Quinone group containing

Fluorescent redox switches based on compounds with electron acceptors and fluorophores have been also reported. For instance, by making use of the quinone/ hydroquinone redox couple a redox-responsive fluorescence switch can be established with molecule 19 containing a ruthenium tris(bpy) (bpy = 2,2 -bipyridine) complex.29 Within molecule 19, the excited state of the ruthenium center, that is, the triplet metal-to-ligand charge transfer (MLCT) state, is effectively quenched by electron transfer to the quinone group. When the quinone is reduced to the hydroquinone either chemically or electrochemically, luminescence is emitted from the ruthenium center in molecule 19. Similarly, molecule 20, a ruthenium (II) complex withhydroquinone-functionalized 2,2 6, 2"-terpyridine (tpy) and (4 -phenylethynyl-2,2 6, 2"- terpyridine) as ligands, also works as a redox fluorescence switch.30... 

As all the organic polymers tried for this reaction may be assumed to contain quinone groups, the most probable explanation for their activity is the capability of groups of this kind to undergo reversible oxidation/reduction. 

To prove that the quinonic structure is responsible for dehydrogenation activity in organic polymers, two polymers were compared, similar in structure, but one containing quinonic groups and the other without 96). 

It is important to appreciate that these ditopic macrocycles contain a polyether moiety on one side and present a diamido motif on the other. Addition of a charged pyridinium cation to the substrate-free form of these macrocycles then generates a highly efficient receptor for chloride, presumably as the result of both template-induced organization and electrostatic effects. The further incorporation of hydro-quinone groups and polyether functionalities into the cyclic framework presumably contributes to the stabilization of the cationic pyridinium component within the final interpenetrated structure. Interestingly, while titration of the pyridinium cation building block alone revealed a preference for oxoanions, the final receptor-anion... 

The chromophore theory originated with Bernthsen and Friedlander, who proposed, simultaneously and independently, that the colorless form of phenolphthalein present in acid solutions possessed a lactone structure, and that the red salt formed by alkalis contained a chromophore quinone group. Hence the color transformation was accompanied by a change in constitution. Later, Hantzsch and his students extended the theory, and ascertained that unless a structural change occurred, the color remained the same. They stated, however, that in many cases the demonstration of a structural change was too difficult to be decisive. 

Imsgard et al. [62] noted that spruce milled-wood lignin contained, in addition to 0.7 quinone groups, 1% catechol groups. Lignin-like catechols form complexes with ferric ions that have a broad absorption from 470-700 nm with around 560-800 nm and s in the range of 1-2 x 10 L mol cm. ... 

It can be seen that the only apparent similarity in these structures is that all of them contain a quinone group. The number of such compounds that has been studied by advanced techniques of pulse radiolysis and flash photolysis is increasing rapidly over nearly last three decades. Around the main objectives cited above, a large number of studies [7-12] have simply been made on the structure-property relationship. 

Dye Intermediate, n.o.s. A cyclic compound, containing an amino, hydroxy, sulfonic acid, or quinone group or a combination of these groups used in the manufacture of dyes. ICAO A2... 

Cell Adhesion and Detachment, Fig. 5 Release of cells from a surface coated with self-assembled mono-layers coupled to the RGD peptide. The left side of the surface has a monolayer that is not electroactive, and the right side of the surface has a monolayer that contains the electroactive quinone group. Fibroblast cells initially adhere on both sides of the surface (a). Upon the application of an electrical potential, the quinone groups are converted to lactone groups and release the RGD groups along with the cells attached to these groups (b) (Taken from Yeo et al. [3])... 

The mean functionality of the monomer, however, can also be smaller than the sum of the functionalities of the groups contained in the monomer molecule. For example, in the Diels-Alder polymerization of 2-vinyl butadiene with p-quinone, the total functionality of the 2-vinyl butadiene in chain formation is two per unbranched macromolecule ... 

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