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At least 19 recordsLinked to original sources
PubMed2004

Fluorophore appended saccharide cyclophane: self-association, fluorescent properties, heterodimers with cyclodextrins, and cross-linking behavior with peanut agglutinin of dansyl-modified saccharide cyclophane.

A saccharide cyclophane bearing an environment-sensitive fluorophore (1) was prepared by introducing not only three branches with a terminal galactose residue but also one with a dansyl moiety into a tetraaza[6.1.6.1]paracyclophane skeleton. Self-association behavior of the dansyl-appended saccharide cyclophane was characterized in aqueous media by fluorescence spectroscopy and dynamic light scattering measurements. At least in the concentrations below 1.0 x 10(-5) M, saccharide cyclophane 1 existed in a monomeric state, whereas it tended to form self-aggregated complexes in the higher concentration. Solvent polarity dependency on the emission spectra of 1 was examined by fluorescence spectroscopy. With increasing dioxane contents in dioxane/water solvents, the fluorescence intensity originating from the dansyl moiety of 1 increased along with a concomitant blue shift of the fluorescence maximum (lambda(em)). In the monomeric state of 1 in water, the dansyl moiety of 1 was not fully included into its cyclophane cavity but partially exposed to the bulk aqueous phase. In the higher concentration ranges in an aggregate state, however, the dansyl group of 1 was located in the apolar cyclophane cavity whose microenvironment was equivalent to the polarity of 1-butanol evaluated on the basis of a correlation between lambda(em) and solvent polarity. This indicates an intermolecular inclusion of the dansyl moiety within the cyclophane. When cyclodextrin (CD) was mixed with 1, the dansyl group of 1 was bound to an internal cavity of CD such as gamma-CD, beta-CD, 6-O-alpha-glucosyl-beta-CD, and 6-O-alpha-maltosyl-beta-CD with binding constants of 7.5 x 10(2), 7.8 x 10(2), 7.7 x 10(2), and 6.0 x 10(2) M(-1), respectively. Such a supramolecular assembling of dansyl-modified cyclophane 1 and CDs caused changes of the fluorescence spectra as well as appearance of induced CD bands in aqueous media. Furthermore, saccharide cyclophane 1 was selectively bound to peanut agglutinin (PNA), galactoside-binding lectin, which was readily monitored by a visible turbidity of the solution due to a cross-linking agglutination of these components, as well as by fluorescence spectroscopy.

Journal Article↗
PubMed2004

Photochemical study of [3(3)](1,3,5)cyclophane and emission spectral properties of [3n]cyclophanes (n = 2-6).

Thephotochemical reaction of [3(3)](1,3,5)cyclophane 2, which is a photoprecursor for the formation of propella[3(3)]prismane 18, was studied using a sterilizing lamp (254 nm). Upon photolysis in dry and wet CH2Cl2 or MeOH in the presence of 2 mol/L aqueous HCl solution, the cyclophane 2 afforded novel cage compounds comprised of new skeletons, tetracyclo[6.3.1.0.(2,7)0(4,11)]dodeca-5,9-diene 43, hexacyclo[6.4.0.0.(2,6)0.(4,11)0.(5,10)0(9,12)]dodecane 44, and pentacyclo[6.4.0.0.(2,6)0.(4,11)0(5,10)]dodecane 45. All of these products were confirmed by the X-ray structural analyses. A possible mechanism for the formation of these photoproducts via the hexaprismane derivative 18 is proposed. The photophysical properties in the excited state of the [3n]cyclophanes ([3n]CP, n = 2-6) were investigated by measuring the emission spectra and determining the quantum yields and lifetimes of the fluorescence. All [3n]CPs show excimeric fluorescence without a monomeric one. The lifetime of the excimer fluorescence becomes gradually longer with the increasing number of the trimethylene bridges. The [3n]CPs also shows excimeric phosphorescence spectra without vibrational structures for n = 2, 4, and 5, while phosphorescence is absent for n = 3 and 6. With an increase in symmetry of the benzene skeleton in the [3(3)]- and [3(6)]CPs, the probability of the radiation (phosphorescence) process from the lowest triplet state may drastically decrease.

Journal Article↗
PubMed2006

Cyclophane and acyclic cyclophane: novel channel blockers of N-methyl-D-aspartate receptor.

The effects of cyclophanes (CPCn, CPPy and TGDMAP) and acyclic cyclophane (ATGDMAP) on various glutamate receptors were studied with these receptors expressed in Xenopus oocytes using voltage-clamp recording. CPCn, CPPy, TGDMAP and ATGDMAP were found to inhibit macroscopic currents at heteromeric NMDA receptors (NR1/NR2), but not Ca(2+)-permeable AMPA receptors (GluR1), Ca(2+)-nonpermeable AMPA receptors (GluR1/GluR2) and metabotropic glutamate receptors (mGluR1alpha). The inhibition of NR1/NR2A receptors by these compounds was more potent than those of the other NMDA receptor subtypes. At a resting potential (-70 mV), the IC(50) values of CPCn, CPPy, TGDMAP and ATGDMAP for NR1/NR2A receptors were 0.5+/-0.1, 1.0+/-0.2, 8.0+/-0.8 and 4.9+/-0.5 microM, respectively. The inhibition by these compounds was voltage-dependent, that is, the degree of inhibition was in the order of negative holding potentials, -100 mV>-70 mV>-20 mV. Results of experiments using mutant NR1 and NR2 subunits identified residues that influence block by CPCn. The inhibition by CPCn was not altered significantly in the mutants at the critical asparagines in the M2 loop, NR1 N616, NR2B N615 and NR2B N616, these residues are known to form the narrowest region of the channel and the binding site of Mg(2+). However, mutations at NR1 N650, located in the vestibule of channel pore, and NR1 D669, located in the extracellular region, reduced the inhibition by CPCn, suggesting that these amino acid residues interact with CPCn. These results suggest that CPCn interacts directly with the mouth or vestibule of the ion channel, like a lid.

Animals↗
PubMed2002

An alternative synthetic route of [3(5)](1,2,3,4,5)cyclophane, and structural properties of multibridged [3(n)]cyclophanes and their charge-transfer complexes in the solid state.

To develop an improved synthetic route to [3(6)](1,2,3,4,5,6)cyclophane (CP) 2, a more practical synthetic route to [3(5)](1,2,3,4,5)CP 3 than the original one was developed, which started from [3(2)](1,3)CP 7 via [3(4)](1,2,4,5)CP 5. The fundamental structural parameters of [3(n)]CPs (n = 3-6) in the solid state were elucidated, and the observed structures were in good agreement with the most stable conformers in solution and those predicted by the theoretical calculations. In the case of [3(6)]CP 2, the most stable C(6)(h) structure was observed in the crystal structure of the 2-TCNQ-F(4) (1:1) complex, whereas the highly strained structure with a D(6)(h) symmetry was observed in the crystal structure of 2 and the 2:TCNQ:benzene (1:1:1) complex because of a severe disorder problem. [3(n)]CPs (n > 3) showed reversible redox processes, and 2 (+0.39 V vs F(c)/F(c)(+), Cl(2)CHCHCl(2)) showed the lowest first half-wave oxidation potential [E(1/2) (I)] in [3(n)]CPs. The E(1/2) (I) data support the strong donating ability of 2 and its lower homologues. This is attributed to their molecular structures where effective hyperconjugation between the benzyl hydrogens and benzene ring is possible. By taking advantage of the strong electron-donating ability of [3(n)]CPs, their CT complexes with TCNE, TCNQ, and TCNQ-F(4) were prepared, and their crystal structural properties were examined. The single-crystal conductivity data of the CT complexes indicated that the TCNQ-F(4) complexes showed higher conductivities than the corresponding TCNQ complexes mainly due to a larger charge separation. Among the [3(n)]CP-TCNQ complexes, the [3(3)](1,3,5)CP 6-TCNQ-F(4) (1:1) complex showed the highest conductivity (10(-)(4) S cm(-)(1)), and this was ascribed to the formation of an infinite column of partially overlapped acceptors with a short acceptor-acceptor distance, while the formation of such a column was not observed in the 2-TCNQ-F(4) complex. Although the conductivities of the cyclophane-CT complexes are much lower than those of the TTF related complexes, this study successfully provides the basic knowledge for understanding the CT interactions in the solid state.

Journal Article↗
PubMed1997

A New Chelating Cyclophane and Its Complexation with Ni(2+), Cu(2+), and Zn(2+): Spectroscopic Properties and Allosterism via Ring Contraction.

A condensation reaction between ethylenediaminetetraacetic dianhydride and p-xylenediamine gave a new chelating cyclophane, 3,10,21,28-tetraoxo-5,8,23,26-tetrakis(carboxymethyl)-2,5,8,11,20,23,26,29-octaaza[12.12]paracyclophane, abbreviated as (32edtaxan)H(4), which has three types of electron-donor groups, i.e., amine, carboxylate, and amide groups. The formation of the cyclophane has been confirmed by a single-crystal X-ray analysis of its Zn(2+) complex, [Zn(2)(32edtaxan)].7.5H(2)O, which crystallized in the monoclinic space group P2(1)/c with a = 19.818(1) Å, b = 13.169(1) Å, c = 18.134(1) Å, beta = 104.491(6) degrees, and Z = 4. Each cyclophane molecule coordinates two Zn(2+) ions and results in the formation of a binuclear chelate molecule. The coordination geometry around each metal ion is distorted octahedral, the donor atoms being two carboxylate oxygen atoms, two amine nitrogen atoms, and two amide oxygen atoms. The new cyclophane exhibited a well-defined fluorescence band at 290 nm with 210 nm excitation. The emission intensity was markedly increased in the Zn(2+) complex, in which the coordination of Zn(2+) ions increases the rigidity of the cyclophane leading to a high fluorescence quantum yield. When the cyclophane was coordinated to Cu(2+) ions, the molar absorptivity of a pi-pi transition band observed at 260 nm was increased by a factor of about 10. Such a large spectral change was not observed for the Zn(2+) and Ni(2+) complexes. In the Cu(2+) complex, the two phenyl rings of the cyclophane are expected to be brought closer, as a result of the coordination of deprotonated amide nitrogens to the central metal ion. This allosterism via ring contraction is responsible for the novel behavior of the absorption spectrum. The emission band of the cyclophane was weakened by coordination of copper and nickel as a result of fluorescence quenching caused by a photo-induced electron transfer.

Journal Article↗
PubMed2004

Azolium-linked cyclophanes: a comprehensive examination of conformations by 1H NMR spectroscopy and structural studies.

The synthesis and characterization of a series of azolium-linked cyclophanes are reported. The cyclophanes consist of two azolium groups (17 examples) or three imidazolium groups (1 example) linked to two benzenoid units (benzene, naphthalene, p-xylene, mesitylene, 1,2,3,4- and 1,2,4,5-tetramethylbenzene, 2,6-pyridine, and p-tert-butylphenol) via methylene groups. Cyclophanes containing ortho-, meta-, and para-substitution patterns in the benzenoid units were examined. The conformations of the cyclophanes were examined in solution by variable-temperature NMR studies and in the solid state by crystallographic studies. The p-cyclophanes and mesitylene-based m- and o/m-cyclophanes are rigid on the NMR time scale, as indicated by sharp (1)H NMR spectra at all accessible temperatures. The non-mesitylene-based m-cyclophanes and the o-cyclophanes are fluxional on the NMR time scale at high temperatures, but in most cases, specific conformations can be "frozen out" at low temperatures. Many structures deduced from solution studies were consistent with those in the solid state.

Journal Article↗
PubMed2007

Multivalent macrocyclic hosts: histone surface recognition, guest binding, and delivery by cyclophane-based resorcinarene oligomers.

As a new class of host for both specific proteins and hydrophobic molecular guests, cyclophane-based resorcinarene oligomers were designed on the basis of a molecular design that allows the assembly of four or 12 anionic resorcinarenes on a cyclophane skeleton. We prepared a cyclophane-based resorcinarene tetramer (4), constructed with a tetraaza[6.1.6.1]-paracyclophane skeleton and four resorcinarenes bearing heptacarboxylic acid residues that connect to the macrocycle through amide linkages. In addition, we prepared an extended analogical dodecamer (12), which was constructed with a pentakis(cyclophane) skeleton and 12 resorcinarenes. The cyclophane-based resorcinarene oligomers exhibited potent recognition capabilities toward histone, a small basic protein of eukaryotic chromatins. The binding constants (K) of cyclophane-based resorcinarene tetramer 4 and dodecamer 12 with histone were determined to be 1.3x107 and 8.4x107 M-1, respectively, by means of surface plasmon resonance measurements. The K values of 4 and 12 with histone were 31- and 200-fold larger than that of an untethered reference resorcinarene, reflecting the multivalency effects in resorcinarenes. In addition to that, cyclophane-based resorcinarene tetramer 4 and dodecamer 12 captured hydrophobic guests such as 6-p-toluidinonaphthalene-2-sulfonate, with respective binding constants of 2.4x103 and 2.5x104 M-1 in an aqueous HEPES buffer as evaluated by fluorescence spectroscopy. Furthermore, the resorcinarene oligomers were also found to act as guest carriers from the bulk aqueous phase to histone surfaces, as confirmed by fluorescence spectroscopy.

Journal Article↗
PubMed2001

Modular synthesis of pi-acceptor cyclophanes derived from 1,4,5,8-naphthalenetetracarboxylic diimide and 1,5-dinitronaphthalene.

Three neutral cyclophanes were synthesized, and their association with indole, an aromatic pi-donor, was studied. The cyclophanes were designed to contain a rigid, hydrophobic binding cavity with 1,4,5,8-naphthalenetetracarboxylic diimide or 1,5-dinitronaphthalene as the pi-acceptor. Two of the cyclophanes also contain a (S)-(valine-leucine-alanine) tripeptide unit to provide chiral hydrogen bonding interactions with guest molecules. Despite the fact that these cyclophanes contain a hydrophobic binding cavity of appropriate dimensions, their association with indole is very weak. In the case of cyclophanes derived from 1,5-dinitronaphthalene, steric interactions force the nitro groups out of the plane of the naphthalene ring, diminishing their effectiveness as pi-acceptors. A simple UV--visible titrimetric method, using N,N,N',N'-tetramethyl-1,4-phenylenediamine (TMPD) as a pi-donor, was used to rank the pi-acceptor strength of these and other aromatic units. These titrations show that 1,4,5,8-naphthalenetetracarboxylic diimide and 1,5-dinitronaphthalene derivatives are weaker pi-acceptors than viologens, which make good pi-acceptor cyclophanes. Methyl viologen is in turn a weaker pi-acceptor than anthaquinone disulfonate, suggesting that the latter may serve as a useful building block for pi-accepting cyclophane hosts.

Ethers, Cyclic↗
PubMed1998

Binuclear Copper(II) Chelates of Amide-Based Cyclophanes.

A chelating cyclophane has been synthesized by cyclocondensation of two ethylenediaminetetraacetic (EDTA) units with two p-phenylenediamine units: the resulting cyclophane is 2,9,18,25-tetraoxo-4,7,20,23-tetrakis(carboxymethyl)-1,4,7,10,17,20,23,26-octaaza[10.10]paracyclophane, abbreviated as (bis-edtapdn)H(4). Cyclocondensation of two EDTA and two 1,5-diaminonaphthalene units has given the naphthalenophane, 2,9,22,29-tetraoxo-4,7,24,27-tetrakis(carboxymethyl)-1,4,7,10,21,24,27,30-octaaza[10.10](1,5)naphthalenophane, (bis-edtanap)H(4). Studies of electronic and EPR spectra have been carried out on the binuclear Cu(2+) complexes of these new ligands and of related chelating cyclophanes, 2,9,25,32-tetraoxo-4,7,27,30-tetrakis(carboxymethyl)-1,4,7,10,24,27,30,33-octaaza[10.1.10.1]paracyclophane, abbreviated as (bis-edtabpm)H(4), and 2,9,25,32-tetraoxo-4,7,27,30-tetrakis(carboxymethyl)-1,4,7,10,24,27,30,33-octaaza-17,40-dioxa[10.1.10.1]paracyclophane, abbreviated as (bis-edtabpe)H(4). Common features of these chelating cyclophanes are as follows: (1) amino, amide, and pendant carboxymethyl donor groups are substituents in the cyclophane ring, and (2) the amide groups are directly bound to the aromatic groups. These ligands formed neutral binuclear Cu(2+) chelates [Cu(2)L](0) that are water-insoluble. In alkaline solutions, these Cu(2+) complexes were converted to anionic chelates [Cu(2)(LH(-)(4))](4)(-) in which deprotonated amide nitrogens coordinated Cu(2+) ions. These anionic metal chelates of (bis-edtapdn)H(4), (bis-edtabpm)H(4), and (bis-edtabpe)H(4) exhibited three pi-pi transition bands in the spectral range 240-340 nm, in contrast to the uncoordinated cyclophanes, which showed a single band in this spectral range. The unusual pi-pi transition spectra of the [Cu(2)(LH(-)(4))](4)(-) complexes originate from the combined effect of metal-ligand charge transfer and proximity of the pi systems. The absorption and emission spectra of (bis-edtanap)H(4) were also influenced by coordination with copper. The EPR spectrum of [Cu(2)(bis-edtanapH(-)(4))](4)(-) in a methanol glass matrix showed a hyperfine structure due to the spin exchange between two Cu(2+) ions. These unusual spectral and magnetic properties arise from the strong coordination between Cu(2+) ions and deprotonated amide nitrogens that are bound to the pi systems.

Journal Article↗
PubMed2006

Efficient construction of biaryls and macrocyclic cyclophanes via electron-transfer oxidation of Lipshutz cuprates.

An efficient method for the homocoupling of aryl halides by electron-transfer oxidation of Lipshutz cuprates (Ar2Cu(CN)Li2) with organic electron acceptors is disclosed. Thus, various types of Lipshutz cuprates are prepared by successive treatment of aryl or heteroaryl bromides with tert-butyllithium and CuCN. The electron-transfer oxidation of Lipshutz cuprates with p-benzoquinones proceeds smoothly to afford the corresponding homocoupling products in moderate to good yields. Furthermore, it can be applied to the construction of either thiophene- or benzene-fused 10-membered ring cyclophanes. For the synthesis of 10-membered cyclophanes, the linear C-Cu-C structure of Lipshutz cuprates should be maintained in the dimetallacyclic intermediates, producing the large ring cyclophanes efficiently. The X-ray analysis of the cyclophanes reveals that the difference in the bridging atoms results in the different conformations of the macrocyclic rings. Thus, the silicon-bridged cyclophane 5a adopts a D2-symmetric structure with a twisted rhombic arrangement of four thiophene rings, whereas the methylene- and oxygen-bridged cyclophanes 5b and 5c possess C2h- and C2-symmetric structures with chair- and boatlike conformations, respectively. The 1H NMR spectrum of C2-symmetric 5c is temperature-dependent, and the activation energy (DeltaG) for the conformational change is 10.1 kcal/mol.

Journal Article↗
PubMed2002

An enaminone-directed benzannulation/macrocyclization approach to cyclophane ring systems.

A straightforward and modular preparative approach to 1,3,5-triaroylbenzene-based functionalized cyclophane ring systems has been developed. The key cyclophane-forming macrocyclization reaction was accomplished during the course of a regioselective cross-benzannulation between bis(aryl ethynyl) ketone and enaminone reactants. Macrocyclic products with ring sizes ranging from 18- to 22-membered were successfully constructed. The composition of the tether connecting the two aryl ethynyl ketone fragments can be easily varied; consequently, this method is suitable for construction of a diverse range of structurally distinct cyclophane products. To illustrate this feature, cyclophanes possessing xylyl, alkyl, di(ethylene triamine), and di(ethylene oxy) bridging units were synthesized in isolated yields of 11-46%. Three new cyclophanes (calixarene-like macrocyles 8 and 9, as well as crownophane 18) were structurally characterized by X-ray diffractometry.

Journal Article↗
PubMed2005

A computational study of [2.2]cyclophanes.

A computational study of isomeric [2.2]cyclophanes, namely [2.2]paracyclophane 1, [2.2]metacyclophane 2, and [2.2]metaparacyclophane 3, has been carried out. For 1, geometry optimizations performed by various methods at different basis sets showed that MP2/6-31+G(d,p) and B3PW91/6-31+G(d,p) provide the best results in comparison to the X-ray data. Compound 1 has D(2) symmetry with distorted bridges. A conformational search was performed for [2.2]cyclophanes 2 and 3. Each cyclophane exists in two conformations which have different energies in the case of 3 but are degenerate in the case of 2. Relative energies and strain energies at the bridges follow the same order, indicating that the relief of bridge tension and repulsion between pi clouds are determining factors for the stability of [2.2]cyclophanes. Through a decomposition of strain energy, it can be concluded that both the rings or the bridges can absorb strain, but it depends on the conformer of butane that is considered in the calculation of SE(br). Changes in aromaticity of these compounds were evaluated by NICS and HOMA and were compared with benzene and xylenes dimers as models. Despite distortions from planarity and shortening and lengthening of the C-C bonds relative to the mean, the phenyl rings are aromatic. NICS suggests a concentration of electronic density between the rings as a result of bridging process. Computed MK, NPA, and GAPT charges were compared for the isomeric cyclophanes. The GIAO chemical shifts were calculated and indicate that 1 has a larger diamagnetic anisotropy than the other isomers.

Journal Article↗
PubMed1995

Cavity depth and width effects on cyclophane-steroid recognition: molecular complexation of cholesterol and progesterone in aqueous solution.

BACKGROUND: Recent X-ray crystal structures show that steroid-binding proteins contain deep hydrophobic cavities defined by aromatic amino-acid side chains which encapsulate steroid molecules. These cavities resemble the binding site of a synthetic macrotricyclic cyclophane receptor which we recently reported to form complexes with cholesterol in aqueous solution. The binding affinity of the cyclophane-cholesterol complex (Ka approximately 10(6) M-1, 295 K) is similar to that measured for the cholesterol complex of steroid-transport proteins such as sterol carrier protein-2 (SCP-2). Here we describe synthesis and binding studies of a related receptor with a cavity that is wider and 2 A deeper than that of the previous cyclophane, and a comparison of the steroid-binding affinity and selectivity of the two synthetic receptors. RESULTS: A new tricyclic cyclophane receptor with a 13 A deep cavity was synthesized to study the effect of increased cavity depth on receptor selectivity for steroids. NMR analysis demonstrated that this receptor provided increased steroidal side-chain encapsulation with a corresponding gain in binding free energy of 0.9 kcal mol-1 (in d4-methanol) as compared to our previously reported 11 A deep receptor. An unexpected consequence of the increase in cavity depth was a corresponding enlargement of the cavity width, as indicated both by steroid-binding studies and molecular modeling. This enlargement in cavity width increases binding affinity for saturated steroids while decreasing the association strength of unsaturated steroids such as cholesterol. In water, cholesterol binds to the new receptor with Ka approximately 1.5 x 10(5) M-1 and exhibits a significant complexation-mediated solubility increase. CONCLUSIONS: Small changes in steroid receptor dimensions have resulted in large differences in steroid selectivity and binding affinity. These results indicate that potentially large gains in steroid-binding free energy may be obtainable from complete hydrophobic encapsulation of the flexible aliphatic steroidal side chain. These results have implications for the design of synthetic receptor mimics of natural steroid binding proteins.

Cholesterol↗
PubMed2000

Separation of aromatic isomers on cyclophane-bonded stationary phases.

A cyclophane (CP66)-bonded silica gel stationary phase (CP66-SP) was prepared and the retention of water-insoluble hydrophobic compounds on it was investigated in comparison with that on the CP44-bonded stationary phase (CP44-SP) reported previously. Like CP44-SP, it retained aromatic compounds more strongly than the corresponding alicyclic compounds, as was expected by the cavity size of the cyclophane. The CP66-SP also showed isomer-selectivity for monosubstituted and disubstituted naphthalenes, but its selectivity was perfectly reversed to that of the CP44-SP. On the CP66-SP, isomers having methyl and ethyl groups at beta-position were eluted prior to those having groups at alpha-position, whereas on the CP44-SP beta-substituted naphthalenes were retained more strongly than alpha-substituted ones. Isomers of three- and four-ring aromatic compounds were also separated on these cyclophane-bonded stationary phases. The retention order on the CP66-SP was almost opposite to that on the CP44-SP; on the CP66-SP, the retention order was phenanthrene > anthracene, and chrysene > 1,2-benzanthracene > 2,3-benzanthracene, whereas on the CP44-SP, anthracene > phenanthrene, and 2,3-benzanthracene > chrysene > 1,2-benzanthracene. The retention mechanism of aromatic compounds is discussed on the basis of the structure of the cyclophane-involved complex.

Chromatography, Liquid↗
PubMed2000

Stereocontrol in cyclophane synthesis: a photochemical method to overlap aromatic rings.

To overlap aromatic rings in cyclophanes, the inter- and intramolecular [2 + 2] photocycloaddition of vinylarenes has been developed. It gives cyclophanes, naphthalenophanes, phenanthrenophanes, thiophenophanes, and carbazolophanes in reasonable to excellent yields. The structures and properties of cyclophanes obtained are reviewed; especially the excimer emission of phenanthrenophanes, naphthalenophanes, and carbazolophanes stressed that many intriguing cyclophanes can be obtained through the fine molecular design of precursors.

Cyclobutanes↗
PubMed2000

Synthesis, molecular modeling, and pharmacological testing of bis-quinolinium cyclophanes: potent, non-peptidic blockers of the apamin-sensitive Ca(2+)-activated K(+) channel.

The synthesis and pharmacological testing of two series of novel bis-quinolinium cyclophanes as blockers of the apamin-sensitive Ca(2+)-activated K(+) (SK(Ca)) channel are presented. In these cyclophanes the two 4-aminoquinolinium groups are joined at the ring N atoms (linker L) and at the exocyclic N atoms (linker A). In those cases where A and L contain two or more aromatic rings each, the activity of the compound is not critically dependent upon the nature of the linkers. When A and L each have only one benzene ring, the blocking potency changes dramatically with simple structural variations in the linkers. One of these smaller cyclophanes having A = benzene-1,4-diylbis(methylene) and L = benzene-1, 3-diylbis(methylene) (3j, 6,10-diaza-1,5(1,4)-diquinolina-3(1,3),8(1, 4)-dibenzenacyclodecaphanedium tritrifluoroacetate, UCL 1684) has an IC(50) of 3 nM and is the most potent non-peptidic SK(Ca) channel blocker described to date. Conformational analysis on the smaller cyclophanes using molecular modeling techniques suggests that the differences in the blocking potencies of the compounds may be attributable to their different conformational preferences.

Alkanes↗
PubMed2001

Syntheses and structures of isomeric [6.6]- and [8.8]cyclophanes with 1,4-dioxabut-2-yne and 1,6-dioxahexa-2,4-diyne bridges.

All three isomers (ortho, meta, and para) of [8.8]cyclophane bearing 1,6-dioxahexa-2,4-diyne bridges have been synthesized and structually characterized by single-crystal X-ray crystallography to determine the conformation of the cyclophanes and their cavity dimensions. The three isomeric [6.6]cyclophanes bearing 1,4-dioxabut-2-yne bridges have also been synthesized from but-2-yne-1,4-diol ditosylate and the isomeric dihydroxybenzenes. The [6.6]orthocyclophane has been structurally characterized by single-crystal X-ray crystallography. The energy-minimized structures from the semiempirical AM1 calculations of these cyclophanes compare very well with the structures obtained by X-ray crystallography.

Journal Article↗