Semiempirical characterization of substituted bis-pyrazolopyridines as new bulky electron donor–acceptor systems in their electronic ground state

Theoretical description of solvent effects on fluorescence spectra of bulky charge transfer compound DMA-DMPP

“…1 is an interesting molecule with respect to the above mentioned items. This donor᎐acceptor compound has been synthesized 17 and studied with semiempirical methods 18,19 to investigate the theories of charge transfer processes. In the course of these characterizations, Ž DMA-DMPP, with its enlarged -system the distance from the methyl carbon atom to the phenyl carbon atom on the opposite side of the compound .…”

“…The complete AM1-optimized 20 geometries of the electronical ground state given in a previous work 18 are used as starting geometries. The torsion angles about the dimethylamino-bis-pyrazolo-Ž .…”

“…1 have been found to be 81Њ and 0Њ, respectively, for the ground state structure in gas phase. The slight pyramidalization at the dimethylamino group and the twist of the two phenyl groups in the 1-and 7-position of 41Њ can be neglected 18 and will not be taken into account in further computations. The rotational angle ␣ was varied in steps of 10Њ from 90Њ down to 40Њ, whereas the twisting angle ␦ was Ž .…”

Fluorescence Properties of An Electron Acceptor Substituted Bis-Pyrazolo-Pyridine Derivative: NO2-DMPP

“…The investigated compounds NO2-DMPP and BPP were synthesized in the Department of Organic Chemistry of the Institute of Chemistry of the Pedagogical University in Kielce, Poland [1,2]. The solvents were of the highest available quality, purified by standard methods if necessary and checked for impurities by means of absorption and fluorescence spectroscopy.…”

“…Their photophysical properties can widely be varied by substitution and electron-donor substituted bis-pyrazolo-pyridines became good examples for compounds with bulky electron donor and acceptor groups. The most important example is DMA-DMPP, 4-(4'-N, N-dimethylamino-phenyl)-3,5-dimethyl-1,7-diphenyl-bis-pyrazolo-[3,4-b;4', 3'-e]-pyridine, which has been investigated experimentally and theoretically [1][2][3][4]. DMA-DMPP fluoresces with large quantum yield in nonpolar solvents.…”