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Improvement in growth yield of single-walled carbon nanotubes with narrow chirality distribution by pulse

Bin Xu, Toshiro Kaneko, Toshiaki Kato

《化学科学与工程前沿（英文）》 2019年第13卷第3期页码 485-492 doi: 10.1007/s11705-019-1831-2

摘要： A pulse plasma chemical vapor deposition (CVD) technique was developed for improving the growth yield of single-walled carbon nanotubes (SWNTs) with a narrow chirality distribution. The growth yield of the SWNTs could be improved by repetitive short duration pulse plasma CVD, while maintaining the initial narrow chirality distribution. Detailed growth dynamics is discussed based on a systematic investigation by changing the pulse parameters. The growth of SWNTs with a narrow chirality distribution could be controlled by the difference in the nucleation time required using catalysts comprising relatively small or large particles as the key factor. The nucleation can be controlled by adjusting the pulse on/off time ratio and the total processing time.

关键词： single-walled carbon nanotubes chirality-controlled synthesis pulse plasma chemical vapor deposition

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Diporphyrin tweezer for multichannel spectroscopic analysis of enantiomeric excess

Daniel T. Payne, Mandeep K. Chahal, Václav Březina, Whitney A. Webre, Katsuhiko Ariga, Francis D’Souza, Jan Labuta, Jonathan P. Hill

《化学科学与工程前沿（英文）》 2020年第14卷第1期页码 28-40 doi: 10.1007/s11705-019-1869-1

摘要： Chiral 1,1’-binaphthyl-linked diporphyrin ‘tweezers’ ( )- /( )- and the corresponding zinc(II) complexes ( )- /( )- were prepared as chiral host molecules, and their utility for chiral analyses (especially enantiomeric excess ( ) determinations) were evaluated. Tris(1- -dodecyl)porphyrins were used for the first time as the interacting units. Host capabilities of the diporphyrin tweezers were investigated by titrations with ( , )- and ( , )-cyclohexane-1,2-diamine (CHDA). The host molecules could be used as multichannel probes of by using UV-vis, circular dichroism (CD), fluorescence emission and H nuclear magnetic resonance ( H-NMR) methods. Chiral configurations could also be differentiated using CD or H-NMR spectroscopy. All three optical techniques give good resolution of with reasonable sensitivity considering the low concentrations used (ca. 10 mol·L ). The determination of CHDA enantiomers using NMR spectroscopy is also possible because of the reasonably well separated resonances in the case of ( , )- and ( , )-CHDA. Non-metallated ( )- /( )- hosts could not be used to detect chiral information in a strongly acidic chiral guest. This work demonstrates the utility of 1,1’-binapthyl-linked chiral hosts for chiral analysis of ditopically interacting enantiomers.

关键词： porphyrin dimer chirality enantiomeric excess CD fluorescence