The Photophysics of Naphthalimide-Phenoselenazine Electron Donor-Acceptor Dyads: Revisiting the Heavy-Atom Effect in Thermally Activated Delayed Fluorescence.

We prepared thermally activated delayed fluorescence (TADF) emitter dyads, NI-PTZ, NI-PTZ-2Br and NI-PSeZ, with naphthalimide (NI) as electron acceptor and 10H-phenothiazine (PTZ) or 10H-phenoselenazine (PSeZ) as electron donor to study the heavy-atom effect on the intersystem crossing (ISC) and reverse ISC (rISC) in the TADF emitters. The delayed fluorescence lifetimes of the dyads containing heavy atoms ( =5.9 μs for NI-PSeZ and =16.

Origin of Intersystem Crossing in Red-Light Absorbing Bodipy Derivatives: Time-Resolved Transient Optical and Electron Paramagnetic Resonance Spectral Studies with Twisted and Planar Compounds.

We studied the intersystem crossing (ISC) property of red-light absorbing heavy atom-free dihydronaphtho[]-fused Bodipy derivatives (with phenyl group attached at the lower rim via ethylene bridge, taking constrained geometry, i.e., and the half-oxidized product ) and dispiroflourene[]-fused Bodipy () that have a twisted π-conjugated framework.

Photophysics and photochemistry of thermally activated delayed fluorescence emitters based on the multiple resonance effect: transient optical and electron paramagnetic resonance studies.

The photochemistry of two representative thermally activated delayed fluorescence (TADF) emitters based on the multiple resonance effect (MRE) (DABNA-1 and DtBuCzB) was studied. No significant TADF was observed in fluid solution, although the compounds have a long-lived triplet state ( 30 μs). We found that these planar boron molecules bind with Lewis bases, , 4-dimethylaminopyridine (DMAP) or an -heterocyclic carbene (NHC).

Photodissociation of deuterated pyrrole-ammonia clusters: H-atom transfer or electron coupled proton transfer?

Several years ago the discovery of a conical intersection offered an explanation for the ultafast photodissociation of pyrrole. Subsequently, the photodissociation of pyrrole ammonia complexes PyH*(NH) with ≥ 3 was studied in the gas phase as a model for a hydrogen-bond forming solvent. Two alternative mechanisms, electron coupled proton transfer (ECPT) and hydrogen atom transfer (HAT, also called the impulsive model, IM), have been proposed.

Origin of intersystem crossing in highly distorted organic molecules: a case study with red light-absorbing ,,,-boron-chelated Bodipys.

To explore the relationship between the twisted π-conjugation framework of aromatic chromophores and the efficacy of intersystem crossing (ISC), we have studied a ,,,-boron-chelated Bodipy derivative possessing a severely distorted molecular structure. Surprisingly, this chromophore is highly fluorescent, showing inefficient ISC (singlet oxygen quantum yield, = 12%). These features differ from those of helical aromatic hydrocarbons, where the twisted framework promotes ISC.

Charge Separation/Recombination, Intersystem Crossing, and Unusually Slow Intramolecular Triplet-Triplet Energy Transfer in Naphthalenediimide-Anthracene Compact Energy Donor-Acceptor Dyads.

Three anthracene (An)-naphthalenediimide (NDI) compact electron donor-acceptor dyads were prepared. Femtosecond transient absorption (fs-TA) spectra show fast charge separation (ca. 0.

Increased glucocorticoid metabolism in diabetic kidney disease.

Aims: Glomerular damage indicated by proteinuria is a main symptom in diabetic nephropathy. Mineralocorticoid receptor (MR) antagonists (MRAs) are beneficial irrespective of aldosterone availability. Thus, we hypothesized an alternatively activated MR to promote glomerular damage in proteinuric diabetic nephropathy.

How Is CYP17A1 Activity Altered in Autism? A Pilot Study to Identify Potential Pharmacological Targets.

Increasing evidence exists that higher levels of androgens can be found in individuals with autism. Evidence yields to a susceptible role of Cytochrome P450 17A1 (CYP17A1) with its catalyzation of the two distinct types of substrate oxidation by a hydroxylase activity (17-alpha hydroxylase) and C17/20 lyase activity. However, to what extent steps are altered in affected children with autism versus healthy controls remains to be elucidated.

Intersystem Crossing and Triplet-State Property of Anthryl- and Carbazole-[1,12]fused Perylenebisimide Derivatives with a Twisted π-Conjugation Framework.

Heavy atom-free triplet photosensitizers (PSs) are particularly of interest concerning both fundamental photochemistry study and practical applications. However, achieving efficient intersystem crossing (ISC) in planar heavy atom-free aromatic organic compounds is challenging. Herein, we demonstrate that two perylenebisimide (PBI) derivatives with anthryl and carbazole moieties fused at the bay position, showing twisted π-conjugation frameworks and red-shifted UV-vis absorption as compared to the native PBI chromophore (by 75-1610 cm), possess efficient ISC (singlet oxygen quantum yield: Φ = 85%) and a long-lived triplet excited state (τ = 382 μs in fluid solution and τ = 4.

Sex- and age-specific reference intervals for diagnostic ratios reflecting relative activity of steroidogenic enzymes and pathways in adults.

Objective: Diagnostic ratios calculated from urinary steroid hormone metabolites are used as a measure for the relative activity of steroidogenic enzymes or pathways in the clinical investigation of steroid metabolism disorders. However, population-based sex- and age-specific reference intervals and day-night differences in adults are lacking.

Methods: Sixty-five diagnostic ratios were calculated from steroid metabolites measured by GC-MS in day- and night-time and in 24-hour urine from 1128 adults recruited within the Swiss Kidney Project on Genes in Hypertension (SKIPOGH), a population-based, multicenter cohort study.

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

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.

Correction: Reference intervals for the urinary steroid metabolome: The impact of sex, age, day and night time on human adult steroidogenesis.

[This corrects the article DOI: 10.1371/journal.pone.

Photophysical properties of -methyl and -acetyl substituted alloxazines: a theoretical investigation.

The electronic structure and photophysical properties of a series of N-methyl and N-acetyl substituted alloxazines (AZs) were investigated with extensive density functional theory (DFT) and time-dependent density functional theory (TD-DFT) based calculations. We showed that non-radiative decays from the lowest singlet and triplet excited states of these AZs are dominant over their radiative counterparts. The fast non-radiative decays of the excited AZs can be attributed to the energy consumption (Ereorg) through structural reorganization facilitated by the intrinsic normal modes of the alloxazine framework, as well as their coupling with those of the functional groups.

Twisted Bodipy Derivative as a Heavy-Atom-Free Triplet Photosensitizer Showing Strong Absorption of Yellow Light, Intersystem Crossing, and a High-Energy Long-Lived Triplet State.

A Bodipy derivative with twisted π-conjugation system is demonstrated that shows efficient intersystem crossing (ISC) (singlet oxygen quantum yield Φ = 55%) and a long-lived triplet state (τ = 197.5 μs) with high energy ( = 1.44-1.

Elucidation of the Intersystem Crossing Mechanism in a Helical BODIPY for Low-Dose Photodynamic Therapy.

Intersystem crossing (ISC) of triplet photosensitizers is a vital process for fundamental photochemistry and photodynamic therapy (PDT). Herein, we report the co-existence of efficient ISC and long triplet excited lifetime in a heavy atom-free bodipy helicene molecule. Via theoretical computation and time-resolved EPR spectroscopy, we confirmed that the ISC of the bodipy results from its twisted molecular structure and reduced symmetry.

Efficient Photooxidation of Sulfides with Amidated Alloxazines as Heavy-atom-free Photosensitizers.

Photooxidation utilizing visible light, especially with naturally abundant O as the oxygen source, has been well-accepted as a sustainable and efficient procedure in organic synthesis. To ensure the intersystem crossing and triplet quantum yield for efficient photosensitization, we prepared amidated alloxazines (AAs) and investigated their photophysical properties and performance as heavy-atom-free triplet photosensitizers and compared with those of flavin (FL) and riboflavin tetraacetate (RFTA). Because of the difference in the framework structure of AAs and FL and the introduction of carbonyl moiety, the absorption of FL at ∼450 nm is blue-shifted to ∼380 nm and weakened (ε = 8.

Long-Lived Triplet Excited State Accessed with Spin-Orbit Charge Transfer Intersystem Crossing in Red Light-Absorbing Phenoxazine-Styryl BODIPY Electron Donor/Acceptor Dyads.

Orthogonal phenoxazine-styryl BODIPY compact electron donor/acceptor dyads were prepared as heavy atom-free triplet photosensitizers (PSs) with strong red light absorption (ϵ=1.33×10  M  cm at 630 nm), whereas the previously reported triplet photosensitizers based on the spin-orbit charge transfer intersystem crossing (SOCT-ISC) mechanism show absorption in a shorter wavelength range (<500 nm). More importantly, a long-lived triplet state (τ =333 μs) was observed for the new dyads.

Are Steroid Hormones Dysregulated in Autistic Girls?

Evidence of altered cholesterol and steroid hormones in autism is increasing. However, as boys are more often affected, evidence mainly relates to autistic males, whereas evidence for affected autistic girls is sparse. Therefore, a comprehensive gas chromatography mass spectrometry-based steroid hormone metabolite analysis was conducted from autistic girls.

Consecutive Photoinduced Electron Transfer (conPET): The Mechanism of the Photocatalyst Rhodamine 6G.

The dye rhodamine 6G can act as a photocatalyst through photoinduced electron transfer. After electronic excitation with green light, rhodamine 6G takes an electron from an electron donor, such as N,N-diisopropylethylamine, and forms the rhodamine 6G radical. This radical has a reduction potential of around -0.

Dimerization of LOV domains of Rhodobacter sphaeroides (RsLOV) studied with FRET and stopped-flow experiments.

The bacterium Rhodobacter sphaeroides has a short LOV (light-oxygen-voltage) domain, which is not connected to an effector domain but has an α-helix extension at the N-terminus as well as a helix-turn-helix (HTH) motiv at the C-terminus. These extensions offer possibilities for interactions with effector enzymes or DNA. Whereas many LOV domains show a tendency to form dimers in the light state, RsLOV is unique in that it is a dimer in the dark state but dissociates into monomers after blue-light excitation.

Spin-Orbit Charge-Transfer Intersystem Crossing (ISC) in Compact Electron Donor-Acceptor Dyads: ISC Mechanism and Application as Novel and Potent Photodynamic Therapy Reagents.

Spin-orbit charge-transfer intersystem crossing (SOCT-ISC) is useful for the preparation of heavy atom-free triplet photosensitisers (PSs). Herein, a series of perylene-Bodipy compact electron donor/acceptor dyads showing efficient SOCT-ISC is prepared. The photophysical properties of the dyads were studied with steady-state and time-resolved spectroscopies.

Can Coumarins Break Kasha's Rule?

Coumarin was reported ( Signore et al., , 2010 , 132 , 1276 and Brancato et al., , 2015 , 119 , 6144 ) to break Kasha's rule.

MELEXIR: maximum entropy Legendre expanded image reconstruction. A fast and efficient method for the analysis of velocity map imaging or photoelectron imaging data.

A fast and efficient method is presented that recovers a three-dimensional cylindrically symmetric probability distribution from its two-dimensional projection onto a plane parallel to the cylinder axis. This problem arises regularly in the analysis of data from velocity map imaging or photoelectron imaging experiments. The data can be considered the (numerically stable) Abel transform of the unknown probability distribution.

Lighting the Flavin Decorated Ruthenium(II) Polyimine Complexes: A Theoretical Investigation.

The emission properties of a series of flavin (FL) decorated Ru (II) polyimine complexes were investigated by extensive time-dependent (TD) density functional theory (DFT) and DFT based calculations. We attributed the moderate emission properties of FL decorated Ru(II) polyimine complex (Ru-1), such as triplet lifetime and luminescence quantum yield, to the dominant fast nonradiative decay due to the small adiabatic energy gap between the ground state and the lowest lying triplet state (Δ E) and the slow radiative decay owing to the ligand localized triplet (IL) nature of the emissive state. Electron withdrawing groups such as F and Cl were attached to the FL moiety of Ru-1 to alter Δ E.