Springer Science and Business Media LLC

Near-infrared (NIR) refers to the section of the spectrum from 650 to 2500 nm. NIR luminescent materials are widely employed in organic light-emitting diodes (OLEDs), fiber optic communication, sensing, biological detection, and medical imaging. This paper reviews organic NIR electroluminescent materials, including organic NIR electrofluorescent materials and organic NIR electrophosphorescent materials that have been investigated in the past 6 years. Small-molecule, polymer NIR fluorescent materials and platinum(II) and iridium(III) complex NIR phosphorescent materials are described, and the limitations of the development of NIR luminescent materials and future prospects are discussed.

We discuss some published results and provide new observations concerning the high level of structural complexity that lies behind the nanoscale correlations in ionic liquids (ILs) and their mixtures with molecular liquids. It turns out that this organization is a consequence of the hierarchical construction on both spatial (from ångström to several nanometer) and temporal (from fraction of picosecond to hundreds of nanosecond) scales, which requires joint use of experimental and computational tools.

This review article discusses historical and contemporary research studies of asymmetric allylic oxidation of olefins using homogeneous and heterogeneous copper complexes of various kinds of oxazoline-based ligands, until the end of 2021. It is revealed that this strategy is a powerful method to form a new stereogenic center bearing an oxygen substituent adjacent to an unchanged C=C bond. Enantioselectivities as well as chemical yields, and also the reactivity, are strongly dependent on the type of substrate, oxidant, the copper salt and its oxidation state, ligand structure, temperature, nature of the solvent, and additives such as phenylhydrazine and porous materials.

The present review highlights recent developments in the chemistry of sulfur radicals. Background material essential to the understanding of these developments is briefly reviewed and references to previous in depth reviews are cited. The exciting applications of current research involving sulfur radicals in bonding theory, organic synthesis, polymer chemistry, materials science, and biochemistry are outlined.

This review first briefly summarizes stoichiometric C–S bond activation by transition metal complexes and then focuses on catalytic synthetic reactions involving C–S bond activation.

Molecules that exhibit thermally activated delayed fluorescence (TADF) represent a very promising emitter class for application in electroluminescent devices since all electrically generated excitons can be transferred into light according to the singlet harvesting mechanism. Cu(I) compounds are an important class of TADF emitters. In this contribution, we want to give a deeper insight into the photophysical properties of this material class and demonstrate how the emission properties depend on molecular and host rigidity. Moreover, we show that with molecular optimization a significant improvement of selected emission properties can be achieved. From the discussed materials, we select one specific dinuclear complex, for which the two Cu(I) centers are four-fold bridged to fabricate an organic light emitting diode (OLED). This device shows the highest efficiency (of 23 % external quantum efficiency) reported so far for OLEDs based on Cu(I) emitters.

Ionic liquids (ILs) are considered as highly useful materials for potential diverse uses such as greener and more convenient alternatives to volatile organic solvents, reagents, additives, ligands and co-solvents. Thermal stability, negligible vapor pressure and high polarity with ionic environments have possibly conferred some unique physico-chemical properties and a wider electrochemical window on ILs. More importantly, these properties are tuneable, depending on variations in alkyl chains and counter-anions. On the other hand, various transition-metal-catalyzed cross-coupling reactions constitute an important backbone of contemporary organic synthesis. A vast number of C–C and C-heteroatom cross-coupling reactions are reported in the presence of ILs, often showing better performance. The influence of IL on the action of a given catalyst or on the course of a reaction can be relatively complex, and is not understood well enough to be able to draw succinct conclusions. However, there are a few reports in the literature that help understand the role of actual and active catalytic species stabilized in an IL environment. Stabilization, which can be either helpful or detrimental to catalysis depends on specific circumstances. This review article is aimed primarily at summarizing the various applications of ILs during the past decade, focusing as far as possible on the task-specific properties of ILs in transition-metal-catalyzed C–C and C-heteroatom cross-coupling reactions. Several successful achievements and noteworthy progress in this field of research leads to the sensible conclusion that future prospects in this field of research are not only bright but promise new horizons.

Photon upconversion (UC) based on triplet–triplet annihilation (TTA) is considered one of the most attractive methodologies for switching wavelengths from lower to higher energy. This two-photon process, which requires the involvement of a bimolecular system, has been widely used in numerous fields such as bioimaging, solar cells, displays, drug delivery, and so on. In the last years, we have witnessed the harnessing of this concept by the organic community who have developed new strategies for synthetic purposes. Interestingly, the generation of high-energetic species by this phenomenon has provided the opportunity not only to photoredox activate compounds with high-energy demanding bonds, expanding the reactivity window that lies outside the energy window of the initial irradiation wavelength, but also to sensitized conventional photocatalysts through energy transfer processes even employing infrared irradiation. Herein, an overview of the principal examples found in literature is described where TTA–UC systems are found to be suitable photosensitizers for several chemical transformations.