Structure of Isolated Xanthone in the T₁ State Obtained via Combined UV/IR Spectroscopy

Abstract

In order to extend combined UV/IR spectroscopy to triplet states, xanthone has been chosen as a model system due to its efficient intersystem crossing (ISC). The IR/R2PI (resonant two-photon ionisation) spectrum of the electronic ground state (S(0)) as well as the IR spectrum of the T(1) state have been recorded in a supersonic jet. We show that the IR spectrum of a triplet state can be recorded subsequent to an ISC. In combination with DFT and TDDFT calculations, structural assignments are performed and geometrical changes are identified.

Solvent effects on the structure of the triplet excited state of xanthone: a time-resolved resonance Raman study

“…These resonance‐enhanced modes are assigned tentatively based on their REPs and TR 3 spectra in two different solvents as discussed in the previous section. The 1293 and 1486 cm −1 peaks observed in our TR 3 experiments of XT in ACN solvent are in excellent agreement with 1275 and 1459 cm −1 in gas phase and in 1292 and 1481 cm −1 in CHL solvent, respectively, observed previously in the different pump‐probe infrared experiments . Therefore, the aforementioned peaks have been assigned to the combined CCH bending and CO stretching mode and the CCH bending modes, respectively.…”

“…Although the triplet state properties of XT have been studied by various techniques like time‐resolved absorption and phosphorescence, they do not give insight into the structural aspects of the transient species in solution, which plays a decisive role in its reactivity. Recently, the structure of the XT triplet state in molecular beam and in chloroform was reported using different pump‐probe infrared techniques. To the best of our knowledge, a comprehensive analysis of the solvent effect on the vibrational structure of XT has not yet been reported.…”

On the Dual Phosphorescence of Xanthone and Chromone in Glassy Hydrocarbon Hosts

“…Following the initial report of a nonexponential phosphorescence relaxation in 1‐indanone by Yang and Murov , the apparently anomalous phosphorescence properties of aromatic ketones became an active area of research . The origins of the dual phosphorescence of xanthone and chromone have been investigated using a variety of approaches including: phosphorescence and its corresponding excitation spectra, polarization and lifetime measurements as a function of temperature in a variety of hosts, optical‐detected magnetic resonance (ODMR), electron paramagnetic resonance, free‐jet phosphorescence excitation spectroscopy and gas‐phase phosphorescence and delayed fluorescence . Early work established that the lowest energy excited singlet state is of nπ* character for both xanthone and chromone .…”

IR Spectroscopic Techniques to Study Isolated Biomolecules

“…Although the opportunity to characterize the electronically excited state is very valuable, both the excited-state lifetime constraint and intersystem crossing effects have resulted in a limited, but promising, application of this method to biomolecular systems [84,103,106,107]. In addition to the UV-IR-UV scheme described above, various other multiple-resonance IR/UV schemes have been developed to study selectively the IR absorption of the electronically excited state.…”