Molecular interactions of dibenzoylmethanatoboron difluoride (DBMBF2) in the excited and ground states in solution

Exciplexes or ground state complexes of (dibenzoylmethanato)boron difluoride and benzene derivatives? A study of their optical properties revisited via liquid state investigations and structure calculations

“…For the binary mixtures of cyclohexane and benzene containing DBMBF2, these authors did not observe any isobestic point in the spectral evolution of DBMBF2 and concluded to the absence of ground state complex in solution. They however mentioned that bright yellow crystals of DBMBF2 could become colorless when in contact with benzene vapor and recover their yellow color when exposed to air [4] and attributed this effect to the formation of a ground state complex of the two reactants, which is unstable towards oxygen. On the other hand, the same authors reported the existence of ground state complexes between DBMBF2 and various electron-rich or electron-donor compounds such as quadricyclene, trimetylamine, cyclohexadiene or trans-anethole (1-methoxy-4-propenyle benzene) in acetonitrile [4].…”

“…They however mentioned that bright yellow crystals of DBMBF2 could become colorless when in contact with benzene vapor and recover their yellow color when exposed to air [4] and attributed this effect to the formation of a ground state complex of the two reactants, which is unstable towards oxygen. On the other hand, the same authors reported the existence of ground state complexes between DBMBF2 and various electron-rich or electron-donor compounds such as quadricyclene, trimetylamine, cyclohexadiene or trans-anethole (1-methoxy-4-propenyle benzene) in acetonitrile [4]. With trans-anethole, the absorption spectrum of DBMBF2 develops a new absorption which extends beyond the longest wavelength edge from 420 to 520 nm [4].…”

“…On the other hand, the same authors reported the existence of ground state complexes between DBMBF2 and various electron-rich or electron-donor compounds such as quadricyclene, trimetylamine, cyclohexadiene or trans-anethole (1-methoxy-4-propenyle benzene) in acetonitrile [4]. With trans-anethole, the absorption spectrum of DBMBF2 develops a new absorption which extends beyond the longest wavelength edge from 420 to 520 nm [4]. This new absorption also appears, though in a lesser extent over 420-435 nm (~820 cm -1 ), in ternary systems with DBMBF2, p-xylene and ethylene diamine (EDTA) in acetonitrile [22] and was assigned to a ground state charge transfer complex of DBMBF2:p-xylene stabilized in the presence of EDTA.…”

“…Thus, (dibenzoylmethanato)boron difluoride (DBMBF2) appeared to be a good candidate, since previous works reported its ability to form highly fluorescent exciplexes with monocyclic aromatic compounds in cyclohexane [2][3][4] or acetonitrile [5] solutions. Moreover, these exciplexes were found to display fluorescence spectra which shift to the red with increasing number of methyl groups on the benzene ring [2,3].…”

[2,3-Bis(3,4-dimethoxyphenyl)-3-oxopropanalato-O,O']difluoroboron(III)

“…Similar difluoroboron complexes are intermediates in the synthesis of 1,3-diketones by boron trifluoride catalysed acylation of ketones (Sagredos, 1966). Some difluoroboron complexes of 1,3-dicarbonyl compounds exhibit interesting photochemical properties (Chow, Cheng & Johansson, 1991;. This paper describes the crystal structure of the difluoroboron complex (1).…”