A distributed modelling approach to assess the use of Blue and Green Infrastructures to fulfil stormwater management requirements

International audienceBlue and Green Infrastructures (B&GI) are nature-based solutions considered as particularly efficient to reduce the potential impact of new and existing developments with respect to stormwater issues. In order to assess their performance at some large scales compatible with urban projects, adapted distributed rainfall-runoff models are required. The latest advancements of the Multi-Hydro platform have made possible the representation of such B &GI. Applied in a virtual new urban development project located in the Paris region, Multi-Hydro has been used to simulate the impact of B&GI implementation, and their ability to fulfil regulation rules authorizing the connexion to the sewer network. The results show that a combination of several B&GI, if they are widely implemented , could represent an efficient tool to meet regulations at the parcel scale, as they can reduce runoff volume about 90%

Spin exchange monitoring of the strong positive homotropic allosteric binding of a tetraradical by a synthetic receptor in water

International audienceThe flexible tetranitroxide 4T has been prepared and was shown to exhibit a nine line EPR spectrum in water, characteristic of significant through space spin exchange (Jij) between four electron spins interacting with four nitrogen nuclei (Jij ≫ aN). Addition of CB[8] to 4T decreases dramatically all the Jij couplings, and the nine line spectrum is replaced by the characteristic three line spectrum of a mononitroxide. The supramolecular association between 4T and CB[8] involves a highly cooperative asymmetric complexation by two CB[8] (K1 = 4027 M–1; K2 = 202 800 M–1; α = 201) leading to a rigid complex with remote nitroxide moieties. The remarkable enhancement for the affinity of the second CB[8] corresponds to an allosteric interaction energy of ≈13 kJ mol–1, which is comparable to that of the binding of oxygen by hemoglobin. These results are confirmed by competition and reduction experiments, DFT and molecular dynamics calculations, mass spectrometry, and liquid state NMR of the corresponding reduced complex bearing hydroxylamine moieties. This study shows that suitably designed molecules can generate allosteric complexation with CB[8]. The molecule must (i) carry several recognizable groups for CB[8] and (ii) be folded so that the first binding event reorganizes the molecule (unfold) for a better subsequent recognition. The presence of accessible protonable amines and H-bond donors to fit with the second point are also further stabilizing groups of CB[8] complexation. In these conditions, the spin exchange coupling between four radicals has been efficiently and finely tuned and the resulting allosteric complexation induced a dramatic stabilization enhancement of the included paramagnetic moieties in highly reducing conditions through the formation of the supramolecular 4T@CB[8]2 complex