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Diporphyrin tweezer for multichannel spectroscopic analysis of enantiomeric excess
Ist Teil von
Frontiers of Chemical Science and Engineering, 2020-02, Vol.14 (1), p.28-40
Ort / Verlag
Beijing: Higher Education Press
Erscheinungsjahr
2020
Link zum Volltext
Quelle
SpringerLink (Online service)
Beschreibungen/Notizen
Chiral 1,1'-binaphthyl-linked diporphyrin 'tweezers' ( R)- 1/( S)- 1 and the corresponding zinc(II) complexes ( R)- 2/( S)- 2 were prepared as chiral host molecules, and their utility for chiral analyses (especially enantiomeric excess ( ee) determinations) were evaluated. Tris(1- n-dodecyl)porphyrins were used for the first time as the interacting units. Host capabilities of the diporphyrin tweezers were investigated by titrations with ( R, R)- and ( S, S)-cyclohexane-1,2-diamine (CHDA). The host molecules could be used as multichannel probes of ee by using UV-vis, circular dichroism (CD), fluorescence emission and 1H nuclear magnetic resonance ( 1H-NMR) methods. Chiral configurations could also be differentiated using CD or 1H-NMR spectroscopy. All three optical techniques give good resolution of ee with reasonable sensitivity considering the low concentrations used (ca. 10 −6 mol·L −1). The ee determination of CHDA enantiomers using NMR spectroscopy is also possible because of the reasonably well separated resonances in the case of ( R, R)- and ( S, S)-CHDA. Non-metallated ( R)- 1/( S)- 1 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.