An Inhibition Effect on an Intracrystalline Reaction by a Crystal Lattice: Analyses of the Chemiluminescence Reaction of 9,10-Diphenylanthracene Endoperoxide Initiated by Heating a Crystal Sample
英文:
An Inhibition Effect on an Intracrystalline Reaction by a Crystal Lattice: Analyses of the Chemiluminescence Reaction of 9,10-Diphenylanthracene Endoperoxide Initiated by Heating a Crystal Sample
Heating crystal samples of 9,10-diphenylanthracene endoperoxide (1) and its deuterated derivative (1-d10) to 200ﾂｰC led to singlet-oxygen chemiluminescence (CL) from the mixtures of the crystalline and molten states. To understand the events in the heated samples, the reactions of 1 and 1-d10 in crystals were investigated by powder X-ray diffraction measurements and thermal analyses. The used crystals of 1 and 1-d10 obtained from a mixture of Et acetate (EA) and n-hexane contained EA. Other crystals of 1 obtained by slow recrystallization with the same solvents had a solvent-free structure (form II) different from the reported one (form I). The results confirmed that the EA-containing crystals of 1 and 1-d10 were transformed to form II in two steps at 40-50 and 60-75ﾂｰC under heating at elevated temperature Thus, the crystal samples had the form-II structure soon after heating to 200ﾂｰC. The behavior of the heated samples indicates that the crystal lattice inhibits the thermal reactivity of 1. Thus, the temperature for initiating the thermolytic reaction of 1 becomes higher than the m.p. An exploration of the potential energy surface (PES) obtained by d. functional theory (DFT) calculations also supports that the deoxygenation of 1 is prevented by retaining the anthracene framework in the crystalline state. This study indicates that the method to use a CL-active compound is a powerful tool to analyze the reaction behavior in the crystalline state.
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