Kerry D. Robinson

Calixarenes as enzyme models

Abstract A review of the progress towards the use of calixarenes as enzyme models is presented. Double recognition of a substrate is illustrated with the crystal structure of (H3O+)[La(ONC5H5)2(H2O)6(p-sulfonatocalix[4]arene)]−·6.5H2O, 1. The binding of zinc to calixarenes in a second-sphere fashion is shown with the crystal structure of Na2[Zn(H2O)4(ONC5H5)2][calix[4]arene]·8.5H2O, 4. The preparation and structures of aminomethylcalix[4]arenes are demonstrated with [p-(4-(2-pyridyl)piperidinomethyl)calix[4]arene], 5, and [p-(4-phenylpiperidinomethyl)calix[4]arene], 6.

Tertiary phosphine adducts of alane and gallane

Abstract Thermally stable mono-tri-t-butylphosphine adducts of alane and gallane, H3MptBu3 (M  Al, 1; M  Ga, 2) and the gallane rich adducts of 1,2-bis(diisopropylphosphino)ethane and 1,2-bis(diphenylphosphino)ethane, [(H3Ga)2{(PR2CH2)2}] (R  iPr, 3; R  Ph, 4), have been prepared from LiMH4/HCI/phosphine; reactions involving H3MNMe3/PtBu3 also yield 1 and 2, for the former via a mixed donor tBu3PAl(H)3NMe3 (5), which decomposes to 1 and NMe3 at ca. 40°C; compounds 1 and 2, and the previously reported alane analogue of 3, viz. [(H3Al)2{(PiPr2CH2)2}] (6) have been shown to be four coordinate (Al-P, 2.471(3) and 2.451(3) A, 1 and 6; Ga-P 2.444(6) A 2). Ab initio calculations on relevant model systems, H3GaPMe3 (DZP level) and H3Al(PR3)2 (R  H or Me; D95* level) are reported, Ga-P 2.550 A, and Al-P 2.828 A (R  H), 2.786 A (R  Me).

Supramolecular assemblies of calix [4] arenes organized by feeble forces

Abstract X-ray crystallographic investigations have shown that dimeric supramolecular assemblies of water-soluble calix[4]arenes are formed by a combination of hydrophobic effects and either hydrogen bonding or secondary bonding. For Na4(pyridinium)[calix[4]arene sulfonate] · 8H2O, a dimeric arrangement based on hydrogen bonding and hydrophobic effects is found. The compound crystallizes in the monoclinic space group P21/n with a = 11.873(3), b = 24.345(6), c = 14.846(3) A, β 96.78(2)°, and Dc = 1.66 g cm−3 for Z = 4. Refinement based on 3492 observed reflections led to a final R value of 0.051. For [Cu(NC5H5)2(H2O)3](Na)3[calix[4]arene sulfonate] · 13 H2O, the dimeric association is based on a secondary bonding interaction between the copper(II) ion and a sulfonate oxygen atom combined with hydrophobic interactions. The compound crystallizes in the monoclinic space group P21/n with a = 14.672(3), b = 25.577(5), c = 15.457(3) A, β = 101.94(4)°, and Dc = 1.55 g cm−3 for Z = 4. Refinement based on 3602 obse...

Preparation and X-ray structure of [H3O+18-crown-6]-[(H5O 2 + )(Cl?)2], a compound containing both H3O+ and H5O 2 + crystallized from aromatic solution

The title compound was synthesized by the reaction of [H3O+·18-crown-6][Cl-H-Cl−]·3.8 C6H5Me with two equivalents of H2O. Colorless crystals, which slowly deposited from the corresponding liquid clathrate, belong to the monoclinic space group P21/n witha=10.648(6),b=9.571(2),c=20.801(6) Å,β=98.67(5)°, andDc=1.24 g cm−3 forZ=4. Refinement based on 1609 observed reflections led to a finalR value of 0.072. In the crystal structure the [H3O+·18-crown-6]+ cations are packed in layers separated by puckered sheets of [(H5O2+)(Cl−)2]−.

Synthesis and X-ray structure of [H3O+·18-crown-6] [Br−Br−Br−]; a compound containing both H3O+ and a linear and symmetrical Br 3 t- ion crystallized from aromatic solution

Abstract[H3O+·18-crown-6][Br−Br−Br−] crystallizes in the triclinic space group P 1 witha=6.105(1),b=8.658(1),c=11.072(1)Å, α=71.35(1), β=77.58(1), γ=71.09(1)0, andDc=1.68 g cm−3 forZ=1. Refinement based on 1112 observed reflections led toR=0.044. The cation exhibits a planar oxonium ion bonded symmetrically to the 18-crown-6 (O(oxonium) resides 0.092 Å out of the plane of the crown ether oxygen atoms). The anion also resides on a center of inversion with Br−Br=2.530(1)Å.

Cationic aluminium hydrides: [H2AlL]+[AlH4]–, L =N,N,N′,N″,N″-pentamethyldiethylenetriamine and 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane

Reaction of H3AlNMe3 with N,N,N′,N″,N″-pentamethyldiethylenetriamine (pmdien) in diethyl ether or 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane (Me4cyclam) in tetrahydrofuran yields [H2Al(pmdien)]+[AlH4]–, which possesses a trigonal bipyramidal cation with the hydrides in the trigonal plane [Al–N′ 2.158(7), Al–N,N″ 2.01(1), Al–H 1.62 A] or [H2Al(Me4 cyclam)]+[AlH4], where the metal centre in the cation is trans-octahedral [Al–N(mean) 2.13, Al–H 1.60, 1.64 A].

Calixarenes as second-sphere ligands for transition metal ions. Synthesis and crystal structure of [(H2O)5 Ni(NC5H5)]2(Na)[calix[4]arene sulfonate] 3.5 H2O and [(H2O)4Cu(NC5H5)2]-(H3O)3 [calix[4]arene sulfonate] 10 H2O

AbstractThe title compounds crystallize such that bilayers of calixarenes are separated by hydrophilic layers. In each case the transition metal has, in addition to a primary sphere of ligands, a second-sphere coordination by a calixarene. [(H2O)5Ni(NC5H5)]2(Na)[calix[4]arene sulfonate]·3.5 H2O,1, crystallizes in the triclinic space groupP

First structural authentication of third-sphere coordination: [p-sulfonatocalix[4]arene]5- as a third-sphere ligand for Eu3+

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