Under the investigation of the mechanism of chemiluminescence which occurred when lophine (2, 4, 5-triphenyl-imidazole) was oxidized in an ethanol solution of potassium hydroxide with an oxidizing agent, there was isolated a new phototropic substance which was considerd to be an imidazole derivative. To the solution of lophine (1 g.) in a solution of potassium hydroxide (12g.) in ethanol (100 cc.), 450 cc. of 1% potassium ferricyanide aqueous solution was added during a period of 1.5 hr. with stirring by a stream of oxygen at room temperature. The violet color of the solution, which initially appeared, gradually disappeared and white precipitates, having a tinge of pale violet, separated out. When the oxidation was carried out in a dark place, a weak greenish blue chemiluminescence was observed. The precipitates were filtered and then washed with water repeatedly until the washing showed no reaction of ferricyanide ion.The precipitates, dried in vacuo (0.9g.) were dissolved in benzene to yield a deep red violet solution.When the solution was concentrated under reduced pressure, a lemon yellow crystalline substance separated out. It was recrystallized from ethanol as lemon yellow

A stable free radical, 2,4,5-triphenylimidazolyl, which was produced by oxidation of 2,4,5-triphenylimidazole, dimerizes to yield two dimers, a photochromic dimer and a piezochromic dimer. The photochromic dimer shows thermochromism and photochromism at temperatures between −196°C and about 200°C both in solution and in solid state. The piezochromic dimer shows piezochromism in solid state and thermochromism both in solution and in solid state. Spectro-scopic and kinetic studies showed that photochromism, thermochromism and piezochromism are caused by radical dissociation of the dimers of triphenylimidazolyl on irradiation, heating and grinding. Dimers of substituted triphenylimidazolyl also showed these phenomena which are due to the same mechanism as that of the dimers of triphenylimidazolyl.

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Lucigenin (10,10′-dimethyl-9,9′-biacridinium dinitrate, DBA2+2NO3−) was found to be a CT complex between DBA2+ and NO3−. In the reaction of lucigenin with several nucleophiles in the absence of molecular oxygen or oxidizing agents the following four types of products were obtained, depending upon the relative power of the nucleophiles to donate electrons to DBA2+: (1) salts of DBA2+ (DBA2+2X−) which are the CT complex between DBA2+ and the nucleophiles, such as Cl−, Br−, SCN−, and I−, (2) the cation radical DBA\underset.+ produced by one-electron transfer from nucleophiles, such as C6H5COCH2− and CH3COCH2−, to DBA2+, (3) the biradical DBA\underset.2 produced by two-electron transfer from nucleophiles such as OH−, CN−, CCl3−, and C6H5S− and (4) 10,10′-dimethyl-9,9′-bi(dihydroacridinylidene) produced from DBA\underset.2. Only the nucleophiles of (3), which produced DBA\underset.2 brought about the luminescence of lucigenin in the presence of oxygen, and DBA\underset.2 also showed luminescence in organic solvents in the presence of oxygen. From these findings it was concluded that the first process of the chemiluminescent reaction of lucigenin was the electron transfer reduction of DBA2+ by the nucleophiles to form the biradical DBA\underset.2.