Organic functionalization/modification

The scope of tire following article is to survey the physical and chemical properties of tire tliird modification of carbon, namely [60]fullerene and its higher analogues. The entluisiasm tliat was triggered by tliese spherical carbon allotropes resulted in an epidemic-like number of publications in tire early to mid-1990s. In more recent years tire field of fullerene chemistry is, however, dominated by tire organic functionalization of tire highly reactive fullerene... 

Posttranslational modifications are a sundry set of transformations that help to diversify the limited genome of organisms. The modifications discussed in this chapter have been shown to modify a wide variety of proteins whose functions vary from cell division to metabolism and regulation. While a large selection of posttranslational modifications has been discussed, the presentation is not all-inclusive of all modifications. Emphasis has been placed on the discoveries made since 2005 and on the more common modifications. The importance of posttranslational modifications on protein structure and function and cellular function has been emphasized. 

The introduction of organofunctional groups, i.e. the use of alkoxysilanes of the type (R O Si—X—A, where A is a functional organic group and X is a chemically inert spacer permanently linking Si and A, results in a more extensive chemical modification of the materials76. The properties of the organic functions A supplement the properties of the polysiloxane matrix formed by hydrolysis and condensation of the Si(OR )3 and Si(OR )4 units. 

Figure 3.7 Grafting (postsynthetic functionalization) for organic modification of mesoporous pure silica phases with terminal organotrialkoxysilanes of the type (R 0)3SiR. R = organic functional group.

Near-infrared spectroscopy (NIR) works in the 800 nm-2.5 pm (12,500— 4,000 cm-1) range. The advantage of NIR is that it can typically penetrate much farther into a sample than the mid-infrared radiation (30-1.4 pm, 4,000-400 cm-1)- It can be used for the quantitative measurement of organic functional groups of soil organic matter, especially O—H, N—H, and C=0 (Siesler et al. 2002). In addition, the structural modifications under the effect of chemical treatments (e.g., acidic treatments) can also be studied by NIR (Madejova et al. 2009). 

New luminescent hybrid mesoporous material was prepared by covalent anchoring rare earth complex onto MCM-41 by a postsynthesis approach. The monomer (referred to here as PABI) which plays double roles, i.e., as a ligand for lanthanide ion and as an organic functional molecule to modify MCM-41 is synthesized and characterized by H NMR and MS. The fluorescence spectra show clearly that the hybrid mesoporous material possesses excellent luminescence characteristics. The hybrid mesoporous material retains the structure of MCM-41 after modification. 

Surface modification is possible by essentially all the reactions which have been developed over the past decades for amorphous silica. Excellent compilations of the different reagents and modifications achieved for ordered mesoporous silica are given in reviews by Anwander [4] and by Sayari and Hamoudi [5]. In almost all cases, trialkoxysilanes, trichlorosilanes, or disilazanes are used, which bear the organic functional group that is to be grafted to the surface of the silica. Also, several other review papers on surface modification with organosilicon groups are available [6 - 8]. 

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