The continued increase in the atmospheric concentration of carbon dioxide due to anthropogenic emissions is predicted to lead to significant changes in climate. About half of the current emissions are being absorbed by the ocean and by land ecosystems, but this absorption is sensitive to climate as well as to atmospheric carbon dioxide concentrations, creating a feedback loop. General circulation models have generally excluded the feedback between climate and the biosphere, using static vegetation distributions and CO2 concentrations from simple carbon-cycle models that do not include climate change. Here we present results from a fully coupled, three-dimensional carbon–climate model, indicating that carbon-cycle feedbacks could significantly accelerate climate change over the twenty-first century. We find that under a 'business as usual' scenario, the terrestrial biosphere acts as an overall carbon sink until about 2050, but turns into a source thereafter. By 2100, the ocean uptake rate of 5 Gt C yr-1 is balanced by the terrestrial carbon source, and atmospheric CO2 concentrations are 250 p.p.m.v. higher in our fully coupled simulation than in uncoupled carbon models, resulting in a global-mean warming of 5.5 K, as compared to 4 K without the carbon-cycle feedback.

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Acceleration of global warming due to carbon-cycle feedbacks in a coupled climate model

Self-Assembly of Discrete Cyclic Nanostructures Mediated by Transition Metals

Low Molecular Mass Gelators of Organic Liquids and the Properties of Their Gels

Nanostructured materials: basic concepts and microstructure☆

Dynamic covalent chemistry relates to chemical reactions carried out reversibly under conditions of equilibrium control. The reversible nature of the reactions introduces the prospects of "error checking" and "proof-reading" into synthetic processes where dynamic covalent chemistry operates. Since the formation of products occurs under thermodynamic control, product distributions depend only on the relative stabilities of the final products. In kinetically controlled reactions, however, it is the free energy differences between the transition states leading to the products that determines their relative proportions. Supramolecular chemistry has had a huge impact on synthesis at two levels: one is noncovalent synthesis, or strict self-assembly, and the other is supramolecular assistance to molecular synthesis, also referred to as self-assembly followed by covalent modification. Noncovalent synthesis has given us access to finite supermolecules and infinite supramolecular arrays. Supramolecular assistance to covalent synthesis has been exploited in the construction of more-complex systems, such as interlocked molecular compounds (for example, catenanes and rotaxanes) as well as container molecules (molecular capsules). The appealing prospect of also synthesizing these types of compounds with complex molecular architectures using reversible covalent bond forming chemistry has led to the development of dynamic covalent chemistry. Historically, dynamic covalent chemistry has played a central role in the development of conformational analysis by opening up the possibility to be able to equilibrate configurational isomers, sometimes with base (for example, esters) and sometimes with acid (for example, acetals). These stereochemical "balancing acts" revealed another major advantage that dynamic covalent chemistry offers the chemist, which is not so easily accessible in the kinetically controlled regime: the ability to re-adjust the product distribution of a reaction, even once the initial products have been formed, by changing the reaction's environment (for example, concentration, temperature, presence or absence of a template). This highly transparent, yet tremendously subtle, characteristic of dynamic covalent chemistry has led to key discoveries in polymer chemistry. In this review, some recent examples where dynamic covalent chemistry has been demonstrated are shown to emphasise the basic concepts of this area of science.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/1521-3773%2820020503%2941%3A9%3C1460%3A%3AAID-ANIE11111460%3E3.0.CO%3B2-N

Dynamic covalent chemistry.

Multicomponent Self-Assembly: Spontaneous Formation of a Cylindrical Complex from Five Ligands and Six Metal Ions†

The interaction of two suitably designed complementary ditopic molecular components (1,2) and (3,4) generates spontaneously an organized supramolecular architecture displaying molecular sorting and orientation.

Molecular recognition directed self-assembly of ordered supramolecular strands by cocrystallization of complementary molecular components

The programmed self-association of the self-complementary nucleotide-like pyrimidinone 5 and pyrimidinedione 6, generates, as predicted, organized supramolecular ribbons. The crystal structure of such a species has been determined. A similar entity is obtained from the pyrimidinetriamine 12 with solvent participation, giving a quadruply hydrogen-bonded ribbon, whose crystal structure has also been determined. These processes give access to the designed generation of organized arrays of functional substituents.

Molecular ribbons from molecular recognition directed self-assembly of self-complementary molecular components

Selbstorganisation von Multikomponenten-systemen: spontane Bildung eines zylinderförmigen Komplexes aus fünf Liganden und sechs Metall-Ionen

Palladium-Mediated Intramolecular Formation of a C-S Bond: Application to the Selective Syntheses of Six- and Seven-Membered Sulfur-Containing Heterocycles

André DeCian

Papers

Multicomponent Self-Assembly: Spontaneous Formation of a Cylindrical Complex from Five Ligands and Six Metal Ions†

Molecular recognition directed self-assembly of ordered supramolecular strands by cocrystallization of complementary molecular components

Molecular ribbons from molecular recognition directed self-assembly of self-complementary molecular components

Selbstorganisation von Multikomponenten-systemen: spontane Bildung eines zylinderförmigen Komplexes aus fünf Liganden und sechs Metall-Ionen

Palladium-Mediated Intramolecular Formation of a C-S Bond: Application to the Selective Syntheses of Six- and Seven-Membered Sulfur-Containing Heterocycles