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Reaction of 2,2'-bis-p-tBu-calix[4]arene (H8L) with Cu(NO3)2·3H2O and N-methyldiethanolamine (Me-deaH2) in a basic dmf/MeOH mixture affords [CuII16(L)2(Me-dea)4(μ4-NO3)2(μ-OH)4(dmf)3.5(MeOH)0.5(H2O)2](H6L)·16dmf·4H2O (4), following slow evaporation of the mother liquor. The central core of the metallic skeleton describes a tetracapped square prism, [Cu12], in which the four capping metal ions are the CuII ions housed in the calix[4]arene polyphenolic pockets. The [CuII8] square prism is held together "internally" by a combination of hydroxide and nitrate anions, with the N-methyldiethanolamine co-ligands forming dimeric [CuII2] units which edge-cap above and below the upper and lower square faces of the prism. Charge balance is maintained through the presence of one doubly deprotonated H6L2- ligand per [Cu16] cluster. Magnetic susceptibility measurements reveal the predominance of strong antiferromagnetic exchange interactions and an S = 1 ground state, while EPR is consistent with a large zero-field splitting.

Reaction of 2,2'-bis-p-tBu-calix[4]arene (H8L) with MnCl2·4H2O, GdCl3·6H2O and 2,6-pyridinedimethanol (H2pdm) affords [MnIIIMnIIGdIII(H3L)(pdmH)(pdm)(MeOH)2(dmf)]·3MeCN·dmf (3·3MeCN·dmf) upon vapour diffusion of MeCN into the basic dmf/MeOH mother liquor. 3 crystallises in the tetragonal space group P41212 with the asymmetric unit comprising the entire cluster. The highly unusual core contains a triangular arrangement of MnIIIMnIIGdIII ions housed within a [MnIIIMnIIGdIII(OR)4]4- partial cubane. Magnetic susceptibility and magnetisation data reveal best fit parameters JMn(II)-Mn(III) = +0.415 cm-1, JMn(III)-Gd(III) = +0.221 cm-1, JMn(II)-Gd(III) = -0.258 cm-1 and DMn(III) = -4.139 cm-1. Theoretically derived magnetic exchange interactions, anisotropy parameters, and magneto-structural correlations for 3 are in excellent agreement with the experimental data.

Reaction of 2,2'-bis-p-tBu-calix[4]arene (H8L) with MnCl2·4H2O, GdCl3·6H2O and 2,6-pyridinedimethanol (H2pdm) affords [MnIIIMnIIGdIII(H3L)(pdmH)(pdm)(MeOH)2(dmf)]·3MeCN·dmf (3·3MeCN·dmf) upon vapour diffusion of MeCN into the basic dmf/MeOH mother liquor. 3 crystallises in the tetragonal space group P41212 with the asymmetric unit comprising the entire cluster. The highly unusual core contains a triangular arrangement of MnIIIMnIIGdIII ions housed within a [MnIIIMnIIGdIII(OR)4]4- partial cubane. Magnetic susceptibility and magnetisation data reveal best fit parameters JMn(II)-Mn(III) = +0.415 cm-1, JMn(III)-Gd(III) = +0.221 cm-1, JMn(II)-Gd(III) = -0.258 cm-1 and DMn(III) = -4.139 cm-1. Theoretically derived magnetic exchange interactions, anisotropy parameters, and magneto-structural correlations for 3 are in excellent agreement with the experimental data.

Calix[4]arenes are versatile ligands, capable of supporting the formation of a wide variety of polymetallic clusters comprising 3d, 4f or 3d-4f metal ions. Calixarene-based metal ion fragments act as both bridging and structure capping moieties in these systems, and this behaviour is systematically extended upon moving to bis-calix[4]arene, a relatively new ligand in which two calix[4]arenes are tethered at the methylene bridge position. N,O-Ligands greatly influence cluster formation with bis-calix[4]arene, affording a remarkable mixed-valence [MnMnMn] cluster that displays coordination chemistry typical of each ligand type, but also new structure capping behaviour for the latter.

Calix[4]arenes are versatile ligands, capable of supporting the formation of a wide variety of polymetallic clusters comprising 3d, 4f or 3d-4f metal ions. Calixarene-based metal ion fragments act as both bridging and structure capping moieties in these systems, and this behaviour is systematically extended upon moving to bis-calix[4]arene, a relatively new ligand in which two calix[4]arenes are tethered at the methylene bridge position. N,O-Ligands greatly influence cluster formation with bis-calix[4]arene, affording a remarkable mixed-valence [MnMnMn] cluster that displays coordination chemistry typical of each ligand type, but also new structure capping behaviour for the latter.

Purpose: In this study, the authors investigated how acoustic distortion affected younger and older adults' use of context in a lexical decision task. Method: The authors measured lexical decision reaction times (RTs) when intact target words followed acoustically distorted sentence contexts. Contexts were semantically congruent, neutral, or incongruent. Younger adults (n = 216) were tested on three distortion types: low-pass filtering, time compression, and masking by multitalker babble, using two amounts of distortion selected to control for word recognition accuracy. Older adults (n = 108) were tested on two amounts of time compression and one low-pass filtering condition. Results: For both age groups, there was robust facilitation by congruent contexts but minimal inhibition by incongruent contexts. Facilitation decreased as distortion increased. Older listeners had slower RTs than younger listeners, but this difference was smaller in congruent than in neutral or incongruent conditions. After controlling for word recognition accuracy, older listeners' RTs were slower in time-compressed than in low-pass filtering conditions, but younger listeners performed similarly in both conditions. Conclusions: These RT results highlight the interdependence between bottom-up sensory and top-down semantic processing. Consistent with previous findings based on accuracy measures, compared with younger adults, older adults were disproportionately slowed when speech was time compressed but more facilitated by congruent contexts.

Reaction of 2,2′-bis-p-tBu-calix[4]arene (H8L) with Cu(NO3)2·3H2O and N-methyldiethanolamine (Me-deaH2) in a basic dmf/MeOH mixture affords [Cu II16 (L)2(Me-dea)4(μ4-NO3)2(μ-OH)4(dmf)3.5(MeOH)0.5(H2O)2](H6L)·16dmf·4H2O (4), following slow evaporation of the mother liquor. The central core of the metallic skeleton describes a tetracapped square prism, [Cu12], in which the four capping metal ions are the CuII ions housed in the calix[4]arene polyphenolic pockets. The [Cu II8 ] square prism is held together "internally" by a combination of hydroxide and nitrate anions, with the N-methyldiethanolamine co-ligands forming dimeric [Cu II2 ] units which edge-cap above and below the upper and lower square faces of the prism. Charge balance is maintained through the presence of one doubly deprotonated H6L2− ligand per [Cu16] cluster. Magnetic susceptibility measurements reveal the predominance of strong antiferromagnetic exchange interactions and an S = 1 ground state, while EPR is consistent with a large zero-field splitting. [ABSTRACT FROM AUTHOR]

An [FeIII8] hexagonal bipyramid displays antiferromagnetic exchange between the two capping tetrahedral ions and the six ring octahedral ions resulting in a spin ground state of S = 10. [ABSTRACT FROM AUTHOR]

Dissolution of FeBr3 in a mixture of acetonitrile and 3,4-lutidine in the presence of an amine results in the formation of an [Fe30] molecular metal oxide containing alternating layers of tetrahedral and octahedral FeIII ions. Mass spectrometry suggests the cluster is formed quickly and remains stable in solution, while magnetic measurements and DFT calculations reveal competing antiferromagnetic exchange interactions. [ABSTRACT FROM AUTHOR]

The reaction of MnCl2·4H2O, H8L (2,2′-bis-p-tBu-calix[4]arene) and NEt3 in a dmf/MeOH solvent mixture results in the formation of a mixed valent decametallic cluster of formula [Mn II6 Mn III4 (L)2(μ3-OH)4(μ-OH)4(MeOH)4(dmf)4(MeCN)2]·MeCN (3). Complex 3 crystallises in the monoclinic space group P21/n with the asymmetric unit comprising half of the compound. Structure solution reveals that the bis-calix[4]arene ligands are arranged such that one TBC[4] moiety in each has undergone inversion in order to accommodate a [Mn III4 Mn II6 ] metallic skeleton that describes three vertex-sharing [Mn III2 Mn II2 ] butterflies. The structure is closely related to the species [Mn III6 Mn II4 (L)2(μ3-O)2(μ3-OH)2(μ-OMe)4(H2O)4(dmf)8]·4dmf (4), the major difference being the oxidation level of the Mn ions in the core of the compound. DFT calculations on the full structures reveal that replacing the MnIII ions in 4 for MnII ions in 3 results in a significant decrease in the magnitude of some antiferromagnetic exchange contributions, a switch from ferromagnetic to antiferromagnetic in others, and the loss of significant spin frustration. [ABSTRACT FROM AUTHOR]

A [Mn18] wheel of wheels is obtained from the reaction of MnBr2·4H2O and LH3 in MeOH. The metallic skeleton reveals two asymmetric [MnIII6MnII2] square wheels connected into a larger wheel via two MnII ions. Magnetic susceptibility and magnetisation data reveal competing exchange interactions, supported by computational studies. [ABSTRACT FROM AUTHOR]