Journal of Photochemistry and Photobiology C: Photochemistry Reviews最新文献

Room-temperature optical manipulation of small molecules is a challenging issue in the field of material science. To increase optical force for a single molecule trapping, it has been recognized that resonant excitation of molecules should be controlled under the light illumination. Strongly interacting molecules with solid surfaces at electrified interfaces show the exotic behavior of electronic excitation by localized surface plasmon. In this review, we emphases that surface-enhanced Raman scattering can be used to evaluate the resonant excitation of target molecules at interfaces. Under such excitation, the diffusion of small molecules can be controlled by the optical force generated by the intensity gradient of a highly localized electric field.

Open-chain tetrapyrroles are ubiquitous and abundant in living organisms (algae, animals, bacteria, and plants), including examples such as bilirubin, biliverdin, phycocyanobilin, phycoerythrobilin, and urobilin. The open-chain tetrapyrroles, collectively termed bilins, arise from biosynthesis or degradation of tetrapyrrole macrocycles. Bilins are now known to play a wide variety of biological roles encompassing light-harvesting (in phycobiliproteins), photomorphogenesis, signaling, and redox chemistry. The absorption spectra of bilins spans the ultraviolet (UV), visible, to near-infrared (NIR) regions depending on the degree of conjugation, thereby providing a wide range of colors from red/orange to blue/green. The fluorescence intensity of bilins is often quite low and hence fewer spectra are available, but can be increased substantially by structural rigidification, as evidenced by the wide use of biliproteins as fluorescent labels. The present article describes a database of absorption and fluorescence spectra of bilins from natural and synthetic origins for 220 compounds (270 absorption and 13 fluorescence spectral traces). Spectral traces of bilins published over the past ∼50 years have been digitized and assembled along with information concerning solvent, photochemical properties (molar absorption coefficient and fluorescence quantum yield), and literature references. The spectral traces (xy-coordinate data files) can be viewed, downloaded, and accessed at www.photochemcad.com. The accessibility of spectral traces in digital format should facilitate identification and quantitative calculations of interest in diverse scientific areas.

Quantum dot light-emitting diodes (QLEDs) have developed rapidly in the last several decades, in which the maximum external quantum efficiency of the three primary color cadmium (Cd)-based QLEDs have exceeded the theoretical maximum value. However, the presence of Cd element has severely hampered their commercialization. Indium phosphide (InP)-based quantum dots (QDs) without heavy metals have continuously adjustable luminescence range from blue to near infrared, which is a competitive alternative for Cd-based QDs. Especially in the last few years, the synthesis techniques and the device structures of InP-based QLEDs have been greatly improved. In this review, we first introduce the properties of InP-based QDs, carrier dynamics and the early development history. Then, we focus on the development of InP-based red, green and blue primary color QLEDs from their first report in 2011 to the current state of the art. The effects of QDs structure (core/shell or gradient-alloyed QDs and organic ligand modified QDs) and device structure (charge transport layer and interfacial engineering) on the performance of InP-based QLEDs are also summarized.

The volatility of noble metals prices, globally increasing demands, and its limited resources drive chemists to find alternatives in the place of expensive transition metal catalysts. So, this is a time for the scientific community to find alternative sources to replace Nobel metals, and it is making genuine changes in developing sustainable synthetic methods. Photoexcited transition-metal catalysis is revitalizing the research area for functionalizing diverse π-bond systems. The massive progression of the two conventional photochemical reactivity modes, photoredox catalysis, and synergetic photocatalyst/transition-metal catalysis, has fueled the search for a next-level mechanistic paradigm visible-light initiated excited-state transition-metal catalysis (Cu, Pd, Fe, Au, Co, Ni, W, and Mn), which can be deployed to harvest light energy and convert it into chemical energy in a single catalytic cycle. This review summarizes early examples of the visible-light-induced photocatalytic activities of conventional transition metals employed in C-H activation, π-bond functionalization, and annulation reactions of unsaturated compounds, and excluding the commonly used expensive photocatalysts (i.e., Ir-, and Ru-based pyridyl complexes). Unlike the other two classical photochemical approaches, the discrete inner-sphere mechanism associated with photoexcited transition metals facilitates reactive substrate-metal-complex interactions. It enables the direct involvement of excited-state catalysts in bond-forming or-breaking processes.

In this account, the reactive oxygen species (ROS) in photodynamic therapy (PDT) were deliberately reviewed. First, the specific definition of ROS and PDT were readily clarified. Afterward, this review focuses on the fundamental principles and applications of PDT. Due to strong oxidation ability of radicals (e.g., •OH and O₂^•-) and non-radical (e.g., ¹O₂ and H₂O₂), these ROS would attack the in vitro and in vivo tumor cells, thus achieving the goal of cancer treatment. Then, ROS in PDT for cancer treatment was thoroughly reviewed, including the mechanism and photosensitizer (PS) selection (i.e., nanomaterials). Ultimately, emphasis was made on the challenges, research gap, and prospects of ROS in cancer treatment and critically discussed. Hopefully, this review can offer detailed theoretical guidance for the researchers who participate in the study regarding ROS in PDT.

I–III–VI multinary semiconductors, which have low toxicity, are attracting much attention as quantum dot (QD) materials for replacing conventional binary semiconductors that contain highly toxic heavy metals, Cd and Pb. Recently, the inherent design flexibility of multinary QDs has also been attracting attention, and optoelectronic property control has been demonstrated in many ways. Besides size control, the electronic and optical properties of multinary QDs can be changed by tuning the chemical composition with various methods including alloying with other semiconductors and deviation from stoichiometry. Due to significant progress in synthetic methods, the quality of such multinary QDs has been improved to a level similar to that of Cd-based binary QDs. Specifically, increased photoluminescence quantum yield and recently narrowed linewidth have led to new application fields for multinary QDs. In this review, a historical overview of the solution-phase synthesis of I–III–VI QDs is provided and the development of strategies for better control of optoelectronic properties, i.e., electronic structures, energy gap, optical absorption profiles, and photoluminescence feature, is discussed. In addition, applications of these QDs to luminescent devices and light energy conversion systems are described. The performance of prepared devices can be improved by controlling the optical properties and electronic structures of QDs by changing their size and composition. Clarification of the unique features of I–III–VI QDs in detail will be the base for further development of novel applications by utilizing the complexity of multinary QDs.

Light possesses momentum, and hence, force is exerted on materials if they absorb and/or scatter light. Laser techniques that use optical forces are currently attracting considerable attention. Optical manipulation for trapping, transporting small particles, and measuring the interparticle force is a representative technique. In addition, photoinduced force microscopy is a promising scanning type of microscopy using optical force. Optical force techniques have recently been used in various fields of research, such as molecular bioscience, organic photochemistry, materials engineering, and molecular fluid dynamics. In these techniques, several types of optical forces such as scattering, absorption, and gradient forces play their respective roles. In this article, we summarize the basics of optical forces and present their elementary expressions for using simplified models of light and matter systems. This will help the readers of this Special Issue to understand how different types of forces are distinguished in the basic expressions used for analyzing the optical force phenomena that appear depending on the light geometry and matter systems. After observing simplified cases of scattering and absorption forces, we introduce general formulae for the optical force and then discuss how different components appear in particular cases of laser geometry and materials.

Phosphazenes, one of the most important classes of organophosphorus compounds containing phosphorus (V) with double bonds between P and N, can be cyclic molecules or high molecular weight polymers that play an important and dominant role in advanced inorganic materials. Phosphazenes have been the subject of many studies over the past two decades as an excellent synthetic platform for the development of fluorescent materials. This study is conducted to evaluate the contribution of phosphazene chemistry to the preparation of fluorescent materials and to emphasize its importance in development of sophisticated materials. This review provides detailed information about the latest developments in the field of cyclic-, dendrimeric- and polymeric phosphazenes based fluorescent materials and their application examples of sensors (fluorescent and electrochemical) and optoelectronic devices (OLED, OFET and electrochromic devices). The future perspective of fluorescence materials based on phosphazenes is also discussed.