- Lewis acid-catalyzed synthesis of dodecamethoxycalix[4]arene from 1,3,5-trimethoxybenzene and its conformational behavior and host-guest property
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Lewis acid-catalyzed condensation of 1,2- and 1,3-dimethoxybenzenes with paraformaldehyde afforded an ortho-bridged cyclic trimer (1) and a meta-bridged cyclic tetramer (2), respectively. Furthermore, condensation of 1,3,5-trimethoxybenzene with paraformaldehyde in the presence of Lewis acid catalyst successfully rendered the first dodecamethoxy-substituted calix[4]arene (3) with high yield. From X-ray crystallography, it was found that 3 formed the partial cone conformation. The conformational behavior of 3 in the solution was investigated by variable temperature 1H NMR measurements. The partial cone structure observed in the solid state was retained in the solution at low temperatures. Furthermore, because of the slow conformational exchanges of 3 on the NMR time scale, bimodal conformational exchanges were found. The host-guest property of 3 with the electron accepting guest, tetracyanoethylene (TCNE) was examined by UV-Vis measurements, and the ability to associate with the 3-TCNE complex was three times higher than that of the 2-TCNE complex. The observation is due to the superior electron donating property and slow conformational exchanges of 3 compared with those of analogous 2.
- Ogoshi, Tomoki,Kitajima, Keisuke,Umeda, Kenji,Hiramitsu, Sachi,Kanai, Suguru,Fujinami, Shuhei,Yamagishi, Tada-aki,Nakamoto, Yoshiaki
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- An electron-transfer induced conformational transformation from non-cofacial "sofa" to cofacial "boat" in cyclotetraveratrylene (CTTV) and formation of charge transfer complexes
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Electro-active polychromophoric assemblies that undergo clam-like electromechanic actuation represent an important class of organic functional materials. Here, we show that the readily available cyclotetraveratrylene (CTTV) undergoes oxidation-induced folding, consistent with interconversion from a non-cofacial "sofa" conformation to a cofacial "boat" conformer. It is found that the non-cofacial "sofa" conformer of CTTV forms stable electron donor-acceptor complexes with chloranil and DDQ. Electron-transfer induced conformational transformation in CTTV provides a framework for the rational design of novel organic functional molecules.
- Wang, Denan,Ivanov, Maxim V.,Mirzaei, Saber,Lindeman, Sergey V.,Rathore, Rajendra
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- Solvolysis reactions at the 13th carbon of 1-aryl organoiron complexes
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Acid-catalysed solvolysis procedures exchange protecting groups on benzyl alcohol derivatives in the synthesis of η5 1-arylcyclohexadienyliron building blocks for alkaloid synthesis. The reaction proceeds via a carbocation intermediate which can also be intercepted by intramolecular electrophilic addition to the tricarbonyl(η4-diene)iron(0) moiety to provide a novel and high-yielding cyclisation reaction forming a 5aα-cyanomethyl-5a,8a-dihydrofluorene tricarbonyliron complex in 96% yield.
- Roe, Caroline,Sandoe, Elizabeth J.,Richard Stephenson
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- A ternary charge-transfer complex composed of cyclotriveratrylene (CTV) and a polyoxometalate (POM) with quinone as an electronic modulator
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Triple stack: A facile synthesis of charge-transfer-type crystals composed of CTV and POM was demonstrated. The crystals further accommodated 1,4-benzoquinone as a guest to form a ternary crystal with a donor-acceptor-acceptor arrangement. The electronic spectra of the crystals suggested that the incorporated quinone served as an electronic modulator to adjust the charge-transfer property. Copyright
- Tashiro, Shohei,Hashida, Shizuka,Shionoya, Mitsuhiko
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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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- Single-crystal-to-single-crystal transformation of the desolvation of a cyclotriveratrylene-acetonitrile inclusion complex: Via a gating mechanism with subsequent polymorphism
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A cyclotriveratrelyne-acetonitrile inclusion complex is shown to undergo a single-crystal-to-single-crystal transformation upon desolvation to an intermediate phase and it is furthermore demonstrated that the preparation conditions may introduce polymorphism of the apohost. We characterised the as-synthesized and desolvated polymorphs using single crystal (polymorph 1) and powder X-ray diffraction, thermal analysis and gas sorption. Successive data collections on the as-synthesized crystal at 50 °C show that the rotation of a single, unique methoxy group of the host molecule may allow evacuation of solvent molecules from the seemingly non-porous crystal.
- Payne, Richard M.,Oliver, Clive L.
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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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- Synthesis of cycloveratrylene macrocycles and benzyl oligomers catalysed by bentonite under microwave/infrared and solvent-free conditions
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Tonsil Actisil FF, which is a commercial bentonitic clay, promotes the formation of cycloveratrylene macrocycles and benzyl oligomers from the corresponding benzyl alcohols in good yields under microwave heating and infrared irradiation in the absence of solvent in both cases. The catalytic reaction is sensitive to the type of substituent on the aromatic ring. Thus, when benzyl alcohol was substituted with a methylenedioxy, two methoxy or three methoxy groups, a cyclooligomerisation process was induced. Unsubstituted, methyl and methoxy benzyl alcohols yielded linear oligomers. In addition, computational chemistry calculations were performed to establish a validated mechanistic pathway to explain the growth of the obtained linear oligomers.
- Miranda, Rene,Valencia-Vazquez, Omar,Maya-Vega, Carlos Abel,Nicolas-Vazquez, Ines,Vargas-Rodriguez, Yolanda Marina,Morales-Serna, Jose Antonio,Garcia-Rios, Erendira,Salmon, Manuel
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p. 12820 - 12844
(2013/11/06)
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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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- Improved synthesis of functional CTVs and cryptophanes using Sc(OTf) 3 as catalyst
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Functional cyclotriveratrylene (CTV) and cryptophane derivatives are synthesized in the presence of scandium triflate [Sc(OTf)3]. This route allows the preparation of new derivatives that could not be prepared or easily obtained by using the previously reported experimental procedures. With a catalytic amount of scandium triflate (1% mol), CTVs were obtained with yields similar to or higher than those reported previously in reactions run under strong acidic conditions. Cryptophanes were also synthesized in fairly good yields by performing the ring-closure step in the presence of a stoichiometric amount of Sc(OTf)3. Interestingly, this novel approach strongly reduces the formation of side products and gives rise to novel functionalized molecules for the construction of supramolecular host-guest systems.
- Brotin, Thierry,Roy, Vincent,Dutasta, Jean-Pierre
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p. 6187 - 6195
(2007/10/03)
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- Synthesis and characterization of bisorthocyclophano-18-crown-6 compounds
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Two novel macrocyclic compounds 5S and 5A combining an 18-crown-6 and two cyclotriveratrylenes were synthesized by means of two methods from dibenzo-18-crown-6.The conformational isomers were separated using complexation with KSCN and their stereostructures were determined on the basis of 1H NMR spectroscopic and thermal equilibration studies.
- Hara, Hiroshi,Watanabe, Shin-ichi,Yamada, Makoto,Hoshino, Osamu
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p. 741 - 746
(2007/10/03)
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- Inclusion chemistry of cyclotetracatechylene
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The synthesis and X-ray crystal structures of the first inclusion complexes of cyclotetracatechylene (CTTC, 1) are reported.Crystals grown from a dimethylformamide (DMF) solution of 1 contain a total of six DMF molecules per CTTC unit (1*6DMF, 5) whilst crystals obtained from methanol in the presence of pyridine vapour form as a 1:2:2 complex (1*2pyridine*2methanol, 6).Hydrogen-bonded interactions between host and guest(s) play an important role in the molecular structure and, in the case of 6, a terminated eleven-atom hydrogen bonded chain is observed.
- Barbour, Leonard J.,Steed, Jonathan W.,Atwood, Jerry L.
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p. 857 - 860
(2007/10/02)
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- A deuterium NMR study of guest molecular dynamics of acetone in two organic inclusion compounds
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Deuterium nuclear magnetic resonance (NMR) spectra and spin-lattice relaxation times (T1) are used to investigate the dynamics of the guest molecule, acetone, in tris(5-acetyl-3-thienyl)methane (TATM) and cyclotriveratrylene (CTV) inclusion compounds. 13C CPMAS powder NMR spectra were obtained for each clathrate, to verify inclusion.In acetone: TATM, the guest molecule is undergoing twofold reorientation about the CO bond, exchanging the two methyl groups.An activation energy of 20.8 (+/-1.4) kJ/mol, for the two-site jump motion, was found, independently, from deuterium NMR spectra and T1 measurements.Acetone in CTV performs the same type of motion as acetone in TATM.Activation energies of 25.0 (+/-3.2) kJ/mol and 24.1 (+/-0.5) kJ/mol were determined using the same two techniques.In both inclusion compounds, the rate of methyl rotation within the acetone molecule is greater than 108 Hz even at the lowest temperature measured (84 K).Analytical expressions for the spin-lattice relaxation time (T1), for a twofold jump, were derived.Calculated values of the effective quadrupolar coupling constant and T1min for the guests agree very well with the experimental data.The 84 K spectrum of acetone: TATM unexpectedly shows some asymmetry, the origin of which is discussed.Finally, these two clathrates are compared to the recently examined acetone: tri-ortho-thymotide inclusion compound. - Keywords: inlusion compounds; deuterium NMR; solid state NMR spectroscopy; molecular dynamics
- Sidhu, Paul S.,Bell, Jason,Penner, Glenn H.,Jeffrey, Kenneth R.
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p. 2196 - 2207
(2007/10/03)
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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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- Cyclo-oligomerization of veratryl alcohol with triflouroacetic acid
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Treatment of veratryl alcohol with a dilute solution of triflouroacetic acid in chloroform yields a mixture of oligomers. Four major products have been separated and identified as the new cyclohexaveratrylene 6 and cyclopentaveratrylene 5, in addition to the known cyclic tetramer 4 and cyclic trimer 3.
- Al-Farhan, Emile,Keehn, Phillip M.,Stevenson, Robert
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p. 3591 - 3594
(2007/10/02)
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- Solid Superacid-Catalyzed Organic Synthesis. 4. Perfluorinated Resinsulfonic Acid (Nafion-H) Catalyzed Friedel-Crafts Benzylation of Benzene and Substituted Benzenes
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Nafion-H, a perfluorinated resinsulfonic acid, catalyzes Friedel-Crafts benzylation of benzene and substituted benzenes with benzyl alcohols under relatively mild experimental conditions.Reactions are clean, and water formed as a byproduct does not deactivate the catalyst.It was also found that this method is applicable to the intramolecular cycloalkylation and oligomerization of methoxybenzyl alcohols.
- Yamato, Takehiko,Hideshima, Chieko,Prakash, G. K. Surya,Olah, George A.
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p. 2089 - 2091
(2007/10/02)
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- Intra- and Intermolecular α-Sulfamidoalkylation Reactions
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The utility of α-sulfamidoalkylation processes for the generation of sulfamides has been examined.Select aryl-substituted sulfamides were prepared and then treated with acid.Both intra- and intermolecular α-sulfamidoalkylation transformations were observed to proceed in moderate to good yields.The pathways for these reactions are discussed.The generality of these processes has been demonstrated using N,N'-di(aryl-substituted)sulfamides, and the utility of these reactions was examined for the preparation of cyclic sulfamides of novel structure.
- Lee, Chai-Ho,Kohn, Harold
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p. 6098 - 6104
(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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- Electrochemical Oxidation of Aromatic Ethers. Part 6. Oxidation of 4-(3,4-Dimethoxybenzyl)-6,7-dimethoxy-2-methyl-1,2,3,4-tetrahydroisoquinoline and Attempted Synthesis of 4-(3,4-Dimethoxybenzyl)-6,7-dimethoxy-2-methyl-1,4-dihydro-3(2H)-isoquinoline
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The cyclisation of 3-(2,4-dimethoxybenzyl)-2-(2-hydroxymethyl-4,5-dimethoxyphenyl)-N-methylpropionamide (5) and related compounds does not yield 4-(3,4-dimethoxyphenyl)-6,7-dimethoxy-2-methyl-1,4-dihydro-3(2H)-isoquinolone, but gives instead dibenzocycloheptane derivatives.Anodic oxidation of 4-(3,4-dimethoxyphenyl)-6,7-dimethoxy-2-methyl-1,2,3,4-tetrahydroisoquinoline affords the corresponding 3,4-dihydroisoquinolinium and 4-(3,4-dimethoxybenzylidene)-6,7-dimethoxy-2-methyl-1,4-dihydroisoquinolinium salts.No intramolecularly aryl-aryl coupled products are isolated and the implication of this result on the design of substrates for the synthesis of biphenyl derivatives is discussed.
- Carmody, Maurice P.,Sainsbury, Malcolm,Newton, Roger F.
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p. 2013 - 2020
(2007/10/02)
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