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Compared with the impressive achievements of catalytic carbonyl-olefin metathesis (CCOM) mediated by Lewis acid catalysts, exploration of the CCOM through Brønsted acid-catalyzed approaches remains quite challenging. Herein, we disclose a synthetic protocol for the construction of a valuable polycycle scaffold through the CCOM with the inexpensive, nontoxic phosphomolybdic acid as a catalyst. The current annulations could realize carbonyl-olefin, carbonyl-alcohol, and acetal-alcohol in situ CCOM reactions and feature mild reaction conditions, simple manipulation, and scalability, making this strategy a promising alternative to the Lewis acid-catalyzed COM reaction.

To date, numerous zirconium cluster-based metal-organic frameworks (Zr-MOFs) with attractive physical properties have been achieved thanks to tailorable organic linkers and versatile Zr clusters. Nevertheless, in comparison with the most-used high-symmetry organic linkers, low-symmetry linkers have rarely been exploited in the construction of Zr-MOFs. Despite challenges in predicting the structure and topology of the MOF, linker desymmetrization presents opportunities for the design of Zr-MOFs with unusual topologies and unexpected functionalities. Herein, we report for the first time the construction of two robust Zr-MOFs ( IAM-7 and IAM-8 ) from two pyrrolo-pyrrole-based low-symmetry tetracarboxylate linkers with a rare rhombic shape. The low symmetry of the linkers arises from the asymmetric pyrrolo-pyrrole core and the varying branch lengths, which play a critical role in the structural diversity between IAM-7 and IAM-8 seen from the structural analysis and lead to hydrophilic channels that contain uncoordinated carboxylate groups in the structure of IAM-7 . Furthermore, the proton conductivity of IAM-7 displays a high temperature and humidity dependence where the proton conductivity increases from 2.84 × 10 -8 S cm -1 at 30 °C and 40% relative humidity (RH) to 1.42 × 10 -2 S cm -1 at 90 °C and 95% RH, making it among one of the most conductive Zr-MOFs. This work not only enriches the library of Zr-MOFs but also offers a platform for the design of low-symmetry linkers toward the structural diversity or irregularity of MOFs as well as their structure-related properties.

Chemically driven colloidal motors capable of implementing different movements under a common environment are of great importance for various complex tasks. However, the key parameters underlying different motion behaviors are incompletely understood. Here, we demonstrate that carbonaceous nanoflask (CNF) motors move spontaneously in glucose powered by the cascade reaction of glucose oxidase and catalase, and their directional propulsion can be premeditated by controlling the surface wettability of nanomotors. The hydrophilic CNF motors move from the round-bottom to the opening neck (backward), whereas the hydrophobic CNF motors swim from the opening neck to the round-bottom (forward). We demonstrate that the backward motion of the hydrophilic CNF motors is driven by the local glucose gradient due to self-diffusiophoresis, and the forward movement of the hydrophobic CNF motors is caused by the locally produced glucose acid gradient. The fluid simulation reveals that the hydrophilic and hydrophobic CNF motors correspond to the puller and pusher models, respectively. Our study offers a minimal strategy to manipulate the direction of motion of motors for specific applications and to change the hydrodynamic behaviors of glucose-powered motors.

Sn-based anode materials have become potential substitutes for commercial graphite anode due to their high specific capacity and good safety. In this paper, ultrafine Sn nanoparticles embedded in nitrogen and phosphorus codoped porous carbon nanorods (Sn@C) are obtained by carbonizing bacteria that adsorb the Sn electroplating sludge extracting solution. The as-prepared Sn@C rod-shaped composite exhibits superior electrochemical Li-storage performances, such as a reversible capacity of approximate 560 mAh/g at 1 A/g and an ultralong cycle life exceeding 1500 cycles, with approximately no capacity decay. The ultrastable structure of the Sn@C was revealed using in situ transmission electron microscope at the nanoscale and indicated that the Sn@C composite could restrict the volume expansion of Sn nanoparticles during the lithiation/delithiation cycles. This work provides a new insight into addressing the electroplating sludge and designing novel lithium ion battery anodes.

We present here the synthesis of one enantiomeric pair of metal-organic framework materials comprised of a unique multioriented double-helix structure from an achiral spirocenter ligand. Our study clearly shows that the chiral MOF material encompasses concurrently multiple nonlinear-optical functions in the solid state: the noncentrosymmetric structural feature brings the chiral MOF high second-harmonic-generation efficiency; the incorporation of the spirocenter ligand can efficiently produce two-photon-excited photoluminescence with a larger-action cross-sectional value.

We report a magnetically actuated peanut-shaped hematite colloid motor that can not only move in a rolling or wobbling mode in fluids but also perform single cell manipulation and patterning in a noncontact way. The peanut motor in a rolling mode can reach a maximal velocity of 10.6 μm s -1 under a rotating magnetic field of 130 Hz and 6.3 mT and achieve a more precisely controllable motion in predefined tracks. While in a wobbling mode, the motor reaches a maximal velocity of 14.5 μm s -1 under a conical rotating magnetic field of 80 Hz and 6.3 mT and can climb over steep slopes to adapt the motor for more complex environments. The fluid flow simulation results reveal that the difference between two movement modes mostly comes from the distribution discrepancy of the flow fields near the motors. Through the integration of the rolling and wobbling movement, these peanut motors can autonomously transport and release cells to a predefined site and thus form complex cell patterns without a physical contact. Such magnetically actuated peanut colloid motors afford a biofriendly technique for manipulation and patterning of cells, cell measurements, and intracellular communication investigations.

A hydroxyl-functionalized ligand was designed for the construction of metal-organic framework (MOF) materials with the aggregation-induced emission (AIE) feature, in which the fluorescence can be deliberately tailored: quenching the fluorescence to an "off" state by the decoration with heterocyclic auxiliary ligand 4,4'-bypyridine (Bpy) in the framework as a quenching agent and triggering the enhanced fluorescence to an "on" state by removal of Bpy through the metal competitive coordination substitution strategy. Our study shows that the occurrence of exciton migration between the AIE linker and conjugated auxiliary ligand Bpy causes fluorescence quenching. Time-dependent density functional theory was employed to understand the photoinduced electron transfer process and explain the origins of fluorescence quenching. Using this strategy, the prepared MOF material can perform as a fluorescence "off-on" probe for highly sensitive detection of Al 3+ in aqueous media. The hydroxyl group plays a crucial role in sensing as it can selectively chelate Al 3+ , which is directly related to the dissociation of nonfluorescent MOF and consequent activation of the AIE process.

The upconversion nanoparticle (UCNP)-based photodynamic therapy (PDT) agents are promising for deep-tissue cancer treatment because they may overcome current limitations due to the shallow penetration depth of visible light. However, limited blood circulation time and poor tumor-targeting capability challenge the therapeutic efficacy of UCNP-based PDT in vivo. Here, we demonstrate intravenous injectable stem-cell-membrane-camouflaged upconversion nanoarchitectures as a biomimetic tumor PDT platform. The biomimetic PDT system is constructed by fusing mesoporous-silica-encapsulated β-NaYF4:Yb 3+ ,Er 3+ UCNPs with stem-cell membranes. Translocation of the stem-cell membranes to the UCNPs led to the translation of multiple membrane components, bringing the membranes' long circulation and tumor-targeting capability to the resulting platform. Multiphotosensitizers were encapsulated and simultaneously activated by a 980 nm single laser because of the multicolor emission capability of the UCNP cores. In vitro and in vivo experiments demonstrate that this novel platform inherits the tumor-targeting properties of stem cells and exhibits remarkable accumulation at the tumor site. In vivo tumor PDT results show higher tumor inhibition efficacy by tail intravenous administration of this new photosensitizer-loaded system. This stem-cell-membrane-camouflaged upconversion nanoarchitecture provides artificial UCNPs with natural cell membranes and holds considerable promise for deep-tissue PDT cancer treatment by systemic administration.

Metallohelical triangles consisting of chromophore units and hydrogen-bonding trigger sites were prepared by modulating two tridentate N(2)O units containing amide groups within a central benzene ring at the meta sites, for the selective detection of adenosine trisphosphate in aqueous media over other ribonucleotides.

A new chemosensor RF1 that combines a ferrocene unit and a rhodamine block via the linkage of a carbohydrazone binding unit was designed and prepared for the highly selective detection of Hg (2+) in natural water. This chemosensor displays great brightness and fluorescence enhancement following Hg (2+) coordination within the limit of detection for Hg (2+) at 1 parts per billion (ppb). The fluorescence intensities are nearly proportional to the amount of Hg (2+) at the ppb level. It is capable of distinguishing between the safe and the toxic levels of inorganic mercury in drinking water. Hg (2+)-binding also arouses the absorption of the rhodamine moiety in RF1 significantly with the chromogenic detection limit for Hg (2+) at 50 ppb. The conventional UV-vis spectroscopic method thus has the potential to provide the critical information about the mercury hazard assessment for industrial wastewater discharging. The obvious and characteristic color change of the titration solution from colorless to pink upon the addition of Hg (2+) demonstrates that RF1 can be used for "naked-eye" detection of Hg (2+) in water. The Hg (2+) complexation also causes a significant shift of the redox potential about the ferrocene/ferrocenium couple. The electrochemical responses provide the possibility to quantitative analysis of Hg (2+) at the parts per million (ppm) level. Preliminary investigations in natural water samples including seawater and freshwater indicate that RF1 offers a direct and immediate Hg (2+) detection in complex media, pointing out its potential utility in environment monitoring and assessment. The responses of RF1 are Hg (2+) specific, and the chemosensor exhibits high selectivity toward Hg (2+) over other Group 12 metals, alkali, alkaline earth metals, and most of the divalent first-row transition metals. The RF1-Hg (2+) complex is successfully isolated and the Hg (2+)-binding is reversible. The crystal structure and spectral properties of its congener RF2 that contains one ferrocene group and two rhodamine 6G moieties were also investigated for a comparison.

A highly sensitive fluorescent probe 1 for selective detection of Hg ion in mixed N,N-dimethylformamide aqueous media was designed and prepared by incorporating the well-known Rhodamine 6G fluorophore and a carbohydrazone binding unit into one molecule. The fluorescent probe 1 can detect the parts per billion level of HgII in a mixed aqueous environment and displays a highly selective response of fluorescence enhancement toward HgII.

A Hg-promoted desulfurization reaction of a thiocarbazone derivative was introduced in the design of a fluorescent sensor for selective Hg(II) detection. Crystal structural and spectroscopic investigations demonstrated the formation of a triazanaphthalene ring and the "turn-on" responding for Hg(II) in aqueous media.