Third-generation concept

Carbene ligands can replace phosphines dne to similar electronic properties. The development of NHC design concepts featnring different substituents and backbones eventually culminated in the most prominent derivative, the SIMes (SDVtes = A, A -bis[2,4,6-(trimethyl)phenyl]imidazolidin-2-ylidene) ligand that is nsed in the second and later also third generation catalysts (complexes 72, 73, 74b and 74c in Fig. 3.28) [105, 109, 114,116],... 

Fig. 14.6). A key is that in many cases solution processing can lead to new structures that are difficult or impossible to attain by other means. This can include, for example, nanofiber arrays, core-shell structures, nanopods, and nanoribbons.30 32 These structures can lead to a variety of new functionalities—from 3D prototyping, to third-generation PV structures, to electronic paper, to a new class of non linear optics, to the ability to order nanostructures at very small length scales and maybe even to the holy grail of the energy field, artificial photosynthesis. Below we briefly discuss how some of these concepts are beginning to be realized.

Rollable displays are particularly attractive for mobile applications, because of their low weight, small form factor, and robustness when rolled into the device, as will be discussed in Section 14.7 on roll-up display device concepts. The availability of rollable display devices will greatly stimulate advances in electronic books, newspapers and magazines, and new services offered by (third generation) mobile net-... 

If the juvenile hormones and their analogs are representative of third-generation pesticides (18), the anti-juvenile hormones may be considered in a fourth-generation concept. 

Finally, it should be noted that the recent development of so-called third generation biosensors to achieve direct electron transfer from redox enzyme, oxidoreductase to the electrode without mediators, but through a series of enzyme cofactors or conductive polymers to transfer electrons from the enzyme redox center to the electrode surface [161-164]. This concept with the current technology for preparing miniature sensors with nanotechnology is of great interest to many researchers trying to develop practical sensors in clinical, environmental and industrial analysis. Whether with mediators or without, research for optimum sensor development for various purposes will be intensive in the future. 

SCHEME 3 Schematic diagram illustrating the concept of the third-generation 02 biosensors based on the biocatalytic activity inherent in SODs toward the dismutation of O2. (Reprinted from [150], with permission from the Royal Society of Chemistry.)... 

Therefore, two fundamental research strategies can be envisaged (i) the development of robust devices made from abundant (nontoxic) materials that exhibit reduced efficiencies and (ii) the development of devices that use the photonic excess energy as, for instance, in tandem or other third-generation photoactive structures. Here, the theoretical efficiency can increase to values above 40% for a two-junction device, depending on the respective energy gaps. In the former approach, concepts and principles from photosynthesis have already been adapted. Examples include the preparation of macromolecules that contain centers with... 

---