Search

Although Ru(II)-based agents are expected to be promising candidates for substituting Pt-drug, their in vivo biomedical applications are still limited by the short excitation/emission wavelengths and unsatisfactory therapeutic efficiency. Herein, we rationally design a Ru(II) metallacycle with excitation at 808 nm and emission over 1000 nm, namely Ru1085, which holds deep optical penetration (up to 6 mm) and enhanced chemo-phototherapy activity. In vitro studies indicate that Ru1085 exhibits prominent cell uptake and desirable anticancer capability against various cancer cell lines, especially for cisplatin-resistant A549 cells. Further studies reveal Ru1085 induces mitochondria-mediated apoptosis along with S and G2/M phase cell cycle arrest. Finally, Ru1085 shows precise NIR-II fluorescence imaging guided and long-term monitored chemo-phototherapy against A549 tumor with minimal side effects. We envision that the design of long-wavelength emissive metallacycle will offer emerging opportunities of metal-based agents for in vivo biomedical applications.

Willis materials exhibit macroscopic cross-coupling between particle velocity and stress as well as momentum and strain. However, Willis coupling coefficients designed so far are intrinsically coupled, which inhibits their full implementation in structural dynamic applications. This work presents a means to eliminate these limitations by introducing an active scatterer in a mechanical meta-layer that exploits piezoelectric sensor–actuator pairs controlled by digital circuits. We experimentally demonstrate abilities of the Willis meta-layer, in beams and plates, for independently engineering transmission and reflection coefficients of flexural waves in both amplitude and phase and nonreciprocal wave propagations. The meta-layer is described by a flexural wave polarizability tensor, which captures independent higher-order symmetric-to-symmetric and symmetric-to-antisymmetric couplings. The active meta-layer is adaptive in real time for reconfigurable broadband operation thanks to its programmability. This work sheds a new light on unsurpassed control of elastic waves, ranging from vibration protections to ultrasonic sensing and evaluation of engineering structures., Here, the authors experimentally demonstrate abilities of a mechanical Willis meta-layer, in beams and plates, for independently engineering transmission and reflection coefficients of flexural waves in both amplitude and phase and nonreciprocal wave propagation.

Catenated cages represent chemistry’s challenging synthetic targets because a three-dimensional assembly is necessary for their formation. Herein, a cyclic bis[2]catenane is constructed through the coordination-driven self-assembly of the interlocked bis-metallacage, by the 90° Pt(II) heteroligation of the endo-functionalized double-bridged tweezer bearing pyridyl moieties and the tetra-carboxylated linker. NMR spectrometry, X-ray crystallography and mass spectrometry confirm the formation of a cyclic bis[2]catenane with “∞”-shaped topology via a 14-component self-assembly. Particularly, reversibly responsive transformation between the bis[2]catenane and the bis-metallacage can be realized by guest exchange, concentration effect and solvent effect. This work represents a novel example of a cyclic cage-based [2]catenane oligomer., Catenated cages are challenging synthetic targets in chemistry. Here, the authors employ a multi-component coordination strategy using a Pt(II) heteroligation to construct a cyclic bis[2]catenane metallacage, which could be reversibly transformed between the catenated structure and the bis-metallacage.

Coordination-driven self-assembly as a bottom-up approach has witnessed a rapid growth in building giant structures in the past few decades. Challenges still remain, however, within the construction of giant architectures in terms of high efficiency and complexity from simple building blocks. Inspired by the features of DNA and protein, which both have specific sequences, we herein design a series of linear building blocks with specific sequences through the coordination between terpyridine ligands and Ru(II). Different generations of polycyclic supramolecules (C1 to C5) with increasing complexity are obtained through the self-assembly with Cd(II), Fe(II) or Zn(II). The assembled structures are characterized via multi-dimensional mass spectrometry analysis as well as multi-dimensional and multinuclear NMR (1H, COSY, NOESY) analysis. Moreover, the largest two cycles C4 and C5 hierarchically assemble into ordered nanoscale structures on a graphite based on their precisely-controlled shapes and sizes with high shape-persistence., Coordination-driven supramolecular assembly provides the ability to build molecular architectures of impressive complexity. Here, the authors use a series of linear metal-organic ligands with specific sequences to construct multiple generations of precisely-controlled, 2D fractal polycyclic supramolecules.

With the aim of mimicking biological machines, in which the delicate arrangement of nanomechanical units lead to the output of specific functions upon the external stimulus, the construction of dual stimuli-responsive rotaxane-branched dendrimers was realized in this study. Starting from a switchable organometallic [2]rotaxane precursor, the employment of a controllable divergent approach allowed for the successful synthesis of a family of rotaxane-branched dendrimers up to the third generation with 21 switchable rotaxane moieties located on each branch. More importantly, upon the addition and removal of dimethylsulfoxide (DMSO) molecule or acetate anion as the external stimulus, the amplified responsiveness of the switchable rotaxane units endowed the resultant rotaxane-branched dendrimers the solvent- or anion-controlled molecular motions, thus leading to the dimension modulation. Therefore, we successfully constructed a family of rotaxane-branched dendrimers with dual stimuli-responsiveness that will be a privileged platform for the construction of dynamic supramolecular materials., Mechanically interlocked molecules are extensively applied as artificial molecular machines but rotaxane-branched dendrimers are rarely explored because of synthetic challenges. Here the authors present the construction of dual stimuli-responsive rotaxane-branched dendrimer which can be stimulated by DMSO or acetate ions.

Nested concentric structures widely exist in nature and designed systems with circles, polygons, polyhedra, and spheres sharing the same center or axis. It still remains challenging to construct discrete nested architecture at (supra)molecular level. Herein, three generations (G2−G4) of giant nested supramolecules, or Kandinsky circles, have been designed and assembled with molecular weight 17,964, 27,713 and 38,352 Da, respectively. In the ligand preparation, consecutive condensation between precursors with primary amines and pyrylium salts is applied to modularize the synthesis. These discrete nested supramolecules are prone to assemble into tubular nanostructures through hierarchical self-assembly. Furthermore, nested supramolecules display high antimicrobial activity against Gram-positive pathogen methicillin-resistant Staphylococcus aureus (MRSA), and negligible toxicity to eukaryotic cells, while the corresponding ligands do not show potent antimicrobial activity., Nested structures are common throughout nature and art, yet remain challenging synthetic targets in supramolecular chemistry. Here, the authors design multitopic terpyridine ligands that coordinate into nested concentric hexagons, and show that these discrete supramolecules display potent antimicrobial activity.

Sophisticated mechanically interlocked molecules (MIMs) with interesting structures, properties and applications have attracted great interest in the field of supramolecular chemistry. We herein report a highly efficient self-assembly of heterometallic triangular necklace 1 containing Cu and Pt metals with strong antibacterial activity. Single-crystal X-ray analysis shows that the finely arranged triangular necklace 1 has two racemic enantiomers in its solid state with intriguing packing motif. The superior antibacterial activity of necklace 1 against both standard and clinically drug-resistant pathogens implies that the presence of Cu(I) center and platinum(II) significantly enhance the bacterium-binding/damaging activity, which is mainly attributed to the highly positively charged nature, the possible synergistic effect of heterometals in the necklace, and the improved stability in culture media. This work clearly discloses the structure-property relationships that the existence of two different metal centers not only facilitates successful construction of heterometallic triangular necklace but also endows it with superior nuclease properties and antibacterial activities., Precise assembly of heterometallic complexes is a challenge. Here, the authors design a heterometallic triangular necklace through a highly efficient threading-and-ring-closing approach driven by metal-ligand coordination, which shows strong bacterium-binding and cell wall/plasma membrane-disrupting capacity for killing bacterial cells.

The preparation of fluorescent discrete supramolecular coordination complexes (SCCs) has attracted considerable attention within the fields of supramolecular chemistry, materials science, and biological sciences. However, many challenges remain. For instance, fluorescence quenching often occurs due to the heavy-atom effect arising from the Pt(II)-based building block in Pt-based SCCs. Moreover, relatively few methods exist for tuning of the emission wavelength of discrete SCCs. Thus, it is still challenging to construct discrete SCCs with high fluorescence quantum yields and tunable fluorescence wavelengths. Here we report nine organoplatinum fluorescent metallacycles that exhibit high fluorescence quantum yields and tunable fluorescence wavelengths through simple regulation of their photoinduced electron transfer (PET) and intramolecular charge transfer (ICT) properties. Moreover, 3D fluorescent films and fluorescent inks for inkjet printing were fabricated using these metallacycles. This work provides a strategy to solve the fluorescence quenching problem arising from the heavy-atom effect of Pt(II), and offers an alternative approach to tune the emission wavelengths of discrete SCCs in the same solvent., Fluorescent supramolecular coordination complexes are of interest for chemical sensing and optical devices. Here the authors synthesize nine organoplatinum metallacycles with high quantum yields, whose fluorescence wavelengths are tuned through manipulation of their photoinduced electron transfer and intramolecular charge transfer properties.

Host−guest interactions are of central importance in many biological and chemical processes. However, the investigation of the formation and decomplexation of host−guest systems at the single-molecule level has been a challenging task. Here we show that the single-molecule conductance of organoplatinum(II) metallocycle hosts can be enhanced by an order of magnitude by the incorporation of a C60 guest molecule. Mechanically stretching the metallocycle-C60 junction with a scanning tunneling microscopy break junction technique causes the release of the C60 guest from the metallocycle, and consequently the conductance switches back to the free-host level. Metallocycle hosts with different shapes and cavity sizes show different degrees of flexibility to accommodate the C60 guest in response to mechanical stretching. DFT calculations provide further insights into the electronic structures and charge transport properties of the molecular junctions based on metallocycles and the metallocycle-C60 complexes.

Coordination-driven self-assembly has emerged as a powerful bottom-up approach to construct various supramolecular architectures with increasing complexity and functionality. Tetraphenylethylene (TPE) has been incorporated into metallo-supramolecules to build luminescent materials based on aggregation-induced emission. We herein report three generations of ligands with full conjugation of TPE with 2,2′:6′,2″-terpyridine (TPY) to construct emissive materials. Due to the bulky size of TPY substituents, the intramolecular rotations of ligands are partially restricted even in dilute solution, thus leading to emission in both solution and aggregation states. Furthermore, TPE-TPY ligands are assembled with Cd(II) to introduce additional restriction of intramolecular rotation and immobilize fluorophores into rosette-like metallo-supramolecules ranging from generation 1–3 (G1−G3). More importantly, the fluorescent behavior of TPE-TPY ligands is preserved in these rosettes, which display tunable emissive properties with respect to different generations, particularly, pure white-light emission for G2., Metal coordination of multitopic ligands is a powerful approach to building complex, functional architectures. Here, the authors construct three generations of fluorescent supramolecular rosettes by coordination of aggregation-induced emissive ligands, including a 2nd-generation macrocycle that emits pure white light.

Versatile controllability of interactions in ultracold atomic and molecular gases has now reached an era where quantum correlations and unconventional many-body phases can be studied with no corresponding analogues in solid-state systems. Recent experiments in Rydberg atomic gases have achieved exquisite control over non-local interactions, allowing novel quantum phases unreachable with the usual local interactions in atomic systems. Here we study Rydberg-dressed atomic fermions in a three-dimensional optical lattice predicting the existence of hitherto unheard-of exotic mixed topological density wave phases. By varying the spatial range of the non-local interaction, we find various chiral density waves with spontaneous time-reversal symmetry breaking, whose quasiparticles form three-dimensional quantum Hall and Weyl semimetal states. Remarkably, certain density waves even exhibit mixed topologies beyond the existing topological classification. Our results suggest gapless fermionic states could exhibit far richer topology than previously expected., Rydberg atomic gases have proven a fertile playground for exploring exotic phases of condensed matter systems. Here, Li and Das Sarma study Rydberg-dressed atomic fermions in a 3D optical lattice and find a series of mixed topological density wave phases having no analogue in conventional materials.

Recent experiments on ultracold atoms in optical lattices have synthesized a variety of tunable bands with degenerate double-well structures in momentum space. Such degeneracies in the single-particle spectrum strongly enhance quantum fluctuations, and often lead to exotic many-body ground states. Here we consider weakly interacting spinor Bose gases in such bands, and discover a universal quantum 'order by disorder' phenomenon which selects a novel superfluid with chiral spin order displaying remarkable properties such as spontaneous spin Hall effect and momentum space antiferromagnetism. For bosons in the excited Dirac band of a hexagonal lattice, such a state supports staggered spin loop currents in real space. We show that Bloch oscillations provide a powerful dynamical route to quantum state preparation of such a chiral spin superfluid. Our predictions can be readily tested in spin-resolved time-of-flight experiments.

Chiral p-wave superfluids are fascinating topological quantum states of matter that have been found in the liquid (3)He-A phase and arguably in the electronic Sr2RuO4 superconductor. They are fundamentally related to the fractional 5/2 quantum Hall state, which supports fractional exotic excitations. Past studies show that they require spin-triplet pairing of fermions by p-wave interaction. Here we report that a p-wave chiral superfluid state can arise from spin-singlet pairing for an s-wave interacting atomic Fermi gas in an optical lattice. This p-wave state is conceptually distinct from all previous conventional p-wave states as it is for the centre-of-mass motion, instead of the relative motion. It leads to spontaneous generation of angular momentum, finite Chern numbers and topologically protected chiral fermionic zero modes bounded to domain walls, all occuring at a higher critical temperature in relative scales. Signature quantities are predicted for the cold atom experimental condition.