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Molecular ultralong room‐temperature phosphorescence (RTP), exhibiting multiple stimuli‐responsive characteristics, has garnered considerable attention due to its potential applications in light‐emitting devices, sensors, and information safety. This work proposes the utilization of photochemical cascade processes (PCCPs) in molecular crystals to design a stepwise smart RTP switch. By harnessing the sequential dynamics of photo‐burst movement (induced by [2+2] photocycloaddition) and photochromism (induced by photogenerated radicals) in a bismuth (Bi)‐based metal‐organic halide (MOH), a continuous and photo‐responsive ultralong RTP can be achieved. Furthermore, utilizing the same Bi‐based MOH, diverse application demonstrations, such as multi‐mode anti‐counterfeiting and information encryption, can be easily implemented. This work thus not only serves as a proof‐of‐concept for the development of solid‐state PCCPs that integrate photosalient effect and photochromism with light‐chemical‐mechanical energy conversion, but also lays the groundwork for designing new Bi‐based MOHs with dynamically responsive ultralong RTP. [ABSTRACT FROM AUTHOR]

Ensuring information security has emerged as a paramount concern in contemporary human society. Substantial advancements in this regard can be achieved by leveraging photonic signals as the primary information carriers, utilizing photonic logical gates capable of wavelength tunability across various time and spatial domains. However, the challenge remains in the rational design of materials possessing space‐time‐color multiple‐resolution capabilities. In this work, a facile approach is proposed for crafting metal‐organic halides (MOHs) that offer space‐time‐color resolution. These MOHs integrate time‐resolved room temperature phosphorescence and color‐resolved excitation wavelength dependencies with both space‐resolved ex situ optical waveguides and in situ heterojunctions. Capitalizing on these multifaceted properties, MOHs‐based two‐dimensional (2D) optical waveguides and heterojunctions exhibit the ability to tune full‐color emissions across the spectra from blue to red, operating within different spatial and temporal scales. Therefore, this work introduces an effective methodology for engineering space‐time‐color resolved MOH microstructures, holding significant promise for the development of high‐density photonic logical devices. [ABSTRACT FROM AUTHOR]

Photocatalytic CO2 reduction is one of the best solutions to solve the global energy crisis and to realize carbon neutralization. The tetradentate phosphine‐bipyridine (bpy)‐phosphine (PNNP)‐type Ir(III) photocatalyst, Mes‐IrPCY2, was reported with a high HCOOH selectivity but the photocatalytic mechanism remains elusive. Herein, we employ electronic structure methods in combination with radiative, nonradiative, and electron transfer rate calculations, to explore the entire photocatalytic cycle to either HCOOH or CO, based on which a new mechanistic scenario is proposed. The catalytic reduction reaction starts from the generation of the precursor metal‐to‐ligand charge transfer (3MLCT) state. Subsequently, the divergence happens from the 3MLCT state, the single electron transfer (SET) and deprotonation process lead to the formation of one‐electron‐reduced species and Ir(I) species, which initiate the reduction reaction to HCOOH and CO, respectively. Interestingly, the efficient occurrence of proton or electron transfer reduces barriers of critical steps. In addition, nonadiabatic transitions play a nonnegligible role in the cycle. We suggest a lower free‐energy barrier in the reaction‐limiting step and the very efficient SET in 3MLCT are cooperatively responsible for a high HCOOH selectivity. The gained mechanistic insights could help chemists to understand, regulate, and design photocatalytic CO2 reduction reaction of similar function‐integrated molecular photocatalyst. [ABSTRACT FROM AUTHOR]

We describe an aromatic amide skeleton for manipulation of triplet excited states toward bright long‐lived blue phosphorescence. Spectroscopic studies and theoretical calculations demonstrated that the aromatic amides can promote strong spin‐orbit coupling between (π,π*) and the bridged (n,π*) states, and enable multiple channels to populate the emissive 3(π,π*), as well as facilitate robust hydrogen bonding with polyvinyl alcohol to suppress non‐radiative relaxations. Isolated inherent deep‐blue (0.155, 0.056) to sky‐blue (0.175, 0.232) phosphorescence with high quantum yields (up to 34.7 %) in confined films are achieved. The blue afterglow of the films can last for several seconds and are showcased in information display, anti‐counterfeiting, and white light afterglow. Owing to the high population of 3(π,π*) states, the smart aromatic amide skeleton provides an important molecular design prototype to manipulate triplet excited states for ultralong phosphorescence with various colors. [ABSTRACT FROM AUTHOR]

A dinuclear Pt(II) compound was reported to exhibit thermally activated delayed fluorescence (TADF); however, the luminescence mechanism remains elusive. To reveal relevant excited‐state properties and luminescence mechanism of this Pt(II) compound, both density function theory (DFT) and time‐dependent DFT (TD‐DFT) calculations were carried out in this work. In terms of the results, the S1 and T2 states show mixed intraligand charge transfer (ILCT)/metal‐to‐ligand CT (MLCT) characters while the T1 state exhibits mixed ILCT/ligand‐to‐metal CT (LMCT) characters. Mechanistically, a four‐state (S0, S1, T1, and T2) model is proposed to rationalize the TADF behavior. The reverse intersystem crossing (rISC) process from the initial T1 to final S1 states involves two up‐conversion channels (direct T1→S1 and T2‐mediated T1→T2→S1 pathways) and both play crucial roles in TADF. At 300 K, these two channels are much faster than the T1 phosphorescence emission enabling TADF. However, at 80 K, these rISC rates are reduced by several orders of magnitude and become very small, which blocks the TADF emission; instead, only the phosphorescence is observed. These findings rationalize the experimental observation and could provide useful guidance to rational design of organometallic materials with superior TADF performances. [ABSTRACT FROM AUTHOR]

Developing Type‐I photosensitizers is considered as an efficient approach to overcome the deficiency of traditional photodynamic therapy (PDT) for hypoxic tumors. However, it remains a challenge to design photosensitizers for generating reactive oxygen species by the Type‐I process. Herein, we report a series of α,β‐linked BODIPY dimers and a trimer that exclusively generate superoxide radical (O2−.) by the Type‐I process upon light irradiation. The triplet formation originates from an effective excited‐state relaxation from the initially populated singlet (S1) to triplet (T1) states via an intermediate triplet (T2) state. The low reduction potential and ultralong lifetime of the T1 state facilitate the efficient generation of O2−. by inter‐molecular charge transfer to molecular oxygen. The energy gap of T1‐S0 is smaller than that between 3O2 and 1O2 thereby precluding the generation of singlet oxygen by the Type‐II process. The trimer exhibits superior PDT performance under the hypoxic environment. [ABSTRACT FROM AUTHOR]

Phytochrome proteins are light receptors that play a pivotal role in regulating the life cycles of plants and microorganisms. Intriguingly, while cyanobacterial phytochrome Cph1 and cyanobacteriochrome AnPixJ use the same phycocyanobilin (PCB) chromophore to absorb light, their excited‐state behavior is very different. We employ multiscale calculations to rationalize the different early photoisomerization mechanisms of PCB in Cph1 and AnPixJ. We found that their electronic S1, T1, and S0 potential minima exhibit distinct geometric and electronic structures due to different hydrogen bond networks with the protein environment. These specific interactions influence the S1 electronic structures along the photoisomerization paths, ultimately leading to internal conversion in Cph1 but intersystem crossing in AnPixJ. This explains why the excited‐state relaxation in AnPixJ is much slower (ca. 100 ns) than in Cph1 (ca. 30 ps). Further, we predict that efficient internal conversion in AnPixJ can be achieved upon protonating the carboxylic group that interacts with PCB. [ABSTRACT FROM AUTHOR]

Whether chemical bonding can regulate the excited‐state and optoelectronic properties of donor–acceptor dyads has been largely elusive. In this work, we used electronic structure and nonadiabatic dynamics methods to explore the excited‐state properties of covalently bonded zinc phthalocyanine (ZnPc)‐fullerene (C60) dyads with a 6–6 (or 5–6) bonding configuration in which ZnPc is bonded to two carbon atoms shared by the two hexagonal rings (or a pentagonal and a hexagonal ring) in C60. In both cases, the locally excited (LE) states on ZnPc are spectroscopically bright. However, their different chemical bonding differentiates the electronic interactions between ZnPc and C60. In the 5–6 bonding configuration, the LE states on ZnPc are much higher in energy than the LE states on C60. Thus, the excitation energy transfer from ZnPc to C60 is thermodynamically favorable. On the other hand, in the 6–6 bonding configuration, such a process is inhibited because the LE states on ZnPc are the lowest ones. More detailed mechanisms are elucidated from nonadiabatic dynamics simulations. In the 6–6 bonding configuration, no excitation energy transfer was observed. In contrast, in the 5–6 bonding configuration, several LE and charge‐transfer (CT) excitons were shown to participate in the energy‐transfer process. Further analysis reveals that the photoinduced energy transfer is mediated by a CT exciton, such that electron‐ and hole‐transfer processes take place in a concerted but asynchronous manner in the excitation energy transfer. It is also found that high‐level electronic structure methods including exciton effects are indispensable to accurately describe photoinduced energy‐ and electron‐transfer processes. Furthermore, this work opens up new avenues for regulating the excited‐state properties of molecular donor–acceptor dyads by means of chemical bonding. [ABSTRACT FROM AUTHOR]

The perovskite CH3NH3PbI3 excited‐state lifetimes exhibit conflicting experimental results under humid environments. Using ab initio nonadiabatic (NA) molecular dynamics, we demonstrate that the interplay between lead vacancy and water can rationalize the puzzle. The lead vacancy reduces NA coupling by localizing holes, slowing electron–hole recombination. By creating a deep electron trap state, the coexistence of a neutral lead vacancy and water molecules enhances NA coupling, accelerating charge recombination by a factor of over 3. By eliminating the mid‐gap state by accepting two photoexcited electrons, the negatively charged lead vacancy interacting with water molecules increases the carrier lifetime over 2 times longer than in the pristine system. The simulations rationalize the positive and negative effects of water on the solar cell performance exposure to humidity. [ABSTRACT FROM AUTHOR]

An organic crystal of 4,4′‐bis(N‐carbazolyl)‐1,1′‐biphenyl (pCBP) exhibits time‐dependent afterglow color from blue to orange over 1 s. Both experimental and computational data confirm that the color evolution results from well‐separated, long‐persistent thermally activated delayed fluorescence (TADF) and room‐temperature phosphorescence (RTP) with different but comparable decay rates. TADF is enabled by a small S1–T1 energy gap of 0.7 kcal mol−1. The good separation of TADF and RTP is due to a 11.8 kcal mol−1 difference in the S0 energies of the S1 and T1 structures, indicating that apart from the excited‐state properties, tuning the ground state is also important for luminescence properties. This afterglow color evolution of pCBP allows its applications in anticounterfeiting and data encryption with high security levels. [ABSTRACT FROM AUTHOR]

Defects, such as halide interstitials, act as charge recombination centers, induce degradation of halide perovskites, and create major obstacles to applications of these materials. Alkali metal dopants greatly improve perovskite performance. Using ab initio nonadiabatic molecular dynamics, it is demonstrated that alkalis bring favorable effects. The formation energy of halide interstitials increases by up to a factor of four in the presence of alkali dopants, and therefore, defect concentration decreases. When defects are present, alkali metals strongly bind to them. Halide interstitials introduce mid‐gap states that rapidly trap charge carriers. Alkalis eliminate the trap states, helping to maintain high current density. Further to charge trapping, the interstitials accelerate charge recombination. By passivating the interstitials, alkalis make carrier lifetimes up to seven times longer than in defect‐free perovskites and up to thirty times longer than in defective perovskites. [ABSTRACT FROM AUTHOR]

In the present work, the direct ab initio quantum trajectory mean‐field and molecular mechanical (QTMF/MM) nonadiabatic dynamics approach has been numerically implemented and used to simulate the photo‐induced ring‐opening process of 2(5H)‐thiophenone in CH3CN solution. Meanwhile, the subsequent processes in the S0 state have been simulated employing a quantum mechanics/molecular mechanics (QM/MM) adiabatic dynamics method that is derived from the direct ab initio QTMF/MM nonadiabatic dynamics approach. Upon irradiation at 267 nm, 2(5H)‐thiophenone is initially populated to its bright 1ππ* state. Subsequently, the ring‐opening reaction is predicted to be an ultrafast process with a time constant of about 228 fs. As a result, the ring‐opening reaction proceeds mainly along the diabatic S2(1ππ*) pathway and the solute‐solvent interaction has little influence on this initial process. Meanwhile, the 1ππ*→1πσ* transition takes place with little probability via the 1πσ*/1ππ* conical intersection and the 1πσ* excited state plays a minor role in the ring‐opening reaction, which is quite different from those reported for many heterocyclic molecules. Reformation of the parent molecule in the S0 state is determined to have a quantum yield of 33.9 % within the simulated period of 3.5 ps, which is considerably underestimated in comparison with a value of ∼60.0 % inferred experimentally. Thioaldehyde‐ketene was experimentally inferred as a product, which is confirmed by the simulations reported herein. [ABSTRACT FROM AUTHOR]

In the present work, mechanism of the O2(1Δg) generation from the reaction of the dissolved Cl2 with H2O2 in basic aqueous solution has been explored by the combined ab initio calculation and nonadiabatic dynamics simulation, together with different solvent models. Three possible pathways have been determined for the O2(1Δg) generation, but two of them are sequentially downhill processes until formation of the OOCl− complex with water, which are of high exothermic character. Once the complex is formed, singlet molecular oxygen is easily generated by its decomposition along the singlet‐state pathway. However, triplet molecular oxygen of O2(Σ3g−) can be produced with considerable probability through nonadiabatic intersystem crossing in the 1Δg/Σ3g− intersection region. It has been found that the coupled solvent, heavy‐atom, and nonadiabatic effects have an important influence on the quantum yield of the O2(1Δg) generation. © 2018 Wiley Periodicals, Inc. Singlet delta oxygen has numerous unique properties that allow its use in many fields of chemistry and biology. The chemical reaction between Cl2 and basic H2O2 aqueous solution is usually used to generate singlet delta oxygen for the chemical oxygen iodine laser. But, the underlying mechanism is still unclear. In the present work, a systematic theoretical study has been performed to achieve a complete understanding of the O2(1Δg) generation from the reaction of Cl2 with H2O2 in basic aqueous solution. More attentions have been paid to the solvent‐mediated nonadiabatic effect on the quantum yield of singlet delta oxygen. [ABSTRACT FROM AUTHOR]

Abstract: The weak photoluminescence of silver nanoclusters prevents their broad application as luminescent nanomaterials. Recent experiments, however, have shown that gold doping can significantly enhance the photoluminescence intensity of Ag29 nanoclusters but the molecular and physical origins of this effect remain unknown. Therefore, we have computationally explored the geometric and electronic structures of Ag29 and gold‐doped Ag29−xAux (x=1–5) nanoclusters in the S0 and S1 states. We found that 1) relativistic effects that are mainly due to the Au atoms play an important role in enhancing the fluorescence intensity, especially for highly doped Ag26Au3, Ag25Au4, and Ag24Au5, and that 2) heteronuclear Au−Ag bonds can increase the stability and regulate the fluorescence intensity of isomers of these gold‐doped nanoclusters. These novel findings could help design doped silver nanoclusters with excellent luminescence properties. [ABSTRACT FROM AUTHOR]

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Abstract: The photoresponsive azobenzene‐tethered DNAs have received growing experimental attention because of their potential applications in biotechnology and nanotechnology; however, little is known about the initial photoisomerization of azobenzene in these systems. Herein we have employed quantum mechanics/molecular mechanics (QM/MM) methods to explore the photoisomerization dynamics of an azobenzene‐tethered DNA duplex. We find that in the S1 state the trans–cis photoisomerization path is much steeper in DNA than in vacuo, which makes the photoisomerization much faster in the DNA environment. This acceleration is primarily caused by complex steric interactions between azobenzene and the nearby unpaired thymine nucleobase, which also change the photoisomerization mechanism of azobenzene in the DNA duplex. [ABSTRACT FROM AUTHOR]

N-alkenyl maleimides are found to exhibit spin state-specific chemoselectivities for [2 + 2] and [5 + 2] photocycloadditions; but, reaction mechanism is still unclear. In this work, we have used high-level electronic structure methods (DFT, CASSCF, and CASPT2) to explore [2 + 2] and [5 + 2] photocycloaddition reaction paths of an N-alkenyl maleimide in the S1 and T1 states as well as relevant photophysical processes. It is found that in the S1 state [5 + 2] photocycloaddition reaction is barrierless and thus overwhelmingly dominant; [2 + 2] photocycloaddition reaction is unimportant because of its large barrier. On the contrary, in the T1 state [2 + 2] photocycloaddition reaction is much more favorable than [5 + 2] photocyclo-addition reaction. Mechanistically, both S1 [5 + 2] and T1 [2 + 2] photocycloaddition reactions occur in a stepwise, nonadiabatic means. In the S1 [5 + 2] reaction, the secondary C atom of the ethenyl moiety first attacks the N atom of the maleimide moiety forming an S1 intermediate, which then decays to the S0 state as a result of an S1 → S0 internal conversion. In the T1 [2 + 2] reaction, the terminal C atom of the ethenyl moiety first attacks the C atom of the maleimide moiety, followed by a T1 → S0 intersystem crossing process to the S0 state. In the S0 state, the second CC bond is formed. Our present computational results not only rationalize available experiments but also provide new mechanistic insights. © 2017 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

The dark- and light-adapted states of YtvA LOV domains exhibit distinct excited-state behavior. We have employed high-level QM(MS-CASPT2)/MM calculations to study the photochemical reactions of the dark- and light-adapted states. The photoreaction from the dark-adapted state starts with an S1→T1 intersystem crossing followed by a triplet-state hydrogen transfer from the thiol to the flavin moiety that produces a diradical intermediate, and a subsequent internal conversion that triggers a barrierless C−S bond formation in the S0 state. The energy profiles for these transformations are different for the four conformers of the dark-adapted state considered. The photochemistry of the light-adapted state does not involve the triplet state: photoexcitation to the S1 state triggers C−S bond cleavage followed by recombination in the S0 state; both these processes are essentially barrierless and thus ultrafast. The present work offers new mechanistic insights into the photoresponse of flavin-containing blue-light photoreceptors. [ABSTRACT FROM AUTHOR]

Electronic structure calculations and nonadiabatic dynamics simulations (more than 2000 trajectories) are used to explore the Z- E photoisomerization mechanism and excited-state decay dynamics of two arylazopyrazole photoswitches. Two chiral S1/S0 conical intersections with associated enantiomeric S1 relaxation paths that are barrierless and efficient (timescale of ca. 50 fs) were found. For the parent arylazopyrazole (Z8) both paths contribute evenly to the S1 excited-state decay, whereas for the dimethyl derivative (Z11) each of the two chiral cis minima decays almost exclusively through one specific enantiomeric S1 relaxation path. To our knowledge, the Z11 arylazopyrazole is thus the first example for nearly stereospecific unidirectional excited-state relaxation. [ABSTRACT FROM AUTHOR]

Photoswitchable azobenzene cross-linkers can control the folding and unfolding of peptides by photoisomerization and can thus regulate peptide affinities and enzyme activities. Using quantum mechanics/molecular mechanics (QM/MM) methods and classical MM force fields, we report the first molecular dynamics simulations of the photoinduced folding and unfolding processes in the azobenzene cross-linked FK-11 peptide. We find that the interactions between the peptide and the azobenzene cross-linker are crucial for controlling the evolution of the secondary structure of the peptide and responsible for accelerating the folding and unfolding events. They also modify the photoisomerization mechanism of the azobenzene cross-linker compared with the situation in vacuo or in solution. [ABSTRACT FROM AUTHOR]

Fluorescence emission of wild-type green fluorescent protein (GFP) is lost in the S65T mutant, but partly recovered in the S65T/H148D double mutant. These experimental findings are rationalized by a combined quantum mechanics/molecular mechanics (QM/MM) study at the QM(CASPT2//CASSCF)/AMBER level. A barrierless excited-state proton transfer, which is exclusively driven by the Asp148 residue introduced in the double mutant, is responsible for the ultrafast formation of the anionic fluorescent state, which can be deactivated through a concerted asynchronous hula-twist photoisomerization. This causes the lower fluorescence quantum yield in S65T/H148D compared to wild-type GFP. Hydrogen out-of-plane motion plays an important role in the deactivation of the S65T/H148D fluorescent state. [ABSTRACT FROM AUTHOR]

Bacterial bioluminescence (BL) has been successfully applied in water-quality monitoring and in vivo imaging. The attention of researchers has been attracted for several decades, but the mechanism of bacterial BL is still largely unknown due to the complexity of the multistep reaction process. Debates mainly focus on three key questions: How is the bioluminophore produced? What is the exact chemical form of the bioluminophore? How does the protein environment affect the light emission? Using quantum mechanics (QM), combined QM and molecular mechanics (QM/MM) and molecular dynamic (MD) calculations in gas-phase, solvent and protein environments, the entire process of bacterial BL was investigated, from flavin reduction to light emission. This investigation revealed that: 1) the chemiluminescent decomposition of flavin peroxyhemiacetal does not occur through the intramolecular chemical initiated electron exchange luminescence (CIEEL) or the 'dioxirane' mechanism, as suggested in the literature. Instead, the decomposition occurs according to the charge-transfer initiated luminescence (CTIL) mechanism for the thermolysis of dioxetanone. 2) The first excited state of 4a-hydroxy-4a,5-dihydroFMN (HFOH) was affirmed to be the bioluminophore of bacterial BL. This study provides details regarding the mechanism by which bacterial BL is produced and is helpful in understanding bacterial BL in general. [ABSTRACT FROM AUTHOR]

The photophysics of 3-methyl-3-pentene-2-one (3M3P2O) after excitation to the S2(ππ*) electronic state were studied using the resonance Raman spectroscopy and complete active space self-consistent field (CASSCF) method calculations. The A-band resonance Raman spectra were obtained in cyclohexane, acetonitrile, and methanol with excitation wavelengths in resonance with the first intense absorption band to probe the structural dynamics of 3M3P2O. The B3LYP-TD/6-31++G(d, p) computation was carried out to determine the relative A-band resonance Raman intensities of the fundamental modes, and the result was used to reproduce the corresponding fundamental band intensities of the 223.1 nm resonance Raman spectrum and thus to examine whether the vibronic-coupling existed in Franck-Condon region or not. CASSCF calculations were carried out to determine the minimal singlet excitation energies of S1, FC, S1,min (nπ*), S2, FC, S2,min (ππ*), the transition energies of the conical intersection points Sn/Sπ, Sn/S0, and the optimized excited state geometries as well as the geometry structures of the conical intersection points. The A-band short-time structural dynamics and the corresponding decay dynamics of 3M3P2O were obtained by the analysis of the resonance Raman intensity pattern and CASSCF computations. It was revealed that the initial structural dynamics of 3M3P2O was towards the simultaneous C3=C4 and C2=O7 bond elongation, with the C3=C4 bond length lengthening greater at the very beginning, whereas the C2=O7 bond length changing greater at the later evolution time before reaching the CI(S2/S1) conical intersection point. The decay dynamics from S2(ππ*) to S1(nπ*) via S2(ππ*)/S1(nπ*) in singlet realm and from S1(nπ*) to T1(nπ*) via ISC[S1(nπ*)/T2(ππ*)/T1(nπ*)] in triplet realm are proposed. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The excited state structural dynamics of 4-cyanobenzaldehyde (p-CNB) were studied by using the resonance Raman spectroscopy and the quantum mechanical calculations. The experimental A- and B-band absorptions were, respectively, assigned to the major nO → π3* and π2 → π3* transitions according to the B3LYP-TD/6-31G(d) and CIS/6-31G(d) computations, and the resonance Raman spectra. It was determined that the actual S2(π2π3) state was in energy lower than S3(π1π3), which was just opposite to the B3LYP-TD/6-31G(d) calculated order of the S2(π1π3) and S3(π2π3). The vibrational assignments were carried out for the A- and B-band resonance Raman spectra. The B-band resonance Raman intensities of p-CNB were dominated by the C2-C3/C5-C6 symmetric stretch mode ν8, the overtones nν8 and their combination bands with the ring C-H bend mode ν17, the C9-N10 stretch mode ν6, the C7-O8 stretch mode ν7 and the remaining modes. The conical intersection between S1(nOπ3) and S2(π2π3) states of p-CNB was determined at complete active space self-consistent field (CASSCF)(8,7)/6-311G(d,p) level of theory. The B-band short-time structural dynamics and the corresponding decay dynamics of p-CNB were obtained by analysis of the resonance Raman intensity pattern and CASSCF computations. The resonance Raman spectra indicated that CI[S1(nOπ3)/S2(π1π2π3π4)] located nearby the Franck-Condon region. The excited state decay dynamics evolving from the S2, FC(π2π3) to the S1(nOπ3) state was proposed. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The article discusses research on gold photochemistry, particularly the photoinduced gold(I)-gold(I) chemical bonding in dicyanoaurate oligomers. It talks about gold chemistry as one of the fields of chemistry. It also offers information of the spectroscopic and excited-state properties of prototypical dicyanoaurate.

The photophysics and photochemistry of pyrazine (C4H4N2, D2h) after excitation to the S2 (1 1B2u, 1ππ*) electronic state were studied by using the resonance Raman spectroscopy and complete active space self-consistent field method calculations. The B-band resonance Raman spectra in cyclohexane solvent were obtained at 266.0, 252.7, and 245.9 nm excitation wavelengths to probe the structural dynamics of pyrazine in the S2 (1 1B2u, 1ππ*) state. Three electronic states 1 1B3u, 1 1B1g, and 1 1B2g were found to couple with the S2 (1 1B2u, 1ππ*) state. Two conical intersection (CI) points CI[ S2(B2u)/ S1(B3u)] and CI[ S1/ S0] and one transition state of the isomerization between pyrazine and pyrimidine were predicted to play important roles in the photochemistry of pyrazine. On the basis of the calculations, the mechanism of the photoisomerization reaction between pyrazine and pyrimidine has been proposed. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

We have taken (dA), (dT), and (dA)·(dT) as model systems to study concerted effects of base pairing and stacking on excited-state nature of DNA oligonucleotides using density functional theory (DFT) and time dependent DFT methods. The spectroscopic states are determined to be of a partial → charge-transfer nature in the oligonucleotides. The → charge-transfer transitions produce dark states, which are hidden in the energy region of the steady-state absorption spectra. This is different from the previous assignment that the → charge-transfer transition is responsible for a shoulder at the red side of the first strong absorption band. The → charge-transfer states were predicted to have relatively high energies in the oligonucleotides. The present calculations predict that the → charge-transfer states are not involved in the spectra and excited-state dynamics of the oligonucleotides. In addition, the influence of base pairing and stacking on the nature of the nπ* and ππ* states are discussed in detail. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011 [ABSTRACT FROM AUTHOR]

BODIPY, photodynamic therapy, photosensitizers, superoxide radical, hypoxia Corrigendum: BODIPY-Based Photodynamic Agents for Exclusively Generating Superoxide Radical over Singlet Oxygen Keywords: BODIPY; hypoxia; photodynamic therapy; photosensitizers; superoxide radical EN BODIPY hypoxia photodynamic therapy photosensitizers superoxide radical 23938 23938 1 10/27/21 20211102 NES 211102 In this Research Article, the absorption and fluorescence spectra of compound B 2 b (Figure 6 b) were incorrect. [Extracted from the article]

Keywords: BODIPY; hypoxia; photodynamic therapy; photosensitizers; superoxide radical EN BODIPY hypoxia photodynamic therapy photosensitizers superoxide radical 24134 24134 1 10/27/21 20211102 NES 211102 In this Research Article, the absorption and fluorescence spectra of compound B 2 b (Figure 6 b) were incorrect. Berichtigung: BODIPY-Based Photodynamic Agents for Exclusively Generating Superoxide Radical over Singlet Oxygen BODIPY, hypoxia, photodynamic therapy, photosensitizers, superoxide radical. [Extracted from the article]