LiMII(IO3)3 (MII=Zn and Cd): Two Promising Nonlinear Optical Crystals Derived from a Tunable Structure Model of α‐LiIO3

Excellent nonlinear optical materials simultaneously meet the requirements of large SHG response, phase‐matching capability, wide transparency windows, considerable energy band‐gap, good thermal stability and structure stability. Herein, two new promising nonlinear optical (NLO) crystals LiM^II(IO₃)₃ (M^II=Zn and Cd) are rationally designed by the aliovalent substitution strategy from the commercialized α‐LiIO₃ with the perfect parallel alignment of IO₃ groups. Compared with parent α‐LiIO₃ and related A^I₂M^IV(IO₃)₆, the title compounds exhibit more stable covalent 3D structure, and overcome the racemic twinning problem of A^I₂M^IV(IO₃)₆. More importantly, both compounds inherit NLO‐favorable structure merits of α‐LiIO₃ and show larger SHG response (≈14× and ≈12×KDP), shorter absorption edge (294 and 297 nm) with wider energy band‐gap (4.21 and 4.18 eV), good thermal stability (460 and 430 °C), phase‐matching behaviors, wider optical transparency window and good structure stability, achieving an excellent balance of NLO properties.     

Consecutive Intermolecular Reductive Amination/Asymmetric Hydrogenation: Facile Access to Sterically Tunable Chiral Vicinal Diamines and N‐Heterocyclic Carbenes

A highly enantioselective iridium‐ or ruthenium‐catalyzed intermolecular reductive amination/asymmetric hydrogenation relay with 2‐quinoline aldehydes and aromatic amines has been developed. A broad range of sterically tunable chiral N,N′‐diaryl vicinal diamines were obtained in high yields (up to 95 %) with excellent enantioselectivity (up to >99 % ee). The resulting chiral diamines could be readily transformed into sterically hindered chiral N‐heterocyclic carbene (NHC) precursors, which are otherwise difficult to access. The usefulness of this synthetic approach was further demonstrated by the successful application of one of the chiral vicinal diamines and chiral NHC ligands in a transition‐metal‐catalyzed asymmetric Suzuki–Miyaura cross‐coupling reaction and asymmetric ring‐opening cross‐metathesis, respectively.     

A trinuclear Cu(II) precursor for solvatochromically distinguishing CH3OH from C2H5OH

Abstract

In order to develop an easy and rapid identification method for distinguishing CH₃OH from C₂H₅OH, a new carbonate-based trinuclear Cu(II) precursor, [Cu₃(bpy)₆(μ₃-CO₃)(CH₃OH)](BF₄)₄·(CH₃OH)₂·(H₂O)₂ (1), has been isolated. We report here the synthesis, crystal structure, and characterizations by various spectroscopic (IR, UV–Vis, powder XRD) techniques, as well as the solvatochromic behavior of this coordination compound. Its X-ray crystal structure reveals that the main structure of 1 consists of three [(bpy)₂Cu]²⁺ centers, which are bridged by carbonate via a μ₃-η¹,η¹,η¹ fashion. Strong O–H?O hydrogen bonding between the carbonate and solvent molecules has been observed for the first time in similar structures. Its ground powder exhibits solvatochromic behavior that selectively distinguishes CH₃OH from C₂H₅OH.     

Development of [3]ferrocenophane-derived N/B frustrated Lewis pairs for the metal-free catalytic hydrogenation of imines

A series of novel [3]ferrocenophane-derived N/B frustrated Lewis pairs (FLPs) were synthesized and successfully applied to the catalytic hydrogenation of imines in 71–93% yields. This approach could be easily conducted on gram scale and provided versatile synthetic route for the key intermediate of sertraline hydrochloride without heavy metal residues.     

Novel multi-responsive fluorescence switch for Hg2+ and UV/vis lights based on diarylethene-rhodamine derivative

A new multi-responsive fluorescent switch DTE-Pip-Rho 1O has been designed and synthesized in this study. For this molecule, the reactive site of spirolactam ring is far away from the diarylethene unit through the intramolecular piperazine. It exhibited high selectivity and sensitivity to Hg²⁺ in addition to obvious color change (colorless-pink) and fluorescence “off-on” (dark-orange) during this process. It is believed that the color change is due to Hg²⁺-assisted hydrolysis of rhodamine hydrazide. Therefore, the new molecule can be used as colorimentric and fluorescent chemosensor for Hg²⁺ with high selectivity. The detection limits of absorbance and fluorescence for Hg²⁺ were calculated to be 1.15?μM and 1.16?μM, respectively. The resulting DTE-Pip-Rho 1O-Hg²⁺ could also function as a reversible fluorescence photo-switch in response to UV/vis light owing to FRET mechanism. Moreover, it has been demonstrated that the photo-switchable system displayed excellent fatigue resistance and remarkable anti-photobleaching capability.     

Synthesis and the effect of alkyl chain length on photochromic properties of diarylethene derivatives

A new class of photochromic diarylethenes bearing pyrrole and thiophene units with different length of alkyl chains at 2-position of thiophene rings have been synthesized. Their characteristics, including photochromism and fatigue resistance were investigated systematically, and each diarylethene derivative showed good photochromic properties whether in solution or in PMMA films. The alkyl group moiety was connected directly to the central cyclopentene ring as a heteroaryl unit and availably participated in photoisomerization reaction. And some properties, for example, the conversion ratio in the photostationary state(PSS) and the absorption coefficient of the ring-closed isomers in acetonitrile were significantly affected by the alkyl chain length. The results revealed that substituents of alkyl chain played an important role in the photoisomerization process of diarylethenes.     

Gasotransmitter Regulation of Phosphatase Activity in Live Cells Studied by Three‐Channel Imaging Correlation

Enzyme activity in live cells is dynamically regulated by small‐molecule transmitters for maintaining normal physiological functions. A few probes have been devised to measure intracellular enzyme activities by fluorescent imaging, but the study of the regulation of enzyme activity via gasotransmitters in situ remains a long‐standing challenge. Herein, we report a three‐channel imaging correlation by a single dual‐reactive fluorescent probe to measure the dependence of phosphatase activity on the H₂S level in cells. The two sites of the probe reactive to H₂S and phosphatase individually produce blue and green fluorescent responses, respectively, and resonance energy transfer can be triggered by their coexistence. Fluorescent analysis based on the three‐channel imaging correlation shows that cells have an ideal level of H₂S to promote phosphatase activity up to its maximum. Significantly, a slight deviation from this H₂S level leads to a sharp decrease of phosphatase activity. The discovery further strengthens our understanding of the importance of H₂S in cellular signaling and in various human diseases.     

Leaving Group Assisted Strategy for Photoinduced Fluoroalkylations Using N‐Hydroxybenzimidoyl Chloride Esters

Redox‐active esters (RAEs) as alkyl radical precursors have been extensively developed for C?C bond formations. However, the analogous transformations of fluoroalkyl radicals from the corresponding acid or ester precursors remain challenging because of the high oxidation potential of the fluoroalkyl carboxylate anions. The newly developed N‐hydroxybenzimidoylchloride (NHBC) ester provides a general leaving group assisted strategy to generate a portfolio of fluoroalkyl radicals, and can be successfully applied in photoinduced decarboxylative hydrofluoroalkylation and heteroarylation of unactivated olefins. In addition, DFT calculations revealed that the NHBC ester proceeds by the fluorocarbon radical pathway, whereas other well‐known RAEs proceed by the nitrogen radical pathway.     

A Metal–Organic Supramolecular Box as a Universal Reservoir of UV,WL, and NIR Light for Long‐Persistent Luminescence

Long persistent luminescence (LPL) materials have a unique photophysical mechanism to store light radiation energy for subsequent release. However, in comparison to the common UV source, white‐light (WL) and near‐infrared (NIR) excited LPL is scarce. Herein we report a metal–organic supramolecular box based on a D–π–A‐type ligand. Owing to the integrated one‐photon absorption (OPA) and two‐photon absorption (TPA) attributes of the ligand, the heavy‐atom effect of the metal center, as well as π‐stacking and J‐aggregation states in the supramolecular assembly, LPL can be triggered by all wavebands from the UV to the NIR region. This novel designed supramolecular kit to afford LPL by both OPA and TPA pathways provides potential applications in anti‐counterfeiting, camouflaging, decorating, and displaying, among others.     

Identification of Nanoparticles via Plasmonic Scattering Interferometry

The development of optical imaging techniques has led to significant advancements in single‐nanoparticle tracking and analysis, but these techniques are incapable of label‐free selective nanoparticle recognition. A label‐free plasmonic imaging technology that is able to identify different kinds of nanoparticles in water is now presented. It quantifies the plasmonic interferometric scattering patterns of nanoparticles and establishes relationships among the refractive index, particle size, and pattern both numerically and experimentally. Using this approach, metallic and metallic oxide particles with different radii were distinguished without any calibration. The ability to optically identify and size different kinds of nanoparticles can provide a promising platform for investigating nanoparticles in complex environments to facilitate nanoscience studies, such as single‐nanoparticle catalysis and nanoparticle‐based drug delivery.