ChemPhotoChem最新文献

Low-cost organic photovoltaic (OPV) devices have shown enormous potential in large-scale industrial applications. And it has attracted widespread attention in the past few decades. However, the photophysical characteristics of these budget-friendly materials haven't been explored much. Here, low-cost small materials, including small molecule 1 (asm1) with ortho-fluorinated side chain and small molecule 2 (asm2) with meta-fluorinated side chain were selected to probe the fluorination effect on the absorption spectra, electrochemical energy levels, electrostatic potential (ESP), etc. The results show that the molecules asm1 and asm2 have good planarity of the backbone. And the meta-fluorinated side chain of asm2 contributes more to the highest occupied molecular orbital and less to the lowest unoccupied molecular orbital than asm1. Moreover, differences in ESP are found between donor and acceptor materials. Furthermore, strong and broad light absorption in the visible region of these low-cost molecules is observed, resulting in a better short-circuit current density for the devices constructed by the donors asm1, asm2, and acceptor Y6. In addition, more charge transfer mechanisms are characterized for the asm1/Y6 system. The introduction of ortho-fluorination in the conjugated side chain of the molecule is a favorable approach, which will provide theoretical guidance for further molecular design experiments.

We explore excited-state dynamics of 4,4’-dimethylaminonitrostilbene (DNS), a push-pull stilbene, undergoing twisted intramolecular charge transfer and/or trans to cis isomerization, which is dependent on solvent polarity. We show how global analysis of femtosecond pump/broadband-probe data aids in elucidating the involvement of interconverting conformers and/or isomers, and the timescales associated with such interconversion, often unexplored in single-wavelength kinetic analysis.

Dual-state emission luminescent materials (DSEgens), which exhibit bright emissions in boththe solid state and solution, have been attracting research interest in the design of multifunctional materials.The delicate manipulation of molecular structures remains challenging in the synthesis of DSEgens. In this article, two novel molecules with dual-state emission were synthesized by combining tetraphenylethylene with anthracene via dihydroisoxazole. Tetraphenylethylene acts as a solid-state emitter, while the anthracene core functions as an emitter in the solution state to achieve DSE fluorescence properties. The THF/DCM mixture resulted in successfully obtaining the crystal structures of TPE−An−H and TPE−An−Cl. The quantum yields (QYs) of TPE−An−H were 31 % and 42 % in EA and the solid state, respectively, while TPE−An−Cl exhibited QYs of 32 % and 34 %. The novel synthesis method in this paper combines AIE with ACQ via dihydroisoxazole to achieve dual-state emission, offering a new and concise approach.

There are many options to design a molecular structure that could result in thermally activated delayed fluorescence (TADF). One promising strategy is to use the donor-π-acceptor motive where an electron-donating unit is linked to an electron-acceptor via an aryl moiety like phenyl. While this approach is widely used and well understood, the performance of the chromophores can be limited by different energy loss pathways, e. g. internal conversion, or by π-stacking. To circumvent these problems rigid structures with sterically demanding substituents are applied. In this work, we designed two TADF emitters based on phenothiazine and nitrile linked via spiro-9,9’-bi[fluorene] or 9,9-dimethylfluorene and compared the effect of the linker on the physical properties of the dyes. This work emphasizes the importance of careful design of conjugated spacer for efficient TADF emitters.

The Front Cover presents a nanohybrid system consisting of the photocatalyst TiO₂, photothermal gold nanoparticles, and thermo-responsive poly-N-isopropylacrylamide (TiO₂-Au-PNM). This system combines the photothermal-controlled cargo release, triggered by visible-light irradiation, mediated by lower critical solution temperature (LCST) and by photothermal conversion effect, with the excellent photocatalytic effect prompted by UVB-light excitation. More information can be found in the Research Article by Salvatore Petralia and co-workers (DOI 10.1002/cptc.202400088).

A series of diphenylboron and 9-borafluoren-9-yl complexes with chiral Schiff-base ligands was synthesized and characterized by NMR spectroscopy. X-ray diffraction analysis revealed that their boron centers were adapted to tetrahedral coordination geometry. Although boron complexes with salicylideneimine backbones exhibited a weak circularly polarized luminescence (CPL), the CPL brightness (B_CPL) was enhanced more than 9-fold by the π-extension of the Schiff base ligands. Time-resolved emission decay analysis and theoretical calculations based on density functional theory (DFT) were conducted to further understand their luminescent properties.

Visible-light induced, photoredox catalysis has opened a wide range in the transformation of organic compounds in recent times. In synthetic organic chemistry HAT (hydrogen atom transfer) and SET (single electron transfer) mechanisms are a very noteworthy routes that has opened a window in favor of C−C single bond formations. Usually, a major role of unsaturated hydrocarbons is to participate in carbon-carbon bond formation as they carry reactive π-bond. Under visible-light, metal-free cross-coupling reactions are particularly favorable because of their atom economy, increased efficiency, and environmentally friendly procedures that result in the construction of C−C bonds. The review emphasizes the latest advancements of visible-light mediated, cross-coupling reactions of unsaturated hydrocarbons in metal-free conditions for constructing carbon-carbon single bonds.

The synthesis of diketopyrrolopyrrole (DPP) derivatives followed the well-known conventional cross-coupling methods such as Suzuki, Stille, Sonogashira, and Negishi cross-coupling reactions. However, these methods required unfavorable reaction conditions, organometallic precursors, and high temperatures. In addition, the synthesis of conventional cross-coupling partners including organoboranes, stannane, and acetylenes required drastic reaction conditions and strong bases. In this work, a wide variety of thiophene-diketopyrrolopyrrole (TDPP)-based semiconducting materials (36 compounds) were synthesized via Pd-catalysed photoredox methodology by using N-hydroxyphthalimide (NHP) based coupling partners, which can be readily prepared from N-hydroxyphthalimide and carboxylic acid or aldehyde derivatives via single step C−O bond formation reactions with good yield (80–90 %). This methodology minimizes additional synthetic steps, harsh reaction conditions, and high temperature (100–150 °C). Optoelectronic studies suggest that the synthesized materials have suitable band gap, HOMO and LUMO levels for variety of optoelectronic applications. To the best of our knowledge, this is the first report on the synthesis of TDPP-based π-conjugated materials via the photoredox method.

Using visible light conditions, we have developed a green protocol to prepare copper oxide-doped graphitic carbon nitride (Cu₂O@g-C₃N₄) photocatalysts with varied ratios of g-C₃N₄ nanosheets to copper oxide-dopant (0.1 %, 0.5 %, 0.7 %, and 5 % respectively) and characterized through various physicochemical techniques. These photo-responsive catalysts were used for the 1,4 radical oxidative addition of trans crotonaldehyde into β-hydroxybutyric acid (BA) as a major product, utilizing 30 % hydrogen peroxide as an oxidant and a white LED (Light Emitting Diode) source. Under the innoculous eco-friendly stipulations, Cu₂O@g-C₃N₄ (5 %) exclusively promoted the aforementioned reaction leading to 99.85 % trans crotonaldehyde conversion with 66.57 %, 24.1 %, and 9.1 % selectivity for β-hydroxybutyric acid, crotonic acid and subsequent radical synthesis, respectively.

Thermally activated delayed fluorescence (TADF) materials have attracted considerable interest due to their ability to enhance electrochemiluminescence (ECL). This is achieved through the efficient upconversion of triplet excitons and the subsequent radiative transitions. However, despite the potential of TADF materials, there have been few studies exploring their application in ECL field. Accordingly, in this concept, a number of TADF materials, which can be categorized into two principal groups based on intramolecular bond charge transfer and intermolecular space charge transfer, are introduced in order to explore the potential for their application in ECL. A brief review of their properties not only helps to deepen the understanding of the nature of TADF materials, but also provides basic guidance and support for the introduction of the TADF mechanism into ECL systems, with the aim of enhancing the luminescence efficiency of ECL.