Crystal structures of dibenzo-14-crown-4 alcohol and diol monohydrates

Monohydrate complexes1–3 ofsym-hydroxydibenzo-14-crown-4,sym-cis-dihydroxydibenzo-14-crown-4 andsym-trans-dihydroxydibenzo-14-crown-4, respectively, have been prepared and their solid state structures determined. For all three complexes the space group wasCmc2₁. The crystal data are: for1,a=16.256(10),b=12.076(5),c=8.767(3) Å,V=1721.0 ų withZ=4; for2,a=16.437(3),b=11.997(4),c=8.640(3) Å,V=1703.8 ų withZ=4; for3,a=16.528(7),b=12.306(3),c=8.540(3) Å,V=1737.0 ų withZ=4. The structures were refined to [R, R _w, unique data withF<n (F)]: for1, 0.066, 0.055, 828, 2.5; for2, 0.034, 0.035, 1090, 3.0; for3, 0.047, 0.036, 1038, 3.0. The three crystal structures have a high degree of isomophism and the dibenzo-14-crown-4 units in the three host-guest complexes are nearly identical. Intramolecular hydrogen bonds link an alcohol oxygen atom of the host to the oxygen atom of the guest water molecule and the oxygen atom of the guest water molecule to ether oxygen atoms of the host in1–3. In2 and3, there is an intermolecular hydrogen bond between the hydrogen atom of an alcohol group of the host and the oxygen atom of a symmetry-related water molecule guest of another complex.     

Evolution of Organized Lariat Ether Alcohol and Diol Hydrate Macrostructures in the Solid State

Lariat ether alcohols and diols derived from dibenzo-14-crown-4crystallize in the anhydrous form or as hydrogen-bondedmonohydrates or networks depending upon thepolyether ring substitutents and the composition of the aqueous organic crystallization solvent. Supramolecular structures are created when the lariat ether alcohol sym-(hydroxy)dibenzo-14-crown-4 (1) with ``sticky ends' of ether oxygens and hydroxyl protons, hydrogen bond to each other via bridging water molecules to form three-dimensional networks. For crystallization of 1 from 30% aqueous acetonitrile, this self-association is sufficiently strong to spontaneously generate a supramolecular structure with water channels.     

Synthesis and selectivity of sym-hydroxydibenzo-14crown-4 ionophores for protons,alkali metal cations,and alkaline earth cations in polymeric membranes

Six derivatives of sym-hydroxydibenzo-14-crown-4 have been prepared and incorporated into solvent-polymeric membranes. Responses of the membranes to protons, alkali metal cations, and alkaline earth cations have been determined. The preferred uptake of protons is attributed to proton complexation by stable crown ether alcohol and diol monohydrate species.     

Online assessment of students’ reasoning when solving example-eliciting tasks: using conjunction and disjunction to increase the power of examples

ZDM – Mathematics Education - We argue that examples can do more than serve the purpose of illustrating the truth of an existential statement or disconfirming the truth of a universal...     

Synthesis of substituted 14-crown-4 compounds

Seventeen new substituted 14-crown-4 derivatives 3-10, 35-40, 42, 45 and 46 are described. A series of nine compounds 2-10 with two, three or four substituents in the 6- and/or 13-positions was synthesized in good yields from the appropriate diols and ditosylates using improved cyclization conditions. The solid state structures of 6,6,13,13-tetra(benzyloxymethyl)-14-crown-4 ( 8 ) and lithium thiocyanate complexes of trans- and cis-6,13-bis(spiro-2,2-dichlorocyclopropyl)-14-crown-4 ( 45 ) and ( 46 ), respectively, have been determined.     

Solid-state Structures for 2-Methoxy-1,3-xylyl-18-crown-5 and 2-Methoxy-1, 3-xylyl-21-crown-6: A Search for C–H···O Interactions

Solid-state structures have been determined for 2-methoxy-1,3-xylyl-18-crown-5 (4) (monoclinic, P2₁/n, a = 11.361(3) Å, b = 8.352(3) Å, c = 18.627(4) Å, β = 91.05(2)°, Z = 4) and 2-methoxy-1,3-xylyl-21-crown-6 (5) (monoclinic, Pc, a = 9.996(2) Å, b = 11.321(2) Å, c = 8.642(2) Å, β = 100.095(4)^o, Z = 2). In both molecules, the aromatic units are tilted with respect to the polyether ring and the methoxyl methyl hydrogens are oriented toward ether oxygen atoms of the rings. The interatomic distances, particularly the H···O distance and angles provide important information regarding the strength of the C–H···O interactions.     

Crystal Structures of Dibenzo-13-crown-4 and sym-(2-Picolyloxy)dibenzo-13-crown-4

Solid-state structures are determined for two compounds which containdibenzo-13-crown-4 rings. These include the parent crown etherdibenzo-13-crown-4 and its lariat ether derivativesym-(2-picolyloxy)dibenzo-13-crown-4. The solid-state structure ofdibenzo-13-crown-4 is complicated by disorder of the carbon atoms in theethylene and propylene bridges. The asymmetric unit of the crystal for thelariat ether derivative consists of two chemically identical, butcrystallographically different, molecules.     

The crystal structure of dibenzo-14-crown-4, a preorganized basis of square pyramid coordination for lithium ions

Dibenzo-14-crown-4 (DB14C4) has a high selectivity for Li⁺. The rigidity of the molecule caused by the two benzene rings suggests that this is a preorganized ligand for metal ions and particularly for Li⁺. A single crystal structure study of the molecule was performed. The crystal data are: space groupP2₁,a = 12.811(2),b = 5.106(1),c = 12.816(3)Å, = 115.44(1)°,V = 757.0(2)ų withZ = 2. The structure was refined toR = 0.049 andR _w, = 0.058 using 1804 unique data withF < 4(F). The conformation of the free ligand was found to be similar to that of the complexed ligand and the conformational parameters of the free ligand and its derivatives are compared to Li⁺ complexes of the ligand and its derivatives.This paper is dedicated to the memory of the late Dr C. J. Pedersen.