Photoinduced nitric oxide (NO) release for complexes [RuNO(L)2(NO2)2OH], where L = methyl isonicotinate (1), ethyl isonicotinate (2), methyl nicotinate (3) and ethyl nicotinate (4) was studied in DMSO, MeCN and water solutions (PBS, CTAB) using spectroscopic methods (UV-vis, IR, EPR) and spectrometric techniques (ESI-МS). Additionally, we present methodological evidence for improving the calculation of the quantum yield (QY) of NO release through the utilization of a combined IR-UV-vis-spectroscopy flow-through setup. According to DFT calculations, the production of nitric oxide occurs through the photoinduced cleavage of the Ru-NO bond, triggered by irradiation at 445 or 532 nm. This cleavage is a consequence of charge transfer from the orbitals of the Ru-OH group and the equatorial ligands (HOMO, HOMO-1) to the Ru-NO antibonding orbital (LUMO). The cytotoxicity and photoinduced cytotoxicity of the investigated compounds were assessed against the breast adenocarcinoma cell line MCF-7. Moreover, the investigation of the lipophilic properties of compounds 1-4 unveiled a significant influence of their lipophilicity on cytotoxic behavior, allowing for the modification of cytotoxicity through changes in the ligand L or by light irradiation.

Photoredox-catalysis was synergistically merged with nickel-catalysis for the synthesis of biologically important 3-benzyl indoles with good functional group tolerance. The merit of this methodology is demonstrated by the synthesis of amino acid derived substrates.

Abstract

Late-stage functionalization of indoles can be a valuable strategy for modifying different existing indolyl-drugs and natural products to get their new analogues. In this study, we report the photoredox-metal catalyzed decarboxylative arylation strategy of indole-3-acetic acids with aryl halides. Here, photoredox-catalysis was synergistically merged with nickel-catalysis for the synthesis of biologically important 3-benzyl indoles with good functional group tolerance. The merit of this methodology is demonstrated by the synthesis of amino acid derived substrates 3 p, 3 v and 3 x.

A shape-editable transparent wood with luminescent BODIPY is applied to smart decoration materials.

Abstract

Transparent wood (TW) combining unique anisotropic structure has broad application prospects in the field of advanced building furniture materials. Many efforts have been made to add quantum dots or nanoparticles to TW to endow it with additional functionality, such as luminescent, electrochromic, and thermochromic TW. However, luminous TW with shape-editable functionality and its new applications have yet to be explored. Benefiting from the excellent luminescence performance in a diluted solution state, BODIPY (4,4-difluoro-4-bora-3a,4a-diazas-indacene) dyes have been widely used for bio-sensing and bioimaging. In addition, vitrimers exhibit excellent stimuli-responsive, shape-memory, and reprocessing properties thanks to exchangeable dynamic covalent crosslinking networks, which are suitable for fabricating smart TW. Herein, combing these advantages, a dual-functional transparent wood composite (P-SEFTW) with photoluminescent and shape editable function was developed by introducing BODIPY dyes and vitrimers into the delignified wood (DW) templates. P-SEFTW displays good UV luminescence, unique light guiding and directional scattering effects. Meanwhile, it shows excellent shape-recovery, shape-programming, shape-erasing, and re-programming capability under thermal-stimulus. These characteristics enable TW to exhibit great prospect as an advanced smart and functional building material.

Indolino-oxazolidine derivatives are a new and pretty confidential family of multimodal molecular switch. Indeed, acid, electrochemical potential, and UV light irradiation can be used to convert these compounds form their colorless closed form to a colorful open form. In this publication, we have investigated the influence of the extension of the p-conjugated system beared by the indolino moiety on their halo-, electro- and photochromic properties. In this context, we have demonstrated that only their photochemical properties are strongly affected by this structural modification. Moreover, quantum chemistry calculations have allowed to rationalize our experimental observations and, noticeably, to evidence an oxidative quenching process in presence of chlorobenzene, which enhances their reactivity.

The photophysics of a helicene derivative in which two benzene units are replaced by thiophene units (thiohelicene, 6H) was studied by steady state and transient absorption and emission spectroscopies covering time ranges from femtoseconds to minutes. Efficient intersystem crossing (ISC) to the triplet state was observed, by far exceeding that of the parent helicene and the corresponding oxo-helicene. Quantum chemical calculations indicate that the helical distortion and the heavy atom effect of sulfur cooperate in promoting spin-orbit coupling, and that the most efficient decay channel involved the T2 or even the T3 state. These insights can help in the design of more efficient triplet sensitizes for may applications.

Photocatalytic hydro-difluoromethylaton of unactivated alkenes has been developed using a commercially available difluoromethylating reagent (CF₂HSO₂Na). This methodology tolerates a variety of functional groups and allows late-stage modification of various alkenes derived from pharmaceutically relevant drugs.

Abstract

In the present manuscript, we have reported a general catalytic strategy that allows the synthesis of a variety of difluoro methylated alkanes from the corresponding unactivated alkenes using commercially available radical difluoromethylating reagent (CF₂HSO₂Na) under visible light photocatalysis. Further, this strategy allows the late-stage modification of various alkenes derived from pharmaceutically relevant drugs.

In this Concept Article the scope, the limits, and the potential of the photoinduced [2+2] and [4+4] cycloaddition–cycloreversion sequence in the development of photoswitchable DNA binders are presented.

Abstract

In the current field of photopharmacology, molecular photoswitches are applied whose interactions with DNA can be triggered or controlled by light. And although several photochromic reactions have been shown to serve this purpose well, the reversible photocycloaddition and photocycloreversion reactions have been largely neglected. This absence of research is surprising because especially the photodimerization of a DNA ligand leads to products with significant change of the size and shape which, in turn, leads to strongly diminished or even suppressed DNA association. Therefore, photocycloaddition–cycloreversion sequences have a huge potential for the photoinduced, reversible deactivation and activation of ligand–DNA interactions, as will be shown with selected examples in this Concept Article. Specifically, heterostyryl and -stilbene derivatives are presented whose DNA–binding properties are efficiently switched in reversible [2+2] photocycloaddition reactions. In addition, the photocontrolled DNA–binding of anthracene derivatives and their heterocyclic benzo[b]quinolizinium analogues in a [4+4] photocycloaddition, as well as the use of this reaction as part of dual–mode switches in combination with redox-active functionalities, are highlighted. Furthermore, examples of conjugates are provided, in which the photochromic unit is bound covalently to nucleic acids or proteins, such that the photocycloaddition reaction can be used for reversible photoinduced crosslinking, ligation, or inhibition of gene expression.

Understanding the intersystem crossing (ISC) mechanism of organic compounds is essential for designing new triplet photosensitizers. We investigated the ISC mechanism of a heavy atom-free Bodipy derivative with thiomethyl substitution (S-BDP). A long-lived triplet state was observed with nanosecond transient absorption spectroscopy with lifetime of 7.5 ms in a polymer film and 178 ms in fluid solution, longer as compared with what was previously reported . Femtosecond transient absorption studies retrieved an ISC time constant of ~3 ns. Time-resolved electron paramagnetic resonance (TREPR) indicated a special triplet electron spin polarization phase (ESP) pattern (a, e, a, e, a, e), different from the typical ESP (e, e, e, a, a, a)  for the spin-orbit coupling mechanism. This indicates that the electron spin selectivity of the ISC of S-BDP is different from  the normal SOC effect in iodo-Bodipy. Simulations of the TREPR spectra give a zero-field-splitting D parameter of -2257 MHz, much smaller as compared to the reference 2,6-diiodo-Bodipy (D = -4380 MHz). The computed SOC matrix elements (0.28-1.59 cm-1) and energy gaps for the S1/Tn states suggest that the energy matching between the S1 and T2/T3 states (supported by the largest kISC ~109 s-1) enhances the ISC for this compound.

This review summarized the recent advances in Selenium-containing non-fullerene acceptors to give a deep insight into the relationship between molecular structure and photovoltaic performance.

Abstract

The diversity in molecular structures and solution processability of non-fullerene acceptors (NFAs), particularly those containing selenium (Se), plays a pivotal role in advancing organic solar cells (OSCs). Among various molecular design strategies, the introduction of selenium atoms, characterized by their large covalent radius, loose electron cloud, and strong polarization properties, can enhance intermolecular Se-Se interactions and improve the electron-donating capability of π-cores. This approach is considered a significant avenue for optimizing the photovoltaic performance of active layer materials. In this review, we provide a comprehensive summary of recent advancements in selenium-containing acceptor molecules. These include ITIC-based fused ring NFAs, Y6-based fused ring NFAs, Y6-based polymer acceptors, non-fused ring electron acceptors and their application in tandem and ternary OSCs. Additionally, we analyze the future prospects and development of selenium-containing NFAs with the goal of achieving OSC efficiencies exceeding 20 %.

Through the incorporation of a polycyclic heteroaromatic π-linker between their thiophene units, dithienylethene switches are shown computationally to exhibit a photocyclization reaction well exploitable for solar-energy storage, while also occupying a sweet spot for such applications where contrasting requirements on energy-storage densities and thermal cycloreversion barriers can be met.

Abstract

Dithienylethene photoswitches with an aromatic π-linker as the bridge between the two thiophene units are attractive starting materials for developing molecular solar thermal energy (MOST) storage systems, partly because the aromaticity of their ring-open forms is a favorable feature with regard to the energy-storage densities of their ring-closed forms produced by photoinduced electrocyclization (photocyclization) reactions. At the same time, this typically leads to small barriers for their thermal cycloreversion reactions, which are not desirable in this context. Here, we use computational methods to show that this problem can be circumvented with polycyclic heteroaromatic π-linkers. Specifically, through the tuning of the aromatic character of the individual rings of such a π-linker (like indole or isoindole), it is shown to be possible to strike a delicate balance between the seemingly contrasting requirements of simultaneously achieving both a high energy-storage density and a large cycloreversion barrier. Furthermore, this design is also found to provide for a quick and efficient photocyclization reaction, owing to the onset of excited-state antiaromaticity in the π-linker upon light absorption of the ring-open form. Altogether, dithienylethenes with polycyclic heteroaromatic π-linkers appear to have both thermal and photochemical properties suitable for further development into future MOST systems.