The atropisomeric properties of N-alkyl and N-aryl 4-substituted 5H-dibenz[b,f ]azepines were investigated. The N-alkylation and N-arylation of 4-Cl or 4-Me substituted compounds was performed; however, none of the atropisomers produced were separated by chiral HPLC. Notably, we observed that the rotation of the four axes (ax. 1-4) in the 4-substituted 5H-dibenz[b,f ]azepine structure is so rapid that N-alkylation or N-arylation is not sufficient to freeze it at room temperature. Additionally, the X-ray crystal structures of N-aryl compounds 13b and 14a indicated that the N atom in the triphenyl amine moiety in their structures shows sp 2 -like property.
In this study, a design of a regenerative damper for low-frequency applications, such as vibration suppression of long period infrastructures, tanks and pipings, and maritime and offshore structures, is presented. In this design, the low-frequency input motion to the damper is transformed to a high-frequency motion of piezoelectric cantilever oscillators by mechanical switching, so that the input work into the damper during the loading phase induces the free vibration of the oscillator. The mechanical energy of the free vibration is converted to the electric energy by a high efficiency interfacing circuit. In this paper, a conceptual model is mathematically formulated and tested to evaluate the potential performance of the proposed idea. It is shown that the combination of the mechanical switching with a circuit switching interface technique can expect the enhancement of the energy regeneration efficiency up to 30%.
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