Molecular chemistry, compared with supramolecular

On the way from molecular to macromolecular and supramolecular chemistry, researchers have realized increasingly complex functional materials however, these still lag behind compared to highly sophisticated macroscopic architectures with precise and predefined structure that are encountered in biological systems. In this review, we have summarized the first steps chemists have taken toward the construction of macromolecular architectures with defined three-dimensional structures. In the past decade, polymers with defined secondary structure mimicking one or more aspects from biological systems have been prepared. Issues important for the programmed organization of synthetic macromolecules that have... 

We have seen in the preceding sections that it is possible to explicitly model the molecular energetics and dynamics of a supramolecular assembly. Here, we shall briefly comment on how to calculate physical quantities that can be directly compared with experimentally measured observables, which is essential if theoretical descriptions and predictions are to be of any meaning. Of course, this endeavor is not special to supramolecular chemistry but is a general task in theoretical and computational chemistry. In supramolecular chemistry, however, new complications arise owing to the many particles involved. Therefore, it is necessary to selectively extract the relevant information needed to describe the features of the supramolecular assembly. 

Also, various spectroscopic quantities can be calculated in order to test experimental assumptions Once a structure of a supramolecular assembly has been assumed, optimized or propagated in time, properties like vibrational frequencies, infrared, Raman [93], or Resonance Raman [159] intensities, NMR or EPR parameters can be calculated with first-principles methods to be compared with the experimentally measured spectra in order to confirm or reject the structural basis assumed in the interpretation of the experimental spectra. It is impossible to review the work and achievements of theoretical chemistry in this respect. Therefore, we concentrate on selected examples in the following. The interested reader is referred to the book by Kaupp, Biihl and Malkin [160] for the calculation of NMR and ESR parameters and to Refs. [161, 162] for more general discussions of molecular property calculations. NMR parameters are molecular properties probed at atomic nuclei and thus ideal for linear-scaling or empirical approaches. An efficient linear-scaling method for supramolecular systems has been presented recently [163]. 

The nature of the 1 1 inclusion complexes of 3 with the fluoride or chloride ion in water were described and compared with the X-ray structure of the relevant compound. Furthermore, simulations involving the uncomplexed ligand and both anions led to the experimentally observed over Cn binding selectivity, which was reproduced quantitatively by free-energy perturbation (FEP) calculations.The latter provide a thermodynamic measure of the relative interaction and binding free energies in solution, these are, of course, of particular interest in supramolecular chemistry, where molecular association is of paramount importance. 

In the last 130 years, chemistry has focused its attention on the behavior of molecules and their construction from the atoms. Atoms are held together in molecules by chemical bonds [1]. This is within the framework of the theoretical of atoms-in-molecules. From a modem point of view, the chemical bond has been designed using theoretical methods based on the quantum mechanical ab initio for molecules isolated with high accuracy by comparing the results with high-resolution spectroscopies [2, 3]. The basic and fundamental unit that we call molecule is interpreted with some detail. However, in the last three decades chemists have moved beyond the atomic and molecular chemistry towards the area of supramolecular chemistry [4—6]. This new area is in the central part of the bottom-up approaches to... 

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