Three dimensional carbon phases

Novel Hypothetical Three-dimensional Carbon Phases... 

Although the possibility of three-dimensional C60 polymer has been discussed experimentally, so far the polymerized crystalline solid C60 phases with firm experimental evidence reported are in the above three phases. On the other hand, theoretically the three-dimensional C60 polymer phase has been proposed from the LDA total-energy optimization under the reduced lattice constants (Fig. 14) [42]. The tetragonal phase is found to go to the three-dimensionally polymerized phase with as many as 24 sp3 carbon atoms at about 20 GPa pressure. Interestingly, this three-dimensional polymer phase is predicted to be metallic with large N( P). 

In most carbon and graphite processes, the initial polymerization reactions occur in the Hquid state. The subsequent stages of crystal growth, heteroatom elimination, and molecular ordering occur in the soHd phase. The result is the development of a three-dimensional graphite stmcture. 

Diamond C is the high-pressure phase of carbon, and the C-C bonding is of sp pure covalent nature. The structure has a three-dimensional framework as indicated in Fig. 9.1, and is different from the low-pressure phase, graphite, which has a sheet structure consisting of sp covalent bonds and Van der Waals bonds connecting the sheets. Other polymorphs called lonsdalite, fullerene, and carbon nanotube, which consist of mixed sp and sp bonds, are also known. 

Proteins and antibodies are natural substrates for affinity columns because of the nature of the enzyme recognition site and the antibody-antigen interaction sites. They have a three-dimensional shape and electrical charge distributions that interact with only specific molecules or types of molecules. Once these substrate sites are identified, molecules can be isolated or synthesized with the key characteristics and used to build affinity supports. These substrates are often bound to a 6-carbon spacer so that they protrude farther away from the packing surface toward the mobile phase and are therefore more available. Certain natural and synthetic dyes have been found to serve as substrate mimics for a class of enzymes call hydrogenases and have been used to build affinity columns for their purification. 

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