A promising application of carboxymethyl cellulose (CMC), which is a congener of the cellulose family, as a supporting material for a variety of imidazolium based ionic liquid catalysts in the chemical fixation of CO 2 has been studied here. The ionic liquids immobilized on the carboxymethyl cellulose (CMIL) showed high catalytic activity and selectivity in the cycloaddition of carbon dioxide with propylene oxide (PO) resulting in propylene carbonate (PC) under mild and solvent free conditions. A new pathway was proposed based on the density functional theory (DFT) calculations performed at the B3LYP/6-31G (d,p) level, where the carboxyl and hydroxyl moieties on the CMC were found to act synergistically with the halide ions to eventuate in the cycloaddition reaction. The carboxyl group entities on the carboxymethyl cellulose support supposedly stabilize the product complex via strong hydrogen bonds, thereby promoting the reaction. The catalyst system also displayed good reusability. † Electronic supplementary information (ESI) available. See

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Model adducts to be used in the identification of biologically formed adducts were synthesized by reaction of fjord-region dibenzo[a,l]pyrene 11,12-dihydrodiol 13,14-epoxides (DB[a,l]PDE) and deoxyadenosine (dA). The (+/-)-anti-DB[a,l]PDE was reacted with dA in dimethylformamide at 100 degrees C for 30 min to give four DB[a, l]PDE-14-N(6)dA adducts: (-)-anti-trans (26%), (+)-anti-trans (26%), (-)-anti-cis (17%), and (+)-anti-cis (17%). The (+/-)-syn-DB[a,l]PDE was reacted with dA under the same conditions to yield four DB[a, l]PDE-14-N(6)dA adducts and one N7Ade adduct: (+)-syn-cis (19%), (+)-syn-trans (13%), (-)-syn-cis (19%), (-)-syn-trans (13%), and (+/-)-syn-DB[a,l]PDE-14-N7Ade (22%). The structures of the eight stereoisomers of DB[a,l]PDE-14-N(6)dA were unequivocally assigned by reacting optically pure (-)-anti-DB[a,l]PDE and (+)-syn-DB[a,l]PDE with dA and by a combination of NMR, circular dichroism, and fast atom bombardment mass spectrometry. Reactions at 100 degrees C yielded mainly the trans-opened adducts at the benzylic C-14 position for both (+/-)-anti-DB[a,l]PDE and (-)-anti-DB[a,l]PDE, whereas (+/-)-syn-DB[a,l]PDE and (+)-syn-DB[a,l]PDE afforded mainly cis-opened adducts. At room temperature, however, only trans-opened adducts were obtained from (+/-)-anti-DB[a,l]PDE and only cis-opened adducts from (+/-)-syn-DB[a,l]PDE. Steric hindrance created by the fjord region may be an important factor for the stereoselectivity observed at room temperature.

A series of cationic iridium complexes (1−6) were synthesized using alkylated imidazole-based ancillary ligands, and the photophysical and electrochemical properties of these complexes were subsequently evaluated. Lightemitting electrochemical cells (LECs) were fabricated from these complexes, and the effects of the alkyl chain length on the electroluminescent properties of the devices were investigated. The LECs based on these complexes resulted in yellow emission (complexes 1, 3, and 5) and green emission (complexes 2, 4, and 6) with Commission Internationale de L'Eclairage (CIE) coordinates of (0.49, 0.50) and (0.33, 0.59), respectively. Our results indicate that the luminance and efficiency of the LECs can consistently be enhanced by increasing the alkyl chain length of the iridium complexes as a result of suppressed intermolecular interaction and self-quenching. Subsequently, a high luminance of 7309 cd m −2 and current efficiency of 3.85 cd A −1 were achieved for the LECs based on complex 5.

The neutral counterparts of the C,H,O+ isomers CH30+(H)CH,, CH,CH,OH, + and C2H, * * * H .**OH, were studied by neutralization-reionization mass spectrometry. Protonated dimethyl ether and its --O(D)+ analogue were produced by protonation (deuteration) of dimethyl ether and also generated as a fragment ion from (labeled) ionized CH,OCH,CH(OH)CH, by loss of CH,CO'. It was observed that the dissociation characteristics of the ions and the stability of their neutral counterpart depended on the internal energy of the protonated ether ions. Stable neutral CH,O(H)CH, was only produced from energy-rich ions. The classical protonated ethanol ion CH,CH,OH, + (a) was produced a! threshold by the loss of CH,CO' from ionized butane-2,3-diol. Mixtures of a with the non-classical ion C,H,.**H.*-OH, (b) were produced by reaction of C,HS+ ions with H,O. As for the protonated ether, only high-energy a and/or b ions yielded stable hypervalent radicals. It is suggested that the stable C,H70 radicals are Rydberg states.