Spatial localization with the spectroscopic imaging technique is normally implemented with the Fourier-transform approach, yielding rectangular voxels, with potentially significant cross-voxel ...contamination. Multidimensional Fourier-series window (FSW) is an alternate approach that generates single voxels of predetermined shape, with minimal out-of-voxel contamination. The spatial location of the voxel is shifted by means of postacquisition processing. A two-dimensional circular voxel is introduced, which for many in vivo applications is a good match of the region of interest. Phantom images illustrate the spatial distribution of signal intensity within the circular FSW voxels. Phantom spectroscopic studies show excellent spatial localization, with no detectable out-of-voxel contamination. The circular FSW voxel approach is implemented in human and animal model studies, demonstrating the technique's utility. This arbitrary shape approach can be extended to three dimensions, defining, for example, cylinders, spheres, or ellipsoids.
Slow diffusion reactions of the pentaphosphaferrocene Cp*Fe(η5‐P5) (Cp*=η5‐C5Me5 (1)) with CuX (X=Cl, Br, I) in different stoichiometric ratios and solvent mixtures result in the formation of one‐ ...and two‐dimensional polymeric compounds 2–6 with molecular formula {Cu(μ‐X)}{Cp*Fe(μ3,η5:η1:η1‐P5)}n (X=Cl (2 a), I (2′c)), {Cu(μ‐I)}{Cp*Fe(μ3,η5:η1:η1‐P5)}n (3), {CuX}{Cp*Fe(μ4,η5:η1:η1:η1‐P5)}n (X=Cl (4 a), Br (4 b), I (4 c), Br (4′b), I (4′c)), {Cu3(μ‐I)2(μ3‐I)}{Cp*Fe(μ5,η5:η1:η1:η1:η1‐P5)}n (5) and {Cu4(μ‐X)4(CH3CN)}{Cp*Fe(μ7,η5:η2:η1:η1:η1:η1:η1‐P5)}n (X=Cl (6 a), Br (6 b)), respectively. The polymeric compounds have been characterised by single‐crystal X‐ray diffraction analyses and, for selected examples, by magic angle spinning (MAS) NMR spectroscopy. The solid‐state structures demonstrate the versatile coordination modes of the cyclo‐P5 ligand of 1, extending from two to five coordinating phosphorus atoms in either σ or σ‐and‐π fashion. In compounds 2 a, 2′c and 3, two phosphorus atoms of 1 coordinate to copper atoms in a 1,2 coordination mode (2 a, 2′c) and an unprecedented 1,3 coordination mode (3) to form one‐dimensional polymers. Compounds 4 a–c, 4′b, 4′c and 5 represent two‐dimensional coordination polymers. In compounds 4, three phosphorus atoms coordinate to copper atoms in a 1,2,4 coordination mode, whereas in 5 the cyclo‐P5 ligand binds in an unprecedented 1,2,3,4 coordination mode. The crystal structures of 6 a,b display a tilted tube, in which all P atoms of the cyclo‐P5 ligand are coordinated to copper atoms in σ‐ and π‐bonding modes.
The right tool for the job: Small changes in the reaction conditions of pentaphosphaferrocene with Cu halides have a decisive impact on the supramolecular self‐assembly process to form 1D and 2D polymers. The novel products have been systematically investigated using single‐crystal X‐ray structure analyses and high‐resolution 31P solid‐state NMR techniques including R‐TOBSY experiments (see figure).
By applying the proper stoichiometry of 1:2 to CpRFe(η5‐P5) and CuX (X=Cl, Br) and dilution conditions in mixtures of CH3CN and solvents like CH2Cl2, 1,2‐Cl2C6H4, toluene, and THF, nine spherical ...giant molecules having the simplified general formula CpRFe(η5‐P5)@{CpRFe(η5‐P5)}12{CuX}25(CH3CN)10 (CpR=η5‐C5Me5 (Cp*); η5‐C5Me4Et (CpEt); X=Cl, Br) have been synthesized and structurally characterized. The products consist of 90‐vertex frameworks consisting of non‐carbon atoms and forming fullerene‐like structural motifs. Besides the mostly neutral products, some charged derivatives have been isolated. These spherical giant molecules show an outer diameter of 2.24 (X=Cl) to 2.26 nm (X=Br) and have inner cavities of 1.28 (X=Cl) and 1.20 nm (X=Br) in size. In most instances the inner voids of these nanoballs encapsulate one molecule of Cp*Fe(η5‐P5), which reveals preferred orientations of π–π stacking between the cyclo‐P5 rings of the guest and those of the host molecules. Moreover, π–π and σ–π interactions are also found in the packing motifs of the balls in the crystal lattice. Electrochemical investigations of these soluble molecules reveal one irreversible multi‐electron oxidation at Ep=0.615 V and two reduction steps (−1.10 and −2.0 V), the first of which corresponds to about 12 electrons. Density functional calculations reveal that during oxidation and reduction the electrons are withdrawn or added to the surface of the spherical nanomolecules, and no Cu2+ species are involved.
Giant spherical molecules (o.d. ca. 2.25 nm) consisting of 90 non‐carbon core atoms and having fullerene‐like structures were obtained by reactions of the pentaphosphaferrocene (η5‐C5Me5)Fe(η5‐P5) with CuI halides. The spheres self‐assemble with the help of pentaphosphaferrocene as the guest (one of two orientations is shown in the picture). Despite their size, they are soluble in mixtures of solvents.
Slow diffusion reactions of the pentaphosphaferrocene Cp*Fe(η5-P5) (Cp*=η5-C5Me5 (1)) with CuX (X=Cl, Br, I) in different stoichiometric ratios and solvent mixtures result in the formation of one- ...and two-dimensional polymeric compounds 2-6 with molecular formula {Cu(µ-X)}{Cp*Fe(µ3,η5:η1:η1-P5)}n (X=Cl (2a), I (2'c)), {Cu(µ-I)}{Cp*Fe(µ3,η5:η1:η1-P5)}n (3), {CuX}{Cp*Fe(µ4,η5:η1:η1:η1-P5)}n (X=Cl (4a), Br (4b), I (4c), Br (4'b), I (4'c)), {Cu3(µ-I)2(µ3-I)}{Cp*Fe(µ5,η5:η1:η1:η1:η1-P5)}n (5) and {Cu4(µ-X)4(CH3CN)}{Cp*Fe(µ7,η5:η2:η1:η1:η1:η1:η1-P5)}n (X=Cl (6a), Br (6b)), respectively. The polymeric compounds have been characterised by single-crystal X-ray diffraction analyses and, for selected examples, by magic angle spinning (MAS) NMR spectroscopy. The solid-state structures demonstrate the versatile coordination modes of the cyclo-P5 ligand of 1, extending from two to five coordinating phosphorus atoms in either σ or σ-and-π fashion. In compounds 2a, 2'c and 3, two phosphorus atoms of 1 coordinate to copper atoms in a 1,2 coordination mode (2a, 2'c) and an unprecedented 1,3 coordination mode (3) to form one-dimensional polymers. Compounds 4a-c, 4'b, 4'c and 5 represent two-dimensional coordination polymers. In compounds 4, three phosphorus atoms coordinate to copper atoms in a 1,2,4 coordination mode, whereas in 5 the cyclo-P5 ligand binds in an unprecedented 1,2,3,4 coordination mode. The crystal structures of 6a,b display a tilted tube, in which all P atoms of the cyclo-P5 ligand are coordinated to copper atoms in σ- and π-bonding modes.
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