US EPA

3830431 

Journal Article 

Synthesis, Structure, and Spectroscopy of Green to Yellow Fluorescent Divinylbipyrroles 

Kawano, Reo; Kato, T; Fukuda, Ryu; Okawara, T; Takehara, K; Nagamura, T 

2016 

ChemistrySelect
ISSN: 2365-6549 

1 

14 

4144-4151 

10.1002/slct.201600843 

WOS:000395422000001 

Green and yellow luminescent 4,4'-dimethyl-5,5'-divinyl-2,2'-bi-pyrrole derivatives bearing ester and amide were synthesized from blue luminescent 5,5'-diformyl-4,4'-dimethyl-2,2'-bipyrrole and diethyl malonate, 2,2-dimethyl-1,3-dioxane-4,6-dione, 1,3-dimethylbarbituric acid, and 1,3-dihexylbarbituric acid under Knoevenagel condensation conditions. All the synthesized products clearly showed a red-shifted pi-pi* transition absorption band in the visible region compared with the starting bipyrrole. Single-crystal X-ray diffraction analysis and H-1 nuclear magnetic resonance (NMR) spectroscopy revealed that the carbonyl moiety interacts with NH to form an intramolecular hydrogen-bonding. Out of the synthesized compounds, a Knoevenagel adduct of 1,3-dimethylbarbituric acid showed fluorescence at 578 nm with an 88% quantum efficiency in dichloromethane, which is the highest value for the bipyrrole system. The highly efficient yellow photoluminescence can be attributed to the rigid molecular structure of the compound. Density Functional Theory (DFT) calculation revealed that the rigid and planar structure is essential for the bathochromically shifted absorption and high photoluminescence quantum yield. 

Bipyrrole; Crystal structure; Density Functional Theory calculations; Knoevenagel condensation; Photophysical properties