The optical thermometer has shown great promise for use in the fields of aeronautical engineering, environmental monitoring and medical diagnosis. Self-referencing lanthanide thermo-probes distinguish themselves because of their accuracy, calibration, photostability, and temporal dimension of signal. However, the use of conventional lanthanide-doped materials is limited by their poor reproducibility, random distance between energy transfer pairs and interference by energy migration, thereby restricting their utility. Herein, a strategy for synthesizing hetero-dinuclear complexes that comprise chemically similar lanthanides is introduced in which a pair of thermosensitive dinuclear complexes, cycTb-phEu and cycEu-phTb, were synthesized. Their structures were geometrically optimized with an internuclear distance of approximately 10.6Å. The sensitive linear temperature-dependent luminescent intensity ratios of europium and terbium emission over a wide temperature range (50–298K and 10–200K, respectively) and their temporal dimension responses indicate that both dinuclear complexes can act as excellent self-referencing thermometers. The energy transfer from Tb3+ to Eu3+ is thermally activated, with the most important pathway involving the 7F1 Eu3+ J-multiplet at room temperature. The energy transfer from the antenna to Eu3+ was simulated, and it was found that the most important ligand contributions to the rate come from transfers to the Eu3+ upper states rather than direct ligand–metal transfer to 5D1 or 5D0. As the first molecular-based thermometer with clear validation of the metal ratio and a fixed distance between the metal pairs, these dinuclear complexes can be used as new materials for temperature sensing and can provide a new platform for understanding the energy transfer between lanthanide ions.

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Hybrid upconversion nanosystems have been reported to improve the low absorption efficiency of lanthanide-doped upconversion nanoparticles (UCNPs). However, the low quantum yield and poor photostability of NIR dyes pose challenges for practical uses. Here, we introduce a bulky moiety, 4-(1,2,2-triphenylvinyl)-1,1′-biphenyl (TPEO), to enhance its quantum yield by suppressing the bond rotation and improve the stability by deactivating the photoinduced oxidization. Compared with the conventional IR806, the formed NIR dye, TPEO-Cy, has been characterized to deliver three times higher quantum yield and seven times better photostability. Moreover, we take advantage of the strong affinity of sulfonate chains on the TPEO-Cy to bind to the surface of UCNPs. Taking together the synergistic effect, we have achieved a 242-fold upconversion emission enhancement over the benchmark of IR806-sensitized system and an ∼800 000-fold increase than the bare UCNPs. Our design of the NIR dyes suggests a new scope to search for more efficient upconversion nanohybrids.

Lanthanide-doped upconversion nanoparticles (UCNPs) have enabled a broad range of emerging nanophotonics and biophotonics applications. Here, we provide a quantitative guide to the optimum concentrations of Yb 3+ sensitizer and Tm 3+ emitter ions, highly dependent on the excitation power densities. To achieve this, we fabricate the inert-

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Microrobots can expand our abilities to access remote, confined, and enclosed spaces. Their potential applications inside our body are obvious, e.g., to diagnose diseases, deliver medicine, and monitor treatment efficacy. However, critical requirements exist in relation to their operations in gastrointestinal environments, including resistance to strong gastric acid, responsivity to a narrow proton variation window, and locomotion in confined cavities with hierarchical terrains. Here, we report a proton-activatable microrobot to enable real-time, repeated, and site-selective pH sensing and monitoring in physiological relevant environments. This is achieved by stratifying a hydrogel disk to combine a range of functional nanomaterials, including proton-responsive molecular switches, upconversion nanoparticles, and near-infrared (NIR) emitters. By leveraging the 3D magnetic gradient fields and the anisotropic composition, the microrobot can be steered to locomote as a gyrating “Euler’s disk”, i.e., aslant relative to the surface and along its low-friction outer circumference, exhibiting a high motility of up to 60 body lengths/s. The enhanced magnetomotility can boost the pH-sensing kinetics by 2-fold. The fluorescence of the molecular switch can respond to pH variations with over 600-fold enhancement when the pH decreases from 8 to 1, and the integration of upconversion nanoparticles further allows both the efficient sensitization of NIR light through deep tissue and energy transfer to activate the pH probes. Moreover, the embedded down-shifting NIR emitters provide sufficient contrast for imaging of a single microrobot inside a live mouse. This work suggests great potential in developing multifunctional microrobots to perform generic site-selective tasks in vivo.

A one-pot three-component reaction, involving condensation of 2-aminopyridines, aldehydes, and ketones/aldehydes under trifluoromethanesulfonic acid catalysis, provides rapid access to highly substituted novel 4H-pyrido[1,2-a]pyrimidines.

Amine–borane complexes have been extensively studied as hydrogen storage materials. Herein, we report a new amine–borane system featuring a reversible dehydrogenation and regeneration at room temperature. In addition to high purity H2, the reaction between ethylenediamine bisborane (EDAB) and ethylenediamine (ED) leads to unique boron–carbon–nitrogen 5‐membered rings in the dehydrogenation product where one boron is tricoordinated by three nitrogen atoms. Owing to the unique cyclic structure, the dehydrogenation product can be efficiently converted back to EDAB by NaBH4 and H2O at room temperature. This finding could lead to the discovery of new amine boranes with potential usage as hydrogen storage materials.