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Open accessJournal ArticleDOI: 10.1039/D0SC05494A

Insight into the drastically different triplet lifetimes of BODIPY obtained by optical/magnetic spectroscopy and theoretical computations.

04 Mar 2021-Chemical Science (The Royal Society of Chemistry)-Vol. 12, Iss: 8, pp 2829-2840
Abstract: The triplet state lifetimes of organic chromophores are crucial for fundamental photochemistry studies as well as applications as photosensitizers in photocatalysis, photovoltaics, photodynamic therapy and photon upconversion. It is noteworthy that the triplet state lifetime of a chromophore can vary significantly for its analogues, while the exact reason was rarely studied. Herein with a few exemplars of typical BODIPY derivatives, which show triplet lifetimes varying up to 110-fold (1.4–160 μs), we found that for these derivatives with short triplet state lifetimes (ca. 1–3 μs), the electron spin polarization (ESP) pattern of the time-resolved electron paramagnetic resonance (TREPR) spectra of the triplet state is inverted at a longer delay time after laser pulse excitation, as a consequence of a strong anisotropy in the decay rates of the zero-field state sublevel of the triplet state. For the derivatives showing longer triplet state lifetimes (>50 μs), no such ESP inversion was observed. The observed fast decay of one sublevel is responsible for the short triplet state lifetime; theoretical computations indicate that it is due to a strong coupling between the Tz sublevel and the ground state mediated by the spin–orbit interaction. Another finding is that the heavy atom effect on the shortening of the triplet state lifetime is more significant for the T1 states with lower energy. To the best of our knowledge, this is the first systematic study to rationalize the short triplet state lifetime of visible-light-harvesting organic chromophores. Our results are useful for fundamental photochemistry and the design of photosensitizers showing long-lived triplet states.

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Topics: Triplet state (68%), Ground state (55%)

11 results found

Journal ArticleDOI: 10.1021/JACS.1C06275
Xueze Zhao1, Qichao Yao1, Saran Long1, Weijie Chi2  +8 moreInstitutions (2)
Abstract: Heavy-atom-based photosensitizers usually exhibit shortened triplet-state lifetimes, which is not ideal for hypoxic tumor photodynamic therapy. Although several heavy-atom-free photosensitizers possess long triplet-state lifetimes, the clinical applicability is limited by their short excitation wavelengths, poor photon capture abilities, and intrinsically hydrophobic structures. Herein we developed a novel NIR heavy-atom-free photosensitizer design strategy by introducing sterically bulky and electron-rich moieties at the meso position of the pentamethine cyanine (Cy5) skeleton, which simultaneously enhanced intersystem crossing (ISC) and prolonged excited-state lifetime. We found that the 1O2 generation ability is directly correlated to the electron-donating ability of the meso substituent in cyanine, and the excited-state lifetime was simultaneously much elongated when the substituents were anthracene derivatives substituted at the 9-position. Our star compound, ANOMe-Cy5, exhibits intense NIR absorption, the highest 1O2 quantum yield (4.48-fold higher than Cy5), the longest triplet-state lifetime (9.80-fold longer than Cy5), and lossless emission intensity (nearly no change compared with Cy5). Such excellent photophysical properties coupled with its inherently cationic and hydrophilic nature enable the photosensitizer to realize photoablation of solid tumor and antitumor lung metastasis. This study highlights the design of a new generation of NIR photosensitizers for imaging-guided photodynamic cancer treatment.

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Topics: Photosensitizer (61%), Intersystem crossing (53%)

3 Citations

Journal ArticleDOI: 10.1021/ACS.ORGLETT.1C02622
Qingbao Gong1, Qinghua Wu2, Qinghua Wu1, Xing Guo1  +4 moreInstitutions (2)
31 Aug 2021-Organic Letters
Abstract: An efficient strategy for building sulfur-bridged oligo-BODIPYs based on the SNAr reaction is described. These oligo-BODIPYs showed broadband and strong visible-near-infrared (NIR) light absorption, strong intramolecular exciton coupling, and efficient intersystem crossing (ISC). Generation of 1O2 as well as O2•- under irradiation was found to give high reactive oxygen species generation efficiencies for those oligomers.

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Topics: Intersystem crossing (56%), BODIPY (53%)

3 Citations

Journal ArticleDOI: 10.1039/D1CP01937F
Muhammad Imran1, Xue Zhang1, Zhijia Wang1, Xi Chen1  +3 moreInstitutions (3)
Abstract: Electron spin dynamics are crucial to photochemical and photophysical processes. However, to a large extent, they are neglected in routine photochemistry studies. Herein, we summarized the recent developments of electron spin dynamics in organic molecular systems. The electron-spin selective intersystem crossing (ISC) as well as charge separation (CS) and charge recombination (CR) of the organic molecular system are discussed, including ISC of the compounds with twisted π-conjugation frameworks and CR-induced ISC in compact orthogonal electron donor–acceptor dyads. We found that the electron spin polarization (ESP) of the triplet state formed in these systems is highly dependent on the molecular structure and geometry. The zero-field-splitting (ZFS) D and E parameters of the triplet state of series chromophores determined with time-resolved electron paramagnetic resonance (TREPR) spectroscopy are presented. Some unanswered questions in related areas are raised, which may inspire further theoretical investigations. The examples demonstrate that the study of electron spin dynamics is not only important in fundamental photochemistry to attain in-depth understanding of the ISC and the charge transfer processes, but is also useful for designing new efficient organic molecular materials for applications including photodynamic therapy, organic light-emitting diodes, and photon upconversion.

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Topics: Intersystem crossing (62%), Triplet state (58%), Electron paramagnetic resonance (52%) ... read more

2 Citations


78 results found

Journal ArticleDOI: 10.1002/WCMS.81
Frank Neese1Institutions (1)
Abstract: ORCA is a general-purpose quantum chemistry program package that features virtually all modern electronic structure methods (density functional theory, many-body perturbation and coupled cluster theories, and multireference and semiempirical methods). It is designed with the aim of generality, extendibility, efficiency, and user friendliness. Its main field of application is larger molecules, transition metal complexes, and their spectroscopic properties. ORCA uses standard Gaussian basis functions and is fully parallelized. The article provides an overview of its current possibilities and documents its efficiency. © 2011 John Wiley & Sons, Ltd.

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6,918 Citations

Open accessJournal ArticleDOI: 10.1038/S41467-018-07882-8
Maksim Kunitski1, Nicolas Eicke2, Pia Huber1, Jonas Köhler1  +12 moreInstitutions (2)
Abstract: Wave-particle duality is an inherent peculiarity of the quantum world. The double-slit experiment has been frequently used for understanding different aspects of this fundamental concept. The occurrence of interference rests on the lack of which-way information and on the absence of decoherence mechanisms, which could scramble the wave fronts. Here, we report on the observation of two-center interference in the molecular-frame photoelectron momentum distribution upon ionization of the neon dimer by a strong laser field. Postselection of ions, which are measured in coincidence with electrons, allows choosing the symmetry of the residual ion, leading to observation of both, gerade and ungerade, types of interference.

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Topics: Ionization (55%), Neon (54%)

4,138 Citations

BookDOI: 10.1002/9783527650002
25 Apr 2012-
Abstract: Preface. Prologue. Introduction. Absorption of UV--visible light. Characteristics of Fluorescence Emission. Effects of Intermolecular Photophysical Processes on Fluorescence Emission. Fluorescence polarization: Emission Ansotropy. Principles of steady--state and time--resolved fluorometric techniques. Effect of polarity of fluorescence emission. Polarity probes. Microviscosity, fluidity, molecular mobility. Estimation by means of fluorescent probes. Resonance energy transfer and its applications. Fluorescent molecular sensors of ions and molecules. Advanced techniques in fluorescence spectroscopy. Epilogue. Index.

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4,053 Citations

Journal ArticleDOI: 10.1021/CR078381N
Aurore Loudet1, Kevin Burgess1Institutions (1)
09 Oct 2007-Chemical Reviews
Topics: BODIPY (66%)

3,700 Citations