Monofunctional systems

Whereas the highly basic Ir1, Rh1 and Ni° complexes which are active in C02 fixation are monofunctional systems, bifunctional [Co(salen)M] complexes (M = K, Na) which bind C02... 

It is important to recall (see Section II,B,2 and II,B,3) the limitation we must ascribe to the meaning of quasi-intermediates as to their being true intermediates in the monofunctional Z-system. We must recognize that similar coupling of a second catalytic system (F) to a previously monofunctional system can be attained where the latter system can be pictured as one generating a low level side-product... 

Certain catalyst materials that may not have been considered to operate as multifunctional catalyst composites may in fact be operative via distinct and separate catalytic sites. Keulemans and Schuit (41) have discussed such possibilities briefly. In this article, we shall not look further into these possibilities however, inasmuch as we have examined various reactions and reaction sequences, it is very appropriate to point out that there undoubtedly exist reactions which have been considered to be catalyzed essentially by monofunctional systems, but which may in fact undergo polystep conversion. Also, quasi-intermediates may exist, appearing as traces of side products or remaining undetectable, that carry a ready... 

To observe complex formation in monofunctional systems, rather high concentrations may be needed, while in the blchromophorlc systems under investigation, two chromophores are near each other even in very dilute solutions. This makes it possible to investigate the excited state behavior of such complexes at high dilution, although the chain, linking the chromophores, may Impose new restrictions on Intramolecular processes. An extensive review on intramolecular exclmers, including excimer formation in polymers, has been made recently by Klopffer (9). Recent developments in this area have broadened substantially the scope of intramolecular complex formation. 

No single test system can serve as an indicator of the entire spectrum of the toxic potential of xenobiotics. Indeed, it will provide only one aspect of the possible impairments. The classical laboratory toxicity tests always relate to the standardized conditions under which they are conducted. Their generally good reproducibility can be achieved only by a substantial abstraction from the (variable) conditions in the real environment. The extrapolation of laboratory test data (obtained in a monofunctional system) to numeric threshold... 

Also, it is worth mentioning that, although most of reported dendrimers are monofunctional systems, the more and more sophisticated synthetic methodologies have allowed the synthesis of some heterofunctional dendrimers, mainly bifunctionals, with two (or more) terminal functional groups (Navath et al., 2010 de Jong et al., 2015). 

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