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In this study, a series of H‐bonded arylamide foldamers bearing benzoselenadiazole ends with solvent‐responsive properties have been synthesized. In dichloromethane or dimethyl sulfoxide solvents, the molecules exhibit meniscus or linear structures, respectively, which can be attributed to the unique intramolecular hydrogen bonding behavior evidenced by 1D 1H NMR and 2D NOESY spectra. UV‐vis spectroscopy experiments show that the absorption wavelength of H‐bonded arylamide foldamers are significantly red‐shifted due to the presence of benzoselenadiazole group. In addition, the crystal structures reveal that effective intermolecular dual Se ⋅ ⋅ ⋅ N interactions between benzoselenadiazole groups induce further assembly of the monomers. Remarkably, supramolecular linear and double helices structures are constructed under the synergistic induction of intramolecular hydrogen bonding and intermolecular chalcogen bonding. Additionally, 2D DOSY diffusion spectra and theoretical modelling based on density functional theory (DFT) are performed to explore the persistence of intermolecular Se ⋅ ⋅ ⋅ N interactions beyond the crystalline state. [ABSTRACT FROM AUTHOR]

Supramolecular chemistry combines the strength of molecular assembly via various molecular interactions. Hydrogen bonding facilitated self-assembly with the advantages of directionality, specificity, reversibility, and strength is a promising approach for constructing advanced supramolecules. There are still some challenges in hydrogen bonding based supramolecular polymers, such as complexity originating from tautomerism of the molecular building modules, the assembly process, and structure versatility of building blocks. In this review, examples are selected to give insights into multiple hydrogen bonding driven emerging supramolecular architectures. We focus on chiral supramolecular assemblies, multiple hydrogen bonding modules as stimuli responsive sources, interpenetrating polymer networks, multiple hydrogen bonding assisted organic frameworks, supramolecular adhesives, energy dissipators, and quantitative analysis of nano-adhesion. The applications in biomedical materials are focused with detailed examples including drug design evolution for myotonic dystrophy, molecular assembly for advanced drug delivery, an indicator displacement strategy for DNA detection, tissue engineering, and self-assembly complexes as gene delivery vectors for gene transfection. In addition, insights into the current challenges and future perspectives of this field to propel the development of multiple hydrogen bonding facilitated supramolecular materials are proposed. [ABSTRACT FROM AUTHOR]

In this paper, two types of solid phase 2D and 3D XBOFs were selectively constructed from identical building blocks of tetraphenylmethane tetrapyridine derivative and 1,4-diiodotetrafluorobenzene by changing the crystallization solvent. This 3D XBOF is a novel hybrid supramolecular organic framework with the synergistic control of hydrogen and halogen bonds. [ABSTRACT FROM AUTHOR]

Abstract: Dimesogenic compounds 1a–c, 2a–i, and 3, that are composed of a hydrogen bonding-induced straight arylamide spacer and two appended cholesterol groups, have been designed and synthesized. The backbones of the rigid spacers of 1a–c, 2a–i, and 3 contain one, three, and five benzene units, which bear two, six, and ten alkoxyl (methoxyl, n-octoxyl, or n-dodecoxyl) groups, respectively. The thermal and optical properties of the compounds are investigated by using the differential scanning calorimetry (DSC), polarizing optical microscopy (POM), and powder X-ray diffraction (PXRD) analysis. It is revealed that 1a–c exhibit one or two liquid crystalline (LC) phases, 2a–i exhibit no, one or two LC phases, while 3 exhibits one LC phase in a wide temperature range. Generally, the more and longer alkoxyl chains facilitate the formation of the LC phases at low temperature. Notably, compound 2g, which bears two methoxyl and four dodecoxyl groups, displays a blue-red color change during both the heating and cooling cycle. The result illustrates that dimesogens with large rigid spacers can exhibit different LC phases when long aliphatic chains are appended to balance the strong stacking of the rigid backbones. [ABSTRACT FROM AUTHOR]

Abstract: This Letter reports the evidences for intramolecular six-membered N–H···O hydrogen bonding in N-benzyl benzamides and five-membered N–H···N hydrogen bonding in N-(pyridin-2-ylmethyl) benzamide. Intramolecular six-membered N–H···X (X=O or F) hydrogen bonding in 2-methoxyl- or 2-fluorobenzamides is used to lock the amide proton from forming strong intermolecular N–H···On bonding. As a result, for the first time the new intramolecular hydrogen bonding patterns are observed in the crystal structures of nine amides, whereas the whole molecules give rise to a new class of three-center hydrogen bonding motif. 1H NMR study in chloroform-d also supports that this weak intramolecular hydrogen bonding pattern exists in solution. [Copyright &y& Elsevier]

Abstract: The capacity of sulfur to form intramolecular five- or six-membered S⋯H–N hydrogen bonding in aromatic amides is assessed. The five-membered S⋯H–N hydrogen bonding is observed in crystal structures of five compounds, whereas the six-membered S⋯H–N hydrogen bonding is revealed in crystal structures of three compounds. The trityl group has been used to promote formation of the weak hydrogen bonding because it efficiently inhibits the competition of the intermolecular CH–N hydrogen bonding. (2D) 1H NMR experiments indicate that both patterns also exist in chloroform. [Copyright &y& Elsevier]

Abstract: Intramolecular three-centered hydrogen bonding has been used to induce dipyridyl anthranilamide 5 and diphenylacetylene anthranilamide 11 to adopt rigid straight conformation. Compound 5 reacted with Pd(dppp)(OTf)2 ( 12a ) or Pt(dppp)(OTf)2 ( 12b ) in dichloromethane to afford square metallocyclophanes 13a and 13b in 70% and 40% yield, respectively. In contrast, the reaction of 11 with 12b in dichloromethane gave triangular metallocyclophane 14 in 15% yield. [Copyright &y& Elsevier]

A series of peptide-appended bisresorcinarenes were synthesized, which adopted tubular conformation induced by intramolecular hydrogen bonds. The derivatives formed unimolecular artificial transmembrane channels in lipid bilayers to enable selective transport of monovalent cations. Importantly, the channels exhibited reversible ligand-gating behavior in response to alkyl amine and Cu2+. [ABSTRACT FROM AUTHOR]

Inspired by arylamide-based oligomeric foldermers that are stabilized by intramolecular hydrogen bonding, a series of polyamides with intramolecular hydrogen-bonding motifs were synthesized viapolycondensation reactions. These polymers can fold into helical conformation different from their linear control. The chirality of helical conformation can further be tuned viaacid–base complexation using chiral residues. [ABSTRACT FROM AUTHOR]

Two hydrogen-bonded 3-mer arylamide foldamers 1 and 2, which bear two pyridine or iodobenzene subunits at the ends, have been designed and prepared. Compound 1 co-assembles with 1,4-diiodotetrafluorobenzene (3) to form 2 + 2 macrocycles through four (py)N…I halogen bonds, whereas compound 2 dimerizes into a macrocycle through two C=O…I hydrogen bonds. Macrocycles formed by 1 and 3 stack to produce a supramolecular tube, with two neighboring macrocycles encapsulating one molecule of 3 through two C=O…I halogen bonds. Through such a cross-layer connection, formally the two molecules also give rise to a new halogen-bonded supramolecular helix, and further stack alternately to afford a double helix. In contrast, the mixture of 1 and fumaric acid (5) did not produce a similar encapsulation-derived helix, even though they also formed a halogen-bonded 2 + 2 supramolecular macrocycle. [ABSTRACT FROM AUTHOR]

Halogen bonding has been used to glue together hydrogen‐bonded short arylamide foldamers to achieve new supramolecular double and quadruple helices in the solid state. Three compounds, which bear a pyridine at one end and either a CF2I or fluorinated iodobenzene group at the other end, engage in head‐to‐tail N⋅⋅⋅I halogen bonds to form one‐component supramolecular P and M helices, which stack to afford supramolecular double‐stranded helices. One of the double helices can dimerize to form a G‐quadruplex‐like supramolecular quadruple helix. Another symmetric compound, which bears a pyridine at each end, binds to ICF2CF2I through N⋅⋅⋅I halogen bonds to form two‐component supramolecular P and M helices, with one turn consisting of four (2+2) molecules. Half of the pyridine‐bearing molecules in two P helices and two M helices stack alternatingly to form another supramolecular quadruple helix. Another half of the pyridine‐bearing molecules in such quadruple helices stack alternatingly with counterparts from neighboring quadruple helices, leading to unique quadruple helical arrays in two‐dimensional space. Glued in place: Halogen bonds glue together short hydrogen‐bonded arylamide molecules to form either one‐ or two‐component helices. The helices stack to produce supramolecular quadruple and double helical structures. [ABSTRACT FROM AUTHOR]

Halogen bonding has been used to glue together hydrogen‐bonded short arylamide foldamers to achieve new supramolecular double and quadruple helices in the solid state. Three compounds, which bear a pyridine at one end and either a CF2I or fluorinated iodobenzene group at the other end, engage in head‐to‐tail N⋅⋅⋅I halogen bonds to form one‐component supramolecular P and M helices, which stack to afford supramolecular double‐stranded helices. One of the double helices can dimerize to form a G‐quadruplex‐like supramolecular quadruple helix. Another symmetric compound, which bears a pyridine at each end, binds to ICF2CF2I through N⋅⋅⋅I halogen bonds to form two‐component supramolecular P and M helices, with one turn consisting of four (2+2) molecules. Half of the pyridine‐bearing molecules in two P helices and two M helices stack alternatingly to form another supramolecular quadruple helix. Another half of the pyridine‐bearing molecules in such quadruple helices stack alternatingly with counterparts from neighboring quadruple helices, leading to unique quadruple helical arrays in two‐dimensional space. [ABSTRACT FROM AUTHOR]

In this paper, N-doped carbon dots (NCDs) were successfully decorated on the spherical porous silica surface in deep eutectic solvents (DESs) as a novel class of green solvents. The appropriate density and hydrophility of DESs guaranteed the fine dispersibility of silica particles and NCDs, resulting in a homogeneous and thin layer of NCDs immobilization. As compared with traditional organic solvents (DMF and THF), higher surface coverage was obtained in the medium of DES, proving its feasibility as a new kind of alternative solvent for hydrophilic nanomaterial-based surface modification of silica spheres. The resulting NCDs-decorated silica particles (Sil-NCDs) were characterized in detail and packed into chromatographic columns to study their initial feasibility as adsorbent material for liquid chromatography. The resultant packing materials demonstrate a selective behavior for polar compounds in hydrophilic interaction liquid chromatography (HILIC) mode. This work gives a typical example of using carbon dots as stationary phase component, and such material is hopeful to be used in other research fields such as solid absorbents, recycling catalysts, and solid-state electrochemistry etc. [ABSTRACT FROM AUTHOR]

Four hydrogen bonded rigid aromatic hydrazide macrocycles, which bear different number of chiral and/or achiral oligo(ethylene glycol) chains, have been synthesized. 1 H NMR, fluorescence, UV–vis absorption, and circular dichroism experiments showed that the three macrocycles bearing chiral side chains gave rise to one-dimensional chiral column aggregates in aqueous solution. Remarkably, the chiral side chains at two different positions induced the helicity chirality in opposite directions. [ABSTRACT FROM AUTHOR]

A hydrogen bonded foldamer unit and an azobenzene unit have been incorporated into the linear component of a tristable [2]rotaxane to give rise to a doubly gated switching system tuned by the folding–defolding of the foldamer unit and the photo-initiated trans–cis isomerization of the azobenzene unit. [ABSTRACT FROM AUTHOR]

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- C3 v 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. [ABSTRACT FROM AUTHOR]

This Personal Account summarizes the development of the design of hydrogen-bonding-driven aromatic foldamers and their applications in supramolecular chemistry. This account begins with a short, non-exhaustive description of the background in the study of hydrogen-bonded aromatic foldamers. The construction of foldamers from discrete aromatic residues, including amide, urea, hydrazide and 1,2,3-triazole units, is then described. In the following parts, the applications of such compact aromatic oligomers in supramolecular chemistry, including the development of acyclic receptors, the construction of hybrid helical sequences through intramolecular stacking, the promotion of the formation of covalently and noncovalently bonded macrocycles, the tuning of the mechanical properties of copolymers, and the regulation of the shuttling behavior of [2]rotaxanes and the controlled release of dye from reverse vesicles formed from them, are described. In the final part, the binding-induced folding of conformationally flexible aromatic amide oligomers and their self-binding are described. [ABSTRACT FROM AUTHOR]

This paper describes the first assessment of intermolecular weak N–H…F and N–H…Cl hydrogen bonding in stabilising hetero- and homodimers in solution. Aromatic amide and urea monomers have been designed and synthesised. The association constants of the heterodimers formed by two complementary monomers and the homodimers formed by self-complementary monomers have been determined by using1H titration and dilution experiments. The results show that both N–H…F and N–H…Cl hydrogen bonds are able to stabilise the corresponding dimers to a measurable extent, even though the stability of the dimers is generally low. [ABSTRACT FROM PUBLISHER]

Compounds 1 a and 1 b were prepared by appending two tetrathiafulvalene (TTF) units to an aromatic amide segment that is driven by six or two intramolecular NH⋅⋅⋅O hydrogen bonds to adopt a folded conformation. UV/Vis absorption experiments revealed that if the TTF units were oxidized to TTF.+ radical cations, the two compounds could form a stable single molecular noncovalent macrocycle in less polar dichloromethane or dichloroethane or a bimolecular noncovalent macrocycle in a binary mixture of dichloromethane with a more polar solvent owing to remarkably enhanced dimerization of the TTF.+ units. The stability of the (TTF.+)2 dimer was evaluated through UV/Vis absorption, electron paramagnetic resonance, and cyclic voltammetry experiments and also by comparing the results with those of control compound 2. The results showed that introduction of the intramolecular hydrogen bonds played a crucial role in promoting the stability of the (TTF.+)2 dimer and thus the noncovalent macrocyclization of the two backbones in both uni- and bimolecular manners. [ABSTRACT FROM AUTHOR]

Folding-induced folding for the construction of artificial hybrid helices from two different kinds of aromatic sequences is described. Linear compounds 1a, 1b, and 2, containing one aromatic amide trimer or pentamer and one or two aromatic 1,2,3-triazole tetramers, have been designed and synthesized. The trimeric and pentameric amide segments are driven by intramolecluar N—H···F hydrogen bonding to adopt a folded or helical conformation, whereas the triazole segment is intrinsically disordered. In organic solvents of low polarity, the amide foldamer segment induces the attached triazole segment(s) to fold through intramolecular stacking, leading to the formation of hybrid helices. The helical conformation of these hybrid sequences has been confirmed by 1H and 19F NMR spectroscopy, UV/Vis spectroscopy, circular dichroism (CD) experiments, and theoretical calculations. It was found that the amide pentamer exhibits a stronger ability to induce the folding of the attached triazole segment(s) compared with that of the shorter trimer. Enantiomers (R)-3 and (S)-3, which contain an R- or S-(1-naphthyl)ethylamino group at the end of a tetraamide segment, have also been synthesized. CD experiments showed that introduction of a chiral group caused the whole framework to produce a strong helicity bias. Densityfunctional- theory calculations on (S)-3 suggested that this compound exists as a right-handed (P) helix. [ABSTRACT FROM AUTHOR]

Abstract: Two 1,2,3-triazole- and amide-incorporated macrocycles have been prepared by 1,3-dipolar cycloaddition of the corresponding dialkyne and diazide precursors. Intramolecular C–H⋯O hydrogen bonding is introduced to lock the C5–H atoms of the 1,2,3-triazole rings. The binding of the two macrocycles to amide, monosaccharide, and halide derivatives in chloroform or dichloromethane has been investigated. It is revealed that the amide units dominate their binding toward the amide and monosaccharide guests through forming intermolecular hydrogen bonding and 1,2,3-triazole is as weak as an intermolecular hydrogen bonding acceptor, but it forms intermolecular halogen bonding when cooperative effect exists. [Copyright &y& Elsevier]

Abstract: The intramolecular six-membered C–H⋯X (X=F, Cl, Br) hydrogen bonding motif of halogen-substituted 1,4-diphenyl-1,2,3-triazole compounds has been assessed. Twelve triazole derivatives have been designed and prepared, which bear fluorine, chlorine or bromine atoms on the ortho- and/or para-positions of the benzene rings. 1H NMR, X-ray crystallography, and DFT calculation investigations revealed that the ortho-fluorine, chlorine, and bromine atoms of the benzene ring on the C-4 of the triazole unit all can form six-membered C–H⋯X hydrogen bonding. In contrast, only fluorine forms similar, relatively stable intramolecular hydrogen bonding on the N-1 side of the triazole unit. [Copyright &y& Elsevier]

Reverse vesicles exhibiting functions similar to thoseof normalvesicles have been constructed through the self-assembly of TTF/CBPQT4+-based pseudo[2]rotaxanes in a nonpolar solvent. The endsof the threads of the pseudo[2]rotaxanes are attached with a Fréchet-typeG-3 dendron and a hydrogen-bonded arylamide foldamer. These vesiclesexhibit a response to redox. By exploiting the dynamic featurespontaneouslyslow disassociation of the pseudorotaxanesthe sustained releaseof dyes embedded in the reverse vesicles has been demonstrated, whichcan be further tuned by changing the solvent polarity. [ABSTRACT FROM AUTHOR]

Abstract: Hydrogen bonded arylamide foldamers have been introduced in switchable pseudo[2]rotaxanes and [2]rotaxanes, which also include a cyclobisparaquat(p-phenylene) (CBPQT4+) 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 CBPQT4+ 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 1H NMR, UV–vis spectroscopy, and cyclic voltammogram experiments. [Copyright &y& Elsevier]

Abstract: 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. [Copyright &y& Elsevier]

Abstract: 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. [Copyright &y& Elsevier]

Abstract: 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. [Copyright &y& Elsevier]

Abstract: 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 C 6-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. [Copyright &y& Elsevier]

Abstract: 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. [Copyright &y& Elsevier]

Abstract: In this paper, we report the synthesis and self-assembling behavior of an F⋯H–N hydrogen bonding-induced arylamide-based dipodal foldamer. SEM, AFM, TEM, and XRD studies reveal that this preorganized oligomer stacks to form vesicles in methanol–chloroform (10–70%) binary solvents due to the strong stacking interaction of the folded segments and the supramolecular polymeric feature of the dipodal molecule in the stacked state. In contrast, a simple folded molecule can give rise to vesicles only when the chloroform content is 45–55%. [Copyright &y& Elsevier]

Abstract: 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. [Copyright &y& Elsevier]

Abstract: This paper describes an investigation of the structural and side-chain factors for the formation of vesicles and gels by hydrogen bonding-mediated aromatic hydrazide foldamers. Six foldamers and one straight analog that bear discrete side chains have been synthesized. SEM and AFM studies reveal that the molecules with the appended 2-(2-(dialkyl-amino)-2-oxoethylamino)-2-oxoethoxyl chains form vesicles, hydrogels or organogels, depending on the solvents. Both the inner amide units and the terminal N,N-dialkylamide units in the chains are revealed to play essential roles in controlling the self-assembly. The former facilitates it by forming the intermolecular hydrogen bonding, while the latter modulates it by providing solubility and balancing the hydrophobicity of the whole molecules in solvents of varying polarity. [Copyright &y& Elsevier]

Abstract: Four porphyrin-bridge-C60 dyads have been synthesized by covalently linking the chromophores at the opposite ends of a hydrogen bonded arylamide-derived foldamer bridge. For comparison, four C60-free porphyrin derivatives of the same frameworks have also been prepared. The fully hydrogen bonded bridges enable the appended porphyrin and C60 moieties to contact in a face-to-face manner. 1H NMR, UV–vis and fluorescent investigations in chloroform indicate that such a structural matching remarkably facilitates the intramolecular energy and electron transfer and charge separation between the two chromophores and also retards the recombination of the charge-separated state. Removing one hydrogen bond considerably reduces the energy and electron transfer. Further removing another one leads to no important interaction between the chromophores to occur. [Copyright &y& Elsevier]

Abstract: This Letter reports the synthesis of three dicationic and two hexacationic receptors in which two porphyrin units are connected with an aryl amide linker. 1H NMR and X-ray crystal structure analysis for model compounds show that in aqueous or DMSO medium the receptors could adopt preorganized U-styled conformation due to intramolecular hydrogen bonding-induced rigidity of the amide linker. 1H NMR, UV–vis and fluorescent investigations revealed that the ionic receptors efficiently complex C60C in aqueous medium with cooperative intermolecular electrostatic and donor–acceptor interactions as driving forces. A 1:1 binding stoichiometry has been established for the complexes and the related association constants have been evaluated. [Copyright &y& Elsevier]

Abstract: This Letter reports the design and synthesis of a new type of hydrogen bonding-mediated foldamer-derived tweezer receptors that are incorporated with two peripheral (zinc)porphyrin units. Due to the existence of four intramolecular hydrogen bonds, the (zinc)porphyrin units are forced to approach and stack with each other. 1H NMR and fluorescent studies revealed that the new receptors could form 1:1 complexes with planar electron-deficient molecules such as naphthalene and benzene diimides and paraquat through a unique sandwich-styled binding pattern. The association constants of the new complexes have been evaluated by the 1H NMR or fluorescent titration methods. [Copyright &y& Elsevier]

Abstract: The self-assembly of a novel series of hydrogen bonding-mediated homodimers in chloroform-d has been described. Six anthranilamide-based monomers have been prepared, in which two self-binding formamido, trifluoroacetamido, acetamido, butyl or methyl ureido units are introduced at the two ends of the backbones. Quantitative 1H NMR investigations in chloroform-d revealed that the formamido and ureido units are more efficient than acetamido to induce the formation of stable homodimers. The association constants of all the new homodimers have been determined by 1H NMR dilution method. Multiply hydrogen bonding-driven binding patterns have been proposed for the homodimers. It is also found that ureido-derived homodimers do not adopt common linear binding pattern observed for simple urea derivatives. [Copyright &y& Elsevier]

Abstract: This paper reports the design and synthesis of a new series of hydrogen bonding-mediated foldamer-derived tweezer receptors that are used for efficient complexation of zinc porphyrin guest. One end of the rigidified aromatic amide backbone is incorporated with one fullerene unit, while another end is connected to one pyridine or imidazole unit. The 1H NMR, UV–vis, and fluorescent investigations in chloroform revealed that, due to the intramolecular hydrogen bonding-driven preorganized folded conformation, the fullerene and pyridine units of the receptors are located with suitable spatial separation and consequently able to co-complex zinc porphyrin with remarkably increased stability. In contrast, the imidazole-incorporated receptor displays a weakened binding affinity possibly due to structural mismatching and large steric hindrance. The association constants of the complexes of the new receptors with zinc porphyrin have been determined. [Copyright &y& Elsevier]

Abstract: Two linear compounds 1 and 2 have been designed and synthesized as new receptors for zinc porphyrins. Both compounds consist of two folded aromatic amide moieties, which are connected with an acetylene linker in 1 or directly in 2. The rigid conformations of their folded moieties are stabilized by intramolecular tri-centered hydrogen bonding, while the whole molecule adopts a ‘S’- or ‘C’-styled conformation depending on the relative orientation of the two rigid moieties. Two pyridine units are introduced at the ends of 1 and 2 for the complexation of zinc porphyrin guests. Although the 1H NMR investigation indicated that both compounds can bind two zinc porphyrin guests at high concentrations (≥5mM) in chloroform, the UV–vis studies revealed that, at low concentration of 1 and 2 (4μM), both compounds complex one zinc porphyrin guest to form structurally unique ‘two-point’-bound 1:1 complexes. The association constants of the 1:1 complexes have been determined with the UV–vis titration experiments. [Copyright &y& Elsevier]

Abstract: This paper describes the self-assembly of a new series of heterotrimers in chloroform-d by utilizing the cooperative interaction of hydrogen bonding and donor–acceptor interaction. Compounds 1 and 11 , in which an 2-ureido-4[1H]-pyrimidinone unit is connected to 34-crown-10 or 36-crown-10, were used as donor monomer, and 2 and 19 , in which an 2-ureido-4[1H]-pyrimidinone unit is connected to NDI, were used as acceptor monomer, while linear compound 4 , which contains two diamido-1,8-naphthyridines, was used as template. A large tri-p-(t-butyl)phenylmethoxyl group was introduced to 19 in order to compare its assembling behavior with that of 2 . Mixing 4 with dimer 1·2 caused 1·2 to fully decompose and to afford 55% of ‘in–in’-oriented heterotrimer 1·4·2 . Adding 4 to the solution of 2·11 or 11·19 in chloroform-d also led to full dissociation of the dimers. However, in these systems the ‘in–in’-arranged heterotrimer 2·4·11 or 11·4·19 could be produced exclusively. [Copyright &y& Elsevier]

Abstract: Two new ditopic porphyrin receptors Zn1 , incorporating a diaza-15-crown-5 unit, and Zn2 , incorporating a diaza-18-crown-6 unit, have been prepared and characterized. UV–vis study in polar methanol has revealed that Zn1 is able to selectively recognize sodium cyanide over potassium cyanide (the ratio of their binding constant is ca. 56), whereas Zn2 exhibits a higher binding affinity for potassium cyanide over sodium cyanide (the ratio of their binding constant is ca. 12). In contrast, both receptors display substantially weaker binding affinity for sodium thiocyanate and potassium thiocyanate presumably due to a monotopic binding fashion. [Copyright &y& Elsevier]

Abstract: The self-assembly of a novel series of intramolecular hydrogen bonding-driven foldamers have been described. Five linear aromatic amide oligomers 1–5 , which bear two to six repeating benzoyl amide subunits, respectively, have been prepared by continuous amide-coupling reactions. The existence of three-centered hydrogen bonds in the oligomers and consequently, the folding conformation of the oligomers in the solid state and solution have been proved by the X-ray analysis (for 2 ) and the 1H NMR and IR experiments. Molecular modeling reveals a planar and rigid conformation for the oligomers and a cavity of 0.86nm in diameter for 6-mer 5 . Fluorescent and 1H NMR experiments have demonstrated that the new aromatic oligo-amide foldamers can bind primary and secondary alkyl ammonium ions in chloroform and the associated binding constants have been determined. It is revealed that 5-mer 4 exhibits the largest binding ability. A face-to-face binding mode has been proposed for the complexes. [Copyright &y& Elsevier]

A hydrogen bonding approach has been developed to facilitate the self-assembly of a new series of rigid and planar metallocyclophanes. Two new anthranilamide derivatives 1 and 2, which are incorporated with two acetylene units, respectively, have been synthesized and characterized. X-ray analysis (for 1), 1D and 2D 1H NMR and IR experiments reveal that, due to the formation of intramolecular three-centered hydrogen bonding, both compounds adopt rigid and planar conformations with the two acetylene units located at the same side of the anthranilamide skeleton. Two new metallocyclophanes 17 and 18 have been constructed in moderate yields from the reaction of 1 and 2 with trans-Pt(PEt3)2Cl2, respectively, in dichloromethane in the presence of diethylamine and cupric chloride. Fluorescent and 1H NMR investigations reveal that both 17 and 18 can efficiently complex mono- and disaccharide derivatives in chloroform, with a binding selectivity for disaccharides, which is driven by intermolecular hydrogen bonding. [Copyright &y& Elsevier]

This paper describes the synthesis and characterization of the first series of hydrogen bonding-driven hydrazide foldamers and their recognition for alkyl saccharides in chloroform. Oligomers 1, 2-4, 5, 6, and 7, which contain one, two, four, six, or twelve repeated dibenzoyl hydrazide residues, respectively, have been prepared. The rigid and planar conformations of 1 and 2 or 4 have been established with X-ray analysis and 1H NMR spectroscopy, whereas the folding and helical conformations of 5-7 have been evidenced by the 1D and 2D 1H NMR and IR spectroscopy and molecular mechanics calculations. Molecular mechanics calculations also revealed that 5, 6, and 7 possess a rigid cavity with size of Ca. 10.6 to 11.1 Å, and half of the carbonyl groups in the folding conformations are orientated inwardly inside the cavity. 1H NMR and CD experiments revealed that 5-7 efficiently complex alkylated mono- and disaccharides 32- 35 in chloroform. The association constants (Kassoc) of the complexes have been determined with the 1H NMR and fluorescent titration methods. The energy-minimized conformation of 6.34 has been obtained with molecular mechanics calculation. The hydrazide-based folding structures described here represent novel examples of hydrogen bonding-driven foldamers that act as artificial receptors for selective molecular recognition. [ABSTRACT FROM AUTHOR]

This paper describes studies on the synthesis, self-assembly behavior, and complexing properties of several strapped porphyrin-incorporated melamine–cyanuric or melamine-barbiturate-based rosette supramolecules in chloroform-d. Strapped porpyrin cyanuric acid H21 and its Zn (II) complex Zn1 were designed and synthesized. Both H21 and Zn1 could combine melamine derivatives 11 or 12 to afford porphyrin rosettes, which are more stable than the model rosette initially reported by Whitesides due to the larger size of the porphyrin unit. The new porphyrin rosettes could efficiently complex tripyridyl derivative 13 through intermolecular, cooperative coordination between Zn (II) and pyridine. Two new pyridine-bearing barbiturates 18a and 18b were also synthesized. Mixing the identical amount of 18a or 18b with 11 or 12 in chloroform-d led to the formation of new isomeric rosettes as a result of different orientation of the pyridine unit of 18a or 18b in the rosettes. 1H NMR study also revealed that porpyrin-bearing rosette Zn13·113 could complex pyridine-bearing rosette 113·18a3, leading to the formation of new two-layer-typed supramolecular architectures. [Copyright &y& Elsevier]

The donor–acceptor interaction-driven supramolecular arrangement of a new series of quadruply hydrogen-bonded homo- and heterodimers have been investigated in chloroform with 1H NMR and UV–Vis spectroscopy. Two kinds of structurally complementary monomers have been prepared. Monomers 3 and 4 are incorporated with one ureidopyrimidone unit and one electron deficient pyromellitic diimide (PDI) or naphthalene diimide (NDI) unit, respectively, monomers 5 and 6 are incorporated with two ureidopyrimidone units and one PDI or NDI unit, respectively, whereas monomers 7 and 8 consist of one electron rich bis-p-phenylene[34]crown-10 unit and one or two 2,7-diamido-1,6-naphthyridine units, respectively. Compounds 3 and 4 exist exclusively as homodimers, respectively. Adding 1equiv. of 7 to the solution of 3·3 and 4·4 induced them to partially or fully dissociate to produce heterodimers 3·7 and 4·7 due to intermolecular donor–acceptor interaction and the formation of a new binding mode between the ureidopyrimidone of 3 or 4 and the 2,7-diamido-1,6-naphthyridine unit of 7. Both 5 and 6 exist as cyclic monomer and dimer in chloroform. Adding 1equiv. of 8 to the solution of 5 or 6 in chloroform caused all the cyclic dimer and most of the cyclic monomer to de-cyclize to form new heterodimers 5·8 and 6·8, respectively. 1H NMR and UV–vis study revealed that heterodimer 5·8 has a structure in which the PDI of 5 is not threaded through the cavity of the bis-p-phenylene[34]crown-10 unit of 8. In contrast, in addition to the heterodimer similar to 5·8, about 40% of heterodimer 6·8 is generated, in which the PDI of 6 is threaded through the cavity of the bis-p-phenylene[3]crown-10 unit of 8 due to the increased donor–acceptor interaction between NDI and bis-p-phenylene[34]crown-10. Steric hindrance and mismatching of the hydrogen bonding moiety play important roles in the arrangement of the new homo- and heterodimers. [Copyright &y& Elsevier]

A new series of multiply hydrogen-bonded heterodimers have been self-assembled in chloroform-d, with ureidopyrimidone derivatives 2 and 3 and 2,7-diamino-1,6-naphthyridine diamide 4 and ureas 5 and 6 as monomers. The self-associating behavior of the compounds and the binding modules of the new heterodimers have been investigated. New tri-center hydrogen bonds have been proposed to explain the stability of the new heterodimers. 2D-NOESY, COSY and temperature variable 1H NMR studies revealed that all the new heterodimers are substantially more stable than the ureidopyrimidone-based quadruply hydrogen-bonded homodimers in chloroform-d. As a result, heterodimers 2·4 and 3·4 were assembled quantitatively, while heterodimers 2·5, 3·5, 2·6, and 3·6 were formed in 80–85% yields. It is also revealed that intramolecular hydrogen bonds formed in monomers 5 and 6 reduce the stability of the corresponding heterodimers. [Copyright &y& Elsevier]