Metallacarboranes are a class of inorganic boron clusters that have recently been recognized as biologically active compounds. Herein, we report on the host–guest complexation of several cobalt bis(1,2-dicarbollide) anions (COSANs) with cyclodextrins (CDs) in aqueous solution. The binding affinities reach micromolar values, which are among the highest known values for native CDs, and exceed those for neutral hydrophobic organic guest molecules. The entrapment of the COSANs inside the cavity of CDs was confirmed using NMR and UV–visible spectroscopy, mass spectrometry, cyclic voltammetry, and isothermal titration calorimetry. Complexation by CDs greatly influences the photophysical and electrochemical properties of COSANs. In combination with indicator displacement assays, a label-free fluorescence-based method was developed to allow real-time monitoring of the translocation of COSANs through lipid bilayer membranes.
We employ the Su–Schrieffer–Heeger model in elastic polymer waveguide arrays to design and realize traveling topologically protected modes. The observed delocalization of the optical field for superluminal defect velocities agrees well with theoretical descriptions. We apply mechanical strain to modulate the lattices’ coupling coefficient. This work demonstrates a novel, to the best of our knowledge, platform for rapid prototyping of topological photonic devices and establishes strain-tuning as a viable design parameter for topological waveguide arrays.
optical properties in both linear and non-linear regimes. [1][2][3][4] They have also been shown to be capable of hosting single-photon emitters. [5][6][7] Besides the tunability of their bandgap in response to electric fields, [8,9] TMDs' exciton dynamics can be further modified through stacking into van der Waals heterostructures, [10] chemical doping, [11] and application of mechanical strain. [12] These properties are of particular interest in the context of Photonic integrated circuits (PICs) where the goal is to couple a photon-routing structure to elements with strong and tunable optical response. [13] Such circuits find applications in optical communication, [14] computation, [15] and sensing. [16][17][18] Integration of TMDs into photonic waveguides can be readily achieved by direct transfer, taking advantage of the material's van der Waals bonding nature. [19,20] To date, most hybrid systems with an optically coupled 2D material realize placement away from the photonic mode's maximum (off-center placement) or at a dielectric interface, for example, close to an exposed fiber core, [21,22] at the end-faceThe effective integration of 2D materials such as monolayer transition metal dichalcogenides (TMDs) into photonic waveguides and integrated circuits is being intensely pursued due to these materials' strong exciton-based optical response. This work presents a platform where a 2D heterostructure (WS 2 -hBN) is directly integrated into the photonic mode-center of a novel polymer ridge waveguide. Finite-difference time-domain simulations and collection of photoluminescence from the guided mode indicate that this system exhibits significantly improved waveguide-emitter coupling and mode confinement over a previous elastomer platform. This is facilitated by the platform's enhanced refractive-index contrast and a new method for mode-center integration of the coupled TMD. The integration is based on a simple dry-transfer process that is applicable to other 2D materials, and the platform's elastomeric nature is a natural fit to explore strain-tunable hybridphotonic devices. The demonstrated ability of coupling photoluminescence to a polymer waveguide opens up new possibilities for hybrid-photonic systems in a variety of contexts.
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