Topologically well-defined

The introduction of the functional group in the course of the synthesis (a priori) presents an elegant way to place the functionalities in topologically well defined locations in the dendrimer. 

Recent advances in topologically well-defined polymers [M. Sawamoto, Kagaku... 

As we all know, there are two aspects that make zeolites unique. First of all, being crystals, their intracrystalline surface is an inherent part of the crystal structure and hence they are topologically well defined. This is in sharp distinction to the ill-defined amorphous solids we are familiar with. The availability of solids with such a large and well defined surface area is certainly exciting and welcoming news to us. 

Dendrimers are complex but well-defined chemical compounds, with a treelike structure, a high degree of order, and the possibility of containing selected chemical units in predetermined sites of their structure [4]. Dendrimer chemistry is a rapidly expanding field for both basic and applicative reasons [5]. From a topological viewpoint, dendrimers contain three different regions core, branches, and surface. Luminescent units can be incorporated in different regions of a dendritic structure and can also be noncovalently hosted in the cavities of a dendrimer or associated at the dendrimer surface as schematically shown in Fig. 1 [6]. 

MHI possess at least two different polymerization initiating sites. The identical sites are selective for a particular class of monomers, and thus the resulting ji-star consists of chemically different arms. In order to obtain well-defined //-stars, these identical active sites should have equal reactivity and furthermore, initiation should be faster than propagation. It is not always possible to achieve these requirements since differentiation in the topology of... 

Extraframework cations are needed in anionic zeolites for charge balance, and for several zeolite topologies their locations are well investigated [281, 282]. Different cations have been investigated by solid state NMR in the past with different NMR properties and different project targets. We restrict this section to a tutorial example on sodium cation motion in sodalite and cancrinite structures [283-285], 23Na has a nuclear electric quadrupole moment, and quadrupolar interaction is useful to investigate jump processes, especially when they are well defined. 

The discovery of new controlled polymerization techniques in the mid-1990s and the progress achieved in living polymerization toward well-defined block copolymers with complex topologies have certainly played a key role in the development of block copolymer micelles. 

The study of chemical reactions requires the definition of simple concepts associated with the properties ofthe system. Topological approaches of bonding, based on the analysis of the gradient field of well-defined local functions, evaluated from any quantum mechanical method are close to chemists intuition and experience and provide method-independent techniques [4-7]. In this work, we have used the concepts developed in the Bonding Evolution Theory [8] (BET, see Appendix B), applied to the Electron Localization Function (ELF, see Appendix A) [9]. This method has been applied successfully to proton transfer mechanism [10,11] as well as isomerization reaction [12]. The latter approach focuses on the evolution of chemical properties by assuming an isomorphism between chemical structures and the molecular graph defined in Appendix C. 

In response to the above characterization problems and an interest in understanding the topology of intramolecular entanglement a membrane viscometer was developed.(A) In the membrane viscometer a solution is passed through a thin ( 10 )im) membrane with well-defined pores of fixed diameter that are nearly perpendicular to the membrane surface. The important feature is... 

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