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Absorption and fluorescence of 8-azasteroids in the gas phase

“…Figure 1a shows the gas-phase absorption spectra of 8-azasteroid I, normalized to 1.0 as to the maximum of the optical density D of the band λ max = 296 nm, at a constant temperature T up = 270 o C and various temperatures giving the vapor pressure T low . They differ markedly from the absorption spectra of the solutions of this steroid in hexane and ethyl alcohol given in [6]. In the spectra of the above solutions, the corresponding band is shifted toward long waves (λ max = 261 and 265 nm).…”

“…The analysis of the absorption, fluorescence, fluorescence excitation spectra, and duration of the excited states of a water solution (pH 7.4) of 2,3-dimethoxy-8-azagona-1,3,5(10),13-tetraene-12,17-dion (hereinafter referred to as 8-azasteroid III) has revealed the existence of two centers emitting a long-wave and a short-wave fluorescence [5]. The fluorescence of 8-azasteroid III and 8-aza-D-homogona-1,3,5(10),13-tetraene-12,17a-dion (hereinafter referred to as 8-azasteroid I) in the neutral solvent hexane has been assigned to three centers of luminescence [6]. Assumptions on the nature of the centers have been made.…”

“…The electronic absorption spectrum of 8-azasteroid I vapors is not an exception either. In [6,10,13], these two absorption bands are associated with the π-π * transitions in the N-C=(-C=O)-C=O chromophore of the enaminodicarbonyl grouping, and the absorption with λ max ≈ 200 nm is associated with the π-π * transition in the aromatic ring.…”

Spectral and kinetic properties of fluorescence of immunoactive steroids in the gas phase

“…Based on analysis of the absorption, fluorescence, fluorescence excitation spectra and the duration of the excited states in aqueous solution (pH 7.4) for 2,3,-dimethoxy-8-azagona-1,3,5(10),13-tetraene-12,17-dione, it has been established that two centers exist that emit long-wavelength and shortwavelength fluorescence [5]. In the neutral solvent hexane, the fluorescence of 2,3-dimethoxy-8-azagona-1,3,5(10), 13-tetraene-12,17-dione and 8-aza-D-homogona-1,3,5(10),13-tetraene-12,17a-dione even appears as three luminescence centers [6].Of special interest are studies of the luminescence of 8-azasteroids in the gas phase, where there is no effect from the surrounding medium and relaxation processes appear in pure form. N. A. Brisevich et al [7] comprehensively studied a number of immunoactive compounds of the 8-azasteroid class in the gas phase, and the presence of three absorption and fluorescence centers was observed.…”

“…Based on analysis of the absorption, fluorescence, fluorescence excitation spectra and the duration of the excited states in aqueous solution (pH 7.4) for 2,3,-dimethoxy-8-azagona-1,3,5(10),13-tetraene-12,17-dione, it has been established that two centers exist that emit long-wavelength and shortwavelength fluorescence [5]. In the neutral solvent hexane, the fluorescence of 2,3-dimethoxy-8-azagona-1,3,5(10), 13-tetraene-12,17-dione and 8-aza-D-homogona-1,3,5(10),13-tetraene-12,17a-dione even appears as three luminescence centers [6].…”