Dibenzo crown properties

Dibenzene chromium(O), physical properties, 6 528t Dibenzo-crown-6, 5 710 molecular formula, 5 713t Dibenzo[18]crown-6, 7 576 24 40, 41 Dibenzo[30]crown-10, 24 43 Dibenzocrown ethers, 24 50 Dibenzofurans, 27 152 Dibenzopyrenquinone dyes, 9 336 Dibenzothiophenes, 27 152 Dibenzoyl peroxide (BPO), 74 283-284 78 427... 

Casnati, A., Sansone, F., Dozol, J.F. 2001. New calyx[4]arene-monobenzo- and dibenzo-crown-6 as cesium selective ionophores in the radioactive waste treatment Synthesis, complexation and extraction properties. J. Inch Phenom. Macro. Chem, 41 (1-4) 193-200. 

The trimethylsilyloxy (TMSO) group is stable under the coupling conditions in acetonitrile (Table 4, number 11). After oxidative dimerization the TMS ether can be mildly hydrolyzed (H and H2O) to the phenol or converted to a dibenzofuran. 1,2-Dialkoxybenzenes have been trimerized to triphenylenes (Table 4, numbers 9, 12, and 13). The reaction product is the triphenylene radical cation, which is reduced to the final product either by zinc powder or in a flow cell consisting of a porous anode and cathode [60]. Dibenzo-crown ethers are converted by anodic oxidation to electroactive polymers. Films of these polytriphenylenes exhibit unusual doping properties 62-64]. 

In addition to PPy and PTh derivatives, numerous reports have focused on the synthesis and the properties of electroactive polymer films electrogenerated from the oxidation of crown ether-substituted benzenes [273-286] and naphthalenes [17, 287-293]. Among them, poly(dibenzo-crown ether)s and, especially, poly(dibenzo-18-crown-6) have been the most extensively studied, owing to their remarkable structural, electrochemical, and complexing properties [278-280]. Furthermore, their affinity for a large variety of cations, including heavy metal and precious metal cations, was greatly improved when they were previously undoped [281-286]. 

J.-P. Bourgeois, P. Seiler, M. Fibbioli, E. Pretsch, F. Diederich, L. Echegoyen, Cyclophane-Type Fullerene-dibenzo [18] crown-6 Conjugates with trans-1, trans-2, and trans-3 Addition Patterns Regioselective Templated Synthesis, X-ray Crystal Structure, Ionophoric Properties, and Cation-Complexation-Dependent Redox Behavior , Helv. Chim Acta 1999, 82,1572-1595. 

The physical properties of many macrocyclic polyethers and their salt complexes have been already described. - Dibenzo-18-crown-6 polyether is useful for the preparation of sharpmelting salt complexes. Dicyclohexyl-18-crown-6 polyether has the convenient property of solubilizing sodium and potassium salts in aprotic solvents, as exemplified by the formation of a toluene solution of the potassium hydroxide complex (Note 13). Crystals of potassium permanganate, potassium Lbutoxide, and potassium palladium(II) tetrachloride (PdClj + KCl) can be made to dissolve in liquid aromatic hydrocarbons merely by adding dicyclohexyl-18-crown-6 polyether. The solubilizing power of the saturated macrocyclic polyethers permits ionic reactions to occur in aprotic media. It is expected that this [)ropcrty will find practical use in catalysis, enhancement of... 

A poly (vinylchloride) membrane electrode was described for local anesthetics, based on dibenzo-24-crown-8 as the electroactive material, and di(2-ethyl)hexyl phthalate as the plasticizer [74]. It was reported that the electrode exhibited a Nemstian response to procaine, and other electrode properties were also presented. The analysis was performed at pH 6 to 6.5 vs. S.C.E., with a 0.2 M lithium acetate agar bridge. Less efficient crown ethers studied at this time were benzo-15-crown-5, dibenzo-18-crown-6, and dibenzo-30-crown-10. 

Many polypodands having terminal donor groups are also available, e.g. (39)-(41).33 These also exhibit cation complexation and phase transfer properties. KMn04 and aqueous alkali metal picrates are much more readily taken into organic phases in the presence of these podands than with dibenzo-18-crown-6.239 The KSCN complex of (39) exhibits a novel coordination geometry as all 10 donor atoms participate in coordination of the metal cation, and in order to do this the three arms wrap around the cation in a propeller-like fashion.240... 

C. Chuit, R. J. P. Corriu, G. Dubois, and C. Reye, Hybrid organic-inorganic materials. Preparation and properties of dibenzo-18-crown-6 ether-bridged polysilsesquioxanes, Chem. Commun. 723-724 (1999). 

Bazan reported the synthesis, structure, and photophysical behavior of a number of boratastilbene derivatives, which are highly emissive in the presence of donor solvents or when crown ethers are added. Extended conjugation in the bifunctional species (156) results in an absorption maximum at 396 nm, which is red-shifted by 55 nm relative to that of the monoftmctional boratastilbene. The change in the absorption and emission spectra upon addition of dibenzo-18-crown-6 suggests a distinct effect of the counterions and of aggregation phenomena on the photophysical properties of these species. 

Figure 2.27 ORTEP diagram of [Na(DB18C6)H20][Tb(L )2] with the thermal ellipsoids drawn at the 30% probability level and the hydrogen atoms removed for clarity [59]. (Reprinted with penmssion from P.N. Remya, S. Bijn, M.L.P. Reddy, A.H. Cowley and M. Findlater, ID Molecnlar ladder of the ionic complex of terbinm-4-sebacoylbis( 1 -phenyl-3-methyl-5-pyrazolonate) and sodium dibenzo-18-crown-6 synthesis, crystal structure, and photophysical properties, Inorganic Chemistry, 47, 7396-7404, 2008. 2008 American Chemical Society.)...

The type of phase-transfer catalyst plays a key role in the phase-transfer catalytic synthesis of l-bromo-1-chlorocyclopropanes, which are formed in good yields and with high selectivity if the reaction of dibromochloromethane with an alkene is performed using a crown ether (dibenzo-18-crown-6, " 3,5-di-fer/-butylbenzo-15-crown-5, " " 3,3, 5,5 -tetra-tert-butyldiben-zo-lS-crown-b ) or tetramethylammonium chloride.For the specific effect of the tetra-methylammonium chloride on the dichlorocyclopropanation of unconjugated dienes, see Section I.2.I.4.2.I.2., and some electrophilic alkenes, see Section I.2.I.4.2.I.8.2. The reason why these catalysts exhibit peculiar properties is not clear,other crown ethers behave like typical phase-transfer catalysts (Table 25). " ... 

Proton or sometimes alkali metal cations are used for countertransport of cationic or cotransport of anionic solutes because of their good transport properties. It is not the case with the coupling anions. In fact, for K+ transport by 18-crown-6 in a BLM, the anion effect differs by more than 100 [96]. Many studies of the anion effect on transport efficiency have been conducted [97-100]. The effects of anion hydration free energy, anion lipophilicity, and anion interactions with solvents have been mentioned, although anion hydration free energy seems to be the major determinant of transport efficiency. For example, transport of K+ with dibenzo-18-crown-6 as a carrier, decreased in the order picrate > PFr, > CIO > IO >... 

The (Z)-stilbene (6) does not form a rotaxane with dibenzo-24-crown-8 but, when the stilbene is isomerized (sensitized by benzil) to the E form, a pseudo-rotaxane is formed.Lewis and Crompton have reported that the photoacidity of the stilbene derivatives (7) and (8) is dependent on the position of the hydroxy group on the stilbene, and as a consequence the meta derivative undergoes isomerism.The influence of the nitrogen atoms on the photochemistry of the 1,4-distyrylbenzene analogue (9) and related compounds has been assessed. The photophysics and conformational analysis of the stilbene dimer (10) have been studied. Modelling of the optical properties of the stilbenophane (11) has been reported. 

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