Relaxation dynamics of higher excited states of perylene-substituted perylene bisimide derivatives.

Stepwise two-photon absorption processes have received considerable attention, especially in photocatalysis, due to their relatively lower power threshold, characteristic spatial selectivity, amplification of chemical reactions, and so on. Meanwhile, studies on the relaxation dynamics of higher excited states in condensed systems have been limited for several molecular systems due to the short-lived nature of these states. In this study, we synthesized perylene-substituted perylene bisimide (PBI) and its derivate as model compounds and investigated their excited-state dynamics, including higher excited states, using pump-repump-probe spectroscopy.

Multiphoton-Driven Photocatalytic Defluorination of Persistent Perfluoroalkyl Substances and Polymers by Visible Light.

Perfluoroalkyl substances (PFASs) and fluorinated polymers (FPs) have been extensively utilized in various industries, whereas their extremely high stability poses environmental persistence and difficulty in waste treatment. Current decomposition approaches of PFASs and FPs typically require harsh conditions such as heating over 400 °C. Thus, there is a pressing need to develop a new technique capable of decomposing them under mild conditions.

Photodoping-based broadband photochromism of semiconductor nanocrystals under air operated by a supramolecular gel.

We herein report photodoping and thereby photochromism of semiconductor nanocrystals under air in a temperature-responsive supramolecular gel and its back reactions induced by direct heating or near-infrared photothermal conversion. We also present their application to the spatiotemporal patterning of photoluminescence.

A Nonlinear Photochromic Reaction Based on Sensitizer-Free Triplet-Triplet Annihilation in a Perylene-Substituted Rhodamine Spirolactam.

Nonlinear photochromic reactions that work with weak incoherent light are important for molecular operations with high spatial resolution and multiple photofunctions based on single molecules. However, nonlinear photochromic compounds generally require complex molecular design, restricting accessibility in various fields. Herein, we report nonlinear photochromic properties in a perylene-substituted rhodamine spirolactam derivative (Rh-Pe), which is synthesized from rhodamine B in facile procedures.

Effect of the bulkiness of alkyl ligands on the excited-state dynamics of ZnO nanocrystals.

Organic ligands on the surface of nanocrystals (NCs) are extremely important in influencing various physical properties, such as dispersibility, electrical properties, and optical properties. Recent studies have revealed that a slight difference in the molecular structure of aliphatic organic ligands significantly affects the dispersibility of the NCs. On the other hand, the effects of the difference in the molecular structure of ligands on the excited-state dynamics of NCs remain elusive.

Unraveling Steric Effects on Ultrafast Bond-Dissociation Processes of Photochromic Radical Complexes.

Photochromic reactions of the phenoxyl-imidazolyl radical complex (PIC), which is one of the rate-tunable fast T-type photoswitches, dramatically change by the introduction of bulky substituents around the photochromic units. While these substituents are expected to affect the initial bond dissociation processes, they have not been elucidated yet. Here, we revealed the ultrafast bond dissociation processes of PIC derivatives with different bulky substituents by subpicosecond to nanosecond transient absorption spectroscopy.

Control survey and analysis for the KEK e-/e+ injector linac.

A control survey technique using a laser tracker and a digital level was introduced to the KEK e-/e+ injector linac in 2020. Control surveys are continuously demonstrated during the machine's downtimes every summer. Analysis of the two-year data reproduces their trends in terms of the fiducial points on the beam line.

Photochromic dinuclear iridium(III) complexes having phenoxyl-imidazolyl radical complex derivatives.

We demonstrate that the phenoxyl-imidazolyl radical complex (PIC), which is a rate-tunable fast photoswitch, can be used as a ligand that directly coordinates with iridium (III) ions. The iridium complexes show the characteristic photochromic reactions originating from the PIC moiety, whereas the behaviour of transient species is substantially different from that of the PIC.

Ion-Pairing Assemblies of Dithienylnitrophenol-Based π-Electronic Anions Stabilized by Intramolecular Interactions.

Dithienylnitrophenols were synthesized as precursors of π-electronic anions, which were stabilized by intramolecular chalcogen bonding, forming various ion pairs in combination with cations. The modes of solid-state charge-by-charge assemblies, along with solution-state stacking and photoinduced electron transfer behaviors, were modulated by the constituent ionic species.

Excited State Engineering in Ag Nanocluster through Peripheral Modification with Silver(I) Complexes for Bright Near-Infrared Photoluminescence.

The optical property of an ionic metal nanocluster (NC) is affected by the ionic interaction with counter ions. Here, we report that the modification of trianionic [Ag(BDT)(TPP)] NC (BDT: 1.3-benzenedithiol; TPP: triphenylphosphine) with silver(I) complexes led to the intense photoluminescence (PL) in the near-infrared (NIR) region.

Substituent-Dependent Photoexcitation Processes of π-Stacked Ion Pairs.

Porphyrin ion pairs, the charge of which is delocalized in core units, form tightly associated structures through π- π interactions. 5,10,15-Triphenyl-substituted porphyrin-Au complex, which is favorable for forming stacked structures in the form of a stable ion, has been synthesized. Ion-pair metathesis based on the hard and soft acids and bases theory enabled combination with porphyrin anions possessing electronic states controlled by electron-donating and electron-withdrawing groups.

Anion-Driven Circularly Polarized Luminescence Inversion of Unsymmetrical Europium(III) Complexes for Target Identifiable Sensing.

Anion-responsive sign inversion of circularly polarized luminescence (CPL) was successfully achieved by NO-type nona-coordinated europium(III) (Eu) complexes [()- and ()-] composed of a less-hindered unsymmetrical N-tridentate ligand (a chiral bis(oxazoline) ligand) and three O-chelating (β-diketonate) ligands. Here, ()- exhibited a positive CPL signal ( - > 0) at the D → F transition of Eu, which can be changed to a negative sign (i.e.

Structure Determination of Europium Complexes in Solution Using Crystal-Field Splitting of the Narrow - Emission Lines.

Nine nona-coordinated Eu(III) complexes (-) studied here have three unsymmetric β-diketonate ligands and one chiral Ph-Pybox ligand, which can produce eight possible coordination isomers, depending on the position of the three unsymmetric β-diketonate ligands. Substituents on the β-diketonate ligands cause a rational structural rearrangement upon crystallization. Substituents with higher polarity, including -CN, -F, -Cl, -Br, -OMe, and -OEt, employ intercomplex hydrogen bonding to generate an association complex through structural rearrangement upon crystallization.

Helix-mediated over 1 nm-range chirality recognition by ligand-to-ligand interactions of dinuclear helicates.

Long-range chirality recognition between the two chiral guest ligands can be tuned based on the helix distances ( = 11.5 and 14.0 Å) of bis-diketonate bridged dinuclear lanthanide complexes ( and , respectively) used as mediators.

Visible Circularly Polarized Luminescence of Octanuclear Circular Eu(III) Helicate.

This work reports on the structural and photophysical characterization of -symmetrical octanuclear circular Ln helicates, [()- or ()-Pr-Pybox](Ln)(THP) (where Ln = Eu and Tb, THP = trianionic tris-β-diketonate, and Pr-Pybox = chiral bis(4-isopropyl-2-oxazolinyl)pyridine). X-ray crystallographic analysis revealed that the octanuclear circular helicate possesses square antiprism architecture and consists of four [()- or ()-Pr-Pybox]Ln(THP) asymmetric units arranged in a closed ring form. Ligand-to-ligand interactions between the THP and the Pr-Pybox ligands have successfully directed formation of enantiopure, homoconfigurational (Δ,Δ,Δ,Δ,Δ,Δ,Δ,Δ)- and (Λ,Λ,Λ,Λ,Λ,Λ,Λ,Λ)- isomers.

Design and Synthesis of Cyclometalated Iridium(III) Complexes-Chromophore Hybrids that Exhibit Long-Emission Lifetimes Based on a Reversible Electronic Energy Transfer Mechanism.

We report on the design and synthesis of triscyclometalated iridium (Ir) complexes that contain aryloxy groups at the end of diamino linkers, which exhibit an extraordinarily long-emission lifetime, and were prepared by regioselective substitution reactions of -tris-homoleptic cyclometalated Ir complexes, -Ir(tpy) (tpy = 2-(4'-tolyl)pyridine). It was found that the Ir(tpy) complex, equipped with approximately one to six 6-,-dimethylamino-2-naphthoic acid (DMANA) groups through the appropriate alkyl linkers, exhibited remarkably long-emission lifetimes of up to 216 μs in DMSO/HO at room temperature through a reversible electronic energy transfer effect between the Ir complex core and the organic chromophore moieties; however, under the same conditions, the lifetime of Ir(tpy) was 1.4 μs.

Utilisation of polarity inversion for phosphorus recovery in electrochemical precipitation with anaerobic digestion effluent.

Phosphorus is a non-replaceable and limited resource, whose future drought is a matter of concern. Its recovery from wastewater has gained attention as a method of making the recovered phosphorus available for beneficial use. This study applied electrolysis with a platinum-coated titanium electrode to an actual anaerobic digestion effluent and investigated the phosphorus removal and precipitation characteristics with various current values.

Unique Access to u-Channel Physics: Exclusive Backward-Angle Omega Meson Electroproduction.

Backward-angle meson electroproduction above the resonance region, which was previously ignored, is anticipated to offer unique access to the three quark plus sea component of the nucleon wave function. In this Letter, we present the first complete separation of the four electromagnetic structure functions above the resonance region in exclusive ω electroproduction off the proton, ep→e^{'}pω, at central Q^{2} values of 1.60, 2.

Significant Enhancement of Absorption and Luminescence Dissymmetry Factors in the Far-Red Region: A Zinc(II) Homoleptic Helicate Formed by a Pair of Achiral Dipyrromethene Ligands.

A homoleptic zinc(II) helicate organized by a pair of achiral dipyrromethene ligands through zinc(II) coordination was synthesized to evaluate the chiroptical properties. This zinc complex showed strong exciton-coupled chiroptical responses from the helical configuration with a large absorption dissymmetry factor |g | (up to 0.20).

The effect of ligand symmetry on the ratiometric luminescence characteristics of lanthanides.

This work demonstrated that the ligand symmetry of europium(iii) complexes controls the ratiometric luminescence characteristics of lanthanides. Nona-coordinated europium(iii) complexes having unsymmetrical β-diketonate ligands (Cs) exhibit distinctive ratiometric spectral variations in the extremely narrow f-f transition bands over the temperature range from 253 to 323 K. In contrast, no such ratiometric change can be observed in a series of nona-coordinated europium(iii) complexes containing symmetrical β-diketonate ligands (C2v).

Separated response function ratios in exclusive, forward π(±) electroproduction.

The study of exclusive π(±) electroproduction on the nucleon, including separation of the various structure functions, is of interest for a number of reasons. The ratio RL=σL(π-)/σL(π+) is sensitive to isoscalar contamination to the dominant isovector pion exchange amplitude, which is the basis for the determination of the charged pion form factor from electroproduction data. A change in the value of RT=σT(π-)/σT(π+) from unity at small -t, to 1/4 at large -t, would suggest a transition from coupling to a (virtual) pion to coupling to individual quarks.

Observation of the (Λ)(7)He hypernucleus by the (e, e'K+) reaction.

An experiment with a newly developed high-resolution kaon spectrometer and a scattered electron spectrometer with a novel configuration was performed in Hall C at Jefferson Lab. The ground state of a neutron-rich hypernucleus, (Λ)(7)He, was observed for the first time with the (e, e'K+) reaction with an energy resolution of ~0.6 MeV.

A shift in sphingolipid composition from C24 to C16 increases susceptibility to apoptosis in HeLa cells.

Sphingolipids, major lipid components of the eukaryotic plasma membrane, have a variety of physiological functions and have been associated with many diseases. They have also been implicated in apoptosis. Sphingolipids are heterogeneous in their acyl chain length, with long-chain (C16) and very long-chain (C24) sphingolipids being predominant in most mammalian tissues.