Jet spectroscopy of buckybowl: Electronic and vibrational structures in the S and S1 states of triphenylene and sumanene

Abstract

Sumanene is a typical buckybowl molecule with C3v symmetry. We observed a fluorescence excitation spectrum and a dispersed fluorescence spectrum of sumanene in a supersonic jet. Bowl effects were clarified by comparing the spectra with those of triphenylene (D3h symmetry), which is a planar prototype of nonplanar sumanene. The S1 (1)A1 ← S0 (1)A1 transition is symmetry allowed. We found the 0(0)(0) band in the fluorescence excitation spectrum at 357.78 nm; this band was missing in the forbidden S1 (1)A1(') ← S0 (1)A1(') transition of triphenylene. The transition moment was shown to be along the oblate symmetric top axis (out of plane) by the observed rotational contour. A large number of vibronic bands were observed, unlike in triphenylene. Some were considered to be out-of-plane vibrational modes, which lead to a bowl-to-bowl inversion reaction assisted by in-plane vibrations. We found that the vibronic bands were markedly weak in the high energy region of triphenylene-d12. This indicates that the fluorescence quantum yield is very low at the high vibrational levels in the S1 state due to the rapid radiationless transition. The main process is considered to be internal conversion to the S0 state. The nonplanar structural distortion may also enhance radiationless transitions. We could not, however, observe weakening of the vibronic bands in the fluorescence excitation spectrum of sumanene.

Supersonic Jet Spectroscopy and Density Functional Theory Study of Isomeric Diazines: 1,4- and 1,8-Diazatriphenylene. Why Do They Differ So Deeply?

“…These bands were observed in fluorescence of 1,8-DAT in Shpolskii matrix at 229 and 414 cm –1 . Fluorescence bands observed in the DF spectrum of 1,8-DAT and assigned above to the fully symmetrical ip modes were also observed in the jet-cooled spectrum of parent triphenylene, indicating weak impact of heteroatoms on the spectrally active modes …”

“…Several bands observed in the LIF spectrum of 1,4-DAT in the 0−500 cm −1 region are not present in LIF of the parent molecule, triphenylene (TPH). 43 Two very pronounced vibrations at 113 and 209 cm −1 are the most intense bands in the spectrum, and contrary to the situation in 1,8-DAT, several bands of medium intensity are present in the region between 250 and 400 cm −1 . Harmonic frequency calculations predict five fundamental modes below 220 cm −1 , and all of them are of oop type with respect to the molecular framework of 1,4-DAT.…”

“…All spectrally active vibrations observed for the complexes above 200 cm −1 have their correspondence in the spectrum of parent TPH. 43 Calculated structures of the 1:1 complexes in S 0 (Figure S3) show a practically planar 1,4-DAT framework. One can notice an asymmetric broadening of the resonance DF band of the 1,4-DAT complexes in comparison to that of the bare molecule (Figure S7).…”

“…29 Fluorescence bands observed in the DF spectrum of 1,8-DAT and assigned above to the fully symmetrical ip modes were also observed in the jetcooled spectrum of parent triphenylene, indicating weak impact of heteroatoms on the spectrally active modes. 43 Figure 7 shows the DF spectra of bare 1,4-DAT and its 1:1 complexes with water and methanol upon excitation at their (0−0) transitions. The spectrum of the bare molecule (Figure 7A) has a much richer structure and very different intensity pattern, when compared to that observed for the 1,8-isomer.…”

Сверхизлучение и синтез наночастиц металла в полистирольном композите с многоспиновыми комплексами Eu при быстром одноосном сдавливании

“…Высокоспиновые элементоорганические магнетики можно использовать для создания электрических проводников, магнитных переключателей, для элементов памяти квантовых компьютеров, для спинтронных устройств [13][14][15][16][17][18]. Комплексы трехвалентного европия проявляют эффект усиления магнитного дипольного излучения для видимого и ультрафиолетового диапазонов [19].…”