in inclusion complex formation with two guest molecules bound in one helicate. While no positive allosteric effects were observed, the chiroptical responses increased strongly upon complexation, with guest-induced circular dichroism (ICD) signals reaching up to ΔΔ ϵ=205 m−1 cm−1. The highest binding affinity was observed for six-membered 1,4-dichalcogens, with binding constants ( K1) of up to 2400 m−1 for 1,4-oxathiane in CD3OD. The X-ray co-crystal structure of 1,4-dioxane bound to a dinuclear triple-stranded helicate confirmed the previously predicted guest orientation inside the helicage, with the two oxygen atoms facing towards the electropositive zinc(II) metal centers. [ABSTRACT FROM AUTHOR]

Stereodynamic optical probes are becoming very popular for their capability to act as molecular sensors for the determination of the enantiomeric excess ( ee) of chiral compounds. Herein, we describe a new molecular architecture formed by the self-assembly of three zinc metal ions, two modified tris(2-pyridylmethyl)amine ligands, and two amino acids. This system is the structural and functional serendipitous evolution of our previous probe for the determination of amino acids ee. In the new system, one of the metals templates in close proximity two chromophores enhancing their exciton coupling. [ABSTRACT FROM AUTHOR]

Two pairs of enantiomeric compounds with formulas ( S)- or ( R)-Co3(ppap)2(4,4′-bpy)2(H2O)2 ⋅4 H2O [( S)- 1 or ( R)- 1], ( S)- or ( R)-Co3(ppap)2(4,4′-bpy)2(H2O)2 ⋅3 H2O [( S)- or ( R)- 2), and related racemic compound Co3(ppap)2(4,4′-bpy)2(H2O)2 ⋅4 H2O ( rac- 3; 4,4′-bpy=4,4′-bipyridine, H3ppap=3-phenyl-2-[(phosphonomethyl)amino]propanoic acid) are reported. Compounds 1 and rac- 3 show identical three-dimensional framework structures, whereas compounds 2 have two-dimensional layer structures. Compounds 1 and 2 are catenation isomers, formation of which is controlled solely by the pH of the reaction mixtures, whereas the formation of isomeric compounds 1 and rac- 3 is controlled purely by the chirality of the phosphonate ligand. The magnetic properties of fully dehydrated ( S)- 1, ( S)- 2, and rac- 3 are highly dependent on both structure and chirality. [ABSTRACT FROM AUTHOR]

In this study, we have conducted a systematic investigation of the chiral recognition of carboxylic anions by D-glucuronic acid/diindolylmethane receptors. We investigate the influence of the anion structure on chiral recognition in the diindolylmethane/glucuronic acid-based receptor 1 a. We found that presence of an additional hydrogen-bond donor at the α position to the carboxylic function is essential for effective chiral differentiation in these systems. Furthermore, we present a synthetic procedure that allows for the synthesis of sugar-decorated receptors that possess a modified substituent at the anomeric position. Four new receptors 1 b- e have been synthesized, and their chiral-discrimination ability toward model carboxylates is studied. The obtained results show that the chiral recognition of these receptors can be fine-tuned by incorporation of a proper substituent into the receptor structure. [ABSTRACT FROM AUTHOR]

The twisting of supramolecular aggregates formed from simple linear bis(benzamides) has been investigated. The antiparallel arrangement of the amide functional groups controls the generation of twisted supramolecular structures. The results presented herein could contribute to elaborate predictive tools applicable in the generation of chiral supramolecular structures. [ABSTRACT FROM AUTHOR]

A chiral selection process in a self-assembled soft monolayer of an achiral amphiphile as a consequence of its interaction with chiral species dissolved in the aqueous subphase, is reported. The extent of the chiral selection is statistically measured in terms of the enantiomorphic excess of self-assembled submillimeter domains endowed with well-defined orientational chirality that is unambiguously resolved using optical microscopy. Our results show that the emergence of chirality is mediated by electrostatic interactions and significantly enhanced by hydrophobic effects. This chiral chemical effect can be suppressed and even reversed by opposing a macroscopic physical influence, such as vortical stirring. This result gives evidence for the crucial role of hydrodynamic effects in supramolecular aggregation. [ABSTRACT FROM AUTHOR]

The C3-symmetric chiral propylated host-type ligands (±)- tris(isonicotinoyl)- tris(propyl)-cyclotricatechylene ( L1) and (±)- tris(4-pyridyl-4-benzoxy)- tris(propyl)-cyclotricatechylene ( L2) self-assemble with PdII into [Pd6L8]12+ metallo-cages that resemble a stella octangula. The self-assembly of the [Pd6( L1)8]12+ cage is solvent-dependent; broad NMR resonances and a disordered crystal structure indicate no chiral self-sorting of the ligand enantiomers in DMSO solution, but sharp NMR resonances occur in MeCN or MeNO2. The [Pd6( L1)8]12+ cage is observed to be less favourable in the presence of additional ligand, than is its counterpart, where L=(±)- tris(isonicotinoyl)cyclotriguaiacylene ( L1 a). The stoichiometry of reactant mixtures and chemical triggers can be used to control formation of mixtures of homoleptic or heteroleptic [Pd6L8]12+ metallo-cages where L= L1 and L1 a. [ABSTRACT FROM AUTHOR]

Herein, we designed chiral photoresponsive tetra(2-phenylthiazole)s, which induce a diastereoselective 6π-electrocyclization reaction in a helically folded structure to freeze the conformational interconversions. The folding conformation with one helical turn of tetra(2-phenylthiazole)s was supported by multiple intramolecular noncovalent interactions including vicinal S⋅⋅⋅N interheteroatom interactions and CH-π and π-π stacking interactions between nonadjacent units, as found in X-ray crystal structures as well as quantum chemical calculations. The introduction of a chiral group at both ends of tetra(2-phenylthiazole) dictates the preferential folding into a one-handed helix conformation by the simultaneous operation of S⋅⋅⋅O and multiple CH-π interactions that involve the chiral end groups. Since the tetra(2-phenylthiazole)s possess two equivalent photoreactive 6π-electron systems and the folded conformation is suitable for photoinduced electrocyclization reaction, they undergo a photocyclization reaction in a stereoselective manner to memorize the chirality of the helix in a resulting diastereomeric closed form. [ABSTRACT FROM AUTHOR]

A 1,1′-binaphthyl-based bis(pyridine) ligand ( 1) was prepared in racemic and enantiomerically pure form to study the formation of [Pd2( 1)4] complexes upon coordination to palladium(II) ions with regard to the degree of chiral self-sorting. The self-assembly process proceeds in a highly selective narcissistic self-recognition manner to give only homochiral supramolecular M2L4 cages, which were characterized by ESI-MS, NMR, and electronic circular dichroism (ECD) spectroscopy, as well as by single-crystal XRD analysis. [ABSTRACT FROM AUTHOR]

A chiral bisurea-based superhydrogelator that is capable of forming supramolecular hydrogels at concentrations as low as 0.2 m M is reported. This soft material has been characterized by thermal studies, rheology, X-ray diffraction analysis, transmission electron microscopy (TEM), and by various spectroscopic techniques (electronic and vibrational circular dichroism and by FTIR and Raman spectroscopy). The expression of chirality on the molecular and supramolecular levels has been studied and a clear amplification of its chirality into the achiral analogue has been observed. Furthermore, thermal analysis showed that the hydrogelation of compound 1 has a high response to temperature, which corresponds to an enthalpy-driven self-assembly process. These particular thermal characteristics make these materials easy to handle for soft-application technologies. [ABSTRACT FROM AUTHOR]

The chiral bicyclic diguanidinium chloride 1 forms gels in aromatic apolar solvents. The gels were characterized at different levels of organization, from the macroscopic to the molecular level by using microscopy, spectroscopy, and powder X-ray diffraction. The dependency on chirality has been highlighted by circular dichroism and electron microscopy. Furthermore, the gel has been shown to be effectively responsive to anionic stimuli, thus allowing the reversible control of the organic-phase gelation in contact with different salted aqueous solutions. [ABSTRACT FROM AUTHOR]

The aggregation of achiral sulfonatophenyl- and phenyl- meso-substituted diprotonated porphyrins to chiral J-aggregates is a hierarchical noncovalent polymerization process preceded by a critical nucleation stage. This allows significant enantiomeric excesses by the formation of a few primary nuclei and the control of their growth by the effect that flows (imperfect mixing) have on the secondary nucleation of the J-aggregate particles. In addition, the results strongly suggest that when only one species of aggregate predominates, the CD signals of the three excitonic bands in the visible region (around 420, 490, and 700 nm) show the same sign. Thus, differences on their relative sign would be due to the presence of different species. [ABSTRACT FROM AUTHOR]