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An open-cage C70 fullerene with a 13-membered ring-opening and a bis(hemiacetal) moiety was synthesized by the reaction of the corresponding open-cage C70 diketone with nucleophilic oxidizing agents. The size of the cage opening could be expanded by a subsequent dehydration reaction. Reaction of the thus obtained open-cage C70 tetraketone with elemental sulfur in the presence of tetrakis(dimethylamino)ethylene resulted in the formation of the first example of an open-cage C69S thiafuilerene with a 12-membered ring-opening. The formation of this sulfur-containing hetero-fullerene reflects a significantly different chemical reactivity for the open-cage C70 tetraketone relative to its C60 analogue. The structures of all novel compounds were unambiguously determined by single crystal X-ray diffraction analyses, in addition to which the electrochemical properties of the thiafuilerene C69S were examined and compared with those of the corresponding C70 analogue. [ABSTRACT FROM AUTHOR]

The synthesis of the methylfulvene- and phenylfulvene-annelated dihydropyrenes 10 and 22 from the cyclopentadiene-fused dihydropyrene 7 in 68% and 80% yields, respectively, are reported. However, the attempted formation of the parent fulvene-fused dihydropyrene 18 failed, both from the cyclopentadiene 7 with formaldehyde and from the cyclopentadienone 5 in Wittig-type reactions. Chemical shift data for the methylfulvene (35) and phenylfulvene (36)-fused dihydropyrenes 10 and 22 were used to estimate the reduction in the dihydropyrene nucleus aromaticity (DHPN) (relative to benzene fusion) in 10 and 22 (12-16% and 22-25% respectively). Calculations revealed that this reduction in diatropicity, contrary to the situation with benzene fusion, is not due to any aromaticity of the annelating fulvenes but instead is caused by Mills-Nixon-type effects. We conclude that methyl- and phenylfulvene are nonaromatic. An improved synthetic route to the cyclopentadienone 5 was found in an unprecedented cyclization of the trans-cinnamic acid analogue 29 in 80% yield. This enabled an X-ray structure of 5 to be obtained, for comparison to that of the saturated ketone 4. Even though crystals of 5 and 4 show diastereomeric disorder, when the average bond length data of cyclopentadienone 5 is compared with those of cyclopentenone 4 and the parent and benzo dihydropyrenes 6 and 33, it is clearly evident that 5 has the opposite bond- alternation pattern, consistent with a [4n] fused annulene. From the bond length data, cyclopentadienone has ∼87% of the effect of a benzene ring on bond alternation, which is in reasonable agreement with the previously found NMR value (78%). Structure and nucleus-independent chnmical shift calculations support these results. [ABSTRACT FROM AUTHOR]

A facile and efficient one-pot synthesis of halogenated pyridin-2(1H)-ones from a series of readily available enaminones under Vilsmeier conditions is described, and a mechanism involving sequential halogenation, formylation, and intramolecular nucleophilic cyclization is proposed. [ABSTRACT FROM AUTHOR]

There is much interest in the development of a nanoscale drug delivery system with MRI visibility to optimize the delivery efficiency and therapeutic efficacy under image guidance. Here we report on the successful fabrication of nanoscale micelles based on biodegradable poly( l-glutamic acid)- b-polylactide (PG- b-PLA) block copolymer with paramagnetic Gd 3+ions chelated to their shell. PG- b-PLA was synthesized by sequential polymerization reactions: anionic polymerization of l-lactide followed by ring-opening polymerization of benzyl glutamate N-carboxylic anhydride. The metal chelator p-aminobenzyldiethylenetriaminepenta(acetic acid) (DTPA) was readily conjugated to the side chain carboxylic acids of poly( l-glutamic acid). The resulting copolymer formed spherical micelles in aqueous solution with an average diameter of 230 nm at pH 7.4. The size of PG(DTPA)- b-PLA micelles decreased with increasing pH value. DTPA−Gd chelated to the shell layer of the micelles exhibited significantly higher spin–lattice relaxivity ( r1) than a small-molecular-weight MRI contrast agent, indicating that water molecules could readily access the Gd ions in the micelles. Because of the presence of multiple carboxylic acid functional groups in the shell layer, polymeric micelles based on biodegradable PG(DTPA−Gd)- b-PLA may be a suitable platform for the development of MRI−visible, targeted nanoscale drug delivery systems. [ABSTRACT FROM AUTHOR]

A nanotubular metal-organic framework (MOF), {[(WS4Cu4)I2(dptz)3]·DMF}n (dptz = 3,6-di(pyridin-4-yl)-1,2,4,5-tetrazine, DMF = N,N-dimethylformamide) for sensing small solvent molecules is presented. When accommodating different solvent molecules as guests, the resulting inclusion compounds exhibit different colors depending on the solvent guests, and more interestingly, the band gaps of these solvent-included complexes are in linear correlation with the polarity of the guest solvents. The solvent molecules can be sensed by the changes of UV-vis spectra of the corresponding inclusion compounds, showing a new way of signal transduction as a new kind of sensor. The sensing by such a MOF occurs within the channel-containing material rather than on the external surface. [ABSTRACT FROM AUTHOR]

A ZnO nanofiber field-effect transistor (FET) was assembled by electrospinning. Uniform ZnO nanofibers with a diameter of ∼70 nm and length over 100 μm were first synthesized by electrospinning. Using two paralleled electrodes as fiber collectors, we have successfully placed a single ZnO nanofiber on the electrodes, and an FET device was fabricated based on the assembled nanofiber. An electrical transport measurement was conducted on the FET device, showing that ZnO nanofibers are intrinsic n-type semiconductors. The present findings demonstrate that electrospinning can potentially be used as a straightforward and cost-effective means for the assembly of one-dimensional nanostuctures for building integrated nanodevices for various applications, such as transistors, sensors, diodes, and photodetectors. [ABSTRACT FROM AUTHOR]

A facile and efficient one-pot synthesis of highly substituted pyridin-2(1H)-ones was developed via Vilsmeier-Haack reactions of readily available enaminones, 2-arylamino-3-acetyl-5,6-dihydro-4H-pyrans, and a mechanism involving sequential ring-opening, haloformylation, and intramolecular nucleophilic cyclization reactions is proposed. [ABSTRACT FROM AUTHOR]

A facileand efficient one-pot synthesis of cyanoformamides wasdeveloped from readily available 1-acyl-1-carbamoyl oximes mediatedby phosphoryltrichloride (POCl3) under mild conditionsin good to high yields. [ABSTRACT FROM AUTHOR]

To explore the charge transport through metalla-aromatics building blocks, three metallacycles complexes were synthesized, and their single-molecule conductances were characterized by using mechanically controllable break junction technique. It is found that the conductance of the metallacycles junction with phosphonium group is more than 1 order of magnitude higher than that without phosphonium group. X-ray diffraction and UV--vis absorption spectroscopy suggested that the attached phosphonium group makes metallacycles more delocalized, which shortened the preferred charge transport pathway and significantly enhanced the singlemolecule conductance. This work revealed that the delocalization of metalla-aromatics could be used to switch the charge transport pathway of single-molecule junctions and thus tune the charge transport abilities significantly. [ABSTRACT FROM AUTHOR]

A novel and convenient strategy for the enantioselective synthesis of γ-lactam derivatives via N-heterocyclic carbene catalyzed formal [3 + 2] annulation of enals with 2-aminoacrylates is disclosed. This activation mode provides a complementary approach to the synthesis of various γ-lactam derivatives in good yields with excellent diastereo- and enantioselectivities. In this process, two consecutive stereocenters are constructed, and a quaternary carbon center is also established. [ABSTRACT FROM AUTHOR]

A facile and efficient synthesis of substituted dihydropyridin-2(3H)-ones is developed from penta-2,4-dienamides, in which an intramolecular C-N bond was formed through thermal 6π-azaelectrocyclization. The intramolecular hydrogen bonding-assisted cyclization reaction opens access to a variety of dihydropyridin-2(3H)-ones. [ABSTRACT FROM AUTHOR]

A facile and efficient one-pot synthesis of substituted thieno[2,3-b]pyridines has been developed. Treatment of enaminones, such as 2-acetyl-3-(dimethylamino)propenamides and -propenoates, with 2-cyanothioacetamide in the presence of potassium carbonate in N,N-dimethylformamide at 80 °C followed by addition of methylene-active bromides at room temperature provided, via intramolecular cyclization, 2,3,5,6-tetrasubstituted thieno[2,3-b]pyridines in yields of 78-90%. This protocol, which combines construction and modification of the thieno[2,3-b]pyridine ring, increases the structural diversity of the final products from readily available materials. [ABSTRACT FROM AUTHOR]

Rare earth oxides LaFe1- x Zn x O3 were synthesized by sol–gel method. The X-ray diffraction patterns (XRD) showed that LaFe1- x Zn x O3oxides are single phase with orthorhombic perovskite structure, they all show p-type semiconducting properties. Among nanocrystalline LaFe1- x Zn x O3 oxides, LaFe0.77Zn0.23O3 exhibits the highest sensitivity of 44.5 to 100 ppm formaldehyde. The optimal working temperature was found to be around 240 °C. Moreover the LaFe0.77Zn0.23O3 exhibites short response and recovery time to 100 ppm formaldehyde. The lattice parameter doesn’t agree with Vegard’s law with the increasing Zn content, and the relative density was 70–80%. [ABSTRACT FROM AUTHOR]