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Protonation behaviour of 2-phenyl-1,3-diazaazulene derivatives

Authors :
Zhi-Xin Guo
Yujun Qin
Dan-Ling Rao
Pu Zhang
Peili Sun
Source :
Tetrahedron. 74:731-739
Publication Year :
2018
Publisher :
Elsevier BV, 2018.

Abstract

Three 2-phenyl-1,3-diazaazulene derivatives were synthesized and their protonation behaviours were investigated systematically via UV–vis absorption titration and 1H NMR titration, as well as theoretical calculations. One of them exhibited a monoprotonation process while the others displayed prominent halochromic diprotonation responses. Interestingly, upon protonation of 2-phenyl-1,3-diazaazulene derivatives, the coplanarity and conjugation of the 16-π-conjugated backbones were well kept, while the electronic structures were controllably adjusted. The response mechanism of 1,3-diazaazulene derivatives towards acid is through the attachment of acid proton to the nitrogen atom in the diazaazulene ring, resulting in the change of the hybridization of protonated-N from sp2 to sp3, which differed from that of the well-known azulene (analogue of 1,3-diazaazulene, protonation at carbon atom). This work would provide a new insight into the protonation research of the organic functional molecules.

Details

ISSN :
00404020
Volume :
74
Database :
OpenAIRE
Journal :
Tetrahedron
Accession number :
edsair.doi...........5b395f36ee189cff4fc1ab3275fcb8d5
Full Text :
https://doi.org/10.1016/j.tet.2017.12.051