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EN
Nuclear magnetic resonance is already a broadly exploited phenomenon both in chemistry and medicine. Magnetic resonance imaging is a routine technique in medical diagnosis readily applied for soft tissues like brain, cardiovascular system or gastrointestinal tract. Contrast agents stepped into the field and enabled better recognition of a lesion in the early stage of a disease. The authors present an introductory description of a fascinating history, classification of contrast agents followed by the mechanisms of their action. Classes of positive and negative contrast agents are described. Further discussion is focused on the T1 (positive) molecular species. The mechanism was divided into (1) inner sphere, where both direct coordination of water molecule and its presence in second sphere is considered (Fig. 1) [1] and (2) an outer sphere mechanism which is assumed for the water molecules diffusing into the surrounding of the paramagnet [21, 28]. Further, the most important requirements for medical applications are given. Those are: high relaxivity, charge-osmolality, stability, toxicity via potential transmetallation of redox activity [42]. Molecular examples are quoted based on previously investigated iron complexes. Majority of them are iron(III) species [68], however, some iron(II) compounds like activable, self-immolative or ParaCEST systems have recently appeared [86, 89]. Iron compounds as positive contrast agents may soon accompany classic gadolinium complexes.
EN
The synthesis and characterization of polycondensation products of methyl alpha-D-mannopyranoside with dialdehyde are described. A new glycopyranoside derivative with 16-membered macrocyclic loop is obtained.
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