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Cone Conformation (cone + conformation)
Selected AbstractsMonophosphanylcalix[6]arene Ligands: Synthesis Characterization, Complexation, and Their Use in CatalysisEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 1 2006Yasushi Obora Abstract Novel phosphanylcalix[6]arenes having mono- O -diphenylphosphanylmethyl (3) and mono- O -(4-diphenylphosphanylphenyl)methyl substituents (5) have been synthesized. The structures of these monophosphanylcalix[6]arenes were determined by NMR spectroscopy, mass spectrometry, and X-ray crystal structure analysis. The X-ray structure reveals that 3 adopts a flattened 1,2,3-alternate conformation in the crystalline state, while the NMR spectra show that 3 and 5 have a cone conformation in solution. Structure optimization and energy calculations for 3 and 5 at the B3LYP/LANL2DZ-CONFLEX5/MMFF94s level of theory show that the cone conformation is slightly more stable than the 1,2,3-alternate conformation by 0.36 kcal,mol,1 for 3 and 0.96 kcal,mol,1 for 5. Complexation of 3 with [PtCl2(COD)] and [Rh(COD)2]BF4 gives cis -coordinated [PtCl2(3)2] and [Rh(COD)(3)2]BF4, respectively. The X-ray analysis of [PtCl2(3)2] shows that 3 adopts a cone conformation upon complexation. Combination of 3 and 5 with [Rh(COD)2]BF4 provides an active catalyst for the hydroformylation of a variety of terminal alkenes.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Synthesis and reactions of conformational isomers of a stable selenenic acid bearing a bridged calix[6]arene frameworkHETEROATOM CHEMISTRY, Issue 4 2001Kei Goto A stable selenenic acid bearing a bridged calix[6]arene framework fixed in the 1,2,3-alternate conformation was synthesized. Its properties were compared with those of its conformational isomer fixed in the cone conformation, indicating that the reactivity of the endohedral SeOH group can be regulated by the conformation of the calix[6]arene framework. © 2001 John Wiley & Sons, Inc. Heteroatom Chem 12:195,197, 2001 [source] 25-Allyloxy-5,11,17,23-tetra- tert -butyl-26,27,28-trihydroxycalix[4]arene chloroform disolvateACTA CRYSTALLOGRAPHICA SECTION C, Issue 7 2010Tobias Gruber In the title solvated calixarene, C47H60O4·2CHCl3, the host chalice displays an almost undistorted cone conformation, stabilized by three strong O,H...O hydrogen bonds at the calixarene's lower rim. One chloroform solvent molecule is fixed in the calixarene cavity by C,H..., interactions, while the second is accommodated in a clathrate-like mode in elliptical packing voids. These voids are spanned by six host molecules connected via C,H..., contacts and van der Waals interactions. Within the crystal structure, one tert -butyl group of the calixarene host is disordered over two orientations, with occupancies of 0.884,(4) and 0.116,(4). Furthermore, both solvent molecules show disorder, with occupancies of 0.857,(2) and 0.143,(2) for the cavitate-type, and 0.9359,(17) and 0.0641,(17) for the clathrate-type chloroform solvent molecules. [source] Two related lithium calixarene complexes, [p-tert -butylcalix[4]arene(OMe)(OH)2(OLi)]2·4MeCN and {p-tert -butylcalix[4]arene(OH)2(OLi)[OLi(NCMe)2]}2·8MeCN, determined using synchrotron radiationACTA CRYSTALLOGRAPHICA SECTION C, Issue 8 2009Darren S. Lee The crystal structures of acetonitrile solvates of two related lithium calixarene complexes have been determined by low-temperature single-crystal X-ray diffraction using synchrotron radiation. Bis(,-5,11,17,23-tetra- tert -butyl-26,28-dihydroxy-25-methoxy-27-oxidocalix[4]arene)dilithium(I) acetonitrile tetrasolvate, [Li2(C45H57O4)2]·4C2H3N or [p-tert -butylcalix[4]arene(OMe)(OH)2(OLi)]2·4MeCN, (I), crystallizes with the complex across a centre of symmetry and with four molecules of unbound acetonitrile of crystallization per complex. Tetraacetonitrilebis(,-5,11,17,23-tetra- tert -butyl-26,28-dihydroxy-25,27-dioxidocalix[4]arene)tetralithium(I) acetonitrile octasolvate, [Li4(C44H54O4)2(C2H3N)4]·8C2H3N or {p-tert -butylcalix[4]arene(OH)2(OLi)[OLi(NCMe)2]}2·8MeCN, (II), also crystallizes with the complex lying across a centre of symmetry and contains eight molecules of unbound acetonitrile per complex plus four more directly bound to two of the lithium ions, two on each ion. The cores of both complexes are partially supported by O,H...O hydrogen bonds. The methoxy methyl groups in (I) prevent the binding of any more than two Li+ ions, while the corresponding two O-atom sites in (II) bind an extra Li+ ion each, making four in total. The calixarene cone adopts an undistorted cone conformation in (I), but an elliptical one in (II). [source] The host,guest complex between cone-25,26:27,28-bis(methylenedioxy)calix[4]arene and dichloromethaneACTA CRYSTALLOGRAPHICA SECTION C, Issue 5 2003Cedric Dielemann The title compound, 25,26:27,28-bis(methylenedioxy)pentacyclo[19.3.1.13,7.19,13.115,19]octacosa-1(25)3,5,7(28),9,11,13(27),15,17,19(26),21,23-dodecaene dichloromethane solvate, C30H24O4·CH2Cl2, possesses crystallographic twofold symmetry in both components. The calixarene shows a pinched cone conformation with an elliptical cavity, in which the guest dichloromethane solvent molecule is accommodated. The contact distance between guest and host (H,ring centroid = 2.44,Å) is extremely short. [source] Exploring the Dynamics of Calix[4]pyrrole: Effect of Solvent and Fluorine SubstitutionCHEMISTRY - A EUROPEAN JOURNAL, Issue 4 2007Ramón Blas Dr. Abstract Molecular dynamics simulations show that calix[4]pyrrole (CP) and octafluorocalix[4]pyrrole (8F-CP) are extremely flexible molecules. CP mainly adopts the 1,3-alternate conformation in all the solvents, although the percentage of alternative conformations increases in polar solvents, especially those with good hydrogen-bonding acceptor properties. However, in the case of 8F-CP, the cone conformation is the most populated in some solvents. Transitions between conformers are common and fast, and both CP and 8F-CP can adopt the cone conformation needed for optimum interaction with anions more easily than would be predicted on the basis of previous gas-phase calculations. Furthermore, the present studies show that when a fluoride anion is specifically placed initially in close proximity to CP and 8F-CP in their respective 1,3-alternate conformations, an extremely fast change to the cone conformation is observed in both cases. The results suggest that preorganization does not represent a major impediment to anion-binding for either CP or 8F-CP, and that ion-induced conformational changes can follow different mechanisms depending on the solvent and the chemical substituents present on the calix[4]pyrrole beta-pyrrolic positions. [source] Synthesis of Novel Calix[4]arenocrowns via Ring-closing MetathesisCHINESE JOURNAL OF CHEMISTRY, Issue 10 2008Lin-Gang LU Abstract A series of novel calix[4]arenocrown derivatives 8a,8c in a cone conformation, in which the lower rim and the upper rim were connected via ring-closing metathesis (RCM) reaction have been synthesized in good yields, and their structures were characterized by 1H NMR, 13C NMR, IR, MALDI-TOF MS techniques and elemental analyses. [source] Studies on Properties of p -Nitrophenylazo Calix[4]arene DerivativesCHINESE JOURNAL OF CHEMISTRY, Issue 2 2003Jin Chuan-Ming Abstract The p -nitrophenylazo calix[4]arene derivatives 1a-1d with nonlinear optical (NLO) properties were prepared by the diazo-coupling reaction of calix[4]arene with p -nitrophenyl diazonium. The diazotization reaction of p -nitroaniline was carried out with isoamyl nitrite as a source of nitrous add in EtONa/EtOH under refluxing condition. X-Ray crystallographic analysis and 1H NMR spectra reveal that they exist as cone conformation in crystal state or in solution. HRS measurements at 1064 nm in THF indicate that p -nitro-phenylazo calix[4]arenes have higher hyperpolarizability ,z values than the corresponding reference compound 4-(4-nitrophenylazo)-2, 6-dimethyl-phenol, without red shift of the charge transfer band. The tetrakis p -nitrophenylazo calix[4]arene (2) with longer alkyl chains can form monolayer at the air/water interface. [source] Synthesis and Conformation Analysis of New Perphosphorylated Calix[4]resorcinarenesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 23 2004Vera I. Maslennikova Abstract The octaphosphorylation of calix[4]resorcinarenes 1 by 2-dialkylamino-1,3,2-diheterophosphorinanes 2 is described, and the effect of different factors on the structures of the resulting perphosphorylated products 3,5 was studied. Conformation analysis of these compounds by correlated 2D NMR spectroscopy and X-ray diffraction analysis was performed, and it was found that compounds 3,5, like the initial resorcinarenes 1, each have the all - cis configuration of the R groups in the methylidene bridges of the calixarene system, but different orientations of benzene rings and phosphorinane fragments with respect to one another and to the macrocycle plane. Perphosphorylated resorcinarenes 3a,c, 4a and 5a with R = alkyl exist in flattened cone conformations with the phosphorinane fragments on the same side of the macrocycle plane. The conformations of the perphosphorylated resorcinarenes 3d, 4b and 5b with R = Ph change to forms intermediate between flattened cone and 1,3 - alternate. The phosphorus fragments in these compounds are located on opposite sides of the macrocycle plane. It was shown that the oxidation and sulfurisation of phosphocalixarenes 3 proceed without any change in the spatial organisation of the macrocyclic system. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] | ||||||||||||||||||||||