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The novel spectral changes from the coordination polymers of Ag+ with a chiral cysteine-based ligand containing a TPE AIEgen.

Natural light-harvesting (LH) systems can divide identical dyes into unequal aggregate states, thereby achieving intelligent "allocation of labor". From a synthetic point of view, the construction of such kinds of unequal and integrated systems without the help of proteinaceous scaffolding is challenging. Here, we show that four octatetrayne-bridged ortho-perylene diimide (PDI) dyads (POPs) self-assemble into a quadruple assembly (POP)4 both in solution and in the solid state. The two identical PDI units in each POP are compartmentalized into weakly coupled PDIs (P520) and closely stacked PDIs (P550) in (POP)4 . The two extreme pools of PDI chromophores were unambiguously confirmed by single-crystal X-ray crystallography and NMR spectroscopy. To interpret the formation of the discrete quadruple assembly, we also developed a two-step cooperative model. Quantum-chemical calculations indicate the existence of multiple couplings within and across P520 and P550, which can satisfactorily describe the photophysical properties of the unequal quadruple assembly. This finding is expected to help advance the rational design of dye stacks to emulate functions of natural LH systems.

Understanding non-covalent molecular recognition events at biomembrane interfaces is important in biological, medicinal, and materials chemistry research.1 Despite the crucial regulatory roles of anion binding/transport processes at biomembranes, no information is available regarding how strongly anions can bind to naturally occurring or synthetic receptors in lipid bilayer environments compared to their well-established behaviour in solutions.2 To bridge this knowledge gap, we synthesised a flat macrocycle that possesses a record aqueous SO42– affinity among neutral receptors and exploited its unique fluorescence response at interfaces. We show that the determinants of anion binding are extraordinarily different in organic solvents and in lipid bilayers. The high charge density of dihydrogen phosphate and chloride ions prevails in DMSO, however in lipids they fail to bind the macrocycle. Perchlorate and iodide hardly bind in DMSO but show significant affinities for the macrocycle in lipids. Our results demonstrate a surprisingly great advantage of large, charge-diffuse anions to bind to a lipid-embedded synthetic receptor mainly attributed to their higher polarisabilities and deeper penetration into the bilayer, beyond the common knowledge of dehydration energy-governed selectivity. The elucidation of these principles enhances our understanding of biological anion recognition functions in membranes and guides the design of ionophores and molecular machines operating at biomembrane interfaces.

We report a supramolecular nanosphere with a diameter of 8.65 nm built in an aqueous solution via dynamic binding of glucose to a thiol ligand bearing a phenylboronic acid group, 4-mercaptophenylboronic acid (4-MPBA), as a hydrophilic component in combination with a hydrophobic thiol ligand, 1-octanethiol (n-C8H17SH), in the presence of Ag+. Highly hydrophilic glucose binding to two neighboring boronic acid groups from 4-MPBA ligands on their Ag+ coordination polymeric backbone, on which the hydrophobic n-C8H17SH ligands locate inwards, drives the coordination polymers into nanospheres. The supramolecular nanospheres are of small diameters with narrow size distribution characteristic of glucose among the tested monosaccharides including fructose and xylose.

We propose to create nanospheres in aqueous solutions from coordination polymers of Ag+ with a combination of a hydrophilic and a hydrophobic thiol, of diameter ca. 2.7 nm in the case of using cysteine and n-butanethiol. A spectral probe for the formation of the nanospheres is a reversal of the CD signal at 253 nm from negative in the case of cysteine alone to positive when cysteine and n-BuSH are both employed, together with an amplification.

Supramolecular helices from helical building blocks represent an emerging analogue of the α-helix. In cases where the helicity of the helical building block is well propagated, the head-to-tail intermolecular interactions that lead to the helix could be enhanced to promote the formation and the stability of the supramolecular helix, wherein homochiral elongation dominates and functional helical channel structures could also be generated. This feature article outlines the supramolecular helices built from helical building blocks, i.e., helical aromatic foldamers and helical short peptides that are held together by intermolecular π-π stacking, hydrogen/halogen/chalcogen bonding, metal coordination, dynamic covalent bonding and solvophobic interactions, with emphasis on the influence of efficient propagation of helicity during assembly, favouring homochirality and channel functions.

Zero-order wave plates play an important role in the polarization measurements and laser industry, wherein few materials can satisfy both the requirements of small birefringence and a deep-ultraviolet (DUV; λ < 200 nm) transparency range. In this study, a new sulfate Li5Cs(SO4)3, crystallized in the centrosymmetric P21/c (no. 14), was obtained by the high temperature melt method. Its single crystal structure features a three-dimensional framework consisting of [SO4], [LiO4] and [LiO5] tetrahedra, and is a congruent-melting compound with a reversible phase transition. The transmission range of Li5Cs(SO4)3 shows that the crystal has a UV cutoff edge below 180 nm, and the theoretical calculations reveal that it has a minimal birefringence of 0.0046 @ 1064 nm. The optical properties indicate that Li5Cs(SO4)3 is a potential zero-order wave plate material.

We report supramolecular helical assembly in water of β-turn structured bis(N-amidothioureas) containing Br-substitutes of moderate halogen bonding ability, promoted by stronger hydrophobic interaction. The helical polymers show an unusual negative nonlinear CD-ee dependence.

Supramolecular chirality of aggregates can be described in terms of the CD signals of the aggregates as a function of the enantiomeric excess of the chiral building block or chiral inducer. While many examples have been reported that show a positive nonlinear CD- ee relationship, indicating chiral amplification, the negative nonlinear dependence has rarely been observed. We recently proposed to build such supramolecular aggregates by using the mesomer of the enantiomeric inducers. Indeed we found that in the presence of enantiomeric dibenzoyltartaric acids (DboTar), achiral perylenebisimide (PBI) dye equipped with two terminal guanidinium groups in alkaline aqueous buffer solution is induced to form chiral supramolecular aggregates, via the known guanidinium-carboxylate salt bridge, that show a positive nonlinear CD- ee relationship, and is turned into negatively nonlinear when 40% or more molar fraction of meso -DboTar was introduced. Absorption and CD spectral titrations suggest that the aggregates led by enantiomers and by mesomer are similar in terms of the supramolecular structure and stability, and when the two kinds of aggregates are mixed no molecular exchange occurs between them. Fluorescence spectral traces of the aggregates show that the mesomer is more powerful in inducing the aggregation of the PBI dyes, and thus dominates the aggregation. Our findings that the mesomer of the enantiomeric inducer could lead to aggregates to exhibit a negative nonlinear CD- ee relationship provide a promising approach to such supramolecular aggregates, which could be of significance for better insight into the mechanism leading to the negative nonlinear dependence and eventually a comprehensive understanding of the supramolecular chirality.

The 2,5-thiophenediamide motif that contains two intramolecular S⋯OC chalcogen bonds was taken to maintain cis-conformation of β-turn structured helical azapeptide that is good to form a supramolecular helix via intermolecular halogen bonding.

Spontaneous resolution leading to conglomerate crystals remains a significant challenge. Here we propose the formation of orthogonal homochiral supramolecular helices in at least two dimensions to allow spontaneous resolution. We suggest the design rationale that the chiral species is made into helical building blocks to allow the helix formation. As a proof-of-concept, acetylalanine was made into a helical short azapeptide, its N-amidothiourea derivative containing a β-turn structure, to which a halogen atom was further introduced at the phenylthiourea aromatic ring. The resultant folded species undergoes both intermolecular hydrogen and halogen bonding across the turn structure to form orthogonal intermolecular hydrogen-bonded and halogen-bonded supramolecular helices in two dimensions, and undergoes chiral resolution upon crystallization. Meanwhile, counterparts containing either an F-substituent with weak halogen bonding or no halogen atom crystallize as racemic compounds.

Conventionally, z-direction modulation of two-dimensional covalent organic frameworks (2D-COFs) is difficult to achieve because they rely on spontaneous π-π interactions to form 3D architectures. Herein, we report a facile construction of a novel intercalated covalent organic framework (Intercalated-COF) by synchronizing operations of supramolecular donor-acceptor (D-A) interactions (A unit: 2,5,8,11-tetra(p-formylphenyl)-perylene diimide (PDI) 1; D unit: perylene 3, as intercalator) in the vertical directions, with polymerizations (by only reacting 1 with p-phenylenediamine 2) in the lateral directions. In this Intercalated-COF, the PDI-based covalent 2D layers are uniformly separated by perylene guest layers. This supramolecular strategy opens the possibility for z-direction modulation of 2D-COFs through "intercalating" various guest molecules and thus may contribute to the exploration of advanced applications of these porous and crystalline frameworks.

We propose using the formation of coordination polymers of Ag+ to probe differences between the perfluorinated alkyl chain and the alkyl chain by deriving a thiol ligand, N-(perfluoroalkanoyl)cysteine. Rapid formation in EtOH of P-/M-helical nanofibrils of high thermostability was found for N-(perfluorooctanoyl)-L-/D-cysteine ethyl esters at the μM level upon mixing with Ag+, but not for the octanoyl counterpart. This difference was also observed in terms of circular dichroism-enantiomeric excess dependence.

The natural DNA double helix consists of two strands of nucleotides that are held together by multiple hydrogen bonds. Here we propose to build an artificial double helix from fragments of two strands connected by covalent linkages therein, but with halogen bonding as the driving force for self-assembling the fragments to the double helix. We succeed in building such a double helix in both solution and solid state, by using a bilateral N-(p-iodobenzoyl)alanine based amidothiourea which in its folded cis-form allows double and crossed C−I···S halogen bonds that lead to right- or left-handed double helix when the two alanine residues are of the same L,L- or D,D-configuration. The double helix forms in dilute CH3CN solution of the micromolar concentration level, e.g., 5.6 μM from 2D NOESY experiments and exhibits a high thermal stability in solution up to 75 °C, suggesting cooperative and thereby strong intermolecular double crossed halogen bonding that makes the double helix stable. This is supported by the observed homochiral self-sorting in solution., Building an artificial double helix is a compelling challenge, and most strategies rely on the intertwining of two helical strands. Here, in a very different approach, the authors construct a supramolecular double helix from multiple synthetic small molecules chained together by double crossed halogen bonds.

The synthesis, structures, and properties of [4]cyclonaphthodithiophene diimides ([4]C-NDTIs) are described. NDTIs as important n-type building blocks were catenated in the α-positions of thiophene rings via an unusual electrochemical-oxidation-promoted macrocyclization route. The thiophene-thiophene junction in [4]C-NDTIs results in an ideal pillar shape. This interesting topology, along with appealing electronic and optical properties inherited from the NDTI units, endows the [4]C-NDTIs with both near-infrared (NIR) light absorptions, strong excitonic coupling, and tight encapsulation of C60 . Stable orientations of the NDTI units in the nanopillars lead to stable inherent chirality, which enables detailed circular dichroism studies on the impact of isomeric structures on π-conjugation. Remarkably, the [4]C-NDTIs maintain the strong π-π stacking abilities of NDTI units and thus adopt two-dimensional (2D) lattice arrays at the molecular level. These nanopillar molecules have great potential to mimic natural photosynthetic systems for the development of multifunctional organic materials.

Exploiting new non-metal-based peroxidase-mimic nanoenzymes for chemodynamic therapy (CDT) in cancer treatment is an active and challenging field. Here, we found that activated carbon nanoparticles (denoted as ANs) fabricated from coconut shell have satisfactory peroxidase-mimic nanoenzyme activity. Based on this positive result, gadodiamide, a clinically used nuclear magnetic imaging contrast agent, was loaded inside the AN pores and encapsulated by polyvinylpyrrolidone (PVP) to obtain Gd@PANs. PANs (ANs modified using PVP) efficiently catalyze the massive decomposition of endogenous hydrogen peroxide (H2O2) inside cancer cells to produce toxic oxidized hydroxyl radicals (˙OH) for the CDT treatment of cancer, but they showed no toxicity toward normal cells. Additionally, under 808 nm laser irradiation, the photothermal conversion efficiency of the PANs reaches 45.20%, ensuring their effective photothermal therapy (PTT) treatment functionality. Simultaneously, during PTT treatment, the heating effect significantly enhances the peroxidase-mimic activity of the PANs to achieve an ideal PTT-CDT synergistic therapeutic outcome. Gd@PANs can also be used for the T1-magnetic resonance imaging (MRI) of tumors to integrate treatment and diagnosis.

We show herein the phosphatase-like catalytic activity of coordination polymers obtained after adding Ag + -ions to thiols bearing hydrophobic alkyl chains terminated with a 1,4,7-triazacyclononane (TACN) group. The subsequent addition of Zn 2+ -ions to the self-assembled polymers resulted in the formation of multivalent metal coordination polymers capable of catalysing the transphosphorylation of an RNA-model compound (2-hydroxypropyl-4-nitrophenyl phosphate, HPNPP) with high reactivity. Analysis of a series of metal ions showed that the highest catalytic activity was obtained when Ag + -ions were used as the first metal ions to construct the backbone of the coordination polymer through interaction with the -SH group followed by Zn 2+ -ions as the second metal ions complexed by the TACN-macrocycle. Furthermore, it was demonstrated that the catalytic activity could be modulated by changing the length of the hydrophobic alkyl chain.

Diverse classes of anion transporters have been developed, most of which focus on the transmembrane chloride transport due to its significance in living systems. Fluoride transport has, to some extent, been overlooked despite the importance of fluoride channels in bacterial survival. Here, we report the design and synthesis of a cyclic azapeptide (a peptide-based N-amidothiourea, 1), as a transporter for fluoride transportation through a confined cavity that encapsulates fluoride, together with acyclic control compounds, the analogs 2 and 3. Cyclic receptor 1 exhibits more stable β-turn structures than the control compounds 2 and 3 and affords a confined cavity containing multiple inner –NH protons that serve as hydrogen bond donors to bind anions. It is noteworthy that the cyclic receptor 1 shows the capacity to selectively transport fluoride across a lipid bilayer on the basis of the osmotic and fluoride ion-selective electrode (ISE) assays, during which an electrogenic anion transport mechanism is found operative, whereas no transmembrane transport activity was found with 2 and 3, despite the fact that 2 and 3 are also able to bind fluoride via the thiourea moieties. These results demonstrate that the encapsulation of an anionic guest within a cyclic host compound is key to enhancing the anion transport activity and selectivity.

We report coordination polymers forming from Ag+ and a chiral thiol ligand that bears a β-turn structure, exhibiting supramolecular chirality showing both the majority rules effect (MRE) and the racemate rules effect (RRE).

Building folded short peptides that are driven by the intramolecular hydrogen bonding in aqueous solutions remains challenging because of their highly competitive intermolecular hydrogen-bonding interactions with water solvent molecules that would have favored the extended conformations. Here, we show folded β-turn structures in acyl amino acid-based N-amidothioureas, the nonclassic azapeptides, in aqueous solutions, as well as in solid-state and organic solvents, by X-ray crystal structures, DFT calculations, 1D and 2D NMR spectra, and absorption and CD spectra. The achiral phenylthiourea chromophore acts as a CD reporter for the β-turn structure that communicates the chirality of the amino acid residue to the achiral thiourea moiety and the relative intensity of the intramolecular hydrogen bond that stabilizes the turn structure. The amidothiourea moiety represents a versatile structural framework for folded short peptides in aqueous environments.

In order to find more active anti-neuroinflammatory sinomenine derivatives, 17 sinomenine 4-hydroxy esters were designed and prepared. All synthesized derivatives were structurally confirmed by ESI-MS and PMR. Their anti-neuroinflammatory effects were evaluated using LPS-stimulated BV-2 microglia cells. Among them, four compounds presented more than 80% of cell viability. Compound 8 showed remarkable inhibition of nitric oxide (NO) release by the Griess method. Furthermore, esters 5–9 were tested to check their suppressive effects on xylene-induced ear edema. It was observed that 8 was more active and less toxic than 5–7 with shorter aliphatic chains.

Traditionally, fluorescence probes have focused on the detection of a single biomarker for a specific process. In this work, we set out to develop a number of fluorescence probes that enable the detection of a chosen analyte in the presence of reactive oxygen/nitrogen species (ROS/RNS). These fluorescence probes when activated result in the formation of the highly fluorescent pink dye, resorufin. Therefore, we have labelled these fluorescent probes as ‘Pinkments’. Our first ‘Pinkment’ was shown to detect biologically relevant concentrations of ONOO− and have an excellent selectivity against other ROS/RNS. Pinkment-OH was developed to provide a core unit which could be easily functionalised to produce a range of ‘AND’ based fluorescence probes for the detection of ROS/RNS and a second analyte. For proof of concept, we synthesised Pinkment-OTBS and Pinkment-OAc. These ‘AND’-based probes were successfully shown to detect ROS/RNS and F− or esterase, respectively.

Herein, we report a conformation switching-based fluorescence sensing scheme using dipeptide-based amidothioureas (azapeptides) that contain a folded β-turn structure. Amidothiourea is equipped at its two termini with an electron acceptor and an electron donor or two fluorophores, such that it exhibits enhanced exciplex or excimer emission because of the turn structure in which the two termini are brought into close proximity; on the other hand, it exhibits a dramatic ratiometric fluorescence response upon anion binding to the thiourea moiety because of the resultant extended conformation of the anion binding complex.

We report that in the Ag+ coordination polymers of a chiral thiol ligand containing an AIE fluorophore, tetraphenylethene (TPE), the TPE chromophores experience H-type aggregation, and yet a substantial enhancement of the fluorescence is observed, though to a lesser extent than that in the aggregates of the thiol ligand itself, which undergoes J-type aggregation. We show that this is not due to the difference in the freedom of the rotation of the fluorophore in the two types of aggregate, but is due to a small increase in the radiation rate constant in the coordination polymers while the much higher radiationless rate constant remains more or less unchanged.

Reported here is the induced helical aggregation of an achiral cationic perylene-3,4-dicarboximide (1) that contains a phenylboronic acid group, together with UMP that bears a cis-diol moiety able to interact with boronic acid and an imide group known to coordinate with Hg2+. In selected solvents, 1 exists in monomer form, even in the presence of either UMP or Hg2+. Helical aggregation only takes place if 1 is mixed with both UMP and Hg2+, which is shown to result from the formation of a building block consisting of five components in the form 1–U–Hg2+–U–1. Strong exciton-coupled circular dichroism signals were observed in the absorption window of the achiral dye chromophore, demonstrating the transfer of the chirality of UMP to the supramolecular aggregates of P-helicity. Synergism was shown to occur upon aggregation of the 1–U–Hg2+–U–1 building block, as substantially enhanced affinity and binding selectivity were observed for UMP and Hg2+, despite the otherwise weak and less selective interactions of 1–UMP and UMP–Hg2+. In support of this synergism, the g-factor of the aggregates was found to be 1.4×10−2, which represents a high value. We thus show a strategy of in situ construction of a building block from multiple components, among which the interactions can be weak and less selective. Therefore, the design and syntheses of the constituent components are substantially simplified, yet diverse functions can be expected from their supramolecular aggregates.

The formation of well-defined finite-sized aggregates represents an attractive goal in supramolecular chemistry. In particular, construction of discrete π-stacked dye assemblies remains a challenge. Reported here is the design and synthesis of a novel type of discrete π-stacked aggregate from two comparable perylenediimide (PDI) dyads (PEP and PBP). The criss-cross PEP-PBP dimers in solution and (PBP-PEP)-(PEP-PBP) tetramers in the solid state are well elucidated using single-crystal X-ray diffraction, dynamic light scattering, and diffusion-ordered NMR spectroscopy. Extensive π–π stacking between the PDI units of PEP and PBP as well as repulsive interactions of swallow-tailed alkyl substituents are responsible for the selective formation of discrete dimer and tetramer stacks. Our results reveal a new approach to preparing discrete π stacks that are appealing for making assemblies with well-defined optoelectronic properties.

As a new emerging area in chemical sensing, sensing using supramolecular aggregates exhibits unique advantages over that using conventional small-molecule chemical sensors, in terms of high sensitivity and selectivity, and the simplicity of the sensory building blocks. This Feature Article outlines the recent research progress made in sensing based on induced supramolecular aggregation-disaggregation. The reviewed sensory building blocks, in general, in the form of a small molecular sensor, yet with a much simpler structure, which form aggregates, are those of perylene derivatives, pyrene derivatives, tetraphenylethylene derivatives, metallophilic species and metal-organic frameworks.

We report a dynamic covalent approach to transmembrane transport of amino acids by the formation of a three-component assembly. A mixture of a squaramide and a lipophilic and electrophilic aldehyde is shown to synergistically transport highly polar glycine (Gly) across vesicle membranes. The transport was investigated by a 13C NMR assay, an osmotic response assay and a newly-developed fluorescence assay suitable for measuring Gly influx, and other fluorescence assays for leakage and pH change. The transport is proposed to occur via a hydrogen-bonded anionic glycine hemiaminal/imine, accompanied by transport of OH- in the opposite direction. Several control experiments support the role of hemiaminal/imine in the observed facilitated Gly transport. Proton NMR studies of a biphasic system show the presence of both the hemiaminal and imine formed between Gly and an aldehyde. Interestingly, the synergistic effect has also been observed for sarcosine (Sar) that can form hemiaminals but not imines. The results demonstrate the potential of hemiaminal formation for the facilitated transport of substrates containing primary and secondary amino groups.

A near infrared probe for sensitive colorimetric and fluorimetric detection of nerve agent mimics, DCP and DCNP, was reported based on the activation of a carboxylic acid group by the mimics to conduct an intramolecular amidation reaction in the heptamethine chromophore, where its absorption or excitation maximum wavelength could be greatly red-shifted by attenuating the electron-donating ability of the amine group in the bridgehead site of heptamethine cyanine.

A mixture of two simple perylene-containing receptors was found to bind bifunctional L-DOPA synergistically and tightly via orthogonal boronate ester and imine bond formation in neutral aqueous solutions, the resulting three-component assembly forming optically active long fibrous aggregates.

One important objective of molecular assembly research is to create highly complex functional chemical systems capable of responding, adapting, and evolving. Compared with living systems, the synthetic systems are still rather primitive and are far from realizing those features. Nature is by far the most important source of inspiration for designing and creating such systems. In this critical review, we summarize an alternative approach, inspired by catalysis, to examine and describe some molecular assembly processes. A new term, "catassembly," is suggested to refer to the increase in the rate and control of a molecular assembly process. This term combines the words "catalysis" and "assembly," and identifiably retains the Greek root "cat-" of catalysis. The corresponding verb is "catassemble" and the noun is "catassembler", referring to the "helper" species. Catassembly in molecular assembly is a concept that is analogous to catalysis in chemical synthesis. After using several examples to illustrate the characteristics of catassembly, we discuss future methodological and theoretical developments. We also emphasize the significance of the synergy between chemical synthesis and molecular assembly, especially for hierarchical assembly systems. Because most efforts in the field of molecular assembly have been devoted to the design and synthesis of molecular building blocks, we wish to stress the apparently missing yet critical link to complex chemical systems, i.e., the design and utilization of molecular catassemblers to facilitate the formation of functional molecular assemblies from building blocks with high efficiency and selectivity. This rational control and accelerated method will promote the systems chemistry approach, and may expand the spectrum of molecular assembly from basic science to applications.

For the efficient extraction of kamebakaurin(KA), the ultrasound-assisted extraction(UAE) of KA from Rabdosia excisa(R. excisa) via response surface methodology(RSM) was investigated with high-performance liquid chromatography(HPLC). Effects of the experimental parameters such as extraction solvent, ratio of liquid to plant material, extraction time and extraction temperature on the extracting efficiency of KA from R. excisa were evaluated, and the purity of KA in residual was calculated. The optimized conditions were 65.5%(volume fraction) acetone, 35 °C, time of 24.6 min with ultrasound of 80 W/L, 40 kHz, ratio of liquid to plant material at 30:1(mL/g). The maximum yield of KA is 0.708 mg/kg, with mean purity of 6.09%, indicating that ultrasound-assisted extraction is a feasible and useful method for extracting KA from R. excisa.

We report the first example of C–I···π halogen bonding driven supramolecular helix in highly dilute solution of micromolar concentration, using alanine based bilateral I-substituted N-amidothioureas that contain helical fragments, the β-turn structures. The halogen bonding interactions afford head-to-tail linkages that help to propagate the helicity of the helical fragments. In support of this action of the halogen bonding, chiral amplification was observed in the supramolecular helix formed in acetonitrile solution. The present finding provides alternative tools in the design of self-assembling macromolecules.

A supramolecular polymeric system that shows an unusual “racemate-rules” chiroptical property, an effect opposite to the well-known “majority-rules”, has been utilized for accurate determination of malic acid enantiopurity at high ee values.

Synthetic transmembrane anion transporters (anionophores) have potential as tools for biomedical research and as therapeutic agents for diseases associated with anion-channel dysfunction. However, the possibility of H+ or OH- transport by anionophores has received little attention, and an anionophore selective for Cl- over H+/OH- is currently unavailable. Here, we show that depending on anionophore acidity, many anionophores facilitate electrogenic H+ or OH- transport, potentially leading to toxicity. Nevertheless, using several liposome-membrane-based assays, we identified two newly developed small molecules that promote electrogenic Cl- transport without effectively dissipating the transmembrane pH gradient, essentially mimicking the electrogenic cationophore valinomycin. The Cl- > H+/OH- selectivity of anionophores showed a consistent positive correlation with the degree of Cl- encapsulation and a negative correlation with the acidity of hydrogen-bond donors. Our study demonstrates that a valinomycin equivalent for Cl--selective transport is achievable., info:eu-repo/semantics/published

Glucose binding via boronate ester linkages selectively triggers imine bond formation between 4-formylphenylboronic acid and octylamine, leading to the formation of vesicular aggregates in aqueous solutions. This "double dynamic covalent assembly" allows the facile selective sensing of glucose against the otherwise serious interferant fructose, without the need to resort to synthetic effort.

Synthetic receptors for diols that incorporate boronic acid motifs have been developed as new sensors and separation tools. Utilizing the reversible interactions of diols with boronic acids to form boronic esters under new binding regimes has provided new hydrogel constructs that have found use as dye-displacement sensors and electrophoretic separation tools; similarly, molecular boronic-acid-containing chemosensors were constructed that offer applications in the sensing of diols. This review provides a somewhat-personal perspective of developments in boronic-acid-mediated sensing and separation, placed in the context of the seminal works of others in the area, as well as offering a concise summary of the contributions of the co-authors in the area.

We report here chirality sensing using achiral Ag(+)-thiol coordination polymers as the framework which becomes CD active upon interaction with chiral species, taking p-mercaptophenylboronic acid as a thiol ligand that bears a binding group for monosaccharides.

A new method for lowering the error of CD based methods for measuring high enantiomeric excess values is described, which exploits the majority rules effect exhibited by certain helical polymers. A proof of principle experiment was conducted.

A fluorescent aminoacid was designed for selective and sensitive detection of Cu(II) in aqueous solution. The designing of this Cu(II) fluorescent chemosensing molecule, N ± (1-naphthyl). aminoacetic acid (NAA), was based on the binding of Cu(II) to aminoacetic acid and the novel charge transfer photophysics of 1-aminonaphthalenes. The fluorescence of NAA was found quenched by Cu (II) and several other metal ions of similar electronic structure such as Co(II), Ni(II) and Zn(II). The quenching was shown to occur via electron transfer within the metal-NAA complex, which required an optimal combination of high binding affinity and favorable redox properties of the components in the metal-NAA complex and hence afforded selective fluorometric detection of Cu(II). The calibration graph obeyed Stern-Volmer theory and was shown for Cu(II) over the range of 0–2.75 ± 10–4 mol/L. The quenching constant of Cu(II) was measured as 8.0 ± 103 mol/L that was two orders of magnitude higher than those of Co(II), Ni(II) and Zn(II). The 3SD limit of detection for Cu(II) was 8.00 ± 10−6 mol/L with a coefficient of variation of 1.65%. Linear range for quantitative detection of Cu(II) was 2.67 ± 10−5-2.75 ± 10−4 mol/L. The method was applied to synthetic sample measurements which gave recoveries of 105%-112%.

Alkali-soluble associative latex thickeners modified with hydrophobic long chain alkyl groups were prepared using common acrylics and varying amount of a functional monomer, ethoxylated behenyl methacrylate (BEM), through emulsion polymerization. It was found that the size of the emulsion particle became larger with addition of BEM. The light transmittance of the thickener latex sharply increased with pH varied from 6 to 7. The associative latex thickener manifested a higher viscosity when solids in the latex thickeners were kept at 0.5 wt% or higher, and the optimal amount of BEM was found to be around 2.5 wt%, or 0.16 mol%. All thickener latexes modified with BEM have better shearing resistance than the BEM-free thickener.

A selective and sensitive intramolecular charge transfer (ICT) fluorescent chemosensor was designed for Cu2+ in neutral aqueous solutions of pH 7.0. The design of this totally water-soluble fluorescent chemosensor was based on the binding motif of Cu2+ to aminoacid, which is coupled to an ICT fluorophore bearing a 1,3,4-thiodiazole moiety in the electron acceptor. The formation of a 1:1 complex of Cu2+ to 2 was suggested to lead to fluorescence quenching. The quenching obeyed Stern-Volmer theory in neutral aqueous solution of pH 7.0 for Cu2+ over 5.0 × 10−7 to 3.0 × 10−5 mol·L−1, with a quenching constant of 1.8 × 105 L·mol−1 and a detection limit of 2.0 × 10−7 mol·L−1. The binding of Cu2+ to 2 can be fully reversed by addition of chelator EDTA, affording a reversible sensing performance.

Organic molecular devices for information processing applications are highly useful building blocks for constructing molecular-level machines. The development of "intelligent" molecules capable of performing logic operations would enable molecular-level devices and machines to be created. We designed a series of 2,5-diaryl-1,3,4-oxadiazoles bearing a 2-(para-substituted)phenyl and a 5-(o-pyridyl) group (substituent X=NMe(2), OEt, Me, H, and Cl; 1a-e) that form a bidentate chelating environment for metal ions. These compounds showed fluorescence response profiles varying in both emission intensity and wavelength toward the tested metal ions Ni(2+), Cu(2+), Zn(2+), Cd(2+), Hg(2+), and Pb(2+) and the responses were dependent on the substituent X, with those of 1d being the most substantial. The 1,3,4-oxadiazole O or N atom and pyridine N atom were identified as metal-chelating sites. The fluorescence responses of 1d upon metal chelation were employed for developing truth tables for OR, NOR, INHIBIT, and EnNOR logic gates as well as "ON-OFF-ON" and "OFF-ON-OFF" fluorescent switches in a single 1,3,4-oxadiazole molecular system.

N-(o-methoxybenzamido)thioureas (2 X/2 Y) are found to show an enhanced anion binding affinity with binding constants over 10(7) mol(-1) L orders of magnitude for AcO(-) and a redshifted absorption of the anion binding complexes in acetonitrile (MeCN) relative to those of N-benzamidothioureas (1) that bear no o-OMe in the N-benzamide moiety, despite the electron-donating character of o-OMe. Absorption of the anion-2 X/2 Y complex was shown to be of the same charge-transfer nature as that of the anion-1 complex, but its dependence on substituent X is interestingly influenced by the o-MeOHNC=O six-membered-ring intramolecular hydrogen bond identified in 2 X/2 Y. Such an intramolecular hydrogen bond is suggested to be responsible for the enhanced anion binding affinity. In the presence of this intramolecular hydrogen bond, the anion binding constant of 2 X was found to be independent of substituent X at the N-phenyl ring, as in the case of 1, whereas that of 2 Y showed an amplified dependence on substituent Y at the N'-phenyl ring, but to a lower extent than that of 1. A similar ring intramolecular hydrogen bond was purported to exist in 2 Za, 2 Zd, and 2 Ze, which bear NHMe, F, and Cl as the ortho substituent in the N-benzamide moiety. In terms of the current roles of thiourea in not only anion recognition and sensing but also organocatalysis and crystal engineering, the present finding would be of significance for a wider structural diversity of smart thiourea derivatives with predesigned functions.

A neutral N-amidothiourea-based excited state intramolecular proton transfer (ESIPT) anion receptor bearing an o-hydroxynaphthamide fluorophore and a thiourea binding site, N-(3-hydroxy-2-naphthamide)-N′-phenylthiourea (1a), was designed and synthesized. Fluorescence and absorption response of 1a toward anions were assessed in acetonitrile. IR and NMR experiments indicated that the “OH⋯O=C” intramolecular hydrogen bond (IHB) in 1a was weak so that it only exhibited the short-wavelength normal emission other than ESIPT fluorescence. Due to the high anion binding affinity of the N-amidothiourea binding site and the formation of a hydrogen binding network in the 1a-anion complex, 1a underwent structural change upon anion binding that strengthens the “OH⋯O=C” IHB, leading to the ESIPT and the observation of the long-wavelength ESIPT emission whereas the normal fluorescence is quenched. On the basis of NMR and fluorescence titrations and control experiments with model compounds, a sensing mechanism of the anion-binding-induced ESIPT was proposed.