Photoluminescence spectra of bisphenol A based pyrazoloquinoline dimers in different solvents: Experiment and quantum chemical calculations

Paper presents measured optical absorption and photoluminescent spectra for several derivatives of bisphenol A based pyrazoloquinoline dimers (BAPQD). BAPQD dyes exhibit the first absorption band in the region of 400-415 nm, whereas their photoluminescence maxima are centered in the spectral region of 430-480 nm depending on solvent polarity. Several phenyl containing BAPQD dyes reveal rather strong solvatochromism of their photoluminescence spectra which is assumed to be related with intramolecular charge transfer. The experimental results are compared with quantum chemical calculations performed by means of semiempirical methods AM1 and PM3 in combination with molecular dynamics simulations at T = 300 K. Both methods well reproduce the overall shape of the measured spectra, however the semiempirical PM3 method exhibits much better agreement with experimental data, especially in predicting spectral position of the first absorption band (absorption threshold) and photoluminescence maxima. The obtained results may be of substantial interest for chemical engineering which deals with a designing of new efficient organic luminophores for electroluminescent applications. BAPQD dyes may be considered as potential dopants for polymer based organic diodes that emit light with different shades of blue color.