The convergent assembly of metal-organic frameworks has enabled the design of porous materials using a structural building unit approach, but functional systems incorporating pre-assembled structural building unit 'pore' openings are rare. Here, we show that the face-directed assembly of a ring-shaped macrocyclic polyoxometalate structural building unit, {P(8)W(48)O(184)}(40-) with an integrated 1-nm pore as an 'aperture synthon', with manganese linkers yields a vast three-dimensional extended framework architecture based on a truncated cuboctahedron. The 1-nm-diameter entrance pores of the {P(8)W(48)O(184)}(40-) structural building unit lead to approximately spherical 7.24-nm(3) cavities containing exchangeable alkali-metal cations that can be replaced by transition-metal ions through a cation exchange process. Control over this process can be exerted by either electrochemically switching the overall framework charge by manipulating the oxidation state of the manganese linker ions, or by physically gating the pores with large organic cations, thus demonstrating how metal-organic framework-like structures with integrated pores and new physical properties can be assembled.

Face-directed self-assembly of an electronically active Archimedean polyoxometalate architecture

Activation of Terminal Alkynes by Frustrated Lewis Pairs

Reaction of 1 with B(C6F5)3 under 1 bar of CO2 led to the instantaneous formation of the frustrated Lewis pair (FLP)-type species [ReHBr(NO)(PR3)2(η2-O═C═O–B(C6F5)3)] (2, R = iPr a, Cy b) possessing two cis-phosphines and OCO2-coordinated B(C6F5)3 groups as verified by NMR spectroscopy and supported by DFT calculations. The attachment of B(C6F5)3 in 2a,b establishes cooperative CO2 activation via the Re–H/B(C6F5)3 Lewis pair, with the Re–H bond playing the role of a Lewis base. The Re(I) η1-formato dimer [{Re(μ-Br)(NO)(η1-OCH═O–B(C6F5)3)(PiPr3)2}2] (3a) was generated from 2a and represents the first example of a stable rhenium complex bearing two cis-aligned, sterically bulky PiPr3 ligands. Reaction of 3a with H2 cleaved the μ-Br bridges, producing the stable and fully characterized formato dihydrogen complex [ReBrH2(NO)(η1-OCH═O–B(C6F5)3)(PiPr3)2] (4a) bearing trans-phosphines. Stoichiometric CO2 reduction of 4a with Et3SiH led to heterolytic splitting of H2 along with formation of bis(triethylsilyl)acet...

Catalytic CO2 Activation Assisted by Rhenium Hydride/B(C6F5)3 Frustrated Lewis Pairs—Metal Hydrides Functioning as FLP Bases

The use of photodynamic therapy (PDT) against cancer has received increasing attention over recent years However, the application of the currently approved photosensitizers (PSs) is limited by their poor aqueous solubility, aggregation, photobleaching and slow clearance from the body To overcome these limitations, there is a need for the development of new classes of PSs with ruthenium(II) polypyridine complexes currently gaining momentum However, these compounds generally lack significant absorption in the biological spectral window, limiting their application to treat deep-seated or large tumors To overcome this drawback, ruthenium(II) polypyridine complexes designed in silico with (E,E')-4,4'-bisstyryl-2,2'-bipyridine ligands show impressive 1- and 2-Photon absorption up to a magnitude higher than the ones published so far While nontoxic in the dark, these compounds are phototoxic in various 2D monolayer cells, 3D multicellular tumor spheroids and are able to eradicate a multiresistant tumor inside a mouse model upon clinically relevant 1-Photon and 2-Photon excitation

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Rationally designed ruthenium complexes for 1- and 2-photon photodynamic therapy.

X-ray crystallography has been fundamental in discovering fine structural features of ultrasmall gold clusters capped by thiolated ligands. For still unknown structures, however, new tools capable of providing relevant structural information are sought. We prepared a 25-gold atom nanocluster protected by the smallest ligand ever used, ethanethiol. This cluster displays the electrochemistry, mass spectrometry, and UV-vis absorption spectroscopy features of similar Au25 clusters protected by 18 thiolated ligands. The anionic and the neutral form of Au25(SEt)18 were fully characterized by (1)H and (13)C NMR spectroscopy, which confirmed the monolayer's properties and the paramagnetism of neutral Au25(SEt)18(0). X-ray crystallography analysis of the latter provided the first known structure of a gold cluster protected by a simple, linear alkanethiolate. Here, we also report the direct observation by electron nuclear double resonance (ENDOR) of hyperfine interactions between a surface-delocalized unpaired electron and the gold atoms of a nanocluster. The advantages of knowing the exact molecular structure and having used such a small ligand allowed us to compare the experimental values of hyperfine couplings with DFT calculations unaffected by structure's approximations or omissions.

Au₂₅(SEt)₁₈, a nearly naked thiolate-protected Au₂₅ cluster: structural analysis by single crystal X-ray crystallography and electron nuclear double resonance.

The exact analytic method of evaluating the absorption during scattering in multifaceted convex crystals is developed in a way that permits efficient computation. A fast and accurate algorithm is given for finding the Howells polyhedra whose determination is fundamental to the analytic method. The algorithm allows for the evaluation of cases when the sample is only partly illuminated, can be adapted to more general situations and can be used to generate an estimate of the error in the computation. In most cases this is to 1 part in 1014. Results of standard tests are given to greater accuracy than previously available and results for multifaceted approximations to a cylinder and a sphere are given to illustrate the power of the method.

J. S. Reid

Papers

The Analytical Calculation of Absorption in Multifaceted Crystals