The squaraine chromophores, which have single, two-branched, and three-branched structures with ethynyl-triphenylamine central units, exhibit efficient two-photon absorption (TPA) with a cross section that corresponds to the number of branches present, indicating an additive effect. Among these chromophores, the three-branched dye displays the highest TPA cross section, reaching a maximum value of 4.0×10³ GM.

Abstract

We developed multi-branched π-conjugated systems using squaraine dyes with triphenylamine cores connected by ethynylene linkers. We investigated the influence of interbranch coupling between squaraine branches on their one-photon (OPA) and two-photon absorption (TPA) properties. These dyes with triphenylamine components showed a red-shifted one-photon absorption (OPA) compared to the precursor squaraine dyes. Among branched dyes, the lack of apparent splitting or shift in the absorption maxima, even as the absorption intensity increased with the number of chromophores, implies the presence of limited exciton coupling between the squaraine branches. The present squaraine dyes with triphenylamine cores exhibited a moderate TPA compared to the precursor squaraine without the triphenylamine core, due to the extended π-conjugation. Notably, both the 3-branched and 2-branched dyes demonstrated additional enhancement in the TPA response, surpassing that of the monochromophoric counterpart. This resulted in achieving a substantial TPA cross section of up to 3905 GM at 830 nm.

Specific nitridation conditions produced distinct types of BaTaO₂N (BTON) particles, one type with overall water splitting activity (Active-BTON) and the other without this activity (Inactive-BTON). Electrochemical and photoelectrochemical properties of the Active- and Inactive-BTON were investigated using the particulate photoelectrodes. Enhanced photocurrent generation by Active-BTON is due to the better semiconducting properties, such as lower carrier concentration related to defects and impurities within BTON particles.

Abstract

A BaTaO₂N (BTON) particulate photocatalyst enables solar water splitting in response to visible light irradiation at wavelengths of up to 640 nm. The specific nitridation conditions produced distinct types of BTON particles with the capability of one-step overall water splitting (Active-BTON) and without the overall water splitting activity (Inactive-BTON). Unveiling the intrinsic differences between the active- and inactive-BTON particles is crucial for obtaining more in-depth information about the water splitting activity. Herein, we investigated the electrochemical (EC) and photoelectrochemical (PEC) properties of these BTON photocatalysts using the particulate-based photoelectrodes for water splitting. EC measurements, including Mott–Schottky analysis, revealed that the flat band potential of Active-BTON is located at a potential that is more positive than that of Inactive-BTON, whereas the carrier concentration of Active-BTON is one-tenth lower than that of Inactive-BTON. Irrespective of the pH value of the 1.0 M potassium phosphate aqueous solution, the Active-BTON-based photoelectrodes showed a higher photocurrent than that of Inactive-BTON under simulated AM 1.5G solar illumination. The PEC performance of the BTON was found to be limited by the electrocatalytic activity of the CoO _x co-catalyst, specifically the electrolyte pH.

Shine bright: Persistent luminescent Cr-doped ZnGa₂O₄ (CZGO) is incorporated into an amorphous calcium phosphate (ACP) matrix. Annealing CZGO prior to ACP integration greatly improves its luminescence intensity and duration. Zn²⁺ redistribution from CZGO to ACP is identified, leading to the formation of Zn₃(PO₄)₂ when immersed in water. The nanocomposite exhibits high stability under prolonged X-ray exposure.

Abstract

Persistent luminescence (PersL) is an optical phenomenon which allows for materials to emit luminescence after ceasing excitation. The long-lasting luminescence is ascribed to the presence of trap states, which can be exploited through the introduction of various dopants and post-synthesis treatment. In this study, ZnGa₂O₄ : Cr³⁺ (CZGO), one of the most widely investigated near-infrared-emitting PersL materials, is synthesized in the form of nanoparticles, and incorporated into amorphous calcium phosphate (ACP) to form a luminescent nanocomposite with drug attachment potential. The effects of annealing CZGO in the composite are comparatively studied alongside the composite that contains unannealed CZGO. We find that ACP with annealed CZGO exhibits much higher luminescence intensity and longer PersL duration. The formation of the nanocomposite also results in the redistribution of Zn, and its influence on the composite luminescence intensity and the long-term chemical stability are investigated.

Zinc phthalocyanines have demonstrated a wide range of applications as photosensitisers, particularly in organic synthesis, photocatalysis and photodynamic therapy. Although the introduction of ionic groups on the macrocycle periphery increases their water solubility, aggregation phenomena remain as a significant drawback for their application. In this study, amphiphilic sulfonatocalix[4]arene-based micelles were used to promote the monomerization of a cationic phthalocyanine through host–guest interactions. A comprehensive spectroscopic characterization was conducted, varying the concentration of sulfonatocalix[4]arene, and binding parameters were calculated to determine the optimal conditions for complete monomerization of the photosensitizer in water. Under these conditions, the combination of sulfonatocalix[4]arene and the photosensitizer activated its photophysical activity in aqueous media, showing significant singlet oxygen photoproduction, photocatalytic capability and photostability.

Photoswitchable and bioactive: We report vinyl phosphonates with laser-induced cis to trans isomerization via a C=C bond. Cis isomers of the compounds possess some butyrylcholinesterase inhibition, while laser-induced trans isomers demonstrate steep inhibition increase. The presented vinyl phosphonates are highly requested objects for photopharmacology, as they ensure a unique combination of photoswitchable and bioactive properties.

Abstract

Photoswitchable molecules are highly requested compounds in various fields and, in particular, biomedicine. The urgent modern task of photopharmacology (an emerging approach in medicine) is the design of molecules that have both photoswitchable and bioactive properties. In this study, we present vinyl phosphonates – diene compounds with ethyl and isopropyl substituents on the phosphonate group. Both compounds demonstrated laser-induced cis-trans isomerization via a C=C bond after irradiation at 266 nm. The photoisomerization quantum yield was 17 % and 20 % for compounds with ethyl and isopropyl groups, respectively. The main advantage of the presented vinyl phosphonates is their bioactivity, unlike other photoswitchable molecules. Rather efficient butyrylcholinesterase inhibition by both presented compounds was demonstrated by IPC-Micro analysis. The notable butyrylcholinesterase inhibition increase by 5 and 9 times was found for the vinyl phosphonates after laser irradiation. Such a sizeable difference in inhibition values for different isomeric states is a critical factor, which opens the way toward promising applications of vinyl phosphonates as photopharmacological agents.

It is all About That Base: Simply by switching the base it is possible to access both bis(aroyl-S,N-ketene acetals) as well as diethylamino-aroyl-S,N-ketene acetals. The latter show strong solid-state emission as well as outstanding aggregation-induced emission properties thus conveying a 53-fold increase in emission intensity.

Abstract

Donor-substituted aroyl-S,N-ketene acetals can be rapidly obtained by nucleophilic attack of triethylamine at the acid chloride with concomitant decarbonylation followed by addition-elimination reaction of in situ generated enamines. These potent chromophores exhibit intensive solid-state emission and pronounced AIE (aggregation-induced emission) characteristics with high quantum yields. By changing the base to diisopropylethylamine, enlarged aroyl-S,N-ketene acetal bi- and trichromophores are easily accessible.

Photoswitchable macrocycles: Recent development of azobenzene, diarylethene, (Stiff-)stilbene or dihydroazulene-based photoswitchable macrocycles, for which conformation, dynamic, photo or thermal isomerization can be controlled by multiple photoswitching units, coordination-driven self-assembly, anion/cation binding or pH modulation, is reviewed, along with applications in encapsulation and release, in the reversible modulation of chemical, biological, electronic, fluorescent and chiroptical properties by light.

Abstract

Thanks to supramolecular interactions of macrocyclic compounds with their guest ions or molecules, macrocycles have found wide applications in molecular and chiral recognition, separation, transportation, molecular machines, and so on. Photoswitchable macrocycles are especially appealing and attracting more and more interest because the embedded molecular photoswitch enables dynamic control of molecular shape, conformation, and different properties by light, a non-invasive, remote and highly tunable stimulus. With available photochromic compounds, various photoswitchable macrocycles have been developed. In this review paper, we describe the recently reported photoswitchable macrocyclic compounds, with a focus on the control of the macrocyclic structure, dynamic, photo or thermal isomerization, as well as their applications on encapsulation and release of ionic or aromatic species, on the reversible modulation of chemical, biological, electronic, fluorescent and chiroptical properties by light.

Chiral luminescent radicals: Based on the origin of chirality, we classified the currently reported chiral luminescence radicals into three categories, intrinsic chiral luminescent radicals, luminescent radicals with chiral substitutions, and field-regulation-induced chiral luminescent radicals. This brief review of their properties aims to provide basic guidelines for the development of these systems and to support further development of novel chiral luminescent radical systems.

Abstract

Chiral luminescent materials are a class of materials capable of emitting circularly polarized light (CPL). Radicals are unique open-shell compounds with exceptional photoelectromagnetic properties that can be exploited in constructing novel chiral luminescent materials. This Concept discussed three main catalogues for producing organic CPL radicals, intrinsic chiral luminescent radicals, luminescent radicals with chiral substitutions, and field-regulation-induced chiral luminescent radicals. The brief review of their properties aims at providing basic guidelines and supporting further development of novel chiral luminescent radical systems.

Recent advances in photoinduced borylation reactions employing an electron donor–acceptor complex photoactivation strategy are reviewed. The milestones achieved in the area as well as the existing limitations are highlighted. Additionally, possible future developments that could further advance this field are discussed.

Abstract

Photoinduced borylation is becoming a fascinating and growing research field in synthetic chemistry. On the other hand, electron donor–acceptor (EDA) complex photoactivation has emerged as an alternative strategy to generate active open-shell species without the need for photosensitizers. Suitable organoboron compounds can serve as the electron donor or acceptor to form the corresponding electron donor–acceptor complexes, which then undergo photoinduced intracomplex single electron transfer (SET) to generate carbon- or boron-centered radicals for the construction of new C−B bonds. In this Concept paper, we review recent advances in photoinduced borylation via the EDA complex photoactivation strategy surveying the relevant literature until December 2022.

Reacting the eosin Y (EOS) dianion and ytterbium(III) in ethanol and under basic conditions afforded an EOS-Yb lake pigment able to transform low-energy photons, specifically near-infrared (NIR) photons, into higher energy photons. The process eventually lead to long-lived sensitized emission of the dye (microseconds) through cooperative sensitization (CS) upconversion.

Abstract

Materials based on organic chromophores and lanthanides able to transform low-energy photons, specifically near-infrared (NIR) photons, into higher energy photons to eventually lead to long-lived sensitized emission of the dye are highly desirable. Cooperative sensitization (CS) upconversion has only been accomplished for lanthanide-based clusters. We used here the eosin Y (EOS) dianion and Yb³⁺ (EOS-Yb), and demonstrate the efficient CS emission of the dye after NIR excitation. Remarkably, the EOS dianion emission exhibits a nearly linear dependence on the EOS-Yb concentration and a quadratic dependence on the laser power density. The emission is non-sensitive to oxygen and its lifetime lasts about 1.76 μs and 12 μs in DMSO and DMSO-d₆ , respectively. Moreover, the effect of temperature (293–363 K range) on the EOS-Yb ¹H NMR spectroscopic shifts demonstrates the reversible dynamic nature of the material.