Issue 14, 2023

N-Cyanomethylmethanimine tethered anthracene dimer: concise synthesis, conformational properties and photoinduced configurational isomerization

Abstract

A new type of anthracene dimer was synthesized through an efficient approach involving the Strecker reaction and self-condensation of α-aminonitrile. This anthracene dimer contains a flexible N-cyanomethylmethanimine (CMMI) bridge, in which the imine C[double bond, length as m-dash]N double bond may adopt either a cis or a trans configuration. The imine condensation reaction yielded a trans product, which has been proven by single crystal X-ray diffraction (XRD) analysis. Solution-phase NMR analysis in conjunction with density functional theory (DFT) calculations has confirmed that configurational isomerization of the C[double bond, length as m-dash]N bond in this anthracene dimer needs to overcome relatively high energy barriers under thermal conditions and thus is difficult to achieve. Photoirradiation, on the other hand, can facilitate the trans-to-cis isomerization of the C[double bond, length as m-dash]N bond, and the resulting cis isomer shows closely engaged intramolecular π–π-stacking between the two anthracene moieties. Detailed photophysical properties of the anthracene dimer as well as related phenylene-CMMI-anthracene analogues were investigated by UV-Vis absorption and fluorescence spectroscopic analyses. The mechanisms for the selective formation of the trans C[double bond, length as m-dash]N double bond during the imine condensation and the reactivity of the CMMI-linked anthracene dimer towards fluoride anions were examined and discussed.

Graphical abstract: N-Cyanomethylmethanimine tethered anthracene dimer: concise synthesis, conformational properties and photoinduced configurational isomerization

Supplementary files

Article information

Article type
Paper
Submitted
27 Dec 2022
Accepted
06 Mar 2023
First published
06 Mar 2023

New J. Chem., 2023,47, 6708-6720

N-Cyanomethylmethanimine tethered anthracene dimer: concise synthesis, conformational properties and photoinduced configurational isomerization

E. A. Younes, N. Aljaar, M. F. Abdollahi, M. Shtaiwi, M. J. Issa and Y. Zhao, New J. Chem., 2023, 47, 6708 DOI: 10.1039/D2NJ06320D

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