Support grafted carbon materials

This chapter begins with a general description of the several strategies to het-erogenize transition-metal complexes onto solid supports, with a special emphasis on those methodologies that have been used for complex grafting onto carbon materials. It will include sections that will focus on the various transition-metal complexes that have been immobilized onto several carbon materials activated carbons, black carbons, carbons xerogels, and carbon nanotubes the specific catalytic reactions with these carbon-based systems are also discussed in some detail. 

Due to the nature of carbon materials, the presentation of representative methods for surface derivatization will follow an approach different from that described in the preceding section, which is based on the spatial target site where physical-chemical modification can take place (1) immobilization performed at edges and/or ends and defects of graphitic sheets, (2) immobilization onto the graphene sheets, and (3) exclusively for CNTs we present some examples of endohedral encapsulation of metal complexes. For the first two cases, covalent bonding and noncovalent interactions can occur directly between the transition metal complex and carbon supports or via spacers grafted to the carbon surface. 

In the present work, AlMCM-41 materials with different nsi/n,y-ratios were used as support for copper and zinc species, which were introduced during the synthesis of the mesoporous molecular sieve. Characterization of the metal-containing materials was primarily achieved by carbon monoxide adsorption and temperature programmed reduction In particular the aim of this work was to distinguish between isolated copper species grafted on the wall of MCM-41 and/or or the formation of copper oxide clusters located in the channels... 

The nature of the supporting material can determine the final catalytic performance. Interestingly, gold catalysts supported on various carbons displayed differences even in the same reaction, which implies that the catalytic performance was affected not only by the nature of the carbon but also by the preparation method [47]. One of the most relevant parameters for the choice ofthe support seems to be the type and distribution of surface groups, as these can favor or inhibit the grafting of the nanoparticles. Hence, acidic or basic treatments of supporting materials... 

A wide variety of natural and synthetic materials have been used for biomedical applications. These include polymers, ceramics, metals, carbons, natural tissues, and composite materials (1). Of these materials, polymers remain the most widely used biomaterials. Polymeric materials have several advantages which make them very attractive as biomaterials (2). They include their versatility, physical properties, ability to be fabricated into various shapes and structures, and ease in surface modification. The long-term use of polymeric biomaterials in blood is limited by surface-induced thrombosis and biomaterial-associated infections (3,4). Thrombus formation on biomaterial surface is initiated by plasma protein adsorption followed by adhesion and activation of platelets (5,6). Biomaterial-associated infections occur as a result of the adhesion of bacteria onto the surface (7). The biomaterial surface provides a site for bacterial attachment and proliferation. Adherent bacteria are covered by a biofilm which supports bacterial growth while protecting them from antibodies, phagocytes, and antibiotics (8). Infections of vascular grafts, for instance, are usually associated with Pseudomonas aeruginosa Escherichia coli. Staphylococcus aureus, and Staphyloccocus epidermidis (9). 

The covalent attachment of MN4-MC on the surface of CNTs has been another way of combining macrocyclic complexes and carbon supports to fabricate functional hybrid materials. Coates et al. [56] described the chemical modification of SWCNTs after their adsorption on GC electrode. The procedure consisted first in the electrochemical grafting of 4-azido benzenediazoium salt on the surface of CNTs, followed by a reaction with ethylpyridine through click chemistry. Finally, the attachment of a FePc was carried out by axial bonding to the pyridine group. An illustration of these steps can be seen in Fig. 9. The sensor was applied in the electrocatalytic detection of hydrazine, with a ten times improvement of the limit of detection over the surface without the CNTs. 

---