Surface properties of a series of amphiphilic dendrimers with short hydrophobic chains

A series of tree-shaped, amphiphilic dendrimers was synthesized. The products belong to the family of one-directional arborols of the form ([9]-n), where the notation signifies that each molecule has nine hydroxyl groups ([9]-) as the hydrophilic head and an alkyl chain as the hydrophobic moiety (n = 6, 8, or 10 carbon atoms). The surfactant character changes dramatically as the number of methylene groups increases. The critical micelle concentration of [9]-6 was determined, and pressure-area isotherms of the less soluble [9]-8 and [9]-10 were obtained. Large structures existed atop the spread layers. Large structures were also found in solutions of [9]-6.     

Construction of a Hexameric Zn(II)‐metallomacrocycle and its Photo‐ and Electroluminescence Properties: [Zn6(O‐hexyl‐3,5‐bis(2,2′:6′,2″‐terpyridine)phenol)6(BF4)12]

Summary: An O‐hexyl‐3,5‐bis(terpyridine)phenol ligand has been synthesized and transformed into a hexagonal Zn(II)‐metallomacrocycle by a facile self‐assembly procedure capitalizing on terpyridine‐Zn(II)‐terpyridine connectivity. The structural composition was confirmed by NMR and mass spectral techniques; photo‐ and electroluminescence properties were also investigated. The OLED device shows green electroluminescent emission at 515 nm with a maximum luminance of 39 cd · m⁻² and maximum efficiency of 0.16 cd · A⁻¹.

Structure and electroluminescent properties of the metallomacrocycle investigated.     

Detecting functional magnetic resonance imaging activation in white matter: Interhemispheric transfer across the corpus callosum

Background  

It is generally believed that activation in functional magnetic resonance imaging (fMRI) is restricted to gray matter. Despite this, a number of studies have reported white matter activation, particularly when the corpus callosum is targeted using interhemispheric transfer tasks. These findings suggest that fMRI signals may not be neatly confined to gray matter tissue. In the current experiment, 4 T fMRI was employed to evaluate whether it is possible to detect white matter activation. We used an interhemispheric transfer task modelled after neurological studies of callosal disconnection. It was hypothesized that white matter activation could be detected using fMRI.     

TerpyridineCuII-mediated reversible nanocomposites of single-wall carbon nanotubes: towards metallo-nanoscale architectures

The self-assembly of Oxi-SWNTs, based on terpyridineCu(II) coordination, produces a thermally stable, neutral [(Oxi-SWNT)(tpyCu(II))m]n nanocomposite possessing notable luminscence properties; quantitative disassembly occurred by treatment with aqueous KCN.     

New Metallo-Supramolecular Terpyridine-Modified Cellulose Functional Nanomaterials

New metallo-supramolecular nanocellulosic derivatives were prepared by surface modification of cellulose nanocrystals with 4-chloro-2,2′:6′,2″-terpyridine and subsequent coupling with other terpyridine-functionalized derivatives via Ru^III/Ru^II reduction. The terpyridine-modified cellulose nanocrystals (CTP) were characterized using transmission electron microscopy (TEM), magic angle spinning ¹³C nuclear magnetic resonance (MAS-¹³C NMR), elemental analysis, as well as Fourier transform infrared (FTIR) and UV-Visible spectroscopy. Metallo-CTP with different optical properties, and expected magnetic and catalytic properties, were easily obtained upon reaction of the prepared CTP with different di- and trivalent transition metal ions (Fe⁺², Mn⁺², Co⁺², and Ru⁺³). Metallo-supramolecular nanocellulosic derivatives with different properties were prepared by subsequent coupling of Ru^III-CTP complex with other terpyridine ligands bearing different functionalities.     

Stoichiometric self-assembly of shape-persistent 2D complexes: a facile route to a symmetric supramacromolecular spoked wheel

An approach to multicomponent coordination-driven self-assembly of the first terpyridine-based, shape-persistent, giant two-dimensional D(6h) supramacromolecular spoked wheel is reported. Mixing core T6, rim T3, and Zn(II) or Cd(II) ions in a stoichiometric ratio (1:6:12) permitted the selective generation of a highly symmetric spoked wheel in 94% isolated yield via geometric and thermodynamic control. The products were characterized by a combination of traveling-wave ion mobility mass spectrometry and NMR techniques together with TEM imaging, which agreed with computational simulations.     

Design, synthesis, and traveling wave ion mobility mass spectrometry characterization of iron(II)- and ruthenium(II)-terpyridine metallomacrocycles

New metallomacrocycles composed of 2,2':6',2″-terpyridine (tpy) ligands and Ru(II) or Fe(II) transition metal ions were prepared by stepwise directed assembly and characterized by 2D diffusion NMR spectroscopy (DOSY), electrospray ionization traveling wave ion mobility mass spectrometry (ESI TWIM MS), and molecular modeling. The supramolecular polymers synthesized include a homonuclear all-Ru hexamer as well as heteronuclear hexamer and nonamer with alternating Ru/Ru/Fe metal centers. ESI MS yields several charge states from each supramacromolecule. If ESI is interfaced with TWIM MS, overlapping charge states and the isomeric components of an individual charge state are separated based on their unique drift times through the TWIM region. From experimentally measured drift times, collision cross-sections can be deduced. The collision cross-sections obtained for the synthesized supramacromolecules are in good agreement with those predicted by molecular modeling for macrocyclic structures. Similarly, the hydrodynamic radii of the synthesized complexes derived from 2D DOSY NMR experiments agree excellently with the radii calculated for macrocyclic architectures, confirming the ESI TWIM MS finding. ESI TWIM MS and 2D DOSY NMR spectroscopy provide an alternative approach for the structural analysis of supramolecules that are difficult or impossible to crystallize, such as the large macrocyclic assemblies investigated. ESI TWIM MS will be particularly valuable for the characterization of supramolecular assemblies not available in the quantity or purity required for NMR studies.     

Improved synthesis of an ethereal tetraamine core for dendrimer construction

A new route to a pentaerythritol-based tetraamine is delineated and subsequently contrasted to a previous report. Access to the pure tetraamine is facilitated by the smooth reduction of its tetraazide precusor. Characterization includes the preparation of a 4:1 Zn-tetraphenylporphyrin/tetraamine complex.     

Synthesis, X-ray structure, and self-assembly of functionalized bis(2,2':6',2' '-terpyridinyl)arenes

meta-Bis(terpyridinyl)phenol has been synthesized from O-benzyl-3,5-di(formyl)phenol in three steps. Its alkylation afforded a series of bisterpyridinylarenes, which can be self-assembled to afford the corresponding hexametallomacrocycles possessing Fe(II), Zn(II), or Ru(II) connectivity. [structure: see text]