Three new anilido-oxazolines, ortho-C(6)H(4)(NHAr')(4,4-dimethyl-2-oxazoline) [Ar'=2,4,6-trimethylphenyl, HNPh(TriMe)Oxa (1); 2,6-diisopropylphenyl, HNPh(DiiPr)Oxa (2); 2-methoxyphenyl, HNPh(OMe)Oxa (3)], have been prepared. Reactions of 1 or 2 with one molar equivalent of ZnEt(2) in tetrahydrofuran or hexane solution give the zinc ethyl complexes (NPh(TriMe)Oxa)ZnEt (4) and (NPh(DiiPr)Oxa)ZnEt (5). The dinuclear zinc benzyloxide complexes, [(NAr'Oxa)Zn(mu-OBn)](2), [Ar'=2,4,6-trimethylphenyl, (6); 2-methoxyphenyl, (7)], were synthesized by the reaction of 4 with one molar equivalent of benzyl alcohol in tetrahydrofuran solution (for 6) or by treatment of with 3 one molar equivalent of ZnEt(2) in tetrahydrofuran solution followed by the addition of one molar equivalent of benzyl alcohol (for 7). The molecular structures are reported for compounds 6 and 7. Their catalytic activities toward the ring opening polymerization reactions are under investigation.
The vibrational characteristics of a cantilevered double-walled carbon nanotube (DWCNT) resonator are studied using molecular dynamics (MD) simulations. The effects of temperature, nanotube type, ratio of tube length to diameter, and ratio of tube length between inner and outer walls on the resonant frequency of DWCNT with a long outer wall are evaluated. The simulated results show that DWCNTs have a very high frequency range from 10 to 250 GHz, which strongly depends on nanotube type and geometry characteristics. The magnitude of frequency of DWCNTs is inversely proportional to the nanotube mass. When the temperature is increased, the frequency of DWCNTs slightly decreases because the kinetic energy of carbon atoms increases. For the same aspect ratio, zigzag nanotubes have a higher resonant frequency than armchair nanotubes. The resonant frequency of DWCNTs increases with decreasing the ratio of tube length to diameter and increasing the ratio of tube length of inner to outer walls. Finally, DWCNT resonators are considered to have the largest THz frequency range at the bridge boundary condition.
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