Blue fluorescent zinc(II) complexes based on tunable imidazo[1,5-a]pyridines

Herein, we investigate the photophysical features of new zinc(II) chlorido complexes containing fluorescent 1,3-substituted imidazo[1,5-a]pyridines as ligands. The derivatives introduce electron-donating or electron-withdrawing moieties in position 3 on the ligand skeleton. The obtained compounds have been characterized with different spectroscopic techniques, their structure has been defined by single-crystal X-ray diffraction and mass spectrometry and their optical properties have been discussed in relation to the chemical structure. The comparison between the emission spectra of the free ligands and of the corresponding zinc(II) chlorido complexes shows an intense hypsochromic shift, due to the modification of the ligands conformation upon metal coordination, and a significant increase of the quantum yield after complexation.