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Concise Synthesis and Two‐Photon‐Excited Deep‐Blue Emission of 1,8‐Diazapyrenes
Author(s) -
He Tingchao,
Too Pei Chui,
Chen Rui,
Chiba Shunsuke,
Sun Handong
Publication year - 2012
Publication title -
chemistry – an asian journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.18
H-Index - 106
eISSN - 1861-471X
pISSN - 1861-4728
DOI - 10.1002/asia.201200192
Subject(s) - excited state , photochemistry , chromophore , fluorescence , conjugated system , intramolecular force , absorption (acoustics) , molecule , chemistry , electroluminescence , materials science , atomic physics , physics , optics , stereochemistry , organic chemistry , polymer , layer (electronics) , composite material
Efficient violet–blue‐emitting molecules are especially useful for applications in full‐color displays, solid‐state lighting, as well as in two‐photon absorption (TPA) excited frequency‐upconverted violet–blue lasing. However, the reported violet–blue‐emitting molecules generally possess small TPA cross sections. In this work, new 1,8‐diazapyrenes derivatives 3 with blue two‐photon‐excited fluorescence emission were concisely synthesized by the coupling reaction of readily available 1,4‐naphthoquinone O , O ‐diacetyl dioxime ( 1 ) with internal alkynes 2 under the [{RhCl 2 Cp*} 2 ]–Cu(OAc) 2 (Cp*=pentamethylcyclopentadienyl ligand) bimetallic catalytic system. Elongation of the π‐conjugated length of 1,8‐diazapyrenes 3 led to the increase of TPA cross sections without the expense of a redshift of the emission wavelength, probably due to the rigid planar structure of chromophores. It is especially noteworthy that 2,3,6,7‐tetra(4‐bromophenyl)‐1,8‐diazapyrene ( 3c ) has a larger TPA cross section than those of other molecules reported so far. These experimental results are explained in terms of the effects of extension of the π‐conjugated system, intramolecular charge transfer , and reduced detuning energy.