-
[show abstract]
[hide abstract]
ABSTRACT: A series of trimeric, Zn(ii)- and Cd(ii)-metallocycles is reported. Structural characterization of the highly stable triangles was supported by traveling-wave ion mobility-mass spectrometry (TWIM-MS) and gradient tandem mass spectrometry (gMS(2)). Their unique photophysical properties and self-assembly to form nanofibers are also described.
Dalton Transactions 08/2012; 41(38):11573-5. · 3.84 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Multicomponent, self-assembled rhomboidal constructs are reported, in which bis-terpyridines possessing 120° or 60° directionality and Zn(II) or Cd(II) in a stoichiometric ratio (1 : 1 : 2) initially form rhomboid and triangle mixtures; whereas, a tris-terpyridine reacts with the 60°-based bis-ligand and metal to quantitatively form a heteroleptic, centrally fused, rhomboidal structure.
Chemical Communications 08/2012; 48(79):9873-5. · 6.17 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Square feat: The synthesis, isolation, and characterization of five novel bisterpyridine-based metallomacrocycles, possessing a folded tetrameric configuration is reported (see figure). The initial dimeric building block with the stable linear {tpy-Ru(II)-tpy} connectivity circumvents the formation of the thermodynamically favored molecular triangles.
Chemistry 08/2012; 18(37):11569-72. · 5.93 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Two novel macromolecular constitutional isomers have been self-assembled from previously unreported terpyridine ligands in a three-component system. The terpyridine ligands were synthesized in high yields via a key Suzuki coupling. Restrictions of the possible outcomes for self-assembly ultimately provided optimum conditions for isolation of either a molecular bowtie or its isomeric butterfly motif. These isomers have been characterized by ESI-MS, TWIM-MS, (1)H NMR, and (13)C NMR. Notably, these structural isomers have remarkably different drift times in ion mobility separation, corresponding to different sizes and shapes at high charge states.
Journal of the American Chemical Society 04/2012; 134(18):7672-5. · 9.91 Impact Factor
-
Chemistry 07/2011; 17(28):7750-4. · 5.93 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: 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.
Journal of the American Chemical Society 06/2011; 133(31):11967-76. · 9.91 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: 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.
Journal of the American Chemical Society 06/2011; 133(30):11450-3. · 9.91 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Tetrameric, metal-based subunits, [Ni4(d-ala)2(l-ala)2] (d-ala = d-alanine anion, l-ala = l-alanine anion), designed as nodes to construct coordination frameworks, allowed the synthesis of a new twofold interpenetrating channel architecture {[Ni4(d-ala)2(l-ala)2(1,2-bpe)4]·17H2O}n [1,2-bpe = 1,2-bis(4-pyridyl)ethylene]. Characterization included thermogravimetric analyses, IR spectroscopy, X-ray powder diffraction, and single crystal X-ray diffraction. Triangular and rectangular short circuits were formed by the tetrameric nodes and 1,2-bpe linkers that consisted of a triangular prism, and they were further assembled into a twofold interpenetrating parallelepiped motif. The hierarchical construction, based on tetramer nodes and the 1,2-bpe linkers in the channel framework, was investigated.
05/2011;
-
[show abstract]
[hide abstract]
ABSTRACT: Cascade polymeric architecture possessing internal functionalities was employed for the preparation of metallo- and nonmetallo-MicellaneTM derivatives. Specifically, tetra- and dodeca-o-carborane superclusters, were obtained via treatment of the corresponding 1st and 2nd generation tetra- and dodeca-alkyne, hydrocarbon cascade (MicellaneTM) derivatives with decaborane. Reaction of the same polyalkyne dendritic precursors with Co2(CO)8 afforded the benzyl protected, CobaltomicellanesTM possessing 12 and 24 internal metal centers, respectively. Control of amide-based, carboxylic acid terminated macromolecular hydrodynamic radius via changes in solution pH was demonstrated. Heterocascade syntheses employing amide and metalligand monomer connectivity were accomplished. The relation of interior cascade reactivity to macromolecular “void volume” was examined.
Macromolecular Symposia 03/2011; 77(1):63 - 71.
-
[show abstract]
[hide abstract]
ABSTRACT: Hexagonal Pd(II)- or Cd(II)-tetrakispyridinyl-based macrocycles are quantitatively self-assembled from 4'-(3-pyridinyl)-4,4''-di(tert-butyl)-2,2' : 6',2''-terpyridine and structurally confirmed by NMR and TWIM-MS.
Chemical Communications 03/2011; 47(16):4658-60. · 6.17 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The synthesis, purification, structural analysis, and photophysical properties of a series of five-, six-, and seven-sided Fe(II) macrocycles and the corresponding hexameric Cd(II) macrocycle, all prepared by self-assembly of a 120° bis(terpyridine) ligand modified with first- and second-generation 1→3 C-branched dendrons, are reported. All metallomacrocycles were fully characterized by (1)H and (13)C NMR spectroscopy, traveling-wave ion-mobility mass spectrometry (TWIM MS), molecular modeling, UV/Vis absorption spectroscopy, photoluminescence, and cyclic voltammetry. A gradual increase of the collision cross sections of the Fe(II) metallomacrocycles was observed with a successive increase of the number and molecular size of the ligands. The combination of ion-mobility mass spectrometry and NMR techniques unveils structural features that agree well with calculations. Extinction coefficients and emission are significantly modulated by increasing the ring size and changing the metal ion center from Fe(II) to Cd(II) .
Chemistry 03/2011; 17(17):4830-8. · 5.93 Impact Factor
-
Angewandte Chemie International Edition 09/2010; 49(37):6539-44. · 13.45 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: A new series of shape-persistent metallomacromolecules G0 and G1 as well as corresponding ligands, based on thiophene-functionalized bisterpyridine-Ru(II) with truxene moieties, as the nodes, were developed. All new compounds were fully characterized by (1) H, COSY, and (13) C NMR, as well as MALDI-TOF MS. Their photophysical properties revealed that the branched scaffold resulted in high molar absorption coefficients and broad absorption making these materials potential candidates for light-harvesting.
Macromolecular Rapid Communications 05/2010; 31(9-10):850-5. · 4.60 Impact Factor
-
Chemistry 03/2010; 16(14):4164-8. · 5.93 Impact Factor
-
Chemistry 02/2010; 16(6):1768-71. · 5.93 Impact Factor
-
01/2010: pages 1-74; · 1.82 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Self-assembly of novel linear and branched carbohydrate-functionalized mono- and di(2,2':6',2''-terpyridinyl)arenes afforded access to a series of twisted self-organized nanofibers.
Chemical Communications 12/2009; · 6.17 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The general concepts, design criteria, and physical parameters, such as component placement and electroluminescence, that relate to the construction of OLED devices are described, followed by a discussion of the current literature detailing the use of branched and dendritic materials as the key electroluminescent elements of single- and multi-layered fabricated devices. Their configurations, efficiencies, emission intensities, and molecular structural implications are also delineated and discussed. This critical review should appeal to researchers in the synthetic, material, and physical sciences (122 references).
Chemical Society Reviews 12/2008; 37(11):2543-57. · 28.76 Impact Factor
-
Chemical Reviews 07/2008; 108(6):1834-95. · 40.20 Impact Factor
-
Annalen der Chemie und Pharmacie 05/2008; 2008(19):3328 - 3334. · 3.10 Impact Factor
