D ‐Fructose‐6‐phosphate aldolase (FSA) is a key biocatalyst for the alternative synthetic construction of biologically active products with known therapeutic and research interest or novel structures relevant to drug discovery. Novel aldol addition reactions of dihydroxyacetone and hydroxyacetone to a variety of aldehydes catalyzed by FSA are presented (see scheme).
Four soluble tetra(2‐methoxyethoxy)metallophthalocyanines 4a‐4d were, in two steps, synthesized from phthalonitrile 1 and 2‐methoxyethanol 2 , and characterized by MS, 1H NMR, UV‐vis, IR and elemental analysis, as well as Cyclic voltammetry. 相似文献
The big “DIP”per : The preparation of both l,l ‐DIP and l,d ‐DIP (see structures) involves a complex case of double asymmetric induction in the key step of the synthesis. The differential ability of each isomer to contribute to thermoprotection in the context of a key enzyme has been assessed and both isomers of DIP are shown to possess biological activity.
Broken‐symmetry DFT calculations on transition‐metal clusters with more than two centers allow the hyperfine coupling constants to be extracted. Application of the proposed theoretical scheme to a tetranuclear manganese complex that models the S2 state of the oxygen‐evolving complex of photosystem II yields hyperfine parameters that can be directly compared with experimental data. The picture shows the metal–oxo core of the model and the following parameters; exchange coupling constant Jij, the expectation value of the site‐spin operator , and the isotropic hyperfine coupling parameters.
A new way to make a bang : Several functionalized 1‐ethyl‐5‐aminotetrazoles, 1‐ethyl‐5‐nitrimino‐tetrazoles, and copper complexes have been synthesized and their chemical and energetic properties have been comprehensively characterized. The compounds belong to all classes of “energetic materials”: explosives, propellants, and pyrotechnics.
Carbonylation gets a phase lift : The usual liquid‐phase, high‐pressure processes for carbonylating formaldehydes are avoided in a novel vapor‐phase reaction. Using an acid zeolite (Faujasite) at near‐atmospheric pressure dimethoxymethane (DMM; the dimethyl acetal of formaldehyde; see scheme) is carbonylated to produce methyl methoxyacetate (MMAc). This approach provides a new route to ethylene glycol under mild conditions.
Buckybowls : The adsorption of penta‐tert‐butylcorannulene, a molecule with fivefold symmetry, on Cu(111), a surface with threefold symmetry, is investigated by scanning tunneling microscopy complemented by structure calculations. The symmetry mismatch is resolved by the formation of threefold‐symmetric subunits consisting of three molecules, which combine with single molecules to form a nearly perfect filling of the plane (see picture).
Wheels on water? A waterwheel‐shaped porphyrin pentamer has been synthesized by palladium‐catalyzed cross‐coupling reactions. The key intermediate is a boronate porphyrin, in which four boronic ester groups are directly attached to the meso‐positions.
Bromide is best : The first [2]rotaxane incorporating the triazolium anion‐binding motif is prepared using bromide anion templation. Preliminary anion‐binding investigations reveal that the rotaxane exhibits the rare selectivity preference for bromide over chloride ions.
Dipolar aggregation : Examples of a novel class of tweezer molecules have been constructed through the tethering of two dipolar merocyanine chromophores. The electrostatic‐interaction‐directed self‐assembly of these tweezers affords centrosymmetric bimolecular complexes with a unique aggregate geometry of four π‐stacked chromophores (see picture) with an alternating arrangement of their dipole moments and very high dimerization constants, even in the good solvating solvent chloroform.
Hydrated ion nanocalorimetry is used to measure reduction energies and H atom affinities of gaseous hydrated ions by determining the energy deposited into these nanodrops from the number of water molecules lost upon reduction by thermally generated electrons (see figure).
Finely tuned optical properties : The optical properties of substituted protected catechol derivatives can be fine‐tuned (see scheme; TBDMS=tert‐butyldimethylsilyloxy). The DFT‐calculated polarisabilities are compared with experimental data.
Translation of specific small peptides on the ribosome can confer resistance to macrolide antibiotics. To reveal the molecular details of this and related phenomena, stable RNA–peptide conjugates that mimic peptidyl‐tRNA would be desirable, especially for ribosome structural biology. A flexible solid‐phase synthesis strategy now allows efficient access to these highly requested derivatives without restriction on the RNA and peptide sequences.
Click to view : Glycopolymers can be used to display glycans on microarrays in native‐like architectures. The structurally uniform alkyne‐terminated mucin mimetic glycopolymers (see picture; TR=fluorophore) were printed on azide‐functionalized chips by microcontact printing in the presence of a copper catalyst. The surface‐bound glycopolymers bind lectins in a ligand‐specific manner.
Crystal‐clear structures : The first crystal structures of organometallic pincer–cutinase hybrids (see figure) provide insight into the 3D structural arrangement of both the protein and the organometallic pincer moiety, and reveal different binding modes for different pincers.
A general solution : In situ synchrotron X‐ray scattering in a high‐pressure pulsed injection reactor (see picture) shows that magnetite nucleation and growth are temporally separated. Gram‐scale crystalline, pure phase, superparamagnetic magnetite nanoparticles were synthesized without surfactants in supercritical water in less than one hour using a laboratory‐scale continuous‐flow reactor.
