32 research outputs found
Self-assembly of corrole trimers in solution and at the solid-liquid interface
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V‑Shaped Bis-Coumarins: Synthesis and Optical Properties
A highly
efficient procedure for the synthesis of bis-coumarins
fused at the pyranone ring has been developed. The electron-rich phenols
reacted with esters of coumarin-3-carboxylic acids, leading to substituted
chromeno[3,4-<i>c</i>]chromene-6,7-diones. The reaction
is catalyzed by both Lewis acids and 4-dimethylaminopyridine. The
most probable mechanistic pathway involves Lewis acid catalyzed or
DMAP catalyzed transesterification, followed by intramolecular conjugate
addition of α,β-unsaturated esters to phenols and subsequent
oxidation of the initially formed intermediate. The reaction is compatible
with various functionalities such as NO<sub>2</sub>, Br, and OMe.
Not only benzene derivatives but also dihydroxynaphthalenes are reactive
in this reaction, and the structure of the product can be controlled
by adjusting the reaction conditions. Furthermore, a double addition
is possible, leading to a horseshoe-shaped system comprised of seven
conjugated rings. Compounds with four structurally unique skeletons
have been obtained and have been shown to strongly absorb in the violet,
blue, and/or green regions of the visible spectrum. Most of them display
strong greenish yellow fluorescence, which can be modulated by both
structural changes and the character of the solvents. Again, introduction
of an electron-donating group in the chromeno[3,4-<i>c</i>]chromene-6,7-diones caused a significant red shift in both the absorption
and emission maxima, and the effect became especially noteworthy in
the case of amino substituents
Synthesis and Characterization of Boron Azadipyrromethene Single-Wall Carbon Nanotube Electron Donor−Acceptor Conjugates
Spectral Properties of Highly Emissive Derivative of Coumarin with N,N-Diethylamino, Nitrile and Tiophenecarbonyl Moieties in Water-Methanol Mixture
Accessing Near-Infrared-Absorbing BF 2
Novel aza-BODIPYs with significant bathochromic shifts were designed and synthesized by installation of strong electron-withdrawing groups on the para-positions of 1,7-phenyls and electron-donating groups on the para-positions of 3,4-phenyls. These dyes show strong NIR fluorescence emissions up to 756 nm, and absorptions up to 720 nm. [Image: see text