Covalent function, from

We have though previously expressed our reservations (10, 11) concerning the combination of ft and ft data for the derivation of a2 and (ZjZ0). Thus, whereas the repulsion parameter, B, is essentially an outer radial quantity (82, 83) the spin-orbit coupling constant, , is dominantly an inner orbital function (84). Moreover the (ZjZo) values derived in most cases indicate a rather small measure of central field covalency. Nevertheless, the a2 values obtained tend to parallel the mm rather than the a 0ot values, especially as the extent of covalency increases from the M(IV) to M(V) to M(VI) series, thus suggesting that flroot values may be too large. On the other hand the values are likely... 

Figure 4.19. Continuous catalysis with non-covalently functionalized dendrimers a) acid-, b) ester-functionalized guest. (Reprinted with permission from ref. 33. Copyright 2001 American Chemical Society)...

From an atomic configuration point of view, a nanotube can be divided into two parts that are generated by curvatures the end caps and sidewall. The end caps are close to the hemispherical fullerene and are curved in 2D, and the sidewall contains less-distorted carbon atoms and is curved in ID (Polizu et al., 2006). Owing to their specific curvatures, the chemical reactivity at the sidewall is significantly lower than that at the end caps The sidewall is thought to be inert and highly reactive agents are required for the covalent functionalization of CNT sidewalls (Wei et al., 2007). 

When the formation of covalent bonds is established between functional groups and a surface, a covalent or chemical functionalization is reached. The main characteristic of this type of functionalization is the change in the carbon hybridization from sp2 to sp3 [104]. Although this covalent functionalization provides the possibility to obtain a... 

Therefore, the principal role of the inclusion of the ionic term in the wave function is the reduction of the kinetic energy from the value in the purely covalent wave function. Thus, this is the delocalization effect alluded to above. We saw in the last section that the bonding in H2 could be attributed principally to the much larger size of the exchange integral compared to the Coulomb integral. Since the electrical effects are contained in the covalent function, they may be considered a first order effect. The smaller added stabilization due to the delocalization when ionic terms are included is of higher order in VB wave functions. 

The results of a valence bond treatment of the rotational barrier in ethane lie between the extremes of the NBO and EDA analyses and seem to reconcile this dispute by suggesting that both Pauli repulsion and hyperconjugation are important. This is probably closest to the truth (remember that Pauli repulsion dominates in the higher alkanes) but the VB approach is still imperfect and also is mostly a very powerful expert method [43]. VB methods construct the total wave function from linear combinations of covalent resonance and an array of ionic structures as the covalent structure is typically much lower in energy, the ionic contributions are included by using highly delocalised (and polarisable) so-called Coulson-Fischer orbitals. Needless to say, this is not error free and the brief description of this rather old but valuable approach indicates the expert nature of this type of analysis. 

Covalent Functionalization by Polymerization - Crafting To and Crafting From ... 

Most of PVA/CNT composites are processed under the form of films. Generally, films are casted and dried from water-based PVA and nanotube dispersions. Different types of water-based dispersions have been used. Carbon nanotubes come from various production sources and can be covalently functionalized. The PVA molecular weight and hydrolysis rate can also be varied as well as the nanotube fraction. This is why comparisons between all the contributions in the literature can sometimes be difficult. Nevertheless some general and important features can still be deduced from all the studies reported on this topic. 

Apart from the cyclization around a metal ion, specific atoms or molecular groups can be construed as temporary, covalently bound templates. There is a fundamental difference between these and supramolecular host-guest systems, in that molecular recognition is not necessary rather, host and guest (here not functioning as such) are joined together by one or more covalent bonds from the outset. 

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