Noncovalent n Interactions

Center for Computational Molecular Science and Technology, School of Chemistry and Biochemistry, and College of Computing, Georgia Institute of Technology, Atlanta, Georgia 

These n interactions can be equally critical in materials chemistry applications, including self-assembled supramolecular architectures.For example, molecular wires can be formed from stacks of aromatic macrocycles.The binding of small molecules to carbon nanotubes and attraction between graphene sheets are both determined by noncovalent n interactions. The crystal structure and charge-transport properties of 7t-conjugated organic materials are also largely determined by n-n interactions.  

Reviews in Computational Chemistry, Volume 26 edited by Kenny B. Lipkowitz and Thomas R. Cundari Copyright 2009 John Wiley Sons, Inc. 

Gas-phase studies of bimolecular complexes afford more control, but these can be quite challenging. Most noncovalent interactions between small molecules feature small binding energies (on the order of a few kilo calories per mole or less), often meaning that very low temperatures must be used to avoid thermal dissociation of the complex. Additionally, it is frequently necessary to use mass selection techniques to ensure that the sample contains only the complex of interest and not larger or smaller clusters. Furthermore, the potential energy surfaces for these systems tend to be fairly flat, meaning that the complexes may be fluxional without a well-defined structure. If the potential surface features two or more potential minima, conversion between them will be easy and rapid except at very low temperatures. 

Many chemical problems can be addressed easily and reliably using Hartree-Fock molecular orbital theory or Kohn-Sham density functional theory with modest-sized basis sets. Unfortunately, 7t interactions, and non-covalent interactions in general, are not among them. In this section we consider the electron correlation and basis set requirements for computations of n interactions. 

---

So far in this review, we have focused on various approaches to computing the strength and geometries of noncovalent n interactions. However, not only can computational chemistry provide such information, but it can also provide a means of analyzing that information. In studies of complex phenom-data analysis can be the most important step if it yields a rational... 

---