An overview of the wide range of nanoreactors that have been constructed from synthetic and biological building blocks using both covalent and noncovalent approaches is given. Focus is on self-assembled systems, varying in size from a few nanometers to tens of micrometers. The review is divided into several sections that cover the development of tailor-made nanoreactors, starting from small organic molecular containers expanding to large compartment-containing assemblies. First, the construction of capsules from low molecular weight compounds by means of covalent synthesis and self-assembly by highly directive and pre-designed interactions is discussed. Second, nanocapsules based on micellar and vesicular assemblies that are built up frow low molecular weight molecules are described. Finally, the construction of nanoreactors from macromolecular building blocks, as well as recent developments in the use of viruses as nanocontainers and reactors are outlined.

/pdf/self-assembled-nanoreactors-4el5gc5op7.pdf

Self-Assembled Nanoreactors

The design of artificial catalysts able to compete with the catalytic proficiency of enzymes is an intense subject of research. Non-covalent interactions are thought to be involved in several properties of enzymatic catalysis, notably (i) the confinement of the substrates and the active site within a catalytic pocket, (ii) the creation of a hydrophobic pocket in water, (iii) self-replication properties and (iv) allosteric properties. The origins of the enhanced rates and high catalytic selectivities associated with these properties are still a matter of debate. Stabilisation of the transition state and favourable conformations of the active site and the product(s) are probably part of the answer. We present here artificial catalysts and biomacromolecule hybrid catalysts which constitute good models towards the development of truly competitive artificial enzymes.

/pdf/supramolecular-catalysis-part-2-artificial-enzyme-mimics-2h1esy0td8.pdf

Supramolecular catalysis. Part 2: artificial enzyme mimics

Recent advances in utilization of transition metal complexes and lanthanides as diagnostic tools

Supercritical carbon dioxide (scCO2) is an environmentally benign reaction medium for highly efficient rhodium-catalyzed hydroformylation reactions. Olefinic substrates can be hydroformylated in scCO2 at 40−65 °C to give the corresponding aldehydes in practically quantitative yields. The reaction course of the hydroformylation of 1-octene in scCO2 was analyzed in detail by online-GC monitoring. The influence of reaction parameters such as temperature, synthesis gas pressure, and [P]/Rh ratio on reaction rates and selectivities is grossly similar to the effects observed in conventional solvents. Maximum turnover frequencies of 1375, 500, and 115 h-1 were determined as lower limits for the catalytic activities under the present conditions for the unmodfied, phosphine-modified, and phosphite-modified systems, respectively. With unmodified catalysts, the hydroformylation rates are considerably higher in scCO2 than in organic solvents or liquid CO2 under otherwise identical conditions. Modified catalytic syste...

Rhodium-Catalyzed Hydroformylation in Supercritical Carbon Dioxide

Molecular and Supramolecular Objects from Glycoluril

A novel supramolecular catalyst functioning according to the principles of enzymatic catalysis is described. It consists of a basket-shaped molecule to which a catalytically active Rh(1) complex is attached. The catalyst selectively hydrogenates and isomerizes allyl-substituted dihydroxyarene substrates that are bound in its cavity. The reactivity of this supramolecular catalyst and its affinity for several substrates is compared with that of the corresponding catalyst without a binding site. Features known from enzymatic catalysis, e.g. Michaelis-Menten kinetics and rate enhancement by cooperative binding, are described and discussed.

/pdf/substrate-selective-catalysis-by-rhodium-metallohosts-1kpsjfgu84.pdf

Substrate selective catalysis by rhodium metallohosts

/pdf/a-rhi-centered-cage-compound-with-selective-catalytic-1lgnf0wden.pdf

A Rhi-Centered Cage Compound with Selective Catalytic Properties

https://pure.uva.nl/ws/files/2936911/870_9901y.pdf

HRh[P(OPh)3]4 as a hydrogenation and isomerization catalyst

To diphenylglycoluril (2), four aliphatic chains were attached, each with a vanillyl alcohol group at the end. In an acid-catalyzed reaction, three of the vanillyl alcohol groups cyclize to form a cyclotriveratrylene unit. The resulting compound (3) has a well-defined cavity and a free, func- tionalized arm. Cyclization of four vanillyl alcohol groups (5) does not occur, probably for steric reasons.

/pdf/a-cage-compound-derived-from-cyclotriveratrylene-and-4xdtkw3vcu.pdf

A cage compound derived from cyclotriveratrylene and diphenylglycoluril sub-units

The design and synthesis of two novel chiral receptors derived from diphenylglycoluril are described. The chirality in these molecules is due to the unsymmetrical positioning of amino functions in the crown ether rings with respect to the diphenylglycoluril subunit.

/pdf/chiral-basket-shaped-host-compounds-derived-from-3yvnstr6sk.pdf

H. K. A. C. Coolen

Papers

Substrate selective catalysis by rhodium metallohosts

A Rhi-Centered Cage Compound with Selective Catalytic Properties

HRh[P(OPh)3]4 as a hydrogenation and isomerization catalyst

A cage compound derived from cyclotriveratrylene and diphenylglycoluril sub-units

Chiral basket-shaped host compounds derived from diphenylglycoluril