A new series of monosubstituted styryl- and bistyryl-2,2'-bipyridine luminophores (compounds 16-23) have been synthesized via Horner-Wadsworth-Emmons reaction involving a monophosphonate and donor aromatic aldehydes. In the title chromophores, the amino donors are varied between acyclic and cyclic while the alkoxy donors are varied in terms of their number and position. The absorption maxima of these chromophores shift predominantly due to intramolecular charge transfer (ICT) between different donor and acceptor moieties. The title donor-acceptor molecules exhibit intense fluorescence in solution at room temperature, and their emissive behavior has been found to be highly sensitive to solvent polarity. The fluorescence spectra and quantum yields of all the chromophores were recorded in four different solvent media, and the chromophores 16, 17, 19, and 21 exhibit fluorescence in the solid state too. The influence of the nature and position of the donor functionalities in the conjugated backbone of the bipyridine moiety on the electronic absorption properties of the title chromophores (16-23) has been demonstrated, which has further been corroborated by DFT and TD-DFT computation both in gas phase and in solution phase. The crystal structure of compound 18 has been described as a representative member of the family (16-23).
We report photo-isomerization of malonaldehyde in its electronic ground state (S0), mediated by coupled 1nπ*(S1)–1ππ*(S2) excited electronic states, accomplished with the aid of optimally designed ultraviolet (UV)-laser pulses.
A low-lying resonance in FeCN− anion was identified through abrupt changes in the spectral dependence of the photoelectron angular distribution. Non-Franck–Condon transitions from the resonance to the neutral FeCN (4Δ), and the corresponding photoelectron angular distributions revealed that the resonance is a dipole scattering state. Significant thermionic electron emission was observed in the resonant photoelectron spectra, indicating a strong coupling of the resonance with the ground state of this triatomic anion and its competition over autodetachment. This low-lying resonance is identified to be an efficient pathway for the formation of FeCN− anion in the outer envelope of IRC+10216. The results in general reveal formation pathways in space for anions with low-lying resonances and large permanent dipole moment.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.