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Biomedical subjects

Peter J Stang

Publications and source records attributed to Peter J Stang.

At least 19 recordsLinked to original sources
PubMed2006

The synthesis of new 60 degrees organometallic subunits and self-assembly of three-dimensional M3L2 trigonal-bipyramidal cages.

By employing the coupling reaction of trans-PtI2(Et3)2 with C-H bonds in alkynes as the key step, two new 60 degrees organometallic subunits with different size from 3,6-dibromophenanthrene were prepared in reasonable yields. The X-ray structures of both di-Pt(II) diiodide complexes showed that they were indeed suitable candidates for 60 degrees building units. By utilizing these novel linkers as ditopic acceptor subunits, three M3L2 trigonal-bipyramidal (TBP) cages were formed. All three TBP cages were characterized with multinuclear NMR and electrospray ionization mass spectrometry (ESI-MS) along with element analysis.

Magnetic Resonance Spectroscopy↗
PubMed2006

Synthesis and solution- and solid-state characterization of gold(I) rings with short Au...Au interactions. Spontaneous resolution of a gold(I) complex.

We report the synthesis and solution- and solid-state characterization of gold(I) rings with short 1,9-transannular Au...Au interactions. The 9- and 16-membered gold(I) rings were prepared by reacting 9,9-dimethyl-4,5-bis(diphenylphosphino)-xanthene and (Me2S)AuCl in the presence of AgNO3 in the molar ratio of 1:0.5:1 and 1:1:1, respectively. X-ray crystallographic measurements in conjunction with solution X-ray diffraction and NMR methods have been used to determine the structure of gold(I) rings, and we also gained insight into the dynamics. The nine-membered gold(I) ring is chiral, and the crystal contains only one of the two enantiomers, either right- or left-handed. To the best of our knowledge this represents the first example of crystallization-induced spontaneous resolution of a binuclear gold(I) cycle. The 16-membered ring with 1,9-transannular Au...Au interaction is in a figure-eight conformation.

Journal Article↗
PubMed2006

Incorporation of 2,6-di(4,4'-dipyridyl)-9-thiabicyclo[3.3.1]nonane into discrete 2D supramolecules via coordination-driven self-assembly.

The synthesis and characterization of three new supramolecular complexes 6-8 (a rhomboid and two hexagons) via coordination-driven self-assembly are reported in excellent yields (>90%). These assemblies have 2,6-di(4,4'-dipyridyl)-9-thiabicyclo[3.3.1]nonane 2 as the bridging tecton. All assemblies were characterized by multinuclear NMR (1H and 31P), mass spectrometry (ESI-MS and ESI-FT-ICR), and elemental analysis. The X-ray structure of the 120 degrees tecton 2 is also discussed.

Bridged Bicyclo Compounds↗
PubMed2006

Ambidentate ligands capable of variable bond angles in the coordination-driven self-assembly of discrete Pt macrocycles.

Flexible, ambidentate pyridyl-carboxylate based donor ligands such as sodium 3-(3-pyridyl)benzoate, sodium 4-(3-pyridyl)benzoate, and potassium 4-(3-pyridyl)ethynylbenzoate self-assemble into discrete [2 + 2] macrocyclic species instead of infinite networks when combined with a 90 degrees platinum-containing acceptor. In each case, only one isomeric ensemble is selectively formed in high yield. All products are characterized by electrospray ionization mass spectrometry (ESI-MS) and 31P{1H} and 1H NMR spectroscopy. They are the first examples of discrete supramolecules incorporating flexible, ambidentate donor ligands. Despite their potential versatility, these pyridyl-carboxylate donors adjust their bonding directionality to accommodate a rigid platinum acceptor in the formation of one discrete ensemble.

Ligands↗
PubMed2006

Incorporating a flexible crown ether into neutral discrete self-assemblies driven by metal coordination.

Driven by metal coordination, a flexible crown ether was self-assembled into neutral discrete complexes with two organoplatinum acceptors. Specifically, a [1 + 1]-assembled structure was separated from self-assemblies with different stoichiometries by vapor diffusion of acetone into their dichloromethane solution. The formation of these crown ether-incorporated self-assemblies was confirmed by NMR, elemental analysis, and X-ray single-crystal analysis.

Crown Ethers↗
PubMed2006

Self-assembly of supramolecular platinum complexes with bis-4-pyridyl cavitands.

The design and self-assembly of six new supramolecular complexes (four triangles and two 2+2 assemblies) are described. These assemblies incorporate two new bispyridyl cavitand building blocks and were prepared in excellent yields (85-95%). The assemblies and building blocks were characterized with multinuclear NMR spectroscopy, electrospray ionization mass spectrometry, and elemental analysis. Isotopically resolved mass spectrometry along with NMR data confirms the existence of the six assemblies.

Ethers, Cyclic↗
PubMed2005

Synthesis and structural characterization of carborane-containing neutral, self-assembled Pt-metallacycles.

[structure: see text] We have combined carborane chemistry with the newly developed directional bonding strategy to synthesize neutral macrocycles. The m- and p-carborane dicarboxylates were utilized as the donor linkers in conjunction with 1,8-bis[trans-Pt(PEt3)2NO3]anthracene 3, 2,9-bis[trans-Pt(PEt3)2NO3]phenanthrene 5, and cis-Pt(PEt3)2(NO3)2 unit 6. Three new platinum-based macrocycles, 4, 7, and 8, were thus synthesized. 31P{1H} NMR as well as the X-ray characterization of Pt-metallacycles reveal the formation of single highly symmetrical neutral species.

Journal Article↗
PubMed2005

Self-organization of a self-assembled supramolecular rectangle, square, and three-dimensional cage on Au111 surfaces.

The structure and conformation of three self-assembled supramolecular species, a rectangle, a square, and a three-dimensional cage, on Au111 surfaces were investigated by scanning tunneling microscopy. These supramolecular assemblies adsorb on Au111 surfaces and self-organize to form highly ordered adlayers with distinct conformations that are consistent with their chemical structures. The faces of the supramolecular rectangle and square lie flat on the surface, preserving their rectangle and square conformations, respectively. The three-dimensional cage also forms well-ordered adlayers on the gold surface, forming regular molecular rows of assemblies. When the rectangle and cage were mixed together, the assemblies separated into individual domains, and no mixed adlayers were observed. These results provide direct evidence of the noncrystalline solid-state structures of these assemblies and information about how they self-organize on Au111 surfaces, which is of importance in the potential manufacturing of functional nanostructures and devices.

Gold↗
PubMed2005

Dynamic NMR study of the hindered Pt-N(bipyridine) rotation in metal-directed self-assembled macrocycles.

[reaction: see text] The activation parameters for the hindered Pt-N(bipyridyl) rotation observed for a self-assembled rectangle and triangle have been investigated by temperature-dependent and selective inversion recovery (SIR) NMR spectroscopy. The enthalpy of activation (DeltaH) and change in entropy (DeltaS) were determined to be +52.2 kJ/mol and -58.2 J/mol.K for the rectangle and +59.1 kJ/mol and -71.8 J/mol.K for the triangle, respectively, by SIR.

Macrocyclic Compounds↗
PubMed2005

Self-assembly of neutral platinum-based supramolecular ensembles incorporating oxocarbon dianions and oxalate.

Five neutral platinum-based macrocycles incorporating cyclic oxocarbondianions, squarate and croconate and their acyclic analogue, oxalate, have been synthesized in 90-95% yield via self-assembly. The combination of the diplatinum molecular clip with all three dianions afforded molecular rectangles, whereas a platinum-based 60 degrees acceptor unit produced a supramolecular rhomboid with croconate ion but a triangle with squarate ion. In all cases, multinuclear NMR spectra were consistent with the formation of single highly symmetrical species. The three rectanglular and the rhomboid assemblies were characterized by single-crystal X-ray crystallography. The triangular species was characterized by FAB mass spectrometry.

Anions↗
PubMed2005

Coordination-driven self-assemblies with a carborane backbone.

The design and self-assembly of five new supramolecular complexes (a rectangle, a triangle, a hexagon, and two squares) are described. These assemblies incorporate carborane building blocks and were prepared in excellent yields (>85%). The assemblies and building blocks were characterized with multinuclear NMR spectroscopy, electrospray ionization mass spectrometry, and elemental analysis. Isotopically resolved mass spectrometry data confirm the existence of the rectangle, triangle, and hexagon, and NMR data are consistent with the formation of all five assemblies. The X-ray structures of two linear carborane building blocks, 1,12-(4-CC(C(5)H(4)N)(2)-p-C(2)B(10)H(10) (1) and 1,12-(trans-(Pt(PEt(3))(2)I)CC)(2)-p-C(2)B(10)H(10) (2), are reported: 1 is monoclinic, P2(1)/c, a = 10.6791(4) A, b = 8.0091(14) A, c = 11.6796(4) A, beta = 107.8461(15) degrees , V = 950.89(5) A(3), Z = 2; 2 is monoclinic, C2/c, a = 62.1128(10) A, b = 22.0071(3) A, c = 14.0494(2) A, beta = 89.9411(8) degrees , V = 19204.4(5) A(3), Z = 16. Crystals of the linear linker 1 exhibit close pi-pi pyridine and pyridine-B(carborane) interactions, which are discussed.

Boranes↗
PubMed2005

Self-assembly of heterobimetallic neutral macrocycles incorporating ferrocene spacer groups: spectroelectrochemical analysis of the double two-electron oxidation of a molecular rectangle.

Two Pt(4)-Fe(2) mixed-metal neutral assemblies, 4 and 5, incorporating four bis(triethylphosphine)platinum(II) centers, two flexible bridging 1,1'-ferrocenedicarboxylates, and two rigid 2,9-phenanthrenediyl (4) or 1,8-anthracenediyl (5) bridges, have been synthesized. X-ray characterization of 4 and 5 reveals the formation of discrete and highly symmetrical heterobimetallic neutral species possessing a rhomboidal and rectangular shape, respectively. The rectangular molecules, 5, could be reversibly oxidized in two two-electron steps, separated by 0.21 V. Spectroelectrochemistry in the UV-vis-NIR region confirms the ferrocene groups as primary oxidation sites; however, the intermediate 5(2+) is EPR silent even at 4 K due to enhanced EPR relaxation involving the oxidizable 1,8-anthracenediyl linkers.

Journal Article↗
PubMed2005

X-ray diffraction and DOSY NMR characterization of self-assembled supramolecular metallocyclic species in solution.

Wide-angle X-ray scattering and diffusion NMR techniques have been used to obtain structural information on three self-assembled metallacyclic supramolecular complexes in solution: a rectangle, a triangle, and a three-diminsional cage. The low-angle region of the measured diffraction patterns and hydrodynamic radii calculations, determined from DOSY NMR experiments, suggest that the supramolecular assemblies retain their shape when dissolved in nitromethane. The experimental structure functions for the large-angle region have been analyzed, and the intramolecular contributions of the platinum-platinum interactions are discussed. These scattering measurements provide evidence that the supramolecular assemblies are not as rigid in solution as they are in the single crystal. Finally, by analysis of the radial distribution functions of the solutions, direct structural information (e.g., platinum-platinum intramolecular distances and coordination number) about the supramolecular assemblies has been obtained.

Magnetic Resonance Spectroscopy↗
PubMed2005

Self-assembly of nanoscale supramolecular truncated tetrahedra.

Two nanoscale truncated tetrahedra were synthesized via Pt(II)-mediated self-assembly. The first resulted from the reaction of 3 equiv of cis-Pt(PMe3)2(OTf)2 and 2 equiv of 1,3,5-tris(4-pyridylethynyl)benzene, giving a truncated tetrahedron with a diameter of approximately 25 A. The second, analogous structure was obtained by the self-assembly of cis-Pt(PMe3)2(OTf)2 and 1,3,5-tris(4-pyridyl-trans-ethenyl)benzene. These two truncated tetrahedra were crystallized after partially exchanging the counterion to cobalticarborane for the X-ray structural analysis.

Journal Article↗
PubMed2005

Synthesis of a bis(pyridyl)-substituted perylene diimide ligand and incorporation into a supramolecular rhomboid and rectangle via coordination driven self-assembly.

The synthesis of a bis(pyridyl)-substituted perylene diimide ligand and its incorporation into a supramolecular rhomboid and rectangle via platinum-mediated self-assembly is reported. Both ensembles are characterized by multinuclear NMR and electrospray ionization mass spectrometry. In addition, the UV/vis spectra of the ensembles exhibit displaced and enhanced absorptions relative to the starting ligand. Size estimations using MM2 simulations show the assemblies are almost 46 A in length.

Journal Article↗