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Two chiral (A)6B-typed supramolecular cages were constructed from hydrogen-bonded C6 -symmetric zinc porphyrin hexamers and chiral C3-symmetric pyridyl hexadentates with a core of 1,3,5-triphenylbenzene. Circular dichroism and molecular simulations revealed that the symmetry of the supramolecular cages switched from pseudo-C3v to C3 with the rotational confinement of the biphenyl backbones at low temperatures, which generated conformationally chiral transfer and amplification. This unique phenomenon suggests a new strategy to develop smart materials with high sensitivity and excellent reversibility.

Reverse vesicles exhibiting functions similar to those of normal vesicles have been constructed through the self-assembly of TTF/CBPQT(4+)-based pseudo[2]rotaxanes in a nonpolar solvent. The ends of the threads of the pseudo[2]rotaxanes are attached with a Fréchet-type G-3 dendron and a hydrogen-bonded arylamide foldamer. These vesicles exhibit a response to redox. By exploiting the dynamic feature-spontaneously slow disassociation of the pseudorotaxanes-the sustained release of dyes embedded in the reverse vesicles has been demonstrated, which can be further tuned by changing the solvent polarity.

One dimensional (1D) nanotubes and three dimensional (3D) flowerlike supernanostructures were transformed reversibly, which was controlled by the oxidation and reduction cycle of aromatic diamide-derived thiol 1 and disulfide 2, as evidenced by SEM study. Their self-assembling patterns were investigated by UV–vis, 1H NMR, X-ray crystallographic, and powder X-ray diffraction experiments.

This paper describes the self-assembling property of three series of p-phenyleneethynylene based comb-like oligomers, which carry multiple peripheral side chains of different polarity. The new oligomers are prepared readily through the formation of the hydrazone bonds from the corresponding aldehyde and gallic acid-derived benzohydrazides. In polar solvents such as methanol and ethanol, the oligomers that bear n-decyl or 2-(2-(dioctylamino)-2-oxoethyl-amino)-2-oxoethoxyl unit (DOAOE) segments as the side chains are revealed to form vesicular structures, while the oligomers carrying hydrophilic oligo(ethyleneglycol) side chains do not. The structures of the vesicles are evidenced by SEM, AFM, TEM, and dye-encapsulation experiments. UV-vis absorption spectroscopic experiments suggest that the vesicles are generated through the stacking of the conjugated backbones, which is promoted by the solvophobic interaction of the peripheral side chains. (C) 2012 Elsevier Ltd. All rights reserved.

Hydrogen bonded arylamide foldamers have been introduced in switchable pseudo[2]rotaxanes and [2] rotaxanes, which also include a cyclobisparaquat(p-phenylene) (CBPQT(4+)) ring and a 'dumbbell' containing tetrathiafulvalene (TTF) and 1,5-dioxynaphthalene (DNP, for rotaxanes). The foldamer size changes through folding and unfolding serve as a steric handle to modulate the mechanical movement of the CBPQT(4+) ring along the dumbbell of the pseudo[2]rotaxanes and [2]rotaxanes. By varying the number of the repeating units in the foldamer, the kinetics of the solvent-dependent slippage/deslippage of pseudo[2]rotaxanes and the switching of the ring between TTF and DNP of the [2]rotoxanes can be tuned remarkably, with the time scope ranging from several minutes to several days, in twelve solvents of varying polarity, which have been confirmed by the H-1 NMR, UV-vis spectroscopy, and cyclic voltammogram experiments. (C) 2011 Elsevier Ltd. All rights reserved.

A series of 1,4-diphenyl-1,2,3-triazole-incorporated amide derivatives have been designed and prepared. X-ray crystallographic and (1D and 2D) (1)H NMR studies reveal that these compounds fold into stable U-shaped conformations driven by three-center intramolecular C-H···O hydrogen-bonding formed between the triazole C-5 H atom and the two ether O atoms. Such folded structures make this 1,4-diphenyl-1,2,3-triazole skeleton a good candidate to be used as β-turn mimic. To prove this, the formation of a β-hairpin structure induced by this β-turn motif has been further demonstrated.

In a preliminary letter (Tetrahedron Lett. 2010, 51, 188), we reported two new hydrazide-based quadruple hydrogen-bonding motifs, this is, two monopodal (1a and 1b) and five dipodal (2a, 2b and 3a–3c) aromatic hydrazide derivatives, and the formation of supramolecular polymers and vesicles from the dipodal motifs in hydrocarbons. In this paper, we present a full picture on the properties of these hydrogen-bonding motifs with an emphasis on their self-assembling behaviors in aqueous media. SEM, AFM, TEM and fluorescent micrographs indicate that all the dipodal compounds also form vesicles in polar methanol and water-methanol (up to 50% of water) mixtures. Control experiments show that 1b does not form vesicles in same media. Addition of 1b to the solution of the dipodal compounds inhibits the latter's capacity of forming vesicles. At high concentrations, 3b and 3c also gelate discrete solvents, including hydrocarbons, esters, methanol, and methanol-water mixture. Concentration-dependent SEM investigations reveal that the vesicles of 3b and 3c fuse to form gels and the gel of 3c can de-aggregate to form the vesicles reversibly.

Slip sliding away: foldamers can function as modular stoppers to regulate the slippage and de-slippage of pseudorotaxanes and the switching kinetics and metastability of bistable rotaxanes. By simply changing the solvent or the length of the hydrogen-bonded foldamer, the lifetime of the metastable co-conformation state can be increased dramatically, from several minutes to as long as several days.

A novel type of chiral layered supramolecular copolymer with high molecular weight has been assembled from a hydrogen bonded C(6)-symmetric zinc porphyrin hexamer and chiral C(3)-symmetric pyridine hexadentate linkers driven by multivalent zinc porphyrin-pyridine coordination. UV-vis, circular dichroism, and static light scattering experiments revealed that the formation of the layered supramolecular copolymers is at first dynamically controlled and then becomes thermodynamically controlled.

Self-sorting is commonplace in biological system but seldom applied to orthogonally fabricating micro/nanoscaled objects. In this Letter, this principle has been employed to construct two different microscaled architectures via self-sorted assembly of size-matched disk-like molecules. A remarkable cooperative reinforcement of hydrogen-bonding and donor–acceptor interaction is also observed.

This study reports a tunable metallo-supramolecular assembly strategy to construct microscaled objects with different morphologies. Three well-defined discrete microstructures—microspheres, microtubes, and microrods—have been fabricated through metal−organic coordination between the same organic unit and different transition metal ions or the same organic unit and metal ion processed in different solvents. The formations of microspheres, microtubes, and microrods have been readily evidenced by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Encapsulation experiments revealed that those microspheres could entrap rhodamine B and might be used as carrier materials. It was also found that the microrods and microtubes could be transformed into each other by adding or removing water to or from the solution. The formation mechanisms of these microstructures have also been discussed on the basis of spectroscopic and crystallographic studies.

Three arylamide-bridged biscoumarin derivatives 1–3 have been designed and prepared. Compounds 1 and 2 are induced by the intramolecular N-H…O and N-H…F hydrogen bonding to possess a helical conformation, and 3 is induced to have an extended conformation. A comparison of their absorption and fluorescent spectra in a variety of solvents of a wide range of polarity with those of control compound 4 reveals that, for foldamers 1 and 2, the intramolecular hydrogen bonding and the helical conformations exist in most solvents, but do not exist or are very weak in DMF and DMSO.

With k8/k16, the ratio of the hydrolytic rate-constants of p-nitrophenyl octanoate (C8) to hexadecanoate (C16), as the indicator of the degree of aggregation, the linear dependence of the degree of aggregation on solvent aggregating power (SAgP) has been established in five aquiorgano solvents, each within a certain range of volume fraction (ϕ values) of the organic cosolvent. The meaning of this linearity has been discussed.

The kinetics of the hydrolysis of p-nitrophenyl esters of three types of single-chain carboxylic acids, namely, saturated, olefinic and acetylenic, was investigated in two aquiorgano binary solvent systems, DMSO-H2O and dioxane (DX)-H2O. The ester probes used are: octanoic (C8), dodecanoic (C12), stearic (C18), oleic (C18-ol), elaidic (C18-el) and stearolic (C18-st). The order of measured CAgC values is: C18-ol>C18-el>C18>C18-st, whereas the order of decreasing magnitude of the observed hydrolytic rate constants of the monomeric species (km) is: C18>C18-el>C18-ol> C18-st. These rather unanticipated results are discussed.

The rate constants (k) of the homo-cycloaddition reactions of five substituted α,β,β-trifluorostyrenes (TFS's), i.e. p-nitrotrifluorostyrene (4), p-cyanotrifluorostyrene (5), p-carbomethoxytri-fluorostyrene (6), p-carboxytrifluorostyrene (7) and p-carbamyltrifluorostyrene (8), have been measured in the temperature range of 110–160°C. The smb polar substituent parameters of these TFS's calculated from 10F NMR chemical shifts are: NO2, 0.86; CN, 0.86; CO3CH3, 0.40; CO2H, 0.31; CONH2, 0.10. The spin delocalization substituent parameters σT˙ of NO2, CN, CO2CH3, CO2H and CONH2 are 0.32, 0.38, 0.31, 0.37 and 0.37 respectively. Thus all these electron-pair attracting groups are also very effective spin-stabilizers.

The effect of temperature on the critical aggregate concentration (CAgC) has been investigated for the first time, by measurement of the hydrolytic rate constants of p-nitrophenyl dodecanoate (C12) and hexadecanoate (C16) at different temperatures in the 30:70 V/V (θ·=0.30) and 40:60 V/V (θ = 0.40) dioxane (DX)-H2O systems. The CAgC values of C12 and C16 increase with the increase of the temperature, i.e., high temperatures disfavor aggregation. Activation energies for the hydrolysis of C12 in the monomeric and aggregated concentration domains have also been discussed.

Nitrogen hyperfine splitting constants (aN values) of seven symmetrically para-disubstituted diphenyl nitroxides (1-Y's) were measured by EPR and used in conjunction with five literature values in our correlation analysis. The correlation of these aN values by single-parameter Eq. 1 and dual-parameter Eq. 2 shows that the application of Eq. 2 does not significantly improve the correlation. But our data can also be interpreted by the proposition that the spin-delocalization effect is not completely nonexistent and that it might have revealed itself through the aN values of two very weakly polar substituents with pronounced spin-stabilizing abilities, i.e., SMe and SiMe3.

Three substituted α, β, β-trifluorostyrenes (TFS's), i. e., p-thiomethyltrifluorostyrene (4), p-cyclopropyltrifluorostyrene (5) and p-t-butyltrifluorostyrene (6), have been synthesized. The rate constants (k2) of the thermal cyclodimerization of these compounds have been measured in the temperature range 120–160°C. The polar parameters σmb of these TFS's calculated from 19F NMR chemical shifts are: for p-thiomethyl, -0.18; p-cyclopropyl, -0.31 and p-t-butyl, -0.22. The spin delocalization substituent parameters σ′T (140°) of p-thiomethyl, cyclopropyl and t-butyl groups are 0.59, 0.27 and 0.30 respectively. Thus all of these groups act as electron-donating groups which can also effectively stabilize a spin.

The CO2 laser induced room temperature reactions of CH3CF2H or another protium-donor CH3CHClCH3 with chlorine-atom donors (Z—Cl) CFCl2CF2Cl, CF2CCl3, CFCl3 or CF2Cl2, have been investigated. Some of these reactions can yield two important monomers (CF2 = CH2 and CF2 = CFCl) for fluoropolymers simultaneously. The yield dependence of these two alkenes on experimental conditions has been studied. A laser-initiated chain process is supported by identification of Z—H intermediates in these reactions.

The fluorescence quenching coefficient (KSV) and the quenching rate constant kq of ten para-substituted styrenes (1-Ys) have been measured and correlation-analyzed by both the dual-parameter equation (Eq. 1) with (ρxσx + ρ· σ·) and the single-parameter equation (Eq. 2) with ρxσx. Excellent results have been obtained for the correlation of KSV against (ρxσmb + ρ· σ·JJ) or (ρxσ+ + ρ· σ·JJ ). Our results suggest that, possibly, there might be no need to use excited-state substituent constant for the fluorescence quenching process of excited states of styrenes.

Effects of self-coiling of organic molecules on intramolecular exciplex formation of compound I, in which the carbazole chromophore and terephthalic acid methylester acceptor group are linked by one (CH^2)^10 chain, and the decrease of the fluorescence intensities of compounds II, III, and IV, in which the carbazole chromophore and 3,5-dinitobenzoate are connected by one aliphatic chain of (CH^2)^10(II), (CH^2)^12 (III), or (CH^2)^4(IV), have been studiend in the dioxane(DX)-H^2Obinary system. The results show that self-coiling of organic molecules in DX-H^2O facilitates intramolecular exciplex formation of I and induces the decrease of fluorescence intensities of II, because of the procimity effect brought about by selfcoiling of organic molecules under dydrophobic-lipophilic interaction (HLI)between the excited carbazole chromophore and the acceptor. Since the similar effects are observed even when the concentrations of the probes are less than their CAgCs(critical aggregate concentrations) in the DX-H^2O mixture with the sam φvalues, formaion of the intermolecular exciplex has been exchuded. The effects are found to be strongly depended on φ values, indicating that they are mainly driven by HLI. The properties of the acceptors can also affect the intramolecular exciplex formation. With terephthalic acid methylester moiety as the acceptor, the carbazole chromophore exhibits the fluorescence spectra of the exciplex, while with 3,5-dinitrobenzoate moiety as the acceptor, only the fluorescence spectra of excited carbazolyl chromophore are observed.

Phosphatidylcholines and their analogs, the functional building block of the membrane, are recently found to mediate multiple physiological processes and exhibit a broad range of desirable pharmacological effects, which involve hydrophobic lipophilic interactions (HLI) between the phospholipid and the cell membrane. The HLI behavior of phosphatidylcholines (Ln) and their analogues 1, 2-diacyl-sn-glycerol-3-phosphoric acid bromoethyl ester (Pn), have been investigated in MeOH-H2O binary systems of different volume fractions (designated as ϕ) of the organic component, by employing α-nephthylethyl lauryl ether (Np-12) as fluorescent probe. A very interesting observation is that the Ln possesses double character, i.e., it behaves both as an aggregator and as a deaggregator. The effects of the structure and the environment on the coaggregation and deaggregation are also discussed.

Two molecules la and Ib consisting of one cyclotriveratrylene (CTV) and three cholic acid pedants have been designed and synthesized. Fluorescent studies in water/dimethoxyethane mixtures reveal an intramolecular coaggregation between the CTV and the attached cholic acid moieties. Their fluorescent emission intensity increases and then decreases with the increase of water content, whereas under the same measuring conditions the intensity of CTV derivative 2a, which possesses no similar cholic acid moiety, increases and then reaches a maximum value. The intensity decrease in la and Ib has been attributed to the decrease of the microenvironmental polarity in media of increasing polarity because of the shielding effect of the hydrophobic face of the cholic acid moiety.

EPR study showed that the semi-quinone radical anion of 2,3-dicyano-5,6-dichloro-1,4-benzoquinone (DDQ) was formed in a charge transfer process between ground-state DDQ as acceptor and each one of following ground state donors, i.e., 4-methyl-4′-tridecyl-2, 2′-bipyridyl; 4-methyl-4′-nonyl-2, 2′-bipyridyl; bis (2,2′-bipyridyl) (4-methyl-4′-heptadecyl-2, 2′-bipyridyl)ruthenium(2+) perchlorate and perylene. EPR study also showed that there are perylene cation radical and pyrene cation radical in the following experimental conditions: (a) in 98% sulfuric add. (b) 10−3 mol/L perylene (or pyrene) was dissolved in trifluoroacetic acid-nitrobenzene (1: 1 V/V).

Four novel cyclotriveratrylene (CTV) derivatives with three benzoate pendants bearing different aliphatic chains have been prepared in good yields, starting from CTV. The complexation behavior of these CTV derivatives towards C60 in arene solvents has been measured by UV-visible spectroscopy and high complexation constants are obtained. It is observed that the complexation is promoted pronouncedly by introducing methyl ester groups to the aromatic pendants, while this promoting effect is reduced when the methyl groups are replaced by longer alkyl groups.

One linear template 13 and one cyclophane template 15, both incorporating two electron rich 1,4-dialkoxybenzene units and one diamide unit, have been synthesized. By utilizing donor-ac-ceptor interaction and/or intermolecular hydrogen bonding assembling principles, one novel hetero[3]rotaxane 22.4CI, possessing one neutral and one tetracationic ring componeents, has been synthesized from 13, through neutral [2]rotaxane 21 as intermediate. With 15 as template, tetracationic [2]rotaxane 21 as intermediate. With 15 as template, tetracationc [2] catenane 23.4PF^6 was assembled by using donor-acceptro interaction, but no neutral [2]rotaxane could be obtained under the typical conditions of hydrogen bonding assembling principle. The interlocked supramolecular compounds have been characterized and their spectral properties are investigated.

Coaggregation-facilitated Electron-transfer (ET) fluorescence quenching processes between an excited 1-alkanoylperylene (Pe-n, n = 4, 8, 12) as an acceptor and an 1-alkanoylferrocene (Fc-m, m = 4, 8, 12, 16) or a 1,1-dialkanoylferrocene (Fc-m-2, m =4, 8, 12, 16) as a donor have been investigated by means of fluorescence spectroscopy in dioxane (DX)-H2O binary solvents of different Θ values, where Θ is the volume fraction of the organic component of an aquiorgano mixture. This is a first observation of an ET processes facilitated by hydrophobic-lipophilic interaction (HLI) with organometallic compounds as donors. The extent of HLI-driven co-aggregation between the acceptor and the donor may be assessed from the efficiency of fluorescence quenching, i. e., the slope B of Eq. (2). The chain-foldability effect and the intramolecular “self-satisfaction” of HLI for Fc-m-2 have been observed. The experimental results show that the behavior of Fc-m as a quencher for fluorescence quenching of Pen is rather similar to that of N-alkylsubstituend phenothiazine.

Six-petal microflowers have been self-assembled in methanol from C 3 -symmetric shape-persistent triangular aromatic hydrazide derivatives. Nine intramolecular hydrogen bonds are used to enhance the planarity of the aromatic backbone, while six 2-(2-(2-methoxyethoxy)ethoxy)-ethoxyl groups are appended to the rigid aromatic backbone. Scanning electron microscopy (SEM) images show that the molecules form unique six-petal flower-like aggregates in methanol. A self-assembling mechanism that is similar to the formation of snowflakes has been proposed.

This Letter describes 2-(2-(dioctylamino)-2-oxoethyl-amino)-2-oxoethoxyl (DOAOE)-tuned self-assembly of vesicles from rigid macrocycles and foldamer-like oligomers. The molecules are prepared through the formation of reversible hydrazone bonds from aldehyde and benzo-hydrazide precursors, which are further facilitated by intramolecular N⋯H–O hydrogen bonding. SEM, AFM, and fluorescent encapsulation studies reveal that the molecules all self-assemble into vesicular structures in methanol, while similar molecules bearing the triethylene glycol or n -decyl chains do not. The results illustrate that DOAOE is robust in promoting the formation of vesicles for aromatic systems in polar solvents.

A new class of chiral eighteen-component three-dimensional supramolecular entities has been assembled in toluene and chloroform from twelve zinc porphyrin-appended 2-(ethylamino)- pyrimido[4,5-b][1,8]naphthyridin-4(3H)-one monomers and six chiral bipyridyl compounds. The heterocyclic segments form two C6-symmetric cyclic hexamers, which are stabilized by a well-established DDA–AAD hydrogen bonding motif, while the six chiral bispyridine ligands are coordinated to the corresponding zinc porphyrin units to give the two-layered architectures. The structures have been characterized by the 1H NMR, UV–vis and circular dichroism experiments, which also reveals that, when the concentration of the monomers is high enough, the chiral supramolecular entity can be formed exclusively.

This paper reports the self-assemblies of vesicles from two tetrathiafulvalene (TTF) derivatives (T1 and T2), that bear four or two amphiphilic side chains, in both polar and nonpolar solvents. The formation of vesicles is evidenced by scanning electron microscopy (SEM), atomic force microscopy (AFM), transmission electron microscopy (TEM), and dynamic light scattering (DLS) experiments, while the microstructural aspects of the vesicles are investigated by UV-vis, (1)H NMR, and high resolution TEM, which support a monolayer model for the vesicles. It is revealed that the formation of vesicles is driven by the combination of multiple noncovalent interactions, including pi-pi stacking, hydrogen-bonding, van der Waals force, and S...S interactions. It is also found that, in the presence of electron-deficient cyclobis(paraquat-p-phenylene) tetracation cyclophane, vesicles of T2 can transform into microtubes as a result of the formation of the pseudo[2]rotaxane between the TTF unit of T2 and the cyclophane. This process can be reversed by introducing pristine TTF into the solution of microtubes, due to release of T2 from the pseudo[2]rotaxane through the formation of a more stable complex between pristine TTF and tetracation cyclophane.

Two new hydrazide-based quadruple hydrogen-bonding motifs are described. Dipodals based on these two motifs are revealed to form supramolecular polymers, which can further aggregate to form vesicles and/or organogels in hydrocarbons. The quadruple hydrogen-bonding motifs are characterized by the X-ray diffraction and (2D) 1H NMR experiments, while the vesicles and organogels are evidenced by SEM, AFM, TEM, and fluorescent microscopy.

This paper reports the gelation and liquid crystal properties of a class of new complexes between zinc and copper bisporphyrin and C60 derivatives. The bisporphyrins are induced by intramolecular hydrogen bonding to adopt a preorganized ‘U’-shaped conformation and therefore efficiently complex the C60 derivatives. As a result, the capacity of their mixtures to gelate alkanes is increased notably. The bisporphyrins themselves and their complexes with the C60 derivatives form the smectic liquid crystal phase. However, the glassy transition temperature of the complexes decreases considerably.