Hierarchical self-assembly,coassembly, and self-organization of novel liquid crystalline lattices and superlattices from a twin-tapered dendritic benzamide and its four-cylinder-bundle supramolecular polymer

The synthesis and structural analysis of the twin-dendritic benzamide 10, based on the first-generation, self-assembling, tapered dendrons 3,4,5-tris(4'-dodecyloxybenzyloxy)benzoic acid and 3,4,5-tris(4'-dodecyloxybenzyloxy)-1-aminobenzene, and the polymethacrylate, 20, which contains 10 as side groups, are presented. Benzamide 10 self-assembles into a supramolecular cylindrical dendrimer that self-organizes into a columnar hexagonal (Phi(h)) liquid crystalline (LC) phase. Polymer 20 self-assembles into an imperfect four-cylinder-bundle supramolecular dendrimer, and creates a giant vesicular supercylinder that self-organizes into a columnar nematic (N(c)) LC phase which displays short-range hexagonal order. In mixtures of 20 and 10, 10 acts as a guest and 20 as a host to create a perfect four-cylinder-bundle host-guest supramolecular dendrimer that coorganizes with 10. A diversity of Phi(h), simple rectangular columnar (Phi(r-s)) and centered rectangular columnar (Phi(r-c)), superlattices are produced at different ratios between 20 and 10. This diversity of LC lattices and superlattices is facilitated by the architecture of the twin-dendritic building block, polymethacrylate, the host-guest supramolecular assembly, and by hydrogen bonding along the center of the supramolecular cylinders generated from 10 and 20.     

Hexagonal Columnar. cis, cis-(3,5-dihydroxycyclohexyl)-3,4,5-tris(alkoxy)benzoates Thermal behaviour and water absorption

The thermal behaviour of freeze dried and water saturated samples of a homologous series of hexagonal columnar, liquid-crystalline cis, cis-(3,5-dihydroxycyclohexyl)-3,4,5-tris(alkoxy)benzoates (three chain diols) is discussed. The water absorption from a saturated atmosphere as well as in direct contact is also described.     

Synthesis and retrostructural analysis of libraries of AB3 and constitutional isomeric AB2 phenylpropyl ether-based supramolecular dendrimers

We report the synthesis of methyl esters of 3-(4-hydroxyphenyl)propionic, 3-(3,4-dihydroxyphenyl)propionic, 3-(3,5-dihydroxyphenyl)propionic, and 3-(3,4,5-trihydroxyphenyl)propionic acids and their use in a convergent iterative strategy to prepare up to four generations of three libraries, one of 3,4,5- and two of constitutional isomeric 3,4- and 3,5-substituted 3-phenylpropyl dendrons. Each library contains 3-[3,4,5-tris(dodecyl-1-oxy)phenyl]propyl-, 3-[3,4-bis(dodecyl-1-oxy)phenyl]propyl-, 3-{3,4-bis[3-(4-dodecyl-1-oxyphenyl)propyl-1-oxy]phenyl}propyl-, and 3-{3,4,5-tris[3-(4-dodecyl-1-oxyphenyl)propyl-1-oxy]phenyl}propyl ether first-generation dendrons on their periphery and -CO2CH3, -COOH, and -CH2OH groups at their apex. Regardless of their generation number and their periphery, internal, and apex structures, these dendrons self-assemble into supramolecular dendrimers that self-organize into all periodic and quasi-periodic assemblies encountered previously and in several unencountered with architecturally related benzyl ether-based supramolecular dendrimers. A variety of porous columnar lattices that were previously obtained only from dendritic dipeptides and hollow supramolecular spheres were also discovered from these building blocks. The more flexible and less compact 3-phenylpropyl ether repeat units are stable under acidic conditions, facilitate a simpler synthetic strategy, provide faster dynamics of self-assembly into higher-order supramolecular structures of larger dimensions, exhibit lower transition temperatures than the corresponding benzyl ether homologues, and demonstrate the generality of the self-assembly concept based on amphiphilic dendrons.     

Exploring and expanding the three-dimensional structural diversity of supramolecular dendrimers with the aid of libraries of alkali metals of their AB(3) minidendritic carboxylates

The synthesis of the alkali metal salts of 3,4,5-tris(n-alkan-1-yloxy)benzoic acid [(3,4,5)nG1-CO(2)M, where n is the number of methylenic units in the alkane group for n=12, 14, 16, 18 and M=Li, Na, K, Rb, Cs] is described. The structural analysis of these AB(3) molecules by a combination of methods which includes X-ray diffraction experiments was performed. These experiments have demonstrated that (3,4,5)nG1-CO(2)M self-assemble at low temperatures into supramolecular cylinders and at high temperatures into spheres which subsequently self-organize into two-dimensional c2mm rectangular columnar, p6mm hexagonal columnar, three-dimensional Pm(-)3n and Im(-)3m cubic lattices. In addition a novel unidentified liquid crystalline lattice was also discovered. The dependence between the symmetry of the lattice and the molecular structure of (3,4,5)nG1-CO(2)M was established. (3,4,5)nG1-CO(2)M represents one of the AB(3) minidendrons (i.e., first-generation monodendron attached to the periphery of larger generation dendrons) that is responsible for the control of the three-dimensional structures created from libraries of larger generations of dendrimers. Therefore, the molecular structure-lattice dependence elaborated here will aid the rational design of the three-dimensional shapes from larger generations of supramolecular dendrimers and of their lattices. In addition, the temperature responsive shape change of these supramolecular objects may generate new supramolecular concepts and technological applications.     

Technologically promising,room temperature luminescent columnar liquid crystals derived from s-triazine core: molecular design,synthesis and characterization

Three fold Horner-Wadsworth-Emmons (HWS) reaction of triphosphonate with achiral/chiral 3,4,5-tris(alkoxy)benzaldehydes yield novel achiral/chiral star-shaped liquid crystals (LCs), in which three fluorophore arms such as 1,2,3-tris(alkoxy)-5-styrylbenzenes are tethered to a central s-triazine core. These LCs, the first of their kind, display a columnar liquid crystalline phase over a wide temperature range existing between well below and above the room temperature, which is evidenced by optical and calorimetric studies. Besides, they show photoluminescence both in solution and mesomorphic states. Thus, given their self-organization into fluid one-dimensional columnar array coupled with light generating capability, these organic ordered-fluids can be regarded as novel media for advanced technological applications.     

Hydroxy group containing liquid crystals. I. Synthesis and characterization of cis, cis-(3,5-dihydroxycyclohexyl)-3,4,5-tris(decyloxy)benzoate and derivatives

The first example of a new class of diol mesogens is described. Cis, cis-(3,5-dihydroxycyclohexyl)-3,4,5-tris(decyloxy)benzoate was synthesized starting from cis, cis-phloroglucitol, which had been protected by phenylboronic acid. Polarizing microscopy and calorimetric measurements provide evidence for a broad mesophase range, including room temperature. The existence of a hexagonal columnar structure is probable. Furthermore several derivatives are described.     

Ultrafast photoinduced charge separation resulting from self-assembly of a green perylene-based dye into pi-stacked arrays

Condensation of 3,4,5-tris(n-dodecyloxy)aniline with the green chromophore 1,7-bis(N-pyrrolidinyl)perylene-3,4;9,10-tetracarboxylic dianhydride yields N,N'-bis(3,4,5-tris(n-dodecyloxy)phenyl)-1,7-bis(N-pyrrolidinyl)perylene-3,4;9,10-bis(dicarboximide), 5PDI-TAP, which absorbs light strongly from 550 to 750 nm. 5PDI-TAP dissolves readily in methylcyclohexane (MCH), resulting in self-assembly into H-aggregates. Small-angle X-ray scattering data obtained on 10(-4) M solutions of 5PDI-TAP in MCH show that the aggregates are pi-stacked monodisperse pentamers. Femtosecond transient absorption spectroscopy on solutions of (5PDI-TAP)5 in MCH shows evidence of charge separation occurring with tau < or = 150 fs between adjacent stacked members of 5PDI-TAP within the pentamer followed by charge recombination with tau = 860 ps. Transmission electron microscopy of 5PDI-TAP films cast from solution show isolated bundles of columnar aggregates. (5PDI-TAP)n is a potentially useful material for organic photovoltaics because efficient photoinduced charge generation is an intrinsic property of the assembly.     

Solid-state hosts by the template polymerization of columnar liquid crystals: locked supramolecular architectures around chiral 2-amino alcohols

The cross-linking of multicomponent liquid crystals could be applied to the synthesis of nanometer-sized porous materials with a well-defined structure. In this work we demonstrate the template polymerization of columnar liquid crystals composed of the salts of a carboxylic acid and enantiopure 2-amino alcohols, and the application of one of them as a solid-state host. The salts of 3,4,5-tris(11-acryloyloxyundecyloxy)benzoic acid with (S)-2-amino-1-propanol and with (1R,2S)-norephedrine showed hexagonal and rectangular columnar liquid-crystalline structures, respectively. The successful application of gamma-ray-induced polymerization to the cross-linking of the liquid-crystalline salts, which was more advantageous than photoinduced polymerization from the standpoint of the retention of the original structural order in the gram-scale preparation of the polymers with a homogeneous columnar structure. The cross-linked polymer thus obtained from the gallic acid derivative and (1R,2S)-norephedrine was applicable as a heterogeneous host to capture amines from a guest solution through acid-amine interactions. When (1R,2S)-norephedrine was replaced with other amines through the guest-exchange reaction, a "template effect" was observed; the size and shape of the guests were determining factors for the efficiency of the guest exchange. The guest adsorption was found to proceed in an enantioselective manner when racemic 2-amino alcohols were used as guests, especially in the cases of substrates possessing a bulky substituent at the C1-position. The guest preference was again elucidated by the template effect, although the enantioselection mode was switched depending on the presence of a C2 substituent.     

Molecular imaging of monodendron jacketed linear polymers by scanning force microscopy

Polystyrene and polymethacrylate with 3,4,5-tris[4-(tetradecyloxy)benzyloxy]benzoic acid and 3,4,5-tris[3,4,5-tris(dodecyloxy)benzyloxy]benzyl alcohol side groups, respectively, were visualized by scanning force microscopy (SFM). The cylindrical molecules did not interpenetrate and their chain ends could be resolved in the images allowing quantitative evaluation of their length distribution. Whereas the polymethacrylate with the sterically most demanding side groups demonstrated a fairly good agreement between the SFM length and the calculated contour length, the polystyrene with the less branched substituent appeared to be at least two times shorter. The reduced length of the polymer chains was attributed to a disordered helixlike conformation.     

Induction of thermotropic bicontinuous cubic phases in liquid-crystalline ammonium and phosphonium salts

Two series of wedge-shaped onium salts, one ammonium and the other phosphonium, having 3,4,5-tris(alkyloxy)benzyl moieties, exhibit thermotropic bicontinuous "gyroid" cubic (Cub(bi)) and hexagonal columnar liquid-crystalline (LC) phases by nanosegregation between ionophilic and ionophobic parts. The alkyl chain lengths on the cationic moieties, anion species, and alkyl chain lengths on the benzyl moieties have crucial effects on their thermotropic phase behavior. For example, triethyl-[3,4,5-tris(dodecyloxy)benzyl]ammonium hexafluorophosphate forms the thermotropic Ia3d Cub(bi) LC phase, whereas an analogous compound with trifluoromethanesulfonate anion shows no LC properties. Synchrotron small-angle diffraction intensities from the Ia3d Cub(bi) LC materials provide electron density maps in the bulk state. The resulting maps show convincingly that the Ia3d Cub(bi) structure is composed of three-dimensionally interconnected ion nanochannel networks surrounded by aliphatic domains. A novel differential mapping technique has been applied successfully. The map of triethyl-[3,4,5-tris(decyloxy)benzyl]ammonium tetrafluoroborate has been subtracted from that of the analogous ammonium salt with hexafluorophosphate anion in the Ia3d Cub(bi) phases. The differential map shows that the counteranions are located in the core of the three-dimensionally interconnected nanochannel networks. Changing from trimethyl- via triethyl- to tripropylammonium cation changes the phase from columnar to Cub(bi) to no mesophase, respectively. This sensitivity to the widened shape for the narrow end of the molecule is explained successfully by the previously proposed semiquantitative geometric model based on the radial distribution of volume in wedge-shaped molecules. The LC onium salts dissolve lithium tetrafluoroborate without losing the Ia3d Cub(bi) LC phase. The Cub(bi) LC materials exhibit efficient ion-transporting behavior as a result of their 3D interconnected ion nanochannel networks. The Ia3d Cub(bi) LC material formed by triethyl-[3,4,5-tris(decyloxy)benzyl]phosphonium tetrafluoroborate shows ionic conductivities higher than the analogous Ia3d Cub(bi) material based on ammonium salts. The present study indicates great potential of Cub(bi) LC nanostructures consisting of ionic molecules for development of transportation nanochannel materials.     

Comparison of the supramolecular structures formed by a polymethacrylate with a highly tapered side chain and its monomeric precursor

Insight into the supramolecular structure formed by a polymethacrylate with a highly tapered side chain is obtained from parallel X-ray analysis of oriented fibers of the polymer and its monomeric precursor. The polymer is poly(2-{2-[2-(2-methacryloyloxyethoxy)ethoxy]ethoxy}ethyl 3,4,5-tris(p-dodecyloxybenzyloxy)benzoate) (abbreviated to 12-ABG-4EO-PMA); the monomeric precursor is the hydroxy-terminated side chain 2-{2-[2-(2-hydroxyethoxy)-ethoxy]ethoxy}ethyl 3,4,5-tris(p-dodecyloxybenzyloxy)benzoate (12-ABG-4EO-OH). The polymer and precursor both form ordered solid state structures that are converted to columnar hexagonal liquid crystalline (φ_h) phases at approximately 40°C and 50°C, respectively. The ordered solid state structures consist of ordered hexagonally packed cylindrical columns, in which the monomer units are probably packed with helical symmetry. For the polymer at 25°C, the column diameter is 60.4Å with an axial repeat of 5.03Å containing eight monomer units. For the precursor at 25°C, the column diameter is reduced to 53.5Å, probably due to the absence of the polymer backbone from the center of the column, and the axial repeat is doubled to 10.04Å. The X-ray data are compatible with a tighter winding of the monomers in a helical structure, but otherwise suggest that there are common features in the stacking of the aromatic groups in the two structures.     

Self-repairing complex helical columns generated via kinetically controlled self-assembly of dendronized perylene bisimides

The dendronized perylene 3,4:9,10-tetracarboxylic acid bisimide (PBI), (3,4,5)12G1-3-PBI, was recently reported to self-assemble in complex helical columns containing tetramers of PBI as basic repeat unit. These tetramers contain a pair of two molecules arranged side-by-side and another pair in the next stratum of the column turned upside-down and rotated around the column axis. Intra- and intertetramer rotation angles and stacking distances are different. At high temperature, (3,4,5)12G1-3-PBI self-assembles via a thermodynamically controlled process in a 2D hexagonal columnar phase while at low temperature in a 3D orthorhombic columnar array via a kinetically controlled process. Here, we report the synthesis and structural analysis, by a combination of differential scanning calorimetry, X-ray and electron diffraction, and solid-state NMR performed at different temperatures, on the supramolecular structures generated by a library of (3,4,5)nG1-3-PBI with n = 14-4. For n = 11-8, the kinetically controlled self-assembly from low temperature changes in a thermodynamically controlled process, while the orthorhombic columnar array for n = 9 and 8 transforms from the thermodynamic product into the kinetic product. The new thermodynamic product at low temperature for n = 9, 8 is a self-repaired helical column with an intra- and intertetramer distance of 3.5 ? forming a 3D monoclinic periodic array via a kinetically controlled self-assembly process. The complex dynamic process leading to this reorganization was elucidated by solid-state NMR and X-ray diffraction. This discovery is important for the field of self-assembly and for the molecular design of supramolecular electronics and solar cell.     

Synthesis of 3,3-bis(2-hydroxyethyl) and 3,3,3’-tris(2-hydroxyethyl) derivatives of 1,1’-[methylenebis(oxy)]bis(triaz-1-ene 2-oxides)

Synthetic procedures to access new potential NO donors that can generate NO in living systems, 3,3-bis(2-hydroxyethyl) and 3,3,3’-tris(2-hydroxyethyl) derivatives of 1,1’-[methylenebis(oxy)]bis(3,3-dialkyltriaz-1-ene 2-oxides), were elaborated. 3,3-Bis(2-acetoxyethyl)-1(chloromethoxy)triaz-1-ene 2-oxide reacts with 1-hydroxytriaz-1-ene 2-oxide sodium salts to give a series of alkylated 3,3-bis(2-acetoxyethyl) derivatives. Deacetylation of the latter produces 3-(2-hydroxyethyl)-11,11-dialkyl-6,8-dioxa-3,4,5,9,10,11-hexaazaundeca-4,9-dien-1-ol 4,10-dioxides and 11-alkyl-3-(2-hydroxyethyl)-6,8-dioxa-3,4,5,9,10,11-hexaazatrideca-4,9-diene-1,13-diol 4,10-dioxides.     

Noncovalent approach to one-dimensional ion conductors: enhancement of ionic conductivities in nanostructured columnar liquid crystals

Noncovalent design of new liquid-crystalline (LC) columnar assemblies based on an ionic liquid has shown to be useful to achieve anisotropic high ionic conductivities. An equimolar mixture of an ionic liquid, 1-butyl-3-methylimidazolium bromide, and 3-[3,4,5-tri(octyloxy)benzoyloxy]propane-1,2-diol, which is partially miscible with the ionic liquid, exhibits an LC hexagonal columnar phase from -4 to 63 degrees C. This columnar supramolecular assembly forming the nanostructures shows the one-dimensional (1D) ionic conductivity of 3.9 x 10(-3) S cm(-1) at 50 degrees C along the column, which is more than 700 times higher than that of the corresponding covalent-type columnar ionic liquid, 1-methyl-3-[3,4,5-tri(octyloxy)benzyl]imidazolium bromide, which is 5.3 x 10(-6) S cm(-1) at 50 degrees C. This significant enhancement of the ionic conductivity is attributed to the increase of the mobility of the ionic part.     

Synthesis and chemical properties of sodium 3,4,5-tris(diethylamino)-1,2-diphosphacyclopentadienide

1,2,3-Tris(diethylamino)cyclopropenylium iodide (1) reacted with sodium polyphosphides to give sodium 3,4,5-tris(diethylamino)-1,2-diphosphacyclopentadienide (2) in high yields. Chemical behavior of compound 2 in the reactions with organic and organoelement electrophiles was studied and compared with that of sodium 3,4,5-triphenyl-1,2-diphosphacyclopentadienide.     

Isomorphism within the hexagonal columnar mesophase of molecular and macromolecular self- and co-assembled columns containing tapered groups

The phase behaviour of binary mixtures of self-assembled tapering molecules based on monoesters of oligooxyethylene glycol and 3,4,5-tris[4-(n-dodecan-1-yloxy)benzyloxy]benzoic acid, their corresponding polymethacrylates, and of 4'-methyl (benzo-15-crown-5)-3,4,5-tris[4-(n-dodecan-1-yloxy)benzyloxy]benzoate within their hexagonal columnar mesophase (Φ_h) is described. The binary blends between molecular tapers co-assemble into a single supramolecular column resulting in isomorphism within their Φ_h mesophase over the entire range of composition. The binary blends between polymethacrylates containing tapered side groups co-assemble into a single Φ_h phase only when the columns of the parent polymers are of similar diameters. This results in binary mixtures which are isomorphic within the Φ_h mesophase over the entire composition range. When the diameters of the columns formed by the parent polymers are dissimilar, isomorphic mixtures are obtained only over a narrow range of composition. Binary mixtures between molecular tapers and macromolecular systems containing tapered side groups co-assemble into a single column to the extent that intercalation of the molecular taper, within the column formed by the macromolecular system containing tapered side groups, is permissible. In all systems increased intracolumnar interactions can be induced by complexation of CF₃SO₃Li by the oligooxyethylenic receptors leading to isomorphism in otherwise non-isomorphic mixtures. Ternary mixtures between molecular tapers with non-specific oligooxyethylenic receptors and specific crown ether receptors and CF₃SO₃ Na as the third component are non-isomorphic within their Φ_h phase due to preferential complexation of the alkali metal cation by the column of the crown ether containing the molecular taper. This results in two columns of dissimilar diameters, which are isomorphic in the Φ_h phase only within a limited range of composition.     

Fluorous,chromatography-free Mitsunobu reaction

[formula: see text] The reaction of secondary and primary alcohols with highly fluorinated 3,4,5-tris(5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,12,12-heptadecafluorododecan- 1-yloxy)benzoic acid in the presence of Ph3P and DIAD in THF at room temperature (fluorous Mitsunobu) resulted in a simple, chromatography-free isolation protocol with excellent yields (83-96%).     

Photochemistry and mobility of stilbenoid dendrimers in their neat phases

Selectively deuterated, dodecyloxy substituted stilbenoid dendrimers of the first and second generation were synthesized by a convergent synthesis, using the Wittig-Horner reaction. The photochemistry and the fluorescence in the different crystalline and liquid crystalline phases were investigated. Molecules deuterated at the alpha-position of the alkoxy chains were used to study the photoreactions in the neat phases by 1H NMR. Reactions of the double bonds are exclusively observed in the liquid crystal phases. No photoreactions occur in the crystalline state. The mobility of the dendrimers was studied by means of 2H solid-state NMR spectroscopy. The onset of the photochemistry for dendrimer 1 [all-(E)-1,3,5-tris[2-(3,4,5-tridodecyloxyphenyl)ethenyl]benzene] corresponds to the increasing mobility at the Cr/LC transition. The first generation dendrimers still show large angle motion, whereas dendrimers of the second generation 2 [all-(E)-1,3,5-tris(2-[3,5-bis[2-(3,4,5-tridodecyloxyphenyl)ethenyl]phenyl]ethenyl)benzene] are restricted to librational motions. Photochemical conversion and fluorescence quenching for first and second generation dendrimers 1 and 2 increase with increasing molecular motion and reach a maximum in the isotropic phase.     

巴比妥酸楔形棒状液晶分子的合成、性质及与三嗪衍生物的氢键识别组装体

合成了一端含巴比妥酸, 另一端含带三条烷基链苯甲酸酯楔形单元, 中间为苯乙烯共轭单元的棒状分子5-{4-[3,4,5-三(十二烷氧基)苯甲酸酯]苯乙烯}-(1H,3H)-2,4,6嘧啶三酮(BA³/12); 采用偏光显微镜(POM)、 示差扫描量热法(DSC)、 X射线衍射(XRD)、 扫描电子显微镜(SEM)、 红外光谱(IR)、 核磁共振波谱(NMR)和荧光光谱等对其进行了表征. 结果表明, BA³/12能自组装形成晶格结构为c2mm的长方柱相液晶; 红外光谱及核磁共振氢谱表征数据初步证实了BA³/12与三嗪化合物6-(5-{4-[3,4-双(十二烷氧基)]苄氧基}苯基)噻吩-2,4-二氨基-1,3,5三嗪(1T²/12)形成的等摩尔氢键复合物BA/T的结构; BA/T不仅具有液晶性质且能形成具有三维网络状结构的超分子凝胶.     

Bis(salicylaldiminate) copper(II) and palladium(II) complexes: towards columnar mesophases

Copper and palladium complexes of new salicylaldimines derived from 3,4,5-tridecyloxyaniline, 2,3,4-tridecyloxyaniline and 4-decyloxyaniline have been synthesized and characterized. All the ligands bear four or more aliphatic chains with the aim of inducing columnar mesophases at low temperatures. In particular, metal complexes derived from 4-(3,4,5-tridecyloxybenzoyloxy)-salicyliden-3,4,5-tridecyloxyaninile display rectangular columnar mesophases at (or near) room temperature. These mesophase assignments have been confirmed by X-ray diffraction. A significant decrease of the melting points of the compounds is observed in the tridecyloxyaniline derivatives compared with those of similar complexes derived from mono- or di-decyloxyaniline.