ChemPhotoChem最新文献

Cover image provided courtesy of Tomohiro Higashi and co-workers from University of Miyazaki, Japan.

Cover image provided courtesy of Tomohiro Higashi and co-workers from University of Miyazaki, Japan.

The Front Cover illustrates the micro-environments associated with photocatalytic cross-dehydrogenative coupling (CDC) reactions, wherein covalent organic frameworks (COFs) function as heterogeneous catalysts. COFs exhibit favorable photocatalytic activity in diverse chemical transformations, owing to their remarkable high crystallinity, excellent stability, and convenient recyclability. The CDC reactions represent an efficient and clean methodology for the formation of C-Nu (Nu = nucleophilic reagent) bonds through activation of C-H and Nu-H bonds, respectively. As expected, the robust COFs offer a highly versatile platform for heterogeneous photocatalytic CDC reactions. More information can be found in the Concept article by Bin Guo, David J. Young, Hong-Xi Li, and co-workers (DOI: 10.1002/cptc.202400274).

We report a pH-responsive system comprising three pH responsive fluorophores, 7-Hydroxy coumarin (7HC), Fluorescein (Flu), and Rhodamine B (RhB) wherein an efficient two-step Förster Resonance Energy Transfer (FRET) process is facilitated. Upon excitation of 7HC, energy is sequentially transferred from 7HC (primary donor) to Flu (primary acceptor) and then to RhB (secondary acceptor). The FRET processes were studied at pH 7 and 12 in the presence of surfactants: cationic Tetradecyltrimethylammonium bromide (TTAB), anionic Sodium Dodecyl Sulfate (SDS), and neutral polyoxyethylene[4] lauryl ether (Brij 30). Differences in FRET efficiencies across surfactant media were interpreted by analyzing the solubilization sites of the fluorophores using UV-Visible and fluorescence spectroscopy. The pH-dependence of the FRET acted as an ON-OFF switch, showing higher efficiency in alkaline media. Among the surfactant systems, the two-step FRET operated most efficiently in alkaline TTAB micelles, with efficiencies reaching up to 50 % for 7HC to Flu (FRET-1), 30 % for Flu to RhB (FRET-2), and 23 % for the overall transfer. At a donor-to-acceptor ratio of 1000/80/80, energy transfer efficiencies touched 74 % for FRET-1 and 84 % for FRET-2. This highlights TTAB micelles as promising scaffolds for efficient multi-step FRET-based artificial light-harvesting systems.

Pnictogen (Pn=As, Sb, Bi)-bridged sulfoximines were synthesized by introducing phenyl (Ph) and benzyl (Bn) groups onto the nitrogen atom. Single-crystal X-ray diffraction analysis and density functional theory (DFT) calculations revealed a weak closed-shell interaction between Pn and N or O. As- and Sb-bridged sulfoximines with a Bn group exhibited dual fluorescence in solution, while the others primarily showed a single emission. The viscosity and polarity of the solvent significantly affected dual-emission behavior. DFT calculations demonstrated the excited-state dynamics, showing that Pn⋅⋅⋅N (or Pn⋅⋅⋅O) interactions were either elongated or shortened upon photo-excitation, depending on the Pn type and the substituent on N.

Coumarins are highly polarized fluorophores with indispensable use in various applications, such as bioimaging, sensing, and optoelectronics, due to their inherent merits of tunable photophysical properties. Despite their established utility, ongoing research aims to further enhance and diversify their emission characteristics. Recent studies have demonstrated that strategic modifications, such as element replacement within the coumarin core, can significantly alter key attributes like absorption, emission, and quantum yields, all while preserving the fundamental benefits of their skeletal framework. This concept article highlights the latest progress in heteroatom substitution, including oxygen-to-nitrogen, silicon, sulfur, and carbon replacements, showcasing their impact on spectral tuning and their potential for the design of next-generation fluorophores.

All-optical modulation and optical switching with nonlinear materials are integral parts of the advancing all-optical communication network. This report discusses the synthesis of a promising pyrylium dye, pyrylium-NH₂ for NLO based applications and probes its spatial self-phase and cross phase modulation (XPM) properties. This dye can be effectively used for all-optical modulation and OR logic gate operation. A 532 nm DPSS laser of tunable power is used to study the intensity dependent nonlinear refractive indices (n₂) of the dye in ethanol, methanol and acetone. The dye has shown significant n₂ compared to the existing literature. Concentration dependence, incident intensity dependence and temporal evolution of the far field diffraction annuli rings in these three solvents were studied. The all-optical modulation of a weak signal beam is demonstrated using a high intensity pump beam via cross phase modulation, paving the way to optical switching applications.

The Front Cover illustrates organohalogenochromism (OHC) which induces a significant hypsochromic or bathochromic shift of photoabsorption band of dye in halogenated solvents. The expression of OHC would be ascribable to the specific intermolecular interaction between the organohalogen and the dye molecules, including halogen−anion interaction (i.e. halogen bond) and halogen/π interaction. The insight into the OHC allows us to create an optical spectroscopic method and functional dye material for detection and visualization of toxic volatile organohalogen compounds. More information can be found in the Concept article by Yousuke Ooyama and co-workers (DOI: 10.1002/cptc.202400187).

Current research on perovskite solar cells (PSCs) predominantly targets terrestrial applications, with limited studies in extreme environments. Deploying PSCs in space and underwater necessitates meeting stringent performance and stability criteria. For space, PSCs must withstand high radiation and temperature extremes, while underwater, light intensity attenuation, spectrum changes, and varying water quality can degrade PSCs performance. Inspiringly, PSCs offer several advantages, including being lightweight, cost-effective, easy to manufacture, and having adjustable bandgaps. These features make them more promising for applications in extreme conditions versus other photovoltaic (PV) devices. To further advance research on PSCs in extreme environments, this concept briefly describes the background of PSC applications in extreme conditions, summarizes the environmental characteristics and their impacts on the devices in both space and underwater settings, and comprehensively reviews the latest advancements in these fields. Finally, potential strategies for ensuring the long-term stable operation of PSCs under extreme stressors are proposed.

Pursuing the development of eco-friendly, cost-effective and flexible materials that offer high-color contrast and low power consumption is a promising approach for advancing the next-generation optoelectronic devices. Herein, we report the synthesis of a heteroleptic copper(I) complex [Xantphos-Cu-cmdf]PF₆ (C1), in high yield, using Xantphos and cmdf ligands. The complex has high thermal stability and displays low-energy absorption between 360 and 470 nm due to the metal-to-ligand charge transfer (MLCT) transition. The electrochemical analysis confirmed the electrochromic properties of C1. A bilayer electrochromic device (ECD) incorporating P3HT and C1 demonstrated excellent color modulation (45 %) and rapid switching times (less than one second). Furthermore, the flexible ECD utilizing C1 showed superior performance compared to its solid-state counterpart, with high efficiency (~200 cm²/C), color modulation (69 %) and sub-second switching times. The high coloration efficiency and fast switching time of the ECDs developed from stable and cost-effective Cu(I) complex, C1, make it a promising candidate for real-world electrochromic applications.