mechanoluminescence (ML) in modern technologies such as wind-driven display, optical sensor, and artificial skin. [2] However, practical application of these systems is hindered by limited range of available ML emission colors. Therefore, development of multicolor ML materials displaying high and equal brightness across the whole spectral range is one of the most urgent tasks in ML research.Since the discovery of ML in 1605, continuous efforts have been devoted to the search for new ML materials and a large diversity of compounds have been found to show ML. [3] Nevertheless, only very few material systems known to date can produce sufficient bright and self-recoverable ML to satisfy technological applications. Efficient ML materials are typically composed of piezoelectric materials such as ZnS, CaZnOS, and LiNbO 3 , which promote the formation of lattice-defect complexes by strain-induced piezoelectric potential due to strong electron-lattice coupling. [4] These lattice-defect complexes function as active energy carriers and migration centers in ML processes. [5] In addition, substitutional dopant ions are usually needed to promote the stress-to-photon conversion processes. Dopant ions are able to capture strain-induced energies associated with lattice defects, and subsequently produce photon emissions at high efficiencies. Dopant ions also introduce additional energy levels to tune the emission profiles. [6] The most commonly used dopant ion is Mn 2+ that substitutes for Zn 2+ in the host materials. Due to their close chemical properties, Mn 2+ can be conveniently incorporated into the host lattice at high concentrations without deleterious effects. [7] Attempts have also been made to activate ML materials with lanthanide dopants that comprise a family of chemically similar elements. [8] Although lanthanides are very successful as luminescent dopants in insulators, their use in ML has been met with limited success because of the low compatibility between lanthanide dopants and semiconducting ML host materials. Activation of ML materials with lanthanide ions requires careful control of host/dopant combination, dopant concentration, and method of preparation. Lanthanide-doped inorganic ML materials in literatures typically comprise low concentrations of Sm 3+ (1 mol%), Er 3+ (0.5 mol%), and Nd 3+ (2 mol%) activators, [9] which render limited emission colors and relatively low ML emission intensities. Particularly, no approach is available to achieve intense ML in Tb 3+ dopants that is known as Mechanoluminescence (ML) featuring photon emission by mechanical stimuli is promising for applications such as stress sensing, display, and artificial skin. However, the progress of utilizing ML processes is constrained by the limited range of available ML emission spectra. Herein, a general strategy for expanding the emission of ML through the use of lanthanide emitters is reported. A lithium-assisted annealing method for effective incorporation of various lanthanide ions (e.g., Tb 3+ , Eu 3+ , Pr 3+ , Sm 3+ , Er 3+ ,...

The Pictet–Spengler reaction (PSR) involves the condensation and ring closure between a β-arylethylamine and a carbonyl compound. The combination of dopamine and ketones in a PSR leads to the formation of 1,1′-disubstituted tetrahydroisoquinolines (THIQs), structures that are challenging to synthesize and yet are present in a number of bioactive natural products and synthetic pharmaceuticals. Here we have discovered that norcoclaurine synthase from Thalictrum flavum (TfNCS) can catalyse the PSR between dopamine and unactivated ketones, thus facilitating the facile biocatalytic generation of 1,1′-disubstituted THIQs. Variants of TfNCS showing improved conversions have been identified and used to synthesize novel chiral 1,1′-disubstituted and spiro-THIQs. Enzyme catalysed PSRs with unactivated ketones are unprecedented, and, furthermore, there are no equivalent stereoselective chemical methods for these transformations. This discovery advances the utility of enzymes for the generation of diverse THIQs in vitro and in vivo.

heterojunctions have been constructed and demonstrated for controlling optical, [1] electrical, [2] mechanical [3] and magnetic characteristics. [4] In particular, semiconductor heterojunctions as the core of light-emitting diodes (LEDs) have played vital roles in electric-driven lighting and display devices. The electric potential of a semiconductor heterojunction has a strong positive effect on charge carrier transport at the interface and can tune/ control the behaviors of light emitting. [5] The advances in lighting technology have greatly promoted the development of artificial intelligence, biotechnology and flexible optoelectronics. [6] At present, almost all LEDs are driven by external power supply through wire connecting electrodes. However, the high-efficiency heterojunction material driven by Newton force to achieve the stress light-emitting devices is still limited in the present research. Thus, the exploration of such a new type of light-emitting device without wires and electrodes not only supplies advanced heterojunction systems for light-emitting but also provides a prospective reference for the future multiapproach energy conversion with extended applications.As a special type of light source, mechanoluminescence (ML) materials are capable of generating photon emissions in response to mechanical stimuli. In comparison with LEDs based on electroluminescence (EL), ML provides sustainable light output by excitation of mechanical energy ubiquitously available in nature. During the past decade, ML materials have attracted widespread interests due to their promising applications in stress sensing, display, artificial skin, bioimaging, anti-counterfeiting, structure fatigue diagnosis, night surveillance and flexible optoelectronics. [7][8][9][10] However, the recent developments of highperformance ML materials are not as fast as other luminescence systems such as photoluminescence (PL)/EL, which is attributed to the lack of rational design of ML material systems guided by the in-depth theoretical exploration in the mechanism. ML materials known to date are typically homogenous structures, which offer limited space for optimizing the ML performance. Therefore, further improving the ML performance by exploiting heterostructures remains a challenge for present research. [11,12] In this work, we fabricate a class of ZnS/CaZnOS heterostructures, which flexibly tune the efficient and reproducible Actively collecting the mechanical energy by efficient conversion to other forms of energy such as light opens a new possibility of energy-saving, which is of pivotal significance for supplying potential solutions for the present energy crisis. Such energy conversion has shown promising applications in modern sensors, actuators, and energy harvesting. However, the implementation of such technologies is being hindered because most luminescent materials show weak and non-recoverable emissions under mechanical excitation. Herein, a new class of heterojunctioned ZnS/CaZnOS piezophotonic systems is presented, which disp...

components including metals, semiconductors, and insulators into various coreshell configurations. The compositional flexibility and structural tunability of coreshell nanocrystals open up tremendous opportunities for obtaining highly designable physical and chemical properties. [5] For most combinations of materials, the epitaxy is associated with the buildup of elastic strains that result from mismatched lattices of the constituent parts. The misfit strain has long been recognized as an important factor that affects the formation and property of epitaxial structures. For example, misfit strain can induce lattice defects such as dislocations, which degrade the quality of the epitaxial layers and cause problems in device fabrication. [6] On the other hand, misfit strain in defect-free epilayers is very useful for optimizing the properties of heterostructures. Elastic strain has been shown to stabilize single crystallite cubic formamidinium lead iodide (FAPbI 3) thin films that offer high quantum efficiency for photodetection. [7] The strain controlled ferroelastic switching in PbTiO 3 thin films also demonstrates high sensitivity for potential applications in pressure sensors and switches. [8] Misfit stain holds more leverage in heteroepitaxial core-shell nanocrystals than in epitaxial thin-films grown on bulk substrates. Owing to the large specific surface area, nanocrystals are enclosed by various crystal facets with distinct crystallographic parameters. Accordingly, nanocrystal heteroepitaxy is characterized by concurrent deposition of epilayers on all the exposed crystal facets of the core nanocrystals. [9] From a crystallographic point of view, epitaxial deposition on different crystal facets may be subjected to a variation of interfacial strains. Besides, misfit strains in core-shell nanocrystals are usually shared by the epilayer and substrate, [10] which gives rise to diversified strain build-up and relaxation processes. Consequently, epitaxial kinetics in different crystallographic directions are largely manipulated by the structure symmetry as well as the size and morphology of the core nanocrystals. [11] On a separate note, nanocrystals are more amenable to strain than the bulk counterparts due to the increase of elasticity at the nanometer length scale. [12] Therefore, strain engineering is increasingly employed to control the formation and functionality of heteroepitaxial nanostructures in recent years. [13] In this review, we summarize recent developments in the understanding and exploitation of misfit strain in heteroepitaxial core-shell nanocrystals (Figure 1). In Section 2, we Heteroepitaxial modification of nanomaterials has become a powerful means to create novel functionalities for various applications. One of the most elementary factors in heteroepitaxial nanostructures is the misfit strain arising from mismatched lattices of the constituent parts. Misfit strain not only dictates epitaxy kinetics for diversifying nanocrystal morphologies but also provides rational control over materials prope...

Chemoenzymatic and enzymatic cascade reactions enable the synthesis of complex stereocomplementary 1,3,4‐trisubstituted tetrahydroisoquinolines (THIQs) with three chiral centers in a step‐efficient and selective manner without intermediate purification. The cascade employs inexpensive substrates (3‐hydroxybenzaldehyde and pyruvate), and involves a carboligation step, a subsequent transamination, and finally a Pictet–Spengler reaction with a carbonyl cosubstrate. Appropriate selection of the carboligase and transaminase enzymes enabled the biocatalytic formation of (1R,2S)‐metaraminol. Subsequent cyclization catalyzed either enzymatically by a norcoclaurine synthase or chemically by phosphate resulted in opposite stereoselectivities in the products at the C1 position, thus providing access to both orientations of the THIQ C1 substituent. This highlights the importance of selecting from both chemo‐ and biocatalysts for optimal results.

The effect of anisotropic interfacial strain on epitaxial growth and optical emission of sodium rare earth fluoride core-shell nanoparticles is investigated. A variety of sodium rare earth fluoride shells are grown on hexagonal phase NaYF 4 :Yb/Er core for providing anisotropic tuning of interfacial strains. Using high-resolution transmission electron microscopy and X-ray diffraction characterizations, the correlations between the epitaxial habits and the interfacial strains are quantitatively addressed. Furthermore, the growth affinity is tuned by controlling precursor concentration in conjunction with Ca 2+ doping, which results in accurate regulation of the anisotropic growth. The lattice strain resulting from mismatched epitaxy is found to enhance luminescence response of the nanoparticles to temperature change.

Coherent ultraviolet light is important for applications in environmental and life sciences. However, direct ultraviolet lasing is constrained by the fabrication challenge and operation cost. Herein, we present a strategy for the indirect generation of deep-ultraviolet lasing through a tandem upconversion process. A core–shell–shell nanoparticle is developed to achieve deep-ultraviolet emission at 290 nm by excitation in the telecommunication wavelength range at 1550 nm. The ultralarge anti-Stokes shift of 1260 nm (~3.5 eV) stems from a tandem combination of distinct upconversion processes that are integrated into separate layers of the core–shell–shell structure. By incorporating the core–shell–shell nanoparticles as gain media into a toroid microcavity, single-mode lasing at 289.2 nm is realized by pumping at 1550 nm. As various optical components are readily available in the mature telecommunication industry, our findings provide a viable solution for constructing miniaturized short-wavelength lasers that are suitable for device applications.

Multimode luminescence with tunable optical properties is reported in lanthanide(III) and manganese(II) co‐doped CaZnOS crystals. The materials display distinct emissions under excitations of X‐ray, ultraviolet, and near‐infrared photons as well as mechanical action, respectively. The excitation dependence of emission spectra stems from varying host‐to‐dopant and dopant‐to‐dopant energy transfer processes involved in different luminescence modes. By controlling intracrystal energy transfer through control of dopant concentration and combination, the emission spectra are precisely tuned across the visible to near‐infrared. These findings highlight a facile approach to constructing multimode luminescent materials with intrinsically encrypted emission characteristics for advanced anticounterfeiting applications.