Search

Four copper(I) and six silver(I) novel co-ordination polymers linked by 1,4-bis(4-pyridyl)butadiyne (4-bpbd) or 1,4-bis(2-pyridyl)butadiyne (2-bpbd) were prepared and seven structures crystallographically characterized, in order to illustrate the structural versatility of co-ordination polymers assembled by the Group 11 metal ions and rod-like nitrogen bidentate ligands with long spacers. Reaction of appropriate copper(I) and silver(I) salts with the 4-bpbd ligand affords 2-D interwoven copper(I) co-ordination polymers {[Cu2(4-bpbd)3(CH3CN)2]X2}n (X = PF61a·2H2O or BF41b) and 1-D straight chain silver(I) co-ordination polymers {[Ag(4-bpbd)]X}n (X = NO32a·CH3CN, ClO42b·(CH3)2CO or CF3SO32c·(CH3)2CO), respectively. On the other hand, reaction of suitable salts with the 2-bpbd ligand provides a 3-D diamondoid copper(I) co-ordination polymer {[Cu(2-bpbd)2]BF4}n3b, a 1-D zigzag chain silver(I) co-ordination polymer {[Ag(2-bpbd)(NO3)]}n4a and a 2-D braid sheet silver(I) co-ordination polymer {[Ag(2-bpbd)(CF3SO3)]}n4c, respectively. On the basis of these structural studies, the unique structural features and the dimensionality of the copper(I) and silver(I) co-ordination polymers are revealed.

The complex formation of α-cyclodextrin and straight-chain aliphatic α,ω-dicarboxylates, –O2C(CH2)nCO2–(n= 6, 7, 8), in aqueous solution has been studied by titration microcalorimetry at 288.15, 298.15 and 308.15 K. Apparent Gibbs energies, enthalpies, entropies and heat capacities for the 1 : 1 complex formations were derived from the calorimetric data. The thermodynamics of binding show typical enthalpy–entropy compensation effects, which result in weak temperature dependences of the Gibbs energies. The heat capacities of binding are large and negative. This confirms the view that the binding of non-polar moieties to cyclodextrins is to a large extent a result of hydrophobic dehydration. Experimental conditions causing deviations from the 1 : 1 model, are also discussed.

The binding of a series of alkan-1-ols, nc= 3–7, to α-cyclodextrin has been investigated by microcalorimetric titration at 288.15, 298.15 and 308.15 K. For nc⩽ 6, the results agree well with a 1 : 1 binding model but for nc= 7, contributions from the formation of 1 : 2 (one alkanol, two α-CD) complexes have to be assumed. Apparent values for changes in standard molar Gibbs energies, enthalpies, entropies and heat capacities have been derived. The values obtained are consistent with the commonly held view that hydrophobic interactions are important in the formation of alkanol–α-CD complexes. However, the results clearly indicate that other effects are also of some importance.

alpha-Methylacyl-CoA racemase (AMACR;double dagger P504S) catalysed exchange of straight-chain fatty acyl-CoA alpha-protons. One alpha-proton was removed in each catalytic cycle, with the pro-S proton preferred. This reaction was most efficient for straight-chain substrates with longer side-chains. 2-Methyldecanoyl-CoA underwent alpha-proton exchange 3x more efficiently (as judged by K-cat/K-m) than decanoyl-CoA.

This research details our investigations into the potential for separating the ionic liquid trihexyl(tetradecyl)phosphonium chloride ([P6 6 6 14]Cl) from nonane using water. A miscible two component mixture of [P6 6 6 14]Cl and straight chain hydrocarbon separates upon addition of water into a three-phase mixture. The phase behaviour for [P6 6 6 14]Cl/water/nonane is presented, showing a stable three-component phase, whereby any additional water or nonane separates into its own immiscible layer. Although this limits the potential use of this system for entirely separating hydrocarbons from this ionic liquid, it has potential for other uses, such as triphasic catalysis.

Cavitand 1 is sufficiently predisposed to form nano-scale capsules in the presence of templating straight-chain hydrocarbons; quaternary complexes are formed when two copies of smaller guests are encapsulated, whilst larger guests form ternary entities.

Hydrothermal reaction of manganese carbonate with 4,4′-biphenyldicarboxylic acid (H2bda) and 1,10-phenanthroline (phen) affords coordination polymers, [Mn(bda)(phen)(H2O)]n·npy·nH2O (1·npy·nH2O, 1a), [Mn(bda)(phen)(H2O)]n·2npip (1·2npip, 1b) and [Mn(bda)(phen)]n (2). The polymer 1 crystallizes into either 1D zigzag chain or straight chain structures depending on the crystallisation solvents used, and both of them stack into a 3D guest-filled porous framework via inter-chain interactions, whereas the polymer 2 organizes into a 3D ligand-filled porous coordination framework in the absence of suitable guests. The polymer 1 represents an unusual example of network isomers formed via the templating of structurally dissimilar but closely related organic guests.

The kinetic resolution of branched and straight chain 2-phenylsulfanyl aldehydes by the Lewis acid-catalysed asymmetric anti aldol reaction followed by reduction to single enantiomers of 1,3-diols and/or acid-catalysed cyclisation with PhS migration provides a route to enantiomerically pure cyclic ethers and lactones with full stereochemical control.

Reaction of [{Rh(η3-C3H5)2Cl}2] with [Fe(CO)4(PPh2H)] in alcohol in the presence of carbon monoxide affords an unusual straight-chain compound, [Fe2Rh2(µ-PPh2)4(µ-CO)2(CO)6], the structure of which has been determined by X-ray methods. The complex crystallizes in space group P21/c with a= 12.468(5), b= 13.354(5), c= 17.293(7)A, β= 95.43(1)°, and Z= 2. The metal-atom skeleton is a centrosymmetric Fe–Rh–Rh–Fe chain with the metal atoms being linked through closed Fe–P–Rh and Rh–P–Rh bridge bonds. The 31P-{1H} n.m.r. spectral data for the compound have been interpreted in terms of the presence of two isomeric forms in solution.

Treatment of [{Rh(η-C3H5)2Cl}2] with [Fe(CO)4-(PPh2H)] in benzene in the presence of CO affords the mixed metal tetranuclear derivative [{RhFe(µ-PPh2)2(µ-CO)(CO)3}2], the structure of which has been determined X-ray crystallographically.

Rate and activation data have been obtained for the protiodeacylation in 89.8%(w/w) sulphuric acid of 10 alkyl mesityl ketones, with straight chain or branched chain alkyl groups, and of four diacylmesitylenes. The reactions have been analysed in terms of a sequence of two or three component ψ-first-order processes.

Values of the enthalpy, entropy and free energy of solution and hydration are reported for cyclopentanol, cyclohexanol, cycloheptanol, butan-2-ol, pentan-3-ol, hexan-3-ol and heptan-4-ol. Aqueous solutions of cyclic alcohols are thermodynamically more stable, mainly because of entropy effects, than those of the corresponding open chain secondary alcohols. ΔH°h varies linearly with ΔS°h, but the values for cyclic and secondary aliphatic alcohols lie on different straight lines.Parameters in the equation ΔH°h=α+β(ΔS°h+ 45) were calculated for all classes of monofunctional compounds so far investigated. The dependence of α on the type of functional group and on the type of hydrocarbon chain, open or cyclic, in which the latter is inserted is discussed.

Precise conductance measurements on dilute aqueous solutions of cyclic and straight chain quaternary ammonium iodides at 298 K are reported. The results are analyzed with the Fuoss-Hsia and Pitts equations for Λ(c) and are shown to provide some evidence for a slight amount of ion association which varies systematically with cation size and is most marked for the larger cations. The ionic resistivity (1/λ°+) of the cation increases by a constant amount (2.1 × 10–3Ω cm–2 mol) per CH2 group and can be related to estimates of the cation volumes V+ by the equation λ°+V⅔+=q.

The Knudsen effusion method has been used to measure vapour pressures from the solid and liquid phases of the ethyl esters of the straight-chain C16, C18, C19, C20, C22, and C23 monocarboxylic acids. Standard heat and entropy terms are evaluated and the former are discussed in relation to the phase structures.