Azamacrocycles applications

The discussed examples clearly demonstrate the importance of azamacrocycles as structural element to create supramolecular function. Their rigid structure, the basicity and transition metal-ion coordinating ability make them suitable as scaffolds and binding sites. Lanthanide chemosensors containing azamacrocyclic ligands have already reached applications in medical diagnostics. Other applications of azamacrocyclic systems with supramolecular functions, particularly in biochemistry, will follow. 

The process of antibody labeling consists of three steps (i) a functionalized azamacrocycle must be developed to coordinate the specific isotope (ii) the macrocycle or its metal complex must be covalently attached to the antibody and (iii), the medical application must be tested. Hereby several points must be fulfilled. As for NMR contrast agents, the macrocyclic metal cornplex must be thermodynamically and kinetically stable so that no dissociation or transmetallation occurs in the body of the patient. The covalent bond between the macrocycle and the antibody must be stable against enzymes which can break it. Finally, the modification of the antibody should not be to drastic as to deactivate it. 

This chapter has been organized by considering several aspects. An introduction concerning the relevance of the electronic properties and applications of the azamacrocycles related to surface phenomena as well as the general aspects and characteristics of the vibrational techniques, instruments and surfaces normally used in the study of the adsorbate-surface interaction. The vibrational enhanced Raman and infrared surface spectroscopies, along with the reflection-absorption infrared spectroscopy to the study of the interaction of several azamacrocycles with different metal surfaces are discussed. The analysis of the most recent publications concerning data on bands assignment, normal coordinate analysis, surface-enhanced Raman and infrared spectroscopies, reflection-absorption infrared spectra and theoretical calculations on models of the adsorbate-substrate interaction is performed. Finally, new trends about modified metal surfaces for surface-enhanced vibrational studies of new macrocycles and different molecular systems are commented. 

Azamacrocyclic ligands with pendant arms have recently attracted considerable attention mainly due to their analytical, biological and catalytic applications [l]. Compounds of this class combine the properties of a rigid macrocyclic structural unit with those of a flexible side-chain to which the functional group can be bound. Such systems are especially interesting for studying the influence of axial coordination on the properties of the coordinated metal ion. 

In this chapter, we also evaluate the application polyalkyne and enediyne azamacrocyclic systems [177,182,183]. Since the macrocyclic systems include a nitrogen atom between multiple bonds, their [2-1-2- -2] cycloaddition reactions represent a route to the structures with the polycyclic aza-heterocycles. 

Veiga et al. (2013) developed a rapid method for efiScient palladium catalyzed N-arylation of polynitrogenated macrocycles. Its applicability for functionalization of protected azamacrocycles of various sizes with substituted aryl bromides of optional electronic properties has been established. The compatibility of the protocol with common N-protecting schemes as well as the impact of electronic versus steric factors was also discussed. This method provides moderate to excellent yields of N-arylated azamacrocycles (45-96%) using a commercially available catalytic system and easily available alkoxide or phenoxide base. 

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