Small molecules that recognize protein surfaces are important tools for modifying protein interaction properties. Since the 1980s, several thousand studies concerning calixarenes and host-guest interactions have been published. Although there is growing interest in protein-calixarene interactions, only limited structural information has been available to date. We now report the crystal structure of a protein-calixarene complex. The water-soluble p-sulfonatocalix[4]arene is shown to bind the lysine-rich cytochrome c at three different sites. Binding curves obtained from NMR titrations reveal an interaction process that involves two or more binding sites. Together, the data indicate a dynamic complex in which the calixarene explores the surface of cytochrome c. In addition to providing valuable information on protein recognition, the data also indicate that the calixarene is a mediator of protein-protein interactions, with potential applications in generating assemblies and promoting crystallization.

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Demonstrated herein is a single rapid approach employed for synthesis of Aggraphene nanocomposites, with excellent antibacterial properties and low cytotoxicity, by utilizing a Continuous Hydrothermal Flow Synthesis (CHFS) process in combination with phexasulfonic acid calix[6]arene (SCX6) as an effective particle stabilizer. The nanocomposites showed high activity against E. coli (Gram-negative) and S. aureus (Gram-positive) bacteria.The materials were characterized using a range of techniques including transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, UV-Vis spectrophotometry, FT-IR and X-ray powder diffraction (XRD). This rapid, single step synthetic approach not only provides a facile means of enabling and controlling graphene reduction (under alkaline conditions), but also offers an optimal route for homogeneously producing and depositing highly crystalline Ag nanostructures into reduced graphene oxide substrate.

Nickel and cobalt seamed metal-organic capsules have been isolated and studied using structural, 5 magnetic and computational approaches. Antiferromagnetic exchange in the Ni capsule results from coordination environments enforced by the capsule framework. The synthesis and characterisation of polymetallic cages of paramagnetic transition metal ions is an area of intense current research since such molecules may exhibit fascinating physical properties,1 potentially acting as, for example, single-molecule magnets (SMMs),2 molecular coolants3 and spin 10 phonon traps.4 Indeed the initial (serendipitous) discovery of all these phenomena has subsequently inspired much beautiful chemistry and physics that promises exciting potential application.5 Introducing new preparative routes towards the synthesis of transition metal cages is thus of interest for the discovery of completely new structural types and as a means of building up families of related compounds so that structure-property relations can be developed.6 Organic ligands thus play a crucial 15 role in successful cage construction, but their nature and variety is surprisingly restricted.7 A family of ligands almost completely ignored in this respect, with a few notable exceptions are calixarenes.8 C-Alkylpyrogallol[4]arenes (general formula PgCn) are cyclic molecules that are typically bowl-shaped and that have been shown to assemble through non-covalent interactions into a) nanotubular arrays,9 b) dimeric capsules,10 and c) hexameric nano-capsules.11 The dimeric and hexameric 20 capsules possess typical internal volumes of ~150 and ~1250 Å3 respectively, and this feature provides them with great potential for study as new host-guest systems. Nanometer scale metal-organic polyhedra are often assembled from many molecular components,12 and we have recently shown that various PgCns can be assembled with different metals into either open or closed shell hexameric metal-organic nano-capsules from Cu, Ga, Ga+Cu or Ga+Zn.13 In addition to this, closed shell 25 dimeric octa-metallated capsules have also been synthesized by reaction of PgCns with a pre-formed zinc(II) nitrate pyridine complex in either pyridine or methanol.14 Given that we had formed a Zn8 wheel as part of a molecular metal-organic capsule, we reasoned that the incorporation of paramagnetic metal centres (e.g. Co or Ni in place of Zn) in the capsule seam may be possible, though a search of the CCDC database reveals that there are no known isostructural Co8, Ni8 and Zn8 cages. 30This would therefore afford species with potential interest in molecular nanomagnetism, whilst also representing a paradigm shift in the chemistry of molecular capsules and their uses. We also reasoned that the inner phase of the capsule arrangement may have an important effect on the overall magnetic properties of these species by the incorporation of different guest molecules. Herein we report an expedient route to a new family of octa-metallated dimeric capsules comprising Ni8 and Co8 wheels, 35and their initial magnetic pro...