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We report a new type of microarray, based on glyconanoparticles (GNPs), to study glycan—lectin interactions. GNPs, synthesized by conjugating carbohydrate ligands on silica nanoparticles, were printed on a photoactive surface followed by covalent immobilization by light activation. The GNP microarrays could be probed by lectins labeled with fluorescein as well as fluorescein-doped silica nanoparticles (FSNPs). Results showed that FSNP as the label enhanced the signals for the higher affinity ligands than the lower ones. [ABSTRACT FROM AUTHOR]

Glyconanomaterials, nanomaterials canying multiple carbohydrate ligands, provide an excellent platform for sensitive protein recognition. Using nanomaterials as the scaffold, multivalent interactions between glycan ligands and pmteins have been demonstrated. However, the quantitative analysis of the binding affinity of these glyconanomaterials has been lacking. In this Article, we report a new method to measure the binding affinity of glyconanoparticle (GNP)-protein interactions based on a fluorescent competition binding assay, which yielded the apparent dissociation constant (Kd) of GNPs with the interacting protein. Au nanoparticles conjugated with underivatized mono-, oligo-, and polysaccharides were synthesized using our recently developed photo coupling chemistry. The affinities of these GNPs with lectins were measured and were several orders of magnitude higher than the corresponding free ligands with lectins. The effect of ligand display on the binding affinity of GNPs was, furthermore, studied where GNPs of varying linker type, spacer length, ligand density, and nanoparticle size were prepared and Kd values determined. The long spacer linker containing hydrocathon and ethylene oxide units gave the highest binding affinity as well as assay sensitivity. The binding affinity increased with ligand density in general, showing a drastic increase in affinity at low ligand density. In addition, the affinity enhancement was more pronounced on smaller NPs than the larger ones. These results not only demonstrate that the binding affinity of GNPs is highly influenced by how the ligands are presented on the nanoparticles but also pave the way for tailor-made glyconanomaterials with tunable affinity by way of ligand display. [ABSTRACT FROM AUTHOR]

Reaction of the half-sandwich complexes MIII(Pc)-(acac) (M = La, Eu, Y, Lu; Pc = phthalocyaninate; acac = acetylacetonate) with the metal-free N-confused 5,10,15,20-tetralds[(4-tert-buryl)phenyl]porphyrin (H2NTBPP) or its N2-position methylated analogue H(CH3)NTBPP in refluxing 1,2,4-trichlorobenzene (TCB) led to the isolation of MIIII(Pc)-(HNTBPP) (M = La, Eu, Y, Lu) or Y,III(Pc)[(CH3)NTBPP] in 8--15% yield. These represent the first examples of sandwich-type rare earth complexes with N-confused porphyrinato ligands. The complexes were characterized with various spectroscopic methods and elemental analysis. The molecular structures of four of these double-decker complexes were also determined by single-crystal X-ray diffraction analysis. In each of these complexes, the metal center is octa-coordinated by four isoindole nitrogen atoms of the Pc ligand, three pyrrole nitrogen atoms, and the inverted pyrrole carbon atom of the HNTBPP or (CH3)NTBPP ligand, forming a distorted coordination square antiprism. For EuIII(Pc)(HNTBPP), the two macrocyclic rings are further bound to a CH3OH molecule through two hydrogen bonds formed between the hydroxyl group of CH3OH and an aza nitrogen atom of the Pc ring or the inverted pyrrole nitrogen atom of the HNTBPP ring, respectively. The location of the acidic proton at the inverted pyrrole nitrogen atom (N2) of the protonated double-deckers was revealed by 1H NMR spectroscopy. [ABSTRACT FROM AUTHOR]

Four coordination polymers Ni(quin-6-c) 2( 1), Zn 2(quin-6-c) 4( 2), Co 2(quin-6-c) 4( 3), and Zn(OH)(quin-6-c) ( 4) (quin-6-c = quinoline-6-carboxylate) have been synthesized by methods of hydrothermal reaction and their crystal structures determined. In the compound 1, quin-6-c ligands act as ditopic linkers bound to Ni atoms, resulting in the formation of an unusually wavelike 2D (4,4) net. The adjacent layers are stacked offset with respect to each other, in an ABAB fashion. Compounds 2and 3are isostructural and feature a unique 2D molecular network composed of crimpled double-line ribbons. The 2D layers stack in a rare, interesting ABCD pattern along the crystallographic caxis. Compound 4forms a novel 3D framework based on uncommon “new” 6 5.8 topology, crystallizes in the acentric orthorhombic space group Pna2 1and displays powder SHG intensity ca.460 times in comparing with that of α-quartz. The [Zn(μ 2-OH)] nhelical chains connected to each other through unsymmetrical quin-6-c ligands in 4have ensured its acentricity and SHG-activity. A discussion of the crystal structures, as well as the coordination properties of quin-6-c ligands upon different geometries of the central ions, is provided. [ABSTRACT FROM AUTHOR]

Through the use of (Bu4N)2[Sn3S4(edt)3] (edt = SCH2CH2S2-) and Sn(SPh)4 as metalloligands, three neutral compounds have been obtained: [(Ph3P)2Cu]2SnS(edt)2 · 2CH2Cl2 · H2O (1a), [(Ph3P)2Cu]2SnS(edt)2 · 2DMF.· H2O (1b), and [(Ph3P)Cu]2Sn(SPh)6 · 3H2O (2). Single-crystal X-ray diffraction studies revealed that compounds 1a and 1b contain the same neutral butterfly-like [(Ph3P)2Cu]2SnS(edt)2 cluster, which consists of one central SnS5 dreich trigonal bipyramid sharing one vertex and two sides with two slightly distorted CuS2P2 tetrahedrons. Compound 2 has a linear [(Ph3P)Cu]2Sn(SPh)6 cluster that is composed of a central distorted SnS6 octahedron sharing two opposite planes with two slightly distorted CuS3P tetrahedrons. Compound la exhibited an emission at 568 nm (τ = 12.86 µs) in the solid state, while in CH2Cl2 solution, la exhibited a green emission at 534 nm (τ = 4.75 µs). Compound 2 showed an intense red emission at 696 nm (τ = 3.64 µs) upon excitation at 307 nm in the solid state. [ABSTRACT FROM AUTHOR]

The nickel-catalyzed reductive coupling of alkynes and imines with Et2Zn as a reductant by using electron-rich phosphine ligands has been developed, affording various allylic amines with high yields and excellent chemoselectivities. Chiral induction was also achieved in this reductive coupling reaction when a nickel catalyst containing a chiral spiro phosphine ligand was used. [ABSTRACT FROM AUTHOR]

Novel monodentate chiral spiro phosphoramidite ligands have been readily synthesized in good yields from enantiomerically pure 1,1'-spirobiindane-7,7'-diol. The new ligands were highly efficient in the copper-catalyzed conjugate addition of Et[sub 2]Zn to enones with up to 98% enantiomeric excess. [ABSTRACT FROM AUTHOR]

The article presents a study on the nickel-catalyzed asymmetric reductive coupling of 1, 3-dienes and aldehydes, which offers a useful method for preparing chiral bishomoallylic alcohols in excellent diastereoselectivity and enantioselectivity. The study examines various chiro spiro monophosphorus ligands in the nickel-catalyzed coupling reaction to produced chiral bishomoallylic alcohols. Results reveal that by using nickel complexes with a reducing agent, the high yields alcohol is obtained.