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Two related compounds containing p-tert-butyl-o-methylene-linked phenol or phenol-derived subunits are described, namely 5,5'-di-tert-butyl-2,2'-dihydroxy-3,3'-methylenedibenzaldehyde, C(23)H(28)O(4), (I), and 6,6'-di-tert-butyl-8,8'-methylenebis(spiro[4H-1,3-benzodioxin-2,1'-cyclohexane]), C(35)H(48)O(4), (II). Both compounds adopt a 'butterfly' shape, with the two phenol or phenol-derived O atoms in distal positions. Phenol and aldehyde groups in (I) are involved in intramolecular hydrogen bonds and the two dioxin rings in (II) are in distorted half-chair conformations.

The title compound, [UO(2)(C(33)H(38)N(2)O(2))(2)](CF(3)SO(3))(2).2C(5)H(5)N, has been obtained by reaction of U(IV) trifluoromethanesulfonate with p-tert-butyltetrahomodioxacalix[4]arene in pyridine. The uranyl ion lies on an inversion centre and is bound to two O atoms from each diphenoxide ligand, which gives the usual square-planar equatorial environment. The zwitterionic diphenoxide species results from nucleophilic attack by pyridine on the benzylic ether C atoms of the homooxacalixarene, assisted by initial U coordination to the ether groups, with subsequent metal oxidation giving the uranyl moiety.

In the title dinuclear uranyl complex, (C(18)H(38)N(2)O(6))[(UO(2))(2)(NO(3))(4)(OH)(2)].H(2)O, each pair of uranyl ions in the two independent centrosymmetric dianionic dimers is bridged by the two hydroxide ions, with the nitrate ions ensuring equatorial hexagonal coordination. The dihydro[2.2.2]cryptand (4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo[8.8.8]hexacosane) dication presents an 'in-in' conformation (endo protonation) and it is hydrogen bonded to the hydroxide ions, either directly or via a water molecule, resulting in the formation of linear hydrogen-bonded polymers.

To investigate how solubility and steric issues affect the laccase-catalysed oxidation of phenols, a series of oligomeric polyphenol compounds, having increasing size and decreasing solubility in water, was incubated with laccase. The extent of substrate conversion, and the nature of the products formed in buffered aqueous solutions, were compared to those obtained in the presence of an organic cosolvent, and also in the presence of two mediating species, i.e. N-hydroxyphthalimide (HPI) and 2,2,6,6-tetramethylpiperidin-1-yloxy (TEMPO). This approach showed not only an obvious role of solubility, but also a significant role of the dimension of the substrate upon the enzymatic reactivity. In fact, reactivity decreases as substrate size increases even when solubility is enhanced by a cosolvent. This effect may be ascribed to limited accessibility of encumbered substrates to the enzyme active site, and can be compensated through the use of the appropriate mediator. While TEMPO was highly efficient at enhancing the reactivity of large, less soluble substrates, HPI proved less effective. In addition, whereas the laccase/HPI system afforded the same products as laccase alone, the use of TEMPO provided a different product with high specificity. These results offer the first evidence of the role of 'oxidation shuttles' that the mediators of laccase may have, but also suggest two promising routes towards an environmentally friendly process for kraft pulp bleaching: (a) the identification of mediators which, once oxidized by laccase, are able to target strategic functional groups present in lignin, and (b) the introduction of those strategic functional groups in an appropriate pretreatment.

Two compounds containing 1,3-benzodioxin groups are reported, namely (+/-)-6-tert-butyl-8-hydroxymethyl-2-phenyl-4H-1,3-benzodioxin, C(19)H(22)O(3), (I), and 2,2,2',2',6,6'-hexamethyl-8,8'-methylenebis(4H-1,3-benzodioxin), C(23)H(28)O(4), (II). The hydroxy groups of neighbouring molecules in (I) are hydrogen bonded to each other, giving rise to double-row chains. The molecule in (II) adopts a 'butterfly' conformation, with the O atoms in distal positions. In both compounds, the dioxin rings are in distorted half-chair conformations.

Four derivatives of 2,6-bis(hydroxymethyl)phenol, with various para substituents, have been investigated; these are 2,6-bis(hydroxymethyl)-4-methylphenol, C(9)H(12)O(3), (I), 2,6-bis(hydroxymethyl)-4-methoxyphenol, C(9)H(12)O(4), (II), 2,6-bis(hydroxymethyl)-4-phenoxyphenol, C(14)H(14)O(4), (III), and 2,6-bis(hydroxymethyl)-4-[1-(4-methoxyphenyl)-1-methylethyl]phenol, C(18)H(22)O(4), (IV). All four structures display hydrogen-bonding networks resulting in sheets, with possible weak inter-sheet pi-pi interactions in one case. In all the structures but one, the molecules form centrosymmetric dimeric subunits held together by two hydrogen bonds between the hydroxymethyl groups and, in two cases, by probable pi-pi interactions.

The title compound, 13,21,35,43-tetramethyl-3,6,9,17,25,28,31,39,46,49-decaoxaheptacyclo[21.21.3.3(11,33).0(2,41).0(10,15).0(19,24).0(32,37)]pentaconta-1,10,12,14,19,21,23,32,34,36,41,43-dodecaene, C(44)H(52)O(10), differs from previously reported 1,3-bridged calix[4]arene[bond]bis-crown compounds in having an enlarged calixarene ring and shorter polyoxyethylene bridges. The cavity is partly filled by the bridges.

Uranyl nitrate hexahydrate reacts with bis[2-(2-hydroxyphenoxy)ethoxy]ethane (C(18)H(22)O(6)), denoted LH(2) hereafter, in the presence of triethylamine to give triethylammonium aqua[2,2'-(3,6-dioxaoctane-1,8-diyldioxy)diphenolato-kappa(2)O,O'](nitrato-kappa(2)O,O')dioxouranium(VI), (Et(3)NH)[UO(2)(H(2)O)L(NO(3))], which possesses a symmetry plane. The uranyl ion is coordinated to the two phenoxide O atoms, a nitrate ion and a water molecule (first sphere); the water molecule is itself held in the crown ether chain by hydrogen-bonding interactions, thus ensuring second-sphere coordination by the ligand L.

2,3,6,7-Tetrahydroxy-9,10-dimethyl-9,10-dihydro-9,10-ethanoanthracene crystallizes with 1,4-dioxane to give a bis-solvate, C(18)H(18)O(4).2C(4)H(8)O(2). The bis(catechol) molecule is located on a twofold axis and the two aromatic rings form a dihedral angle of 130.61(4) degree. Hydrogen bonds are formed between the hydroxyl groups and either a neighbouring bis(catechol) molecule or the ether-O atom of a dioxane molecule.

The title compound, 2,2'-(3-oxapentane-1,5-diyldioxy)diphenol, crystallizes as a methanol solvate, C16H18O5*CH4O. The methanol molecule, roughly perpendicular to the mean plane of the polyether molecule, is hydrogen bonded to the two polyether OH groups and to the central ether O atom. Possible C-H...pi intermolecular interactions are present.

Three methoxy-ether and one methoxy-ether/crown-ether derivatives of p-tert-butyltetrahomodioxa- and p-R-octahomotetraoxacalix[4]arenes (R = methyl, tert-butyl, H) have been investigated. The first three compounds, 7,15,21,27-tetra-tert-butyl-29,30,31,32-tetramethoxy-3,11-dioxapentacyclo[23.3.1.1(5,9).1(13,17).1(19,23)]ditriaconta-1(29),5,7,9(30),13,15,-17(31),19,21,23(32),25,27-dodecaene, C(50)H(68)O(6), 33,34,35,36-tetramethoxy-7,15,23,31-tetramethyl-3,11,19,27-tetraoxapentacyclo[27.3.1.1(5,9).1(13,17).1(21,25)]hexatriaconta-1(33),5,7,9(34),13,15,17(35),21,23,25(36),29,31-dodecaene, C(40)H(48)O(8), and 7,23-di-tert-butyl-33,34,35,36-tetramethoxy-3,11,19,27-tetraoxapentacyclo[27.3.1.1(5,9).1(13,17).1(21,25)]hexatriaconta-1(33),5,7,9(34),13,15,17(35),- 21,23,25(36),29,31-dodecaene, C(44)H(56)O(8), in the partial-cone or 1,2-alternate conformations, present the common feature of methoxy-ether self-inclusion, while the fourth, 42,43-dimethoxy-7,15,23,31-tetramethyl-3,11,19,27,34,37,40-heptaoxahexacyclo[15.15.9.1(5,9).1(21,25).0(13,41).0(29,33)]tritetraconta-5(42),6,8,13(41),14,16,21(43),22,24,29(33),30,32-dodecaene, C(42)H(50)O(9), adopts the 1,3-alternate conformation owing to the presence of a 1,3-polyether chain.

The title compound, 7,13,21,27-tetramethyl-3,17-dioxapentacyclo[23.3.1.1(5,9).1(11,15).1(9,23)]ditriaconta-1(29),5,7,9(30),11(31),-12,14,19(32),20,22,25,27-dodecaene-29,30,31,32-tetraol, C34H36O6, assumes in the solid state a very distorted cone-like conformation stabilized by intramolecular simple and bifurcated hydrogen bonds involving both phenolic and ether O atoms. One part of the molecule, comprising an ether link, is included in the cavity of an adjacent calixarene related by a screw axis, giving rise to a one-dimensional self-inclusion polymer.

The title compound, 7,13,21,27-tetra-tert-butyl-3,17-dioxapentacyclo[23.3.1.1(5,9).1(11,15).1(9,23)]ditriaconta-1(29),5,7,9(30),11(31),12,14,19(32),20,22,25,27-dodecaene-29,30,31,32-tetraol, crystallizes as a solvate with one molecule of chloroform and one molecule of tetrahydrofuran, C46H60O6.CHCl3).C4H8O. The calixarene assumes a cone-like conformation stabilized by intramolecular hydrogen bonds involving both phenolic and ether O atoms. The two solvent molecules are located in each of the two half-cone cavities of the calixarene.