Christopher Glidewell

Bio: Christopher Glidewell is an academic researcher from University of St Andrews. The author has contributed to research in topics: Hydrogen bond & Molecule. The author has an hindex of 27, co-authored 910 publications receiving 5556 citations. Previous affiliations of Christopher Glidewell include University of Guelph.

Nitrosyl Complexes of Iron-Sulfur Clusters

Abstract: Publisher Summary This chapter discusses nitrosyl complexes of iron-sulfur clusters. The recent upsurge of interest in iron-sulfur-nitrosyl complexes has been stimulated in part by the reported isolation of [ Fe2(SMe)2(NO)4] from natural sources, by the obvious resemblances between these complexes and the naturally occurring [2Fe–2S] and [4Fe–4S] clusters of iron-sulfur proteins, and by the connections between tetrairon-sulfur-nitrosyls and cubane-type clusters. Salts containing the anions [ Fe2S2(NO)4]2– and [Fe4S3(NO)7]– are often called, from their colors, Roussin's red and black salts, respectively. Similarly, the organic derivatives [Fe2(SR)2(NO)4] are often called esters of Roussin's red salt. The number of iron-selenium-nitrosyl complexes is substantially smaller than the iron-sulfur-nitrosyl species, and there are a number of differences between the sulfur systems and their analogs containing selenium or tellurium. For selenium it is convenient to divide the complexes into three classes, dependent upon the stoichiometry of the metal-chalcogen framework. A variety of routes have been employed for the synthesis of heterometallic clusters containing Fe(NO)S fragments, and examples of such systems have been described. The diamagnetic behavior of the diiron and tetrairon complexes, despite the presence of formally d7 and/or d9 iron centers, indicates very strong coupling between the individual paramagnetic centers.

meso-5,5,7,12,12,14-Hexamethyl-1,4,8,11-tetra­azacyclotetradecane as a building block in supramolecular chemistry; salts formed with 2,2′-biphenol, 4,4′-biphenol, 4,4′-thiodiphenol, 4,4′-sulfonyldiphenol, 3- and 4-hydroxybenzoic acids, 3,5-dihydroxybenzoic acid and phenylphosphonic acid; supramolecular structures in zero, one, two and three dimensions

Abstract: The structure of meso-5,5,7,12,12,14-hexamethyl-1,4,8,11-tetra­azacyclotetradecane–2,2′-biphenol (1/2), (C16H36N4).(C12H10O2)2 (1), is a salt [C16H38N4]2+.2[HOC6H4C6H4O]−: the cations are centrosymmetric with two protons held within the N4 cavity of the macrocycle by N—H⋯N hydrogen bonds, and the phenolate anions contain intramolecular O—H⋯O− hydrogen bonds. The ions are linked into a finite centrosymmetric aggregate by means of N—H⋯O hydrogen bonds. meso-5,5,7,12,12,14-Hexamethyl-1,4,8,11-tetraazacyclotetradecane–4,4′-thiobiphen­ol–methanol (1/2/2), (C16H36N4).(C12H10O2S)2.(CH4O)2 (2), and meso-5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane–4,4′-sulfonylbiphe­nol–methanol (1/2/2), (C16H36N4).(C12H10O4S)2.(CH4O)2 (3), are isomorphous: each is a salt, [C16H38N4]2+.2[HOC6H4SC6H4O]−.2MeOH (2) and [C16H38N4]2+.2[HOC6H4SO2C6H4O]−.2MeOH (3), and in each the phenolate anions are linked by O—H⋯O− hydrogen bonds into chains; antiparallel pairs of chains are cross-linked by the cations to form molecular ladders, with neutral methanol molecules acting as spacer units. In meso-5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane–3-hydroxybenzoic acid–methanol (1/2/2) (4), 3-hydroxybenzoate anions form chains, again cross-linked in pairs by the [C16H38N4]2+ cations to form molecular ladders, different from those in (2) and (3) in that the neutral methanol units are pendent from the ladders, rather than forming a part of it. meso-5,5,7,12,12,14-Hexamethyl-1,4,8,11-tetraazacyclotetradecane–4-hydroxybenzoic acid–methanol (1/2/1) (5) is again a salt, [C16H38N4]2+.2[HOC6H4COO]−.MeOH: chains of 4-hydroxybenzoate anions are continuously cross-linked by two different types of [C16H38N4]2+ cation into a two-dimensional net. Only one of the two types of cation is linked to the chains via neutral methanol spacer units. meso-5,5,7,12,12,14-Hexamethyl-1,4,8,11-tetraazacyclotetradecane–phenylphosphonic acid–water (1/4/2) (6) is a salt, [C16H40N4]4+.4[C6H5PO3H]−.2H2O, containing the centrosymmetric tetra-protonated amine units, which have a conformation quite different from the trans-III conformation uniformly found in the [C16H38N4]2+ cations. The phenylphosphonate anions and the water molecules are linked into chains of fused rings, which are linked by the cations into two-dimensional nets. In meso-5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane–3,5-dihydroxybenzoic acid (1/2) (7), the 3,5-di­hydroxybenzoate anions in the unsolvated salt [C16H38N4]2+.2[(HO)2C6H3COO]− are linked into continuous two-dimensional nets, which are in turn linked by the centrosymmetric cations to form a three-dimensional framework. meso-5,5,7,12,12,14-Hexamethyl-1,4,8,11-tetraazacyclotetradecane–4,4′-biphenol (1/3) (8) is a salt containing both neutral and anionic biphenol units, [C16H38N4]2+.2[HOC6H4C6H4O]−.[HOC6H4C6H4OH]. The two types of biphenol unit form two-dimensional nets and these nets are linked by the cations to form three independent, three-dimensional frameworks which are fully interwoven, but not bonded to one another.

Chain, Sheet and Framework Structures in the Adducts of Phenylphosphonic Acid with 4,4'-Bipyridyl (1/1), Piperazine (2/1) and 1,4-Diazabicyclo[2.2.2]octane (2/1)

Abstract: Phenylphosphonic acid–4,4′-bipyridyl (1/1), (1), C6H7O3P.C10H8N2, triclinic, P1¯, a = 6.9026 (8), b = 9.7086 (9), c = 12.201 (2) A, α = 77.138 (9), β = 74.345 (10), γ = 75.477 (8)°, with Z = 2, is a salt, C10H9N2+.[C6H5PO2(OH)]−, containing singly protonated 4,4′-bipyridyl cations: the cations and anions are linked by N—H⋯O and C—H⋯O hydrogen bonds in an R^{2}_{2}(7) motif and these aggregates are linked into centrosymmetric R^{2}_{2}(8) dimers by O—H⋯O hydrogen bonds; the dimer units are linked into chains by C—H⋯O hydrogen bonds. Phenylphosphonic acid–piperazine (2/1), (C6H7O3P)2.C4H10N2 (2), monoclinic, P21/n, a = 6.0042 (9), b = 19.746 (3), c = 8.651 (2) A, β = 105.63 (2)°, with Z = 2, is a salt, C4H12N22+. [{C6H5PO2(OH)}−]2, containing doubly protonated piperazine: the anions are linked by O—H⋯O hydrogen bonds into centrosymmetric R^{2}_{2}(8) dimers and these dimers are linked to the centrosymmetric cations by N—H⋯O hydrogen bonds: each cation is hydrogen-bonded to four different anion dimers and each anion dimer is hydrogen-bonded to four different cations; the overall structure consists of two-dimensional sheets built from R^{4}_{6}(16) and R^{4}_{4}(18) rings. Phenylphosphonic acid–1,4-diazabicyclo[2.2.2]octane (2/1), (3), (C6H7O3P)2.C6H12N2, monoclinic, P21/n, a = 6.3607 (3), b = 21.8300 (11), c = 14.5965 (9) A, β = 92.558 (6)°, with Z = 4, is a salt in which one nitrogen of the diamine is fully protonated and the other is partially protonated: the anionic components are linked into C(4) chains by O—H⋯O hydrogen bonds, and these chains are cross-linked via the diamines by means of N—H⋯O and O—H⋯N hydrogen bonds. The resulting sheets built from R^{8}_{8}(34) rings are linked by C—H⋯O hydrogen bonds into a three-dimensional framework.

Free Radicals in the Physiological Control of Cell Function

Abstract: At high concentrations, free radicals and radical-derived, nonradical reactive species are hazardous for living organisms and damage all major cellular constituents. At moderate concentrations, how...