Ultrafast Intersystem Crossing in Xanthone from Wavepacket Dynamics

Most aromatic ketones containing first-row elements undergo unexpectedly fast intersystem crossing in few tens of picoseconds and a quantum yield close to unity. Among them, xanthone (9H-xanthen-9-one) possesses one of the fastest singlet-triplet rates of ~1.5 ps. The exact mechanism of this unusually fast transition is still under debate. Here, we perform the wavepacket dynamics of the photochemistry of xanthone in the gas phase and in polar solvents. We show that xanthone follows El-Sayed's rule for intersystem crossing. From the second singlet excited state, the mechanism is sequential: (i) an internal conversion between singlets 1pipi*-1npi* (85 fs), (ii) an intersystem crossing 1npi*-3pipi* (2.0 ps), and (iii) an internal conversion between triplets 3pipi*-3npi* (602 fs). Each transfer finds its origin in a barrierless access to electronic state intersections. These intersections are close to minimum energy structures, allowing for efficient transitions from the initial singlet state to the triplets.

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Ultrafast intersystem crossing in xanthone from wavepacket dynamics simulations

10.33774/chemrxiv-2021-k6hqt-v2 ◽

2021 ◽

Author(s):

Marc Alías Rodríguez ◽

Coen De Graaf ◽

Miquel Huix-Rotllant

Keyword(s):

Gas Phase ◽

Internal Conversion ◽

Minimum Energy ◽

Dynamics Simulation ◽

Intersystem Crossing ◽

Singlet Excited State ◽

Radiationless Transition ◽

Wavepacket Dynamics ◽

Dynamics Simulations ◽

Triplet Transition

Most aromatic ketones containing first-row elements undergo unexpectedly fast intersystem crossing in few tens of picosecond and a quantum yield close to unity. Among them, xanthone (9H-xanthen-9-one) possesses one of the fastest intersystem crossing rates of ~1.5 ps, despite containing only first-row elements. The exact mechanism of this unusually fast singlet-triplet transition is still under debate. Here, we perform a complete wavepacket dynamics simulation of the internal conversion and intersystem crossing reactions of xanthone in the gas phase. We show that xanthone follows El-Sayed's rule for intersystem crossing. From the second singlet excited state, the mechanism is sequential: (i) an internal conversion between singlets 1pipi*-1npi* (~0.14 fs), (ii) an intersystem crossing 1npi*-3pipi* (~1.8 ps), and (iii) an internal conversion between triplets 3pipi*-3npi* (~27 ps). Each transfer finds its origin in a barrierless access to electronic state intersections. These intersections are close to minimum energy structures, allowing for an efficient radiationless transition from 1pipi* to 3npi*.

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Role of intersystem crossing in the dynamics of the O(3P)+ICl reaction

Molecular Physics ◽

10.1080/00268979650027225 ◽

1996 ◽

Vol 87 (4) ◽

pp. 865-877

Author(s):

L. J. POWELL

Keyword(s):

Intersystem Crossing

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Spin-Forbidden Excitation Enables Infrared Photoredox Catalysis

10.26434/chemrxiv.12124215.v1 ◽

2020 ◽

Author(s):

Tomislav Rovis ◽

Benjamin D. Ravetz ◽

Nicholas E. S. Tay ◽

Candice Joe ◽

Melda Sezen-Edmonds ◽

...

Keyword(s):

Excited State ◽

Ground State ◽

Intersystem Crossing ◽

Photoredox Catalysis ◽

Infrared Irradiation ◽

Triplet Excitation ◽

New Family ◽

Ir Light

We describe a new family of catalysts that undergo direct ground state singlet to excited state triplet excitation with IR light, leading to photoredox catalysis without the energy waste associated with intersystem crossing. The finding allows a mole scale reaction in batch using infrared irradiation.

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Intersystem crossing processes in the 2CzPN emitter: a DFT/MRCI study including vibrational spin–orbit interactions

Physical Chemistry Chemical Physics ◽

10.1039/d0cp06011a ◽

2021 ◽

Vol 23 (5) ◽

pp. 3668-3678

Author(s):

Angela Rodriguez-Serrano ◽

Fabian Dinkelbach ◽

Christel M. Marian

Keyword(s):

Quantum Chemical Calculations ◽

Quantum Chemical ◽

Intersystem Crossing ◽

Spin Orbit ◽

Spin Orbit Interactions

Multireference quantum chemical calculations were performed in order to investigate the (reverse) intersystem crossing ((R)ISC) mechanisms of 4,5-di(9H-carbazol-9-yl)-phthalonitrile (2CzPN).

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Electron transfer sensitized photolysis of 'onium salts

Canadian Journal of Chemistry ◽

10.1139/v88-055 ◽

1988 ◽

Vol 66 (2) ◽

pp. 319-324 ◽

Cited By ~ 55

Author(s):

R. J. DeVoe ◽

M. R. V. Sahyun ◽

Einhard Schmidt ◽

N. Serpone ◽

D. K. Sharma

Keyword(s):

Electron Transfer ◽

Flash Photolysis ◽

Laser Flash Photolysis ◽

Laser Flash ◽

Quantitative Model ◽

Intersystem Crossing ◽

Single Electron Transfer ◽

Onium Salts ◽

Encounter Complex ◽

Back Electron Transfer

We have studied the anthracene-sensitized photolyses of both diphenyliodonium and triphenylsulphonium salts in solution using both steady-state and laser flash photolysis techniques. Photoproducts, namely, phenylated anthracenes along with iodobenzene or diphenylsulphide, respectively, are obtained from both salts with quantum efficiencies of ca. 0.1 at 375 nm. We infer the intermediacy of diphenyliodo and triphenylsulphur radicals formed by single electron transfer from the singlet-excited anthracene. We have developed a quantitative model of this chemistry, and identify the principal sources of inefficiency as back electron transfer, which occurs at nearly the theoretically limiting rate, intersystem crossing from the initially formed sensitizer–'onium salt encounter complex, and in-cage radical recombination.

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