RESEARCH ARTICLE
Diporphyrin tweezer for multichannel spectroscopic analysis of enantiomeric excess
. WPI Center for Materials Nanoarchitectonics, National Institute for Materials Science, Ibaraki 305-0044, Japan.. Department of Macromolecular Physics, Faculty of Mathematics and Physics, Charles University, 18000 Prague, Czech Republic.. Department of Chemistry, University of North Texas, Denton, TX 76203, USA.. Department of Advanced Materials Science, Graduate School of Frontier Sciences, The University of Tokyo, Chiba 277-8561, Japan
Accepted: 2020-01-07
Available online: 2020-01-07
Abstract
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.
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