Dynamic chemical devices: Modulation of contraction/extension molecular motion by coupled-ion binding/pH change-induced structural switching

Dynamic hybrid materials for constitutional self-instructed membranes

“…More generally, like in biology in which up-regulation means ''the increase in the number of counts of a cellular component as response of external stimuli'' (37), the chemical membrane systems described here undergo the spatial development (up-regulation) of the most adapted 3D ion-channel superstructure formed from molecular components' binding of the ion effectors (38,39). Finally the results obtained extend the application of constitutional dynamic chemistry (40) from materials science to functional constitutional devices (41). The membrane AAM-ODS-1 and mixed-membrane AAM-ODS-{1, 2} systems represent dynamic constitutional systems evolving over time to form the fittest ion channels from a library of molecular and supramolecular components, or selecting the fittest ion pairs from a mixture of salts, demonstrating flexible adaptation.…”

Is it the shape of the cavity, or the shape of the water in the cavity?

“…Past explanations of molecular recognition, based on semi-quantitative experimental physical-organic studies in semi-polar organic solvents such as chloroform and methylene chloride, [5][6][7][8] do not account for a (or perhaps, the) key component of all biomolecular recognition events:…”

“…ΔJ°b ind = ΔJ°h ydration + ΔJ°i nteraction + ΔJ°c onformation + ΔJ°t rans,rot (6) The magnitude of each of the terms on the right-hand side of eq. 6 depends on the molecular details (i.e., the structures of the protein and the ligand, and the structure of water close to the protein and ligand) of each system.…”

Theoretical Investigation of the Second‐Order Nonlinear Optical Properties of Helical Pyridine–Pyrimidine Oligomers

“…Chiral induction and amplification mechanisms have also been studied in a variety of (helical) polymers bearing chiral groups [22] as well as in chiral columnar stacks of C 3 -symmetry molecules. [23] Starting from the principle that 2,2'-bipyridine adopts an s-trans conformation, Lehn and co-workers proposed several helical structures based on heterocycles, [24][25][26][27][28][29] including pyridine-pyridazine, pyridine-naphtyridine, and pyridine-pyrimidine units, which can be considered as coiled molecular wires of nanometric size, possessing electron-acceptor properties associated with the nature of their subunits and subAbstract: The structure and secondorder nonlinear optical properties of a series of helical pyridine-pyrimidine oligomers recently synthesized by Barboiu and Lehn have been investigated theoretically by combining molecular mechanics and quantum chemistry approaches. In the absence of substituents, the hyper-Rayleigh scattering response (b HRS ) and the projection of the first hyperpolarizability on the dipole moment (b k ) exhibit periodic variations with chain length, but these nonlinear optical responses remain small.…”