- Convenient synthesis of selectively substituted tribenzo[a,d,g] cyclononatrienes
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Convenient laboratory procedures for obtaining selectively substituted dihydro-5H-tribenzo[a,d,g]cyclononatrienes have been achieved. X-ray structure determination indicates that 2d is present in the solid state in the crown conformation to yield H-bonded columns and pillars with a hydrophilic interior and hydrophobic exterior that can be used for the design of specific sensor materials.
- Chakrabarti, Ananya,Chawla,Hundal, Geeta,Pant
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- Sugar-functionalized water-soluble cyclotriveratrylene derivatives: Preparation and interaction with fullerene
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Cyclotriveratrylene (CTV) has attracted much attention because of its good chemical stability, small cavity, stable conformation, and facile modification. In this article, two water-soluble CTV derivatives (CTV-G and CTV-L) functionalized by glucose and lactose residues were synthesized, respectively. Unexpectedly, sugar-bearing CTVs exhibit a distinct photoluminescence, which might be ascribed to the enhanced planar conformation of cyclotriveratrylene ring derived from the spatial effect of bulky branch groups. The interaction between the water-soluble CTV derivatives and C60 was investigated in organic solvent and aqueous solution, which was further characterized by fluorescence spectra, ultraviolet-visible spectra, and Raman spectra. CTV-G can associate with C60 to form supramolecular complex with 1:1 molar ratio (Ka = 1.38 × 105 M-1, 298 K). As for CTV-L, a similar complex with a lower association constant (Ka = 5.09 × 104 M-1, 298 K) can also be formed.
- Yang, Fen,Chen, Qi,Cheng, Qian-Yi,Yan, Chao-Guo,Han, Bao-Hang
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- Silane catecholates: Versatile tools for self-assembled dynamic covalent bond chemistry
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Shape-persistent macrocycles and 3D nanocages have been prepared in one-pot under MeCN-promoted dynamic covalent bond conditions starting from silane catecholates, whose structures were confirmed by X-ray crystallography. Cation-exchange reactions of macrocycles and nanocages were performed along with the encapsulation of ammonium ions within the cavity of an anionic macrocycle and a tetrahedral nanocage.
- Kawakami, Yoshiteru,Ogishima, Tsuyoshi,Kawara, Tomoki,Yamauchi, Shota,Okamoto, Kazuhiko,Nikaido, Singo,Souma, Daiki,Jin, Ren-Hua,Kabe, Yoshio
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supporting information
p. 6066 - 6069
(2019/06/03)
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- Hydrogen-bonded molecular capsules: Probing the role of water molecules in capsule formation in modified cyclotricatechylene
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Two new pyridine moiety-appended cavitands, CTC(Py)2(OH)2 and CTC(Py)3, were synthesized and characterized. The solid state structures of both cavitands were studied by single crystal X-ray diffraction. CTC(Py)2(OH)2 resulted in a hydrogen-bonded dimeric molecular capsule, entrapping two molecules of DMSO and intervening water molecules that formed hydrogen bonding to DMSO and CTC(Py)2(OH)2. When crystallized in the absence of water, it forms a 2D polymer by hydrogen bonding of pyridine nitrogen and phenolic hydrogen atoms. CTC(Py)3 forms no such capsule.
- Illa, Giri Teja,Hazra, Sohan,Satha, Pardhasaradhi,Purohit, Chandra Shekhar
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p. 4759 - 4765
(2017/08/22)
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- Homochiral columns constructed by chiral self-sorting during supramolecular helical organization of hat-shaped molecules
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A library of dendronized cyclotriveratrylene (CTV) crowns substituted with chiral, racemic, or achiral peripheral alkyl chains, including enantiopure R and S branched alkyls, "racemic by mixture", "racemic by synthesis", n-octyl, and n-dodecyl groups was synthesized. In solvophobic solvents and in bulk they self-assemble in helical columns. Their solution and bulk shape-persistent supramolecular structures were determined by a complementary combination of circular dichroism (CD) and UV in solution and thin film, microspot CD in thin film, differential scanning calorimetry combined with fiber X-ray diffraction, computer simulation, and molecular models. In solution, self-assembly via a cooperative mechanism generates single-handed columns from enantiopure CTVs and mixtures of right-and left-handed columns from racemic by mixture, racemic by synthesis, other combinations of R and S, and even from achiral compounds. In bulk state all supramolecular columns form a 3D hexagonal crystalline phase, φhk (P63 symmetry), that can be obtained only from single-handed columns and a columnar hexagonal 2D liquid crystal, φh. The highest order φhk consists of enantiopure single-handed columns that are slightly distorted 12-fold triple helices. The "hat-shaped" dendronized CTV assembles in bent-branch pine-tree columns that allow interdigitation of alkyl groups in adjacent columns regardless of their direction. Enantiomerically rich, racemic, and achiral compositions undergo deracemization in the crystal state by transfer of the transient disc-like conformer of dendronized CTV from column to column during crown inversion. Solid state NMR experiments identified motional processes that allow such transfer. This unprecedented supramolecular chiral self-sorting will impact the creation of functions in complex systems.
- Roche, Cécile,Sun, Hao-Jan,Prendergast, Margaret E.,Leowanawat, Pawaret,Partridge, Benjamin E.,Heiney, Paul A.,Araoka, Fumito,Graf, Robert,Spiess, Hans W.,Zeng, Xianbingon,Ungar, Goran,Percec, Virgil
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supporting information
p. 7169 - 7185
(2014/06/09)
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- Self-assembly of dendritic crowns into chiral supramolecular spheres
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The synthesis and structural and retrostructural analysis of a library of dendronized cyclotriv- eratrylene containing seven nonchiral and sevenchiral self-assembling dendrons is reported. These dendronized cyclotri veratrylenes exhibit a crown conformation that we named dendritic crown.Selected examples of dendritic crowns self-assemble into helical pyrami dal columns that self-organize into columnar crystals or into 2-D columnar hexagonal lattices with intracolumnar order. A second group of dendritic crowns self-assembles into helical pyramidal columns and spherical supramolecular dendrimers that self- organize into cubic and tetragonal lattices. A third group of dendritic crowns self-assembles only in spherical supramolecular dendrimers. The helical pyramidal columns and spherical supramolecular dendrimers assembled from dendronized cyclotriveratrylene containing nonchiral dendrons are chiral but racemic while those generated from chiral dendrons exhibit amplified chirality. Structural analysis by a combination of X-ray diffraction methods and CD experiments demonstrated a new mechanism for the assembly of chiral supramolecular spheres that involves an intramolecular structure containing short fragments of helical pyramidal columns.
- Percec, Virgil,Imam, Mohammad R.,Peterca, Mihai,Wilson, Daniela A.,Heiney, Paul A.
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supporting information; experimental part
p. 1294 - 1304
(2009/06/28)
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- Molecular structure of helical supramolecular dendrimers
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The molecular structure of helical supramolecular dendrimers generated from self-assembling dendrons and dendrimers and from self-organizable dendronized polymers was elucidated for the first time by the simulation of the X-ray diffraction patterns of their oriented fibers. These simulations were based on helical diffraction theory applied to simplified atomic helical models, followed by Cerius2 calculations based on their complete molecular helical structures. Hundreds of samples were screened until a library containing 14 supramolecular dendrimers and dendronized polymers provided a sufficient number of helical features in the X-ray diffraction pattern of their oriented fibers. This combination of techniques provided examples of single-92 and -11 3 helices, triple-61, -81, -91, and -121 helices, and an octa-321 helix that were assembled from crownlike dendrimers, hollow and nonhollow supramolecular crownlike dendrimers, hollow and nonhollow supramolecular disklike dendrimers, and hollow and nonhollow supramolecular and macromolecular helicene-like architectures. The method elaborated here for the determination of the molecular helix structure was transplanted from the field of structural biology and will be applicable to other classes of synthetic helical assemblies. The determination of the molecular structure of helical supramolecular assemblies is expected to provide an additional level of precision in the design of helical functional assemblies resembling those from biological systems.
- Peterca, Mihai,Percec, Virgil,Imam, Mohammad R.,Leowanawat, Pawaret,Morimitsu, Kentaro,Heiney, Paul A.
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supporting information; body text
p. 14840 - 14852
(2009/02/08)
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- Bowl-shaped Liquid Crystals - New Derivatives of Cyclotriveratrylene and Calixarene
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Some new Calixarenes and Cyclotriveratrylenes incorporating cyclohexane rings, phenyl rings or ether oxygen atoms in their lateral chains have been synthesised and investigated by calorimetry and X-ray studies.Only some long chain calixarenes exhibit mesomorphic behaviour.The mesomorphic ranges and clearing temperatures of the mesophases of hexasubstituted cyclotriveratrylenes are largely increased by the introduction of cyclohexane rings or oxygen atoms into the alkyl chains.X-ray studies proved the columnar structure of the mesophases. Key Words: Liquid Crystals / Molecular Structure
- Budig, H.,Paschke, R.,Diele, S.,Letko, I.,Pelzl, G.
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p. 1355 - 1357
(2007/10/02)
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- Structure and Dynamics of Pyramidic Liquid Crystals by Deuterium MNR and X-Ray Diffraction
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Pyramidic liquid crystals are mesogens derived from the cone-shaped tribenzocyclononene (TBCN) core, substituted with appropriate side chains.The pyramidic mesophases consist of two-dimensional columnar structures in which the rigid cores of the mesogen molecules are stacked in parallel on top of each other.In the present work X-ray and deuterium NMR measurements on the solid and mesomorphic phases of homologues of the alkyloxy (I-n) and alkanoyloxy series (II-n) are reported.In the PA mesophase of series I-n, the columns for a two-dimensional hexagonal array with a single molecule per unit cell.Deuterium NMR measurements on three specifically deuterated isotopomers of I-8 (including species deuterated at the unsubstituted aromatic sites, crown-ring methylenes and α-methylene of the side chain) indicate that within this mesophase two types of uncorrelated motions with very different correlation times can be distinguished: (i) fast fluctuations of the molecular C3 axis, which results in an effective orientational order of S = 0.85, essentially independent of temperature; (ii) planar reorientation about the C3 axis.The rate of the latter process is within the dynamic range of deuterium NMR, allowing its determination by line-shape analysis.Assuming this motion to correspond to planar diffusion, a diffusion constant at room temperature of DR(300 K) = 6.8E5 rad2/s with an activation energy of ΔE = 63 kJ/mol is derived from the experimental spectra.At least the first three atoms in the alkyloxy side chains do not participate in fast (on the NMR time scale) conformational isomerization in the solid or in the PA mesophase.The high-temperature mesophase of series II-n, PC, is very similar to the PA mesophase of I-n.It has an hexagonal structure with, however, four columns per unit cell.Deuterium line-shape analysis on specifically deuterated II-13 species indicates the same type of averaging motions as in the PA mesophase with an orientational order parameter of S = 0.93 (independent of temperature), and DR(373 K) = 1.4E5 rad2/s with ΔE = 112 kJ/mol.The low-temperature mesophase of this series, PD, is biaxial and appears to be rectangular or very nearly so.It is much less mobile than the PC mesophase, as evidenced by lack of planar reorientation, although there are still fast fluctuations of the molecular C3 axis (giving S = O.93).Unlike in the alkyloxy (I-n) series, in the alkanoyloxy (II-n) series there is fast side-chain isomerization in the PC and PD mesophases and to some extent even in the solid.The line shape of the α-methylene deuterons in the PD mesophase suggest a two-site jump process, while in the high-temperature PC phase, additional motions appear to set in, resulting in further narrowing of the spectrum width.Additional deuterium NMR measurements on deuterated I-8, II-11, and II-13 dissolved in nematic solvents in order to determine molecular structural parameters are reported.
- Poupko, R.,Luz, Z.,Spielberg, N.,Zimmermann, H.
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p. 6094 - 6105
(2007/10/02)
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