Localized surface plasmon resonance: nanostructures, bioassays and biosensing--a review

Localized surface plasmon resonance (LSPR) is an optical phenomena generated by light when it interacts with conductive nanoparticles (NPs) that are smaller than the incident wavelength. As in surface plasmon resonance, the electric field of incident light can be deposited to collectively excite electrons of a conduction band, with the result being coherent localized plasmon oscillations with a resonant frequency that strongly depends on the composition, size, geometry, dielectric environment and separation distance of NPs. This review serves to describe the physical theory of LSPR formation at the surface of nanostructures, and the potential for this optical technology to serve as a basis for the development bioassays and biosensing of high sensitivity. The benefits and challenges associated with various experimental designs of nanoparticles and detection systems, as well as creative approaches that have been developed to improve sensitivity and limits of detection are highlighted using examples from the literature.     

Si-Fluoro substituted quasisilatranes (N → Si) FYSi(OCH2CH2)2NR

The reaction of fluorosilanes XYSiF₂ (X = Y = F; X = F, Y = Ph; X = Ph, Y = Me) with diethanolamines and their O-trimethylsilyl derivatives affords novel Si-fluoro substituted quasisilatranes 3, 5 and 9. These compounds were characterized by the multinuclear NMR spectroscopy and X-ray diffraction analysis. Experimental and theoretically calculated electron density distribution functions in crystal structure of 9 have shown that the N → Si coordination bond corresponds to polar bond with pronounced ionic contribution. Calculated N → Si bond order in the compound 9 does not exceed 1/3 of the normal Si-N bond. A strong N → Si coordination bond exists in compounds 3, 5 and 9 the length of which varies in the range 1.98-2.175 Å.     

Voltammetric Sensing of Mercury and Copper Cations at Poly(EDTA‐like) Film Modified Electrode

Complexing polymer‐coated electrodes have been synthesized by oxidative electropolymerization of ethylenediamine tetra‐N‐(3‐pyrrole‐1‐yl)propylacetamide (monomer L ). The presence of four polymerizable pyrrole fragments on the same EDTA skeleton was thought to confer enhanced rigidity and controlled dimensionality to the resulting complexing materials, which were used for the electrochemical detection of Hg(II), Cu(II), Pb(II) and Cd(II) ions by means of the chemical preconcentration‐anodic stripping technique. The polyamide electrode material showed particularly a significant selectivity towards mercury ions, even in the presence of a large excess of other metal cations. Moreover, the use of imprinted polymer‐coated electrodes prepared by electropolymerization of L in the presence of metal cations turned out to significantly improve the detection limits, down to 5×10^?10 mol L^?1 for Hg(II) and Cu(II) species.     

Semisynthesis of new D-seco-C-nor-taxane derivatives containing a polyfunctionalized furanosyl or cyclopentenyl or cyclopentyl C-ring

The synthesis of new D-seco-C-nor-taxane derivatives in which the D-ring has been deleted and the C-ring has been transformed into a new pentatomic ring, i.e., the polyfunctionalized tetrahydrofuranosyl and cyclopentenyl or cyclopentyl ring, was performed starting from baccatin III derivatives. The synthetic strategy adopted took advantage of the oxetane ring opening and disconnection of the C4-C5 bond, followed by an intramolecular condensation. The formation of furanosyl or cyclopentyl rings is strictly dependent on the presence of unprotected or protected oxygen at C-7 in the starting material. The reactions proceeded with good diastereoselectivity with control of the stereochemistry of one or two stereocenters.     

1‐(9H‐Carbazol‐4‐yloxy)‐3‐{[2‐(2‐methoxyphenoxy)ethyl]amino}propan‐2‐ol hemihydrate: a carvedilol solvatomorph

In the title racemic hemihydrated solvatomorph of carvedilol (carv), C₂₄H₂₆N₂O₄·0.5H₂O, the asymmetric unit contains two independent organic moieties and one water molecule. Within this 2(carv)·H₂O unit, the molecular components are strongly linked by hydrogen bonds and the unit acts as the basic building block for the crystal structure. Interactions parallel to (10) generate hydrogen‐bonded layers which are further linked by much weaker C—H...N/O interactions. The conformations of the organic molecules, as well as the hydrogen‐bonding interactions connecting them, are compared with other related structures in the literature.     

Photochemistry of Dihydrido(hydrotris(3,5-dimethylpyrazolyl)borato)(Z-cyclooctene)iridium. Synthetic Intermediates and Mechanism of the Photochemical Formation of Hydridophenyl(hydrotris(3,5-dimethylpyrazolyl)borato)(trimethyl phosphite)iridium

The photolysis of a benzene solution of [Tp(Me2)IrH(2)(COE)], 1 (Tp(Me2) = hydrotris(3,5-dimethylpyrazolyl)borate, COE = Z-cyclooctene), in the presence of P(OMe)(3), gives the stable novel complex [Tp(Me2)IrH(C(6)H(5))(P(OMe)(3))], 3a. The photochemical syntheses of [Tp(Me2)IrH(2)(P(OMe)(3))], from 1 and P(OMe)(3) in diethyl ether, and [Tp(Me2)IrH(2)(CH(2)=CHCOO(t)Bu)], from 1 in tert-butyl acrylate, are also reported. The above reactions and several experiments using C(6)D(6) and P(OCD(3))(3) show that, in all cases, the primary photoproduct is the 16-electron, five-coordinate iridium(III) intermediate {Tp(Me2)IrH(2)}, 6a, produced by loss of COE from 1. The above experiments also allow the postulation of a mechanistic pathway for the formation of 3a which involves the oxidative addition of an aromatic C-H bond by 6a. Furthemore, the photochemical reaction of 1 in the presence of P(OCD(3))(3) shows that, under the reaction conditions used, oxidative addition of C-H bonds of P(OMe)(3) and of coordinated Tp(Me2)-ligands, presumably, to the intermediates 6a and {Tp(Me2)IrH(C(6)H(5))}, also occurs. Thus, coordinatively unsaturated iridium(III) species readily activate C-H bonds.     

catena-Poly­[[di­aqua(1,10-phen­anthroline-N,N′)­manganese(II)]-μ-(thiosulfato-O:S)] and bis(2,2′-bipyridyl-N,N′)(tetra­thionato-O,O′)manganese(II)

The structures of [Mn(S₂O₃)₂(C₁₂H₈N₂)(H₂O)₂] and [Mn(S₄O₆)(C₁₀H₈N₂)₂] are presented. The former consists of pairs of polymeric chains formed by manganese polyhedra bridged by bidentate thio­sulfate anions, which are in turn related to each other by a pseudo-twofold screw axis. The latter has crystallographic twofold symmetry and consists of monomers in which manganese displays its typical octahedral coordination provided by the bidentate bites of two bi­pyridine bases and a tetra­thionate anion, which is, to our knowledge, the first chelating tetra­thionate to be reported in the literature.     

N-propargylic beta-enaminones: common intermediates for the synthesis of polysubstituted pyrroles and pyridines.

N-Propargylic beta-enaminones have been used as common intermediates for the synthesis of polysubstituted pyrroles and pyridines. Best results have been obtained using DMSO as solvent. In the presence of Cs(2)CO(3) N-propargylic beta-enaminones are cyclized to pyrroles in good to high yields, whereas omitting bases and using CuBr leads to the selective formation of pyridines.