Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:Q86TM3 (cage)
 29,987 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The crystal structure of cyclo (D-Val-D-Hyi-D-Val-L-Hyi-L-Val-D-Hyi-L-Val-L-Hyi -L-Val-D-Hyi-D-Val-L-Hyi).2H2O has been solved by x-ray direct methods. The crystals (grown from a mixture of octane/CH2Cl2) are an orthorhombic, centrosymmetric space group Pbca, cell parameters a = 11.458 (2), b = 25.613 (3), c = 23.691 (3) A, Z = 4; therefore the molecule lies on a center of inversion in the cell. The atomic coordinates for the C, N, and O atoms were refined in the anisotropic thermal motion approximation (allowing for H-atom contribution to Fcal) to a standard R-factor value of 0.081. In contrast to meso-valinomycin, the analogue under study does not adopt an octahedral cage bracelet conformation. It has an unusual centrosymmetric elongated form with two type II terminal beta-bends formed by N-H ... C=O 4-->1 type intramolecular H bonds. Two symmetry-related water molecules reside in the elongated molecular cavity of the centrosymmetric depsipeptide ring.
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PMID:Crystal and molecular structure of the centrosymmetric meso-valinomycin analogue--cyclo (D-Val-D-Hyi-D-Val-L-Hyi-L-Val-D-Hyi-L-Val-L-Hyi-L-Val-D-Hyi-D-Val-L-Hy i) (C60H102N6O18). 757 53

The synthesis of novel acetal thia-cage compounds has been accomplished by the direct substitution for the oxygen atom by the sulfur atom in the reaction of the acetal groups of oxa-cages with Lawesson reagent (LR). Reaction of the tetraoxa-cage compound 2 with LR in dichloromethane at 25 degrees C sequentially gave the monothia-, dithia-, trithia-, and tetrathia-cage compounds 3, 6, 7, and 9. The reaction mechanism for the conversion from oxa-cages into thia-cages was proposed. The diacetal trioxa-cages 18-20 and 24-26 were also transformed into the thia-cages 21-23 and 27-29, respectively. Reaction of the trioxa-cages 34 and 35 with LR under the same reaction conditions gave the thia-cages 36 and 37 with the carbonyl group intact. Treatment of the pentaoxa[5]peristylane 40 with LR in chloroform under supersonic shaking at refluxing temperature gave the monothia[5]peristylane 41 and the dithia[5]peristylane 42. Attempts to synthesize the thia[5]peristylanes from the tetraoxa-cage 51 and the transformation from the parent (unsubstituted) pentaoxa[5]peristylane 46 to the thia-cages have been made. Reaction of the pentaoxa[5]-peristylane 40 with P(2)S(5) in refluxing toluene gave 41, 42, and a rearrangement product 47. The synthesis of new heterocyclic cage compounds 59 and 60, which contain oxygen, nitrogen, and sulfur atoms in the same molecule, was also accomplished.
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PMID:Synthesis of novel acetal thia-cage compounds. 1142 81

Electron and energy transfer from copper 1,10-phenanthroline excited states is observed at room temperature in organic solvents. The copper phenanthroline excited states are metal-to-ligand charge-transfer in nature and have lifetimes of approximately 70-250 ns in dichloromethane solution if methyl or phenyl substituents are placed in the 2- and 9-positions of the phenanthroline ligand. The unsubstituted cuprous compound Cu(phen)(2)(PF(6)) is nonemissive under these conditions, and the excited state lifetime is <20 ns. The rate and efficiency of energy transfer to anthracene or electron transfer to viologens is reported. The cage escape efficiency of [Cu(dpp)(2)(2+), MV(+)(*)], where dpp is 2,9-diphenyl-1,10-phenanthroline, is close to unity within experimental error. Back electron transfer to ground state products occurs at the diffusion limit, 2 x 10(10) M(-)(1) s(-)(1).
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PMID:Photodriven Electron and Energy Transfer from Copper Phenanthroline Excited States. 1166 87

The deep-red, air-stable complexes [Pt(2)Hg(2)(P(2)phen)(3)](PF(6))(2), 1, or [Pd(2)Hg(2)(P(2)phen)(3)](PF(6))(2), 2, (P(2)phen is 2,9-bis(diphenylphosphino)-1,10-phenanthroline) are most conveniently prepared by the stoichiometric reaction of either Pt(dba)(2) or Pd(2)(dba)(3).CHCl(3) (dba is dibenzylideneacetone) with P(2)phen and a single drop of elemental mercury in refluxing dichloromethane under an atmosphere of nitrogen. The (31)P[(1)H] NMR spectrum (CD(3)CN) of 1 shows a single sharp resonance at 43.1 ppm for the phosphorus atoms of the P(2)phen ligand with both (195)Pt ((1)J(P-Pt) = 4350 Hz) and (199)Hg ((2)J(P-Hg) = 620 Hz) satellites indicating the Hg(2)(2+) unit is dynamic. Compound 2 has a similar resonance at 44.9 ppm with (199)Hg satellites ((2)J(P-Hg) = 638 Hz). The (199)Hg NMR (CD(2)Cl(2), vs Hg(OAc)(2)) spectrum of 2 shows a heptet pattern at 833 ppm while for 1 a heptet superimposed on a doublet of heptets is observed at 770.8 ppm. The (195)Pt NMR spectrum of 1 displays a quartet at -3071 ppm with (199)Hg satellites and a (1)J(Pt-Hg) value of 1602 Hz. Characterization of 1 and of 2(BF(4)(2) by single-crystal X-ray diffraction studies confirms the metallocryptand structure consisting of three phosphine-imine ligands forming a D(3) symmetric cage with a Hg(2)(2+) ion in its center coordinated to two phenanthroline rings with the Hg-Hg bond (1, 2.7362(6); 2(BF(4)(2), 2.6881(4) A) oriented perpendicular to the vector between the trigonally coordinated Pt(0) or Pd(0) atoms on each end. The Pt-Hg separations in 1 average 2.8143(6) A while in 2(BF(4)(2) the average Pd-Hg separation is 2.7698(5) A. Excitation into the low energy excitation bands of 1 (475 nm) and 2 (430 nm) produces weak emissions centered at 593 nm with shoulders at 530 and 654 nm in 1 and centered at 524 nm with a shoulder at 545 nm in 2.
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PMID:Pd(0) and Pt(0) metallocryptands encapsulating a spinning mercurous dimer. 1247 50

The slightly yellow polymeric complexes [Au(2)Cl(2)(P(2)pz)(3)](n), 1 x 6CHCl(3), (P(2)pz is 3,6-bis(diphenylphosphino)pyridazine) and [[Au(2)(P(2)pz)(3)](PF(6))(2)](n), 2, are prepared by the stoichiometric reaction of AuCl(tht) (tht is tetrahydrothiophene) and P(2)pz in either dichloromethane or dichloromethane/methanol, respectively. Addition of 2 equiv of AuCl(tht) to a dichloromethane solution of 1 equiv of P(2)pz generates the simple (AuCl)(2)(P(2)pz) compound, 3. Compound 3 contains nearly linear P-Au-Cl units with intermolecular Au.Au separations of 3.570 A. Au(2)I(2)(P(2)pz)(3), 4, is prepared by reacting excess NaI with 2 in a dichloromethane/methanol mixture. Characterization of 1, 2, and 4 by X-ray crystallography confirms the 2:3 gold/ligand ratio of all three complexes. The coordination polymer 1 maintains a high degree of solvation in the solid-state with three chloroform adducts hydrogen-bonded to the chloride ligand on each gold atom. These chloroform molecules are sandwiched between the two-dimensional polymeric sheets of 1. The crystal structure of 4 reveals an empty, iodide-capped metallocryptand cage with the tetrahedrally distorted gold atoms and the nitrogen atoms on the pyridazine rings directed away from the center of the cavity. No metal ion encapsulation was observed for complex 4. Complex 2 forms one-dimensional arrays of [Au(2)(P(2)pz)(2)](2+) metallomacrocycles connected to each other by a third P(2)pz ligand. The electronic absorption spectra (CH(2)Cl(2)) of 1-4 show broad, nearly featureless absorption bands that tail into the visible with pi-pi bands at 296 nm and discernible shoulders at 314 nm for 2 and 334 nm for 3. Excitation into the low energy band of 2 produces only a modest emission in solution at 540 nm (lambda(ex) 468 nm) and 493 nm (lambda(ex) 403 nm). Under identical conditions, the P(2)pz ligand also emits at 540 and 493 nm.
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PMID:Three- and four-coordinate gold(I) complexes of 3,6-bis(diphenylphosphino)pyridazine: monomers, polymers, and a metallocryptand cage. 1263 53

Femtosecond visible pump-IR probe studies of Cp2W2(CO)6 in P(OMe)3 and CH2Cl2 have allowed direct observation of a 19-electron intermediate and of disproportionation into CpW(CO)3- and CpW(CO)3P(OMe)3+ on the ultrafast time scale. A new disproportionation mechanism involving in-cage electron transfer between a 19-electron intermediate and a 17-electron radical has been proposed.
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PMID:The role of odd-electron intermediates and in-cage electron transfer in ultrafast photochemical disproportionation reactions in Lewis bases. 1536 68

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.
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PMID:Photochemical study of [3(3)](1,3,5)cyclophane and emission spectral properties of [3n]cyclophanes (n = 2-6). 1549 32

Reaction of one equivalent of tris(3,5-di-tert-butyl-2-hydroxy)methane with TaCl5 in CH2Cl2 along with Et3N gave a solid which on prolonged crystallisation led to a small quantity of crystalline material. An X-ray crystal structure determination showed one crystal was [TaCl3[[OC6H2(CMe3)2-2,4]3CH]]- Et2NH2+.3C6H6.1.5H2O with the anion consisting of three chloro ligands and three phenoxides of the tripodal ligand about the tantalum centre. The triphenylmethyl group proton was located and refined and was found to be enclosed in a cage making contacts of 2.09(8), 2.09(8) and 1.89(12)A with the phenoxide ligand oxygens consistent with weak C-H bond hydrogen bonding. The hydrogen atom points at the tantalum atom at a distance of 2.14(11) A from it, the TaH-C angle is 166 degrees and the C-H bond distance is 1.04(12) A. DFT calculations at the B3LYP level indicate that where a hydrogen atom is attached to the triphenylmethyl carbon on the inside of the cage, there is good agreement with the crystal structure. The C-H bond points directly at the tantalum centre and an NBO analysis indicates there is significant overlap of the triphenylmethyl C-H bond electron density in a linear sense with an "unfilled" metal d orbital. Based on the NBO analysis, the C-HTa overlap would appear to be an example of a linear agostic interaction under the definition of agostic bonding.
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PMID:A case for linear agostic interactions: identification by DFT calculation in a complex of Ta containing a uniquely caged triphenylmethyl C-H hydrogen. 1551 46

The reaction between [tmndH][hypho-1,2-S(2)B6H9](tmnd =N,N,N',N'-tetramethylnaphthalene-1,8-diamine) and [RuCl(PPh3)2(eta5-Cp)] in CH2Cl2 at room temperature afforded two ruthenathiaboranes, [5-(eta(5)-Cp)-5-(PPh3)-5,4,6-RuS2B6H9], 1, and [Ru(eta(1)-1,2-S2B6H9)(PPh3)2(eta5-Cp)], 2, in 6 and 48% yields, respectively. The heating of a solution of [Ru(eta(1)-1,2-S2B6H9)(PPh3)2(eta5-Cp)] 2 in CH2Cl2 at reflux temperature afforded 1 in 59% yield. Compound 1 could be described as either a hypho nine-vertex {RuS2B6} cluster or a coordination compound of ruthenium which contains a bidentate eta2-dithiaborate cluster ligand; the latter description is preferred. Compound 2 contains an eight-atom hypho-type {1,2-S2B6} cage bonded to the ruthenium atom of the {Ru(PPh3)2(eta5-Cp)} unit by one sulfur atom and may be described as a compound of ruthenium coordinated eta(1)- to the dithiaborate cluster ligand. The reaction between [tmndH][hypho-1,2-S2B6H9] and [RuCl2(eta6-MeC6H4Pri)]2 in CH2Cl2 at room temperature afforded [5-(eta6-MeC6H4Pri)-arachno-5,4,6-RuS2B6H8], 3, in 94% yield. Further reaction of 3 and PMePh2 afforded another arachno{RhS2B6}cluster, [5-(eta6-MeC6H4Pri)-8-(PMePh2)-arachno-5,4,6-RuS2B6H6], 4, in 25% yield. Compounds 1, 2, and 4 were characterised with single crystal X-ray analyses.
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PMID:Coordination and cluster compounds of ruthenium with the [hypho-1,2-S2B6H9]- ligand. 1590 46

We study the hydrogen abstraction reaction from pentane by chlorine radicals using four different experimental approaches. We use two different solvents (CH2Cl2 and CCl4) and two different chlorine atom sources (photodissociation of dissolved Cl2 and two-photon photolysis of the solvent) to investigate their effects on the recombination and reactivity of the chlorine radical. All four experimental schemes involve direct probing of the transient chlorine population via a charge transfer transition with a solvent molecule. In one of the four approaches, photolysis of Cl2 in dichloromethane, we also monitor the nascent reaction products (HCl) by transient vibrational spectroscopy. Probing both the reactants and the products provides a comprehensive view of this bimolecular reaction in solution. Between one-third and two-thirds of the chlorine radicals that initially escape the solvent cage undergo diffusive geminate recombination with their partner radical (either another chlorine atom or the solvent radical). The rest react with pentane with the bimolecular rate constants k(bi) = (9.5 +/- 0.7) x 10(9) M(-1) s(-1) in CH2Cl2 and k(bi) = (7.4 +/- 2) x 10(9) M(-1) s(-1) in CCl4. The recombination yield phi(rec) depends on both the chlorine atom precursor and the solvent and is larger in the more viscous carbon tetrachloride solutions. The bimolecular reaction rate k(bi) depends only on the solvent and is consistent with a nearly diffusion-limited reaction.
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PMID:Time-resolved spectroscopic study of the reaction Cl + n-C5H12 --> HCl + C5H11 in solution. 1650 30


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