| Abstract
| - Ten new strongly luminescent (quantum yield as high as 90%) pyrrolopyridazine derivatives are reported. The heterocycles are luminescent in the solid state, which indicates that there is little self-quenching in these systems. Furthermore, the optical properties of pyrrolopyridazines can be tuned by substitutions in different ring positions.
- We report here the synthesis, X-ray structures, optical and electrochemical properties,and density functional calculations for new pyrrolopyridazine derivatives. Ten stronglyluminescent heterocycles were synthesized by 1,3-dipolar cycloaddition reactions betweenalkylated pyridazine or cinnoline and naphthoquinone or dimethyl acetylenedicarboxylate(DMAD). They are benzo[f]pyridazino[6,1-a]isoindole-5,10-diones (BPID) 1−4, benzo[f]pyridazino[6,1-a]isoindole (BPI) 5, pyrrolo[1,2-b]cinnolines (PC) 6 and 7, and pyrrolo[1,2-b]pyridazines (PP) 8−10. The relative luminescence quantum yield can be as high as 90%and the heterocycles are luminescent in the solid state, which indicates that there is littleself-quenching in these systems. Furthermore, we have shown that the optical properties ofpyrrolopyridazines can be tuned by substitutions in different ring positions. An unexpectedblue shift and a large red shift with a different π conjugation system were explained byaromaticity arguments using DFT calculations and X-ray crystal structures. Electrochemicalinvestigation has shown that the redo potentials of the new heterocycles could be controlledby design. The synthesis of a series of compounds allowed detailed analysis of substituenteffects on structures, frontier orbitals, and luminescent and electrochemical properties.
|
