Conversion of electronic excitation into thermal energy. Effect of solvent and substituents in the 4 and 5 positions on absorption and fluorescence spectra of 1,3-diphenyl-.DELTA.2-pyrazolines

New reaction of photoaromatization of aryl- and hetarylpyrazolines

“…The 1 H NMR signals of the starting compounds and the signals of the formed pyrazoles, which were used for moni toring the photoaromatization process, are presented in Table 1. Absorption band maxima (λ) and molar absorption coefficients (ε λ /L (mol cm) -1 ) in the electronic absorption spectra of compounds 1-4 (ССl 4 The conversion values for the starting pyrazolines es timated from a decrease in the intensity of their signals in the electronic absorption spectra are also listed in Table 2. The data obtained suggest that the new photoaromatization reaction of aryl and hetarylpyrazolines can also be of preparative interest, in particular, for the oxidation of pyrazolines that are unstable when traditional (for ex ample, inorganic) oxidants are used.…”

“…Electronic absorption spectra of compound 3 in ethanol in the presence of CCl 4 (4 wt.%) before (1) and after(2)(3)(4)(5)(6)(7) irradiation with the visible light for 1 min (2) → 5 min (7…”

Organic scintillators with unusually large Stokes' shifts

“…(1) 1,3-Diphenyl-2-pyrazoline, mp 151 °C,10 Xmax 355 nm, e 2.05 X 104 (isooctane); (2) l,3,5-triphenyl-2-pyrazoline, mp 136 °C,n Xmax 357 nm, e 2.03 X 104 (isooctane); (3) l-phenyl-3-mesityl-2-pyrazoline, mp 96 °C, Xmax 292.5 nm, ( 1.40 X 104 (isooctane); (4) l-phenyl-3-(2',4',6'-trimethoxyphenyl)-2-pyrazoline, mp 150 °C, Xmax 297.5 nm, e 1.58 X 104 (isooctane); (5) l-phenyl-3-(2',6/-dimethoxyphenyl)-2-pyrazoline, mp 131 °C, Xmax 295 nm, e 1.34 X 104 (isooctane); (6) l-(2,6-dimethylphenyl)-3-(2',5,-dimethoxyphenyl)-2-pyrazoline, mp 82 °C, Xmax 339.5 nm, e 1.73 X 104 (isooctane); (7) l-(2,6-dimethylphenyl)-3-(2',6'-dimethoxyphenyl)-2-pyrazoline, mp 117 °C, Xmax 285 nm, e 0.95 X 104 (isooctane); (8) l-phenyl-3-(4'-methoxyphenyl)-2-pyrazoline, mp 142 °C,12 Xmax 358 nm, e 2.03 X 104 (benzene); (9) l-phenyl-3-(3'-methoxyphenyl)-2pyrazoline, mp 73 °C, Xmax 364 nm, e 1.99 X 104 (benzene); (10) l-phenyl-3-(2'-methoxyphenyl)-2-pyrazoline, mp 110 °C, Xmax 361 nm, e 1.65 X 104 (benzene); (11) 1-phenyl-3-(2',4'-dimethoxyphenyl)-2-pyrazoline, mp 106 °C, Xmax 356 nm, e 1.72 X 104 (benzene); (12) l-phenyl-3-(2',5'-dimethoxyphenyl)-2-pyrazoline, mp 90 °C, Xmax 368 nm, e 1.73 X 104 (benzene); (13) l-phenyl-3-(3',4'-dimethoxyphenyl)-2-pyrazoline, mp 124 °C, Xmax 360 nm, c 2.30 X 104 (benzene); (14) l-phenyl-3-(3',5'-dimethoxyphenyl)-2pyrazoline, mp 126 °C, Xmax 363.5 nm, e 2.11 X 104 (benzene); (15) l-phenyl-3-(3',4',5'-trimethoxyphenyl)-2pyrazoline, mp 135 °C, Xmax 363 nm, e 2.17 X 104 (benzene).…”