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Summary Electrically pumped organic lasers have been eagerly sought for several decades, although they have not been fully demonstrated yet. Recently, impressive progresses have been made with respect to molecular design, theoretical prediction, and device fabrication for light-emitting organic semiconductors. In this perspective, we outline the key issues of balanced optical gain, carrier mobility, and excitonic losses as well as other challenges associated with electrical pump of organic lasers after examining the breakthroughs made in recent efforts. Then, we provide a concise overview of several potential solutions to the challenges from the viewpoint of lasing principle by exploring the relationship between lasing emissions and molecular structures, device engineering, and exciton dynamics, which might stand out as the most promising way toward the pursuit of electrically driven lasing with organic semiconductors.

Rare earth doping has been widely applied in many functional nanomaterials with desirable properties and functions, which would have a significant effect on the growth process of the materials. However, the controlling strategy is limited into high concentration of lanthanide doping, which produces concentration quenching of the lanthanide ion luminescence with an increase in the Ln3+ concentration, resulting in lowering the fluorescence quantum yield of lanthanide ion. Herein, for the first time, we demonstrate simultaneous control of the structures and luminescence properties of BaCO3 nanocrystals via a small amount of Tb3+ doping strategy. In fact, Tb3+ would partially occupy Ba2+ sites, resulting in the changes to the structures of the BaCO3 nanocrystals, which is primarily determined by charge modulation, including the contributions from the surfaces of crystal nuclei and building blocks. These structurally modified nanocrystals exhibit tunable luminescence properties, thus emerging as potential candidates for photonic devices such as light-emitting diodes and color displays.

A new type of flavone-based fluorescent probe (DMAF) capable of cysteine (Cys)/homocysteine (Hcy) sensing with high selectivity over other amino acids was developed. Such type of probe undergoes Cys/Hcy-mediated cyclization reaction with the involvement of its aldehyde group, which suppresses of the photoinduced electron transfer (PET) process of the probe molecule and consequently leads to the enhancement of fluorescence emission upon excitation using visible light. The formation of product of the Cys/Hcy-mediated cyclization reaction was confirmed and the preliminary fluorescence imaging experiments revealed the biocompatibility of the as-prepared probe and validated its practicability for intracellular Cys/Hcy sensing.

In this paper, with K + , Ca 2+ and Fe 3+ as the objects of study, retardation of soil–bentonite (SB) barrier materials for metal ions with different valences is investigated, and the adsorption mechanism, migration patterns and permeation behavior are explored so as to provide a theoretical basis for their application. The results show that the adsorption process for metal ions with different valences by SB barrier materials is fast, and the higher the valence, the greater the adsorption capacity. The fitting of the adsorption process conforms to pseudo -second-order adsorption kinetics and Langmuir–Freundlich adsorption equation, which explains that chemical adsorption is the dominating state and that the SB surface has certain heterogeneity. The permeability coefficient of K + , Ca 2+ and Fe 3+ in SB each has a maximum and the higher the valence, the sooner the maximum appears. Also the higher the valence, the more obvious the effect on SB retardation performance; and the sooner the ion breaks through the barrier wall completely, that is, the wall's retardation performance for higher valent ions may decline.

In this paper we report the synthesis and crystal structures of emissive organic molecule (1a) based on pyrido[3,4-g]isoquinoline framework as well as its isomers 1b and 1c. The emission quantum yields decrease after transformation of pyridine moieties in 1a into the cyclic-amides in 1b and 1c. The fluorescent spectral results reveal that 1a, 1b, and 1c exhibit no AIE behavior. This is tentatively attributed to intramolecular weak C⋯H interactions, which may impede the intramolecular rotations based on the crystal structures of 1a and 1c. Interestingly, 1a, 1b, and 1c are emissive in the solid state, and among them 1a possesses the highest emission quantum yield (0.22). Moreover, the fluorescence of 1a in solution and solid state can be reversibly tuned by reactions with trifluoroacetic acid and triethylamine. Microarea PL studies reveal that microrods of 1a and these after exposure to HCl gas show typical waveguide behavior.

The structure of an organic dye 1,5-diaminoanthraquinone (DAAQ) nanowire was studied by both electron diffraction and X-ray powder diffraction. The unit cell of the crystal was determined from a series of tilted selected area electron diffraction patterns (monoclinic: a =3.78 A, b =9.73 A, c =15.01 A and β =82.4°). By using precession electron diffraction, the following extinction conditions were determined, 0 k 0: k =2 n and 00 l : l= 2 n , which give the space group as P 2 1 / C (no. 14). The powder charge flipping algorithm was applied to resolve the phase problem and the structural model of the DAAQ crystal was built.

The hierarchical self-assembly of an organic low-molecular-weight compound, 4,5-diphenylimidazole (DPI), from single molecules to 2D building blocks to higher-order mesostructures was induced successfully by the cooperation of coordination and several weak interactions at copper-solution interface. The morphologies and properties of the as-obtained DPI hierarchical mesostructures can be readily controlled by changing the assembly conditions such as the sort of solvent, the DPI concentration and the ripening time. The measurements of ESI-MS, FT-IR and Auger electron spectroscopes indicate that the complex formed by the coordination between DPI and copper plays an important role in that it provides a center for the nucleation and growth of the 2D sheet-like basic units. The DPI mesostructures can change the property of copper surface and endow the copper with novel surface performances. Moreover, it should be feasible to extend the strategy described here to other metal-ligand systems.