Differential properties and effects of fluorescent carbon nanoparticles towards intestinal theranostics.

Given the potential applications of fluorescent carbon nanoparticles in biomedicine, the relationship between their chemical structure, optical properties and biocompatibility has to be investigated in detail. In this work, different types of fluorescent carbon nanoparticles are synthesized by acid treatment, sonochemical treatment, electrochemical cleavage and polycondensation. The particle size ranges from 1 to 6 nm, depending on the synthesis method. Nanoparticles that were prepared by acid or sonochemical treatments from graphite keep a crystalline core and can be classified as graphene quantum dots. The electrochemically produced nanoparticles do not clearly show the graphene core, but it is made of heterogeneous aromatic structures with limited size. The polycondensation nanoparticles do not have CC double bonds. The type of functional groups on the carbon backbone and the optical properties, both absorbance and photoluminescence, strongly depend on the nanoparticle origin. The selected types of nanoparticles are compatible with human intestinal cells, while three of them also show activity against colon cancer cells. The widely different properties of the nanoparticle types need to be considered for their use as diagnosis markers and therapeutic vehicles, specifically in the digestive system.

Ru-Catalysed synthesis of fused heterocycle-pyridinones and -pyrones.

The synthesis of fused heterocycle-pyridinones has been achieved by oxidative coupling of N-unprotected primary heterocycle-amides with internal alkynes. The reaction, which is catalysed by Ru(ii) and assisted by Cu(ii), takes place through C-H and N-H bond activation of the heterocyclic unit. The scope of the reaction includes a variety of alkynes, electron-rich thiophenes, furans and pyrroles, and even electron-poor pyridines. The reaction is fully regioselective with respect to the position of the C-H bond activation due to the directing effect of the amide group. In the same way, the synthesis of fused heterocycle-pyrones (isocoumarins) has been developed by Ru-catalysed oxidative coupling of heterocyclic carboxylic acids and internal alkynes. The reaction involves C-H and O-H bond activation. This reaction also has a broad scope, from electron-rich thiophenes, furans and pyrroles to electron-deficient pyridines and quinolines.

Strong 1,4-P-O intramolecular interactions as a source of conformational preferences in alpha-stabilized phosphorus ylides.

For the first time, the existence of a strong intramolecular 1,4-interaction between the phosphorus atom and the oxygen atom in alpha-keto-stabilized ylides has been demonstrated by means of theoretical calculations. This interaction has a notable influence on the conformational preferences and rotational barriers of alpha-stabilized phosphorus ylides and bis-ylides.

Saccharinate as a versatile polyfunctional ligand. Four distinct coordination modes, misdirected valence, and a dominant aggregate structure from a single reaction system.

The reaction system consisting of copper, saccharinate, and the auxiliary ligands H(2)O, PPh(3), and NH(3) produces a sequence of compounds in which saccharinate is coordinated to copper in four distinct manners. The complex trans-[Cu(sacch)(2)(H(2)O)(4)] (2) (produced by thermal dehydration of trans-[Cu(sacch)(2)(H(2)O)(4)].2H(2)O (1)) reacts with triphenylphosphine in CH(2)Cl(2) to produce any or all of three Cu(I) complexes, depending upon conditions. The three Cu(I) compounds are Cu(sacch)(PPh(3))(3) (3), in which saccharinate binds to copper through the carbonyl group of the ligand, Cu(sacch)(PPh(3))(2) (4), in which sacch binds to Cu through its charge-bearing nitrogen atom; and [Cu(sacch)(PPh(3))](2) (5), a dinuclear complex in which saccharinate bridges two Cu centers through its imidate nitrogen and carbonyl oxygen atoms. Complexes 3-5 can be isolated individually, although in solution they exist in a complex equilibrium which has been examined by NMR spectroscopy. Each of the three Cu(I) products reacts with NH(3) in CH(2)Cl(2) solution to produce trans-[Cu(sacch)(2)(NH(3))(4)] (6), an unstable Cu(II) complex that exhibits misdirected valence at the Cu-N(sacch) bond. Complex 6 evolves spontaneously to [Cu(sacch)(NH(3))(4)](sacch).H(2)O (7), which in the solid state is dominated by a supramolecular aggregate of two formula units, linked by hydrogen bonding in which the water molecule plays a central role. Alternative pathways exist to several of the products. The X-ray crystal structure analyses of 3-7 are reported and establish the coordination modes of saccharinate, the misdirected valence in 6, and the supramolecular aggregation in 7. The structure analysis of 7 by single-crystal neutron diffraction is reported and together with the previously reported neutron structure analysis of 1 establishes the substitution of the auxiliary ligand H(2)O by NH(3) in the Cu(II) products.