Investigations of triplet excimer of naphthalenophane by emission and transient absorption measurements in solution

By using syn-[3.4](1,5)naphthalenophane (44NPP) whose naphthalene rings are in a parallel form, photophysical and photochemical properties of naphthalene triplet excimer are reported. 34NPP emits only excimer fluorescence at 295 and 77 K, and phosphorescence was absent even at 77 K. Based on the transient absorption spectra of 34NPP, it is shown that the excimeric triplet state of 34NPP is formed without the locally excited triplet at 295 and 77 K. The triplet excimer of 34NPP is produced via intersystem crossing from the singlet excimer state with a rate of 1.4×107 s−1 at 295 K. The triplet excimer in a parallel configuration is shown to be non-phosphorescent.