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Inspired by the synthetic and biological potential of organotellurium substances, a series of five‐ and six‐membered ring organotelluranes containing a Te−O bond were synthesized and characterized. Theoretical calculations elucidated the mechanism for the oxidation‐cyclization processes involved in the formation of the heterocycles, consistent with chlorine transfer to hydroxy telluride, followed by a cyclization step with simultaneous formation of the new Te−O bond and deprotonation of the OH group. Moreover, theoretical calculations also indicated anti‐diastereoisomers to be major products for two chirality center–containing compounds. Antileishmanial assays against Leishmania amazonensis promastigotes disclosed 1,2λ4‐oxatellurane LQ50 (IC50=4.1±1.0; SI=12), 1,2λ4‐oxatellurolane LQ04 (IC50=7.0±1.3; SI=7) and 1,2λ4‐benzoxatellurole LQ56 (IC50=5.7±0.3; SI=6) as more powerful and more selective compounds than the reference, being up to four times more active. A stability study supported by 125Te NMR analyses showed that these heterocycles do not suffer structural modifications in aqueous‐organic media or at temperatures up to 65 °C. [ABSTRACT FROM AUTHOR]

Recent investigations of supramolecular polymers based on chiral triphenylene‐2,6,10‐tricarboxamides (TTAs) showed how temperature‐induced changes in solvation can greatly influence the preferred helical conformation of the supramolecular polymers formed. Here, we combine chiral TTA with achiral copolymerization partners to further investigate temperature‐dependent solvation effects. Systematic variation of the system's composition shows clear impacts on the temperature window where the conformational change occurs. Further, simple chain length variations in the achiral comonomer greatly affect the ability to influence the conformational change in the copolymer, while the differences in the properties of the individual homopolymers are rather small. We herein highlight how subtle changes in the monomers can impact the observed copolymer properties drastically; an effect arising from the emerging complexity of multicomponent interactions in supramolecular copolymers with solvent‐solute interactions being more important than typically thought. [ABSTRACT FROM AUTHOR]

The objective of this pen-and-paper study is to witness the emergence of stereoisomeric properties when comparing lower to higher families of homologs. Specifically, the study compares all acyclic hexanes (five constitutional isomers, a.k.a. regioisomers), all nine heptanes, all 18 octanes, all 35 nonanes, and all 75 decanes. The first part of the work examines the nature and number of stereoisomeric properties seen to emerge in chemical structures featuring one chiral center (i.e., enantiomerism) or two such centers, in which case more complex stereoisomeric features emerge (enantiomerism, diastereoisomerism, pseudoasymmetry, and meso-isomers). The first emergence of chirality (i.e., enantiomerism) occurred in some heptanes. Diastereoisomerism and meso-isomers appear with some octanes, while a pseudoasymmetric center exists in a decane regioisomer. The second part of the work is an attempt to rationalize the numbers of regioisomers, chiral centers, and stereoisomers as these numbers grow from one family of regioisomers to the higher ones. Far from being random, such increases prove regular and ordered. [ABSTRACT FROM AUTHOR]

This paper clarifies the relationship between the molecular structures of chiral nematic liquid crystals and the shift in their reflection spectrum resulting from contact with volatile organic compounds (VOCs). We also propose a mechanism to explain the red- or blue-shift in the peak wavelength upon contact with VOC vapor. Furthermore, enhancement of the sensitivity of this method of VOC detection is discussed. [ABSTRACT FROM AUTHOR]

Introduction of heterocycles into the helical skeleton of helicenes allows modulation of their redox, chiroptical, and photophysical properties. This paper describes the straightforward preparation and structural characterization by single-crystal X-ray diffraction of thiadiazole-[7]helicene, which was resolved into M and P enantiomers by chiral HPLC, together with its S-shaped double [4]helicene isomer, as well as the smaller congeners thiadiazole-[5]helicene and benzothiadiazole-anthracene. A copper(II) complex with two thiadiazole-[5]helicene ligands was structurally characterized, and it shows the presence of both M and P isomers coordinated to the metal center. The emission properties of the heterohelicenes are highly dependent on the helical turn, as the [7]- and [5]helicene are poorly emissive, whereas their isomers, that is, the S-shaped double [4]helicene and thiadiazole-benzanthracene, are luminescent, with quantum efficiencies of 5.4 and 6.5 %, respectively. DFT calculations suggest quenching of the luminescence of enantiopure [7]helicenes through an intersystem-crossing mechanism arising from the relaxed excited S1 state. [ABSTRACT FROM AUTHOR]

A strategy to reversibly switch the parallel/antiparallel helical conformation of aromatic double helices through the formation/breakage of a disulfide bond is presented. Single‐crystal X‐ray structures, NMR, and circular dichroism spectroscopy demonstrate that the double helices with terminal thiol groups favor an antiparallel helical arrangement both in the solid state and in solution, while the P/M bias of helicity induced by chiral segments from another extremity of the sequence is weak in this structural motif. The antiparallel helices can be rearranged to parallel helices through the disulfide connection of the sequences. This change enhances the bias of helical handedness and results in absolute chirality control of the double helices. The handedness‐mediated process can be governed by the oxidation‐reduction cycle, thereby switching the structural arrangement and the enhancement of chiral bias. In addition, we find that the sequences can dimerize into an intermolecular double helix with the disulfide connection. And the helical handedness is also fully controlled due to the head‐to‐head structural motif. [ABSTRACT FROM AUTHOR]

A new class of chiral C2‐symmetric diphosphines (MediPhos) was recently shown to give superior results in the Pd‐catalyzed asymmetric N‐allylation of amino acid esters. We here describe a new, improved protocol for the preparation of such ligands through bidirectional SN2‐coupling of a tartrate‐derived ditosylate with 6‐alkyl‐2‐bromophenols followed by double lithiation/phosphanylation. This method gave access to a series of nine ligands with branched alkyl substituents, which were benchmarked in the enantioselective Pd‐catalyzed N‐allylation of tert‐butyl glycinate with racemic (E)‐2,8‐dimethylnona‐5‐en‐4‐yl methyl carbonate (up to 95 % ee). In addition, the analogous transformation of tert‐butyl glycinate with methyl (E)‐nona‐5‐en‐4‐yl carbonate was optimized. The obtained allylic amines were then used in the stereoselective synthesis of the conformationally restricted proline‐derived dipeptide analogs ProM‐17 and ProM‐21. [ABSTRACT FROM AUTHOR]

Continuous intensification of reaction screening methodologies has required the development of novel high‐throughput analytical technologies. This urge involves also chirality related fields where nowadays novel methods for reliable, fast and effective analysis are developed. Within this field, chiroptical spectroscopies have emerged as promising techniques, in particular when they are combined with stereodynamic probes for optical signal amplification. We report here the synthesis and characterisation of a series of molecular architectures based on a modified tris(2‐pyridylmethyl)amine (TPMA) complex which are able to amplify the electronic CD signal of phenylalanine. The study reports the synthesis of six novel TPMA based supramolecular architectures characterised by the presence of two different metals within the same molecule. Besides the synthesis, the study highlights how mixing metals influences the chiroptical properties of the formed compounds. [ABSTRACT FROM AUTHOR]

The Cover Feature shows a supramolecular catalytic system, envisioned as a factory machine. The worker uses a chiral cyclohexane to control the chirality in the remote rhodium machine head which does the selective hydrogenation reaction. The transfer of chirality is achieved by stacked phenyl‐phosphine gears shown in the insides of the machine. The system has enabled distant chirality transfer, named 𠄌backdoor induction", for hydrogenation of model substrates with very high selectivity (up to 97% ee). The future goal is to apply this system to industrially relevant substrates. More information can be found in the Full Paper by S. I. Kirin et al. [ABSTRACT FROM AUTHOR]

Rhodium(I) floating between the five nitrogen atoms of sapphyrin and how this affects chirality of the corresponding complex are depicted in the cover image. In addition, this work focuses on the CF3‐stabilized derivative and its ability to catalyze cyclopropanation. More information can be found in the Full Paper by Z. Gross et al. on page 17255. [ABSTRACT FROM AUTHOR]

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]

In this paper, both gyrotropy and chirality are introduced in some composite bianisotropic chiral- and chiroferrite–ferrite microstrip line structures. The propagation characteristics are investigated using the generalized exponential technique in the spectral domain combined with the Galerkin's method. These microstrip structures include shielded single, edge-coupled, broadside coupled, and bilateral edge-coupled geometries. Numerical calculations are performed so as to examine the compatible effects of changing different variables associated with the operating frequency, gyrotropy and chirality parameters on the dominant mode propagation constant or the differential phase shifter of forward and backward waves, respectively. It is shown that the influences of chirality are just diverse, and it could be exploited as a new freedom to adjust the differential phase in chiral- and chiroferrite–ferrite microstrip lines. Such compatible properties are useful for the design of new planar microstrip integrated devices. Copyright © 1999 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Two‐dimensional hybrid halide perovskites with single chiral and ferroelectricity together with various structural phase transitions provide the possibility for more diverse functional properties. Here, we present a 2D chiral hybrid halide perovskite ferroelectric, [C6H5(CH2)4NH3]2CdCl4 (4PBA−CdCl4, 4PBA=4‐phenylbutylamine) that experiences two continuous phase transitions from centrosymmetric triclinic P1‾ to polar chiral monoclinic P2 and then to another centrosymmetric tetragonal P4/mmm with increasing temperature, accompanied by symmetry breaking, due to the prominent octahedral distortion and disorder transformation of organic 4PBA cations. In the polar chiral phase, 4PBA−CdCl4 gives a significant CD signal and has a moderate ferroelectric polarization of 0.35 μC/cm2. In addition, 4PBA−CdCl4 occupies a wide band gap of 4.376 eV that is chiefly contributed by the inorganic CdCl6 octahedron. This finding offers an alternative pathway for designing new phase transitions and related physical properties in hybrid halide perovskites and other hybrid crystals. [ABSTRACT FROM AUTHOR]

The first asymmetric catalytic approach to multilayer 3D chirality has been achieved by using Suzuki‐Miyaura cross‐couplings. New chiral catalysts were designed and screened under various catalytic systems that proved chiral amide‐phosphines to be more efficient ligands than other candidates. The multilayer 3D framework was unambiguously determined by X‐ray structural analysis showing a parallel pattern of three layers consisting of top, middle and bottom aromatic rings. The X‐ray structure of a catalyst complex, dichloride complex of Pd‐phosphine amide, was obtained revealing an interesting asymmetric environment nearby the Pd metal center. Three rings of multilayer 3D products can be readily changed by varying aromatic ring‐anchored starting materials. The resulting multilayer products displayed strong luminescence under UV irradiation and strong aggregation‐induced emission (AIE). In the future, this work would benefit not only the field of asymmetric synthesis but also materials science, in particular polarized organic electronics, optoelectronics and photovoltaics. [ABSTRACT FROM AUTHOR]

Mono‐ and di‐boranil‐substituted helicenes were prepared by BF2‐borylation of the corresponding anils, readily synthesized by condensation of 2‐amino‐ and 2,15‐diamino‐helicenes with 4‐(diethylamino)salicylaldehyde. After enantiomeric resolution using HPLC, their chiroptical properties including circularly polarized fluorescence in solution and in PMMA films were investigated and rationalized with the help of NMR, X‐ray and quantum‐chemical calculations. [ABSTRACT FROM AUTHOR]

Enzyme stereoselectivity control is still a major challenge. To gain insight into the molecular basis of enzyme stereo‐recognition and expand the source of antiPrelog carbonyl reductase toward β‐ketoesters, rational enzyme design aiming at stereoselectivity inversion was performed. The designed variant Q139G switched the enzyme stereoselectivity toward β‐ketoesters from Prelog to antiPrelog, providing corresponding alcohols in high enantiomeric purity (89.1–99.1 % ee). More importantly, the well‐known trade‐off between stereoselectivity and activity was not found. Q139G exhibited higher catalytic activity than the wildtype enzyme, the enhancement of the catalytic efficiency (kcat/Km) varied from 1.1‐ to 27.1‐fold. Interestingly, the mutant Q139G did not lead to reversed stereoselectivity toward aromatic ketones. Analysis of enzyme–substrate complexes showed that the structural flexibility of β‐ketoesters and a newly formed cave together facilitated the formation of the antiPrelog‐preferred conformation. In contrast, the relatively large and rigid structure of the aromatic ketones prevents them from forming the antiPrelog‐preferred conformation. [ABSTRACT FROM AUTHOR]

The dynamic interplay between two types of chiral structures; fully conjugated racemic hetero[7]helicenes and DNA strands prone to fold into G‐quadruplex structures is described. Both the [7]helicenes and the G‐quadruplex DNA structures exist in more than one conformation in solution. We show that the structures interact with and stabilise each other, mutually amplifying and stabilising certain conformations at increased temperatures. The [7]helicene ligands L1 and L2 stabilise the parallel conformation of k‐ras significantly, whereas hybrid (K+) and antiparallel (Na+) h‐telo G‐quadruplexes are stabilised upon conformational switching into altered G‐quadruplex conformations. Both L1 and L2 induce parallel G‐quadruplexes from hybrid structures (K+) and L1 induces hybrid G‐quadruplexes from antiparallel conformations (Na+). Enantioselective binding of one helicene enantiomer is observed for helicene ligand L2, and VTCD melting experiments are used to estimate the racemisation barrier of the helicene. [ABSTRACT FROM AUTHOR]

The finite element formulation for three-dimensional (3-D) chirowaveguides cannot be applied to 2-D ones because all components of the electromagnetic field in chiral media, even if a 2-D system is considered, are coupled. In this paper, the finite element formulation is described for the analysis of 2-D chirowaveguides. To show the validity of the present formulation, nuntrical results are shown for homogeneous chirowaveguides and are compared with exact solutions. Furthermore, to demonstrate the applicability of the present approach, chirowaveguides with graded chirality admittance profiles are investigated. [ABSTRACT FROM AUTHOR]

Controlling chromophore chirality in three‐dimensional space is crucial for understanding the structure–chiroptical relationship. Such control enables the prediction of ideal materials for use in chiral photonic applications. In this study, optically active multipyrene systems are synthesized on peptoids. Pyrene‐based chiral submonomers, (S)‐ and (R)‐1‐pyrenylethylamine (s1pye and r1pye), are successfully incorporated into peptoids as the respective (S)‐ and (R)‐N‐(1‐pyrenylethyl)glycine (Ns1pye and Nr1pye) units. NMR spectroscopy revealed length‐ and N‐acetylation‐dependent conformational homogeneity enhancement in solution, stabilizing cis‐amides in Ns1pye‐containing peptoids. The X‐ray crystal structure of Ns1pye tetramer displayed a polyproline type‐I (PPI)‐like helix. All of the pyrene‐related absorptions are circular dichroism (CD) active, and the CD signal related to the long‐axis‐polarized transition increased with helical stabilization. Intramolecular excimer generation yielded significant circularly polarized luminescence (CPL) in the excimer emission region. Early‐stage peptoids emitted left‐handed CPL, but upon acquiring a PPI‐like helix character, CPL handedness became inverted. The CPL dissymmetry factor (glum) was comparable or superior (10−2) to that of chiral organic dyes (10−5–10−2). This new class of helical pyrene‐containing peptoids provides a CPL‐active intramolecular excimer, modulating optical activity through peptoid secondary structure homogeneity. [ABSTRACT FROM AUTHOR]

A family of transition metal complexes of meso‐aryl‐2‐aza‐21‐carbaporphyrin (N‐confused porphyrin, NCP) derivatives acting as ortho‐metallating ligands for ruthenium(II), rhodium(III), and iridium(III) is synthesized and characterized by XRD, spectroscopic, and electrochemical methods. The chirality of these systems is shown by the separation of the enantiomers and analyzed by circular dichroism and DFT. A preliminary catalytic study indicates the activity of the iridium(III) ortho‐metallated complexes in the N‐heterocyclization of primary amines with diols. [ABSTRACT FROM AUTHOR]

In general, the optical properties of any general twisted nematic cells consist of two complementary effects: LC-birefringent and LC-director-twist effects. In this paper, electro-optical properties of ITN cells without chiral dopants with different pretilt angles have been investigated for the first time to differentiate the LC-birefringent effect from the LC-twist effect. We have investigated transient responses of the ITN cell and found that the optical-bounce (LC backflow) effect of the ITN cell occurred in the transition from homeotropic-to-planar states under high applied voltages where the LC-twist-effect dominated. We have also explained the superiority of high contrast ratio of the ITN cell over the tilted homeotropic cell with same pretilt angle due to mutual compensation between two surface-LC layers adjacent to ITN-cell substrates in quiescent state. [ABSTRACT FROM AUTHOR]

Controlling the sign of Excimer-Origin Circularly Polarised Luminescence by Balancing Hydrophilicity/Hydrophobicity in Bipyrenyl Arginine Peptides Keywords: arginine; chirality; circularly polarised luminescence (CPL); peptides; pyrene EN arginine chirality circularly polarised luminescence (CPL) peptides pyrene 2 2 1 01/20/21 20210101 NES 210101 B In this paper b , the circularly polarised luminescence (CPL) properties of peptides with pyrene in water is described. Arginine, chirality, circularly polarised luminescence (CPL), peptides, pyrene. [Extracted from the article]

Enantiomerically pure diarylmethylamines are important building blocks in active pharmaceutical ingredients. Herein, we report a rhodium precatalyst with a chiral disulfoxide ligand that effects the 1,2-addition of arylboroxines to aromatic imines to give high yields and high enantioselectivities of these products. The present paper describes a system that is very simple, where the ease of synthesis of the chiral ligand is combined with low catalyst loadings and reaction conditions that do not need any additives or external base. [ABSTRACT FROM AUTHOR]

Homopolypeptide-based alignment media can induce different orientations of enantiomers as a result of their α-helical structures. This property enables the discrimination of enantiomers through anisotropic NMR parameters such as residual dipolar couplings (RDCs). In this paper, the enantiodiscriminating properties of two alignment media derived from polyglutamic acid derivatives - poly-γ-benzyl- L-glutamate (PBLG) and poly-γ-ethyl- L-glutamate (PELG) - are compared and discussed. The two analytes, isopinocampheol and β-pinene, are investigated, and the role of the lateral side chain of the homopolypeptide in the orientation process is examined. [ABSTRACT FROM AUTHOR]

One of the greatest challenges in modern chemical processing is to achieve enantiospecific control in chemical reactions using chiral media such as chiral mesoporous materials. Herein, we describe a novel and effective synthetic pathway for the preparation of enantioselective nanoporous carbon, based on chiral ionic liquids (CILs). CILs of phenylalanine (CIL(Phe)) are used as precursors for the carbonization of chiral mesoporous carbon. We employ circular dichroism spectroscopy, isothermal titration calorimetry (ITC), and chronoamperometry in order to demonstrate the chiral nature of the mesoporous carbon. The approach presented in this paper is highly significant for the development of a new type of chiral porous materials for enantioselective chemistry. In addition, it contributes significantly to our understanding of the structure and nature of chiral nanoporous materials and surfaces. [ABSTRACT FROM AUTHOR]

Designing chiral AIEgens without aggregation‐induced emission (AIE)‐active molecules externally tagged to the chiral scaffold remains a long‐standing challenge for the scientific community. The inherent aggregation‐caused quenching phenomenon associated with the axially chiral (R)‐[1,1′‐binaphthalene]‐2,2′‐diol ((R)‐BINOL) scaffold, together with its marginal Stokes shift, limits its application as a chiral AIE‐active material. Here, in our effort to design chiral luminogens, we have developed a design strategy in which 2‐substituted furans, when appropriately fused with the BINOL scaffold, will generate solid‐state emissive materials with high thermal and photostability as well as colour‐tunable properties. The excellent biocompatibility, together with the high fluorescence quantum yield and large Stokes shift, of one of the luminogens stimulated us to investigate its cell‐imaging potential. The luminogen was observed to be well internalised and uniformly dispersed within the cytoplasm of MDA‐MB‐231 cancer cells, showing high fluorescence intensity. [ABSTRACT FROM AUTHOR]

A series of macrocycles that contain two quinoline oligoamide foldamers (QOFs) using various length of alkyl chains as linkers (2, 3, 6, 8 or 12 hydrocarbons) were synthesized. The two QOFs interact with each other through the linkers and the intramolecular helix chiral communications between the two QOFs were studied by 1H NMR spectroscopy and crystal structures. Investigations show that the intensity of the intramolecular helix chiral communications between the two QOFs is dependent on the length of the linkers, and the interaction between the two QOFs increases with decreasing length of the linkers. When the length of the linkers decreased to C2 linkers, only one conformer is present in solution. Moreover, increasing the length of the foldamers would enhance the intramolecular helix chiral communication if the linkers are short, indicating that the length of the foldamers also has significant impact on intramolecular helix chiral communication. [ABSTRACT FROM AUTHOR]

In a recent paper [ Huang, Gog, Kim, Kasman, Said, Casa, Wieczorek, Hönnicke & Assoufid (2018). J. Appl. Cryst.51, 140–147], a description of the structure of quartz was given that is incorrect. There is a long history of such errors in publications describing the quartz structure. This was fully and correctly discussed in 1978 [ Donnay & Le Page (1978). Acta Cryst. A34, 584–594], and yet these errors still persist. In the present paper the description by Huang et al. is corrected and the seminal work of Donnay and Le Page revisited. [ABSTRACT FROM AUTHOR]

This work shows that the intuitive assumption of the sterically less hindered amide group being solvated preferentially does not hold for the cases of two 2,6‐pyridinediyl‐dialkylamides. Using vibrational circular dichroism (VCD) spectroscopy, solvation is found to induce significant conformational changes, which are not immediately apparent from 1H NMR data. More information can be found in the Full Paper by D. P. Demarque and C. Merten on page 17915. [ABSTRACT FROM AUTHOR]

The synthesis of molecular propellers featuring low ‐ energy activation barriers of the racemization reaction remains elusive. The trimerization reaction of enantiomerically ‐ pure binaphthols with hexakis(bromomethyl)benzene enabled the one ‐ step preparation of enantiomerically ‐ pure molecular propellers, in which three binaphthyl rings are held together through dioxecine rings. X ‐ ray diffraction analysis revealed that the six naphthyl moieties adopt a folded conformation, which shows a striking similarity to the mythological Sicilian symbol of Trinacria. More information can be found in the Full Paper by D. Bonifazi et al. on page 15348. [ABSTRACT FROM AUTHOR]

Cyclic silylated chalconium borates 13[B(C6F5)4] and 14[B(C6F5)4] with peri‐acenaphthyl and peri‐naphthyl skeletons were synthesized from unsymmetrically substituted silanes 3, 4, 6, 7, 9 and 10 using the standard Corey protocol (Chalcogen Ch=O, S, Se, Te). The configuration at the chalcogen atom is trigonal pyramidal for Ch=S, Se, Te, leading to the formation of cis‐ and trans‐isomers in the case of phenylmethylsilyl cations. With the bulkier tert‐butyl group at silicon, the configuration at the chalcogen atoms is predetermined to give almost exclusively the trans‐configurated cyclic silylchalconium ions. The barriers for the inversion of the configuration at the sulfur atoms of sulfonium ions 13 c and 14 a are substantial (72–74 kJ mol−1) as shown by variable temperature NMR spectroscopy. The neighboring group effect of the thiophenyl substituent is sufficiently strong to preserve chiral information at the silicon atom at low temperatures. [ABSTRACT FROM AUTHOR]

The best-known application of salen complexes is the use of a chiral ligand loaded with manganese to form the Jacobsen complex. This organometallic catalyst is used in the epoxidation of unfunctionalized olefins and can achieve very high selectivities. Although this application was proposed many years ago, the mechanism of oxygen transfer remains a question until now. In this paper, the epoxidation mechanism is investigated by an ab initio kinetic modeling study. First of all a proper DFT functional is selected that yields the correct ordering of the various spin states. Our results show that the epoxidation proceeds via a radical intermediate. If we start from the radical intermediate, these results can explain the experiments with radical probes. The subtle influences in the transition state using the full Jacobsen catalyst explain the product distribution observed experimentally. [ABSTRACT FROM AUTHOR]

In this paper, the use of clarithromycin lactobionate, a kind of antibiotic chiral selector, in combination with four neutral cyclodextrin derivatives (glucose-β-cyclodextrin, hydroxyethyl-β-cyclodextrin, methyl-β-cyclodextrin and hydroxypropyl-β-cyclodextrin) was reported for the first time. As a result, these dual systems gave much better resolution of nefopam (the Rs increased to 3.58, 2.72, 1.49 and 1.42, respectively) compared to the single systems. The effects of buffer pH and selector concentration on the separation of nefopam were also investigated. Additionally, some other basic drugs including metoprolol, atenolol, propranolol, bisoprolol, esmolol and ritodrine were tested for the investigation and evaluation of the enantiorecognition capability of the four dual systems. As expected, the synergistic effect was observed in four systems. Different results of these dual systems were also summarized. [ABSTRACT FROM AUTHOR]

In this second part of our review article on the preferred screw sense and interconversion of peptide helices, we discuss the most significant computational and experimental data published on helices formed by the most extensively investigated categories of noncoded α-amino acids. They are as follows: (i) N-alkylated Gly residues (peptoids), (ii) C α-alkylated α-amino acids, (iii) C α, β- sp2 configurated α-amino acids, and (iv) combinations of residues of types (ii) and (iii). With confidence, the large body of interesting papers examined and classified in this editorial effort will stimulate the development of helical peptides in many diverse areas of biosciences and nanosciences. Copyright © 2015 European Peptide Society and John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This paper describes the synthesis of both polysubstituted oxazolo-pyrrolidinones and -piperidinones by a domino process. The methodology is based on the reaction between hydroxyl halogenoamides and Michael acceptors, which leads efficiently to bicyclic lactams. The process is compatible with unsymmetrical electron-withdrawing groups on the Michael acceptor, which allows the formation of two contiguous and fully controlled tertiary and quaternary stereocenters. In the case of tetrasubstituted Michael acceptors, two adjacent quaternary stereocenters are formed in good yield. Starting from ( R)-phenylglycinol derived amides results in the formation of enantioenriched bicyclic lactams in low to good yields and with high levels of stereoselectivity, thus greatly increasing the scope and interest of this strategy. The origins of chirality transfer and diastereoselectivity were studied by DFT calculations and have been attributed to a kinetic control in one of the last two steps of the reaction sequence. This selectivity is dependent upon both the substituents on the Michael acceptor and the sodium cation chelation. [ABSTRACT FROM AUTHOR]

This paper highlights a new concept on how to induce chirality in a hexaphenyl Geländer-type system. Bridging a terphenyl backbone with a considerably longer benzyl ether oligomer enforces a continuous twist of the molecule, while preventing an achiral meso form. By highlighting cross-coupling strategies and explored synthetic pathways, this report aims to serve as an Ariadne's thread for the synthesis of precisely functionalized, complex polyaromatic systems. The synthetic challenges and considerations required to access the designed target are outlined and solutions to each step of the assembly are presented. Encountered isomerizations are discussed as much as synthetic tools to access highly functionalized intermediates with multiorthogonal moieties. A strong focus is made on the employment of Suzuki-Miyaura protocols for the targeted connection of polyaromatic fragments and ultimately the desired oligomeric structure. [ABSTRACT FROM AUTHOR]

The exciton chirality method (ECM) is commonly recognized as one of the best approaches to assign the absolute configuration of biaryls. This paper reports the first exception to this method for a simple biaryl system. ECD and VCD measurements in combination with DFT (B3LYP/6-311G*), TDDFT (CAM-B3LYP/6-311G*), and Coupled-Cluster (RI-SCS-CC2) calculations were used to determine the absolute configurations of axially chiral BODIPY DYEmers. The ECM fails to predict the sign of the intense CD couplet at 500 nm of the 1,1′-coupled dimer. The odd behavior was rationalized by considering the strong transition magnetic dipole associated with the 500 nm transition, which leads to an unexpected dominance of the μm coupling at the expense of the μμ one in these compounds. This is the first case in which a strong μm coupling hampers the use of the ECM, but this behavior should not be restricted to the BODIPY chromophore. [ABSTRACT FROM AUTHOR]

P‐chirogenic compounds are useful ligands and organocatalysts in asymmetric synthesis. However, the lack of preparative methods and their configurational instability have significantly hampered their development. Herein, we report a simple strategy for the preparation of enantiomerically pure P,C‐chirogenic diphosphines. Amidation of the borane adducts of rac‐phosphinobenzoic acids with enantiomerically pure trans‐1,2‐diaminocyclohexane afforded a 1:2:1 mixture of the diastereomers (C*,C*,Rp,Rp), (C*,C*,Rp,Sp), and (C*,C*,Sp,Sp), which were separated by column chromatography on silica gel. The prepared (C*,C*,Rp,Rp) and (C*,C*,Sp,Sp) stereoisomers were identical to those obtained from the enantiopure phosphines, which were synthesized by a multi‐step route using chiral auxiliaries. Hence, this simple, short and convenient route towards P,C‐chirogenic diphosphines obviates the use of chiral auxiliaries and enables the access to diphosphines with differently configured P‐stereocenters. [ABSTRACT FROM AUTHOR]

Hydrogen bonds can efficiently guide the self‐assembly of organic materials, enabling to tune the properties of the aggregation processes. In the case of π‐conjugated materials, several parameters such as temperature, concentration and solvent can be used to modify the aggregation state while tuning the optoelectronic properties. Chirality can be included within the impacting parameters due to the differences in molecular packing. Here, chiral and achiral thiophene‐capped diketopyrrolopyrrole derivatives were designed and synthesized containing amide bonds, with the aim to study the interplay between chiral assemblies and their stabilization through hydrogen‐bonding. Differences in aggregation properties were observed with spectroscopy and microscopy, and a contactless microwave‐based technique was used to study their intrinsic charge carrier mobility. The positive role of hydrogen‐bonding has been highlighted and the differences between chiral and achiral compounds have been elucidated. [ABSTRACT FROM AUTHOR]

The analysis of patch antennas loaded by general inhomogeneous and lossy chiral media is presented in this paper, implementing a new method-of-lines (MoL) procedure, which considers inhomogeneous planar structures loaded by any bi-isotropic material. Presented results refer to the effect of a chiral cover on the resonance frequency of a simple squared-patch structure. Design charts are presented to simply analyze the separate effects of cover thickness and chirality. © 2002 John Wiley & Sons, Inc. Microwave Opt Technol Lett 32: 143–145, 2002. [ABSTRACT FROM AUTHOR]

Systems that show circularly polarized luminescence (CPL) are usually constructed in one of two possible ways: either covalently binding the chiral moieties (usually organic compounds) to luminophores (inorganic or organic compounds) or associating the luminophores as guests with chiral hosts (usually organic compounds). Herein, we propose inorganicbased CPL-active systems constructed by the “chiral hostluminescent guest” strategy, in which silica acts as a chiral host to endow various luminescent guests with CPL. The chiral silica was modified by silane coupling with amino or phenyl groups to allow interaction with luminescent guests, and then used in combination with acidic achiral dyes, lead-halide type perovskites, and aggregation-induced emission luminogens (AIEgens). Interestingly, when these achiral guests were noncovalently confined in surface-modified chiral silica, the guests showed chiroptical behavior in the circular dichroism (CD) spectra, and thus became CPL active, even though they are not inherently chiral. The surface functional groups on the silica play very important roles in transferring the chiral information from the silica to the guests. This work provides a new concept for constructing CPL-active systems using inorganic materials as a chiral source. [ABSTRACT FROM AUTHOR]

Magnetic groups are applied to three‐dimensional fluid flows with chirality, which are called Beltrami flows (or force‐free fields in plasma physics). First, six Beltrami flows are derived so that their symmetries and antisymmetries are described by six different hexagonal magnetic groups. The general Wyckoff positions are used to derive the flows. Special Wyckoff positions are shown to be useful for finding the zero points of the flows. Tube‐like surfaces called invariant tori are observed to interlace and form various crystal‐like structures when streamlines winding around the surfaces are numerically plotted. Next, two simpler hexagonal Beltrami flows are derived, and their zero points and invariant tori are studied. Some families of the invariant tori have arrangements similar to those observed in materials science. [ABSTRACT FROM AUTHOR]

In this paper, adsorption of lactic acid (LA) on the outer surface, inside and in the edge of Si-doped Single Walled Carbon Nanotubes (SWCNTs) with different chirality has been investigated. The results showed that the adsorption of lactic acid onto the outer surface of Si-doped carbon nanotubes is thermodynamically favored. More details will be discussed by Dr. A. N. Chermahini and his group on page 250-260 in this issue. [ABSTRACT FROM AUTHOR]

ABSTRACT This paper reports on the occurrence, biosynthesis, metabolism, biological and toxicological profile, and assessment of the authenticity of linalool. The main biological properties of linalool - sedative, anxiolytic, analgesic, anticonvulsant, anti-inflammatory, local anaesthetic - are discussed in terms of the molecule's chirality influence, the mechanisms of activity and type of study ( in vitro, in vivo, clinical studies). Also, there is a discussion of the recent data on the skin sensitizing potential of linalool based on numerous scientific studies which have been performed in the last few years. Comments of the authenticity assessment of linalool are made considering the limitations imposed by the chemical structure, vegetal matrix or processing methods, but also from the perspective of the powerful and sophisticated analytical techniques available today (GC-C-IRMS, enantio-MDGC coupled to GC-C-IRMS, SNIF-NMR). Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Significant advances have been made recently in generating chiral polymer surfaces and materials using a range of methods such as block copolymer self-assembly, layer-by-layer assembly and surface functionalization by polymer brushes. This paves the way for novel chiral materials that can harness and tailor chiral interactions for specific functionalities and properties in a range of biomedical and bioanalytical applications. This paper reviews these advances and speculates on the future of chiral surfaces. © 2013 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

This paper reviews the present state of the catalytic enantioselective Reformatsky reaction. Advancements in asymmetric versions of this reaction have recently led to a considerable extension of its scope and applicability, principally due to the use of highly active chiral ligands and very specific reaction conditions. [ABSTRACT FROM AUTHOR]

This paper describes the synthesis and characterization of 5-(diphenylphosphanyl)isophthalic acid bioconjugates (Lig-[R]2). In addition to symmetrically disubstituted conjugates with amino acids, peptides or amines, a convenient one-pot, two-step procedure for the synthesis of conjugates bearing two different substituents is reported. The 28 prepared phosphanes were used as monodentate ligands in the rhodium(I)-catalyzed hydrogenation of 2-acetamidoacrylate and ( Z)-α-acetamidocinnamate. The ligand with the smallest side-chain substituents Lig-[Ala-OMe]2 ( 1a) revealed the highest selectivity, with up to 84 % ee. The catalysts presented herein are models of artificial metalloenzymes in which the outer-coordination sphere controls the selectivity in catalysis. The chirality of distant hydrogen-bonded amino acids is transmitted by 'backdoor induction' to the prochiral RhI center. [ABSTRACT FROM AUTHOR]

In this paper, we describe for the first time the synthesis of new chiral nanosized metal oxide surfaces based on chiral self-assembled monolayers (SAMs) coated with metal oxide (TiO2) nanolayers. In this new type of nanosize chiral surface, the metal oxide nanolayers enable the protection of the chiral self-assembled monolayers while preserving their enantioselective nature. The chiral nature of the SAM/TiO2 films was characterized by variety of unique techniques, such as second-harmonic generation circular dichroism (SHG-CD), quartz crystal microbalance, and chiral adsorption measurements with circular dichroism spectroscopy. The chiral resolution abilities of the SAMs coated with metal oxide (TiO2) nanolayers were investigated in the crystallization of a racemic mixture of threonine and glutamic acid. Our proposed methodology for the preparation of nanoscale chiral surfaces described in this article could open up opportunities in other fields of chemistry, such as chiral catalysis. [ABSTRACT FROM AUTHOR]

In this paper, we present a new study of the electromagnetic wave propagation inside a rectangular waveguide partially loaded with an isotropic chiral medium, by means of the coupled mode method. Along this analysis some new features related to the variation of the propagation constant versus frequency and the chirality parameter, which have not been previously reported in the literature, are introduced. Among them, we highlight the existence of a frequency point wherein all the dispersion curves cross each other, and the increasing of the cutoff frequency of the fundamental mode with the chirality of the medium. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1206-1212, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27534 [ABSTRACT FROM AUTHOR]

A unique and effective interaction between the peripheral aromatic blades makes hexaarylbenzenes (HABs) attractive in fundamental research as well as for various applications such as molecular wires, sensors, and supramolecular assemblies. The chiroptical responses of HABs are susceptible to environmental factors such as solvent and temperature owing to the dynamic conformational transitions between the conformers. In this study, pressure dependence on the propeller chiral HABs in two different solvents was studied in detail. The effective differential volumes for two different equilibria were determined by quantitative analyses of CD spectra, affording very large differential volumes from the propeller to toroidal conformer (ΔVT‐C) of +43 and +42 cm3 mol−1, for H2 and H6, respectively, in methylcyclohexane. The value of H6 was further enhanced to +72 cm3 mol−1 in hexane, the largest value for the typical unimolecular conformational change. Such a response of propeller chirality in HABs is expedient in designing more advanced piezo‐sensitive materials. Pressure on: A unique response of propeller chirality of hexaarylbenzenes (HABs) under pressure is examined. Significantly large differential volumes are obtained for the conformational transition through the crucial solvation and/or desolvation on the propellers. [ABSTRACT FROM AUTHOR]