Macrocycles history

Macrocycles history, 21 metal complexes protonation, 423 Macrocyclic ligands isomerism, 204 Magnesium gravimetry, 528... 

Ring Size. Shortly after Pedersen s discovery of macrocycles (16)y the size-match selectivity theory was proposed. It suggests that macrocycle-cation binding is dictated by the closeness of fit between ionic radii and the breadth of the inner macrocyclic cavity (5J 1,17). This concept has been cited for most of macrocyclic history, and continues to be used to explain empirical phenomena, though current research shows it to be largely coincidental (8,10,13,18 20). 

Nitrogen-containing macrocycles are highly complementary for first row transition metals as in the examples shown in Section 1.6. Common azamacrocycles include cyclen ([12]ane-N4) and cyclam (3.45) and many have a history that significantly pre-dates the crown ethers. Unlike the crown ethers which do not have donor atom substituents, the binding constants of azamacrocycles such as cyclam are greatly affected by N-alkylation. Alkylated amines are significantly more basic than ammonia, for... 

History. Braun and Tschemak [23] obtained phthalocyanine for the first time in 1907 as a byproduct of the preparation of o-cyanobenzamide from phthalimide and acetic anhydride. However, this discovery was of no special interest at the time. In 1927, de Diesbach and von der Weid prepared CuPc in 23 % yield by treating o-dibromobenzene with copper cyanide in pyridine [24], Instead of the colorless dinitriles, they obtained deep blue CuPc and observed the exceptional stability of their product to sulfuric acid, alkalis, and heat. The third observation of a phthalocyanine was made at Scottish Dyes, in 1929 [25], During the preparation of phthalimide from phthalic anhydride and ammonia in an enamel vessel, a greenish blue impurity appeared. Dunsworth and Drescher carried out a preliminary examination of the compound, which was analyzed as an iron complex. It was formed in a chipped region of the enamel with iron from the vessel. Further experiments yielded FePc, CuPc, and NiPc. It was soon realized that these products could be used as pigments or textile colorants. Linstead et al. at the University of London discovered the structure of phthalocyanines and developed improved synthetic methods for several metal phthalocyanines from 1929 to 1934 [1-11]. The important CuPc could not be protected by a patent, because it had been described earlier in the literature [23], Based on Linstead s work the structure of phthalocyanines was confirmed by several physicochemical measurements [26-32], Methods such as X-ray diffraction or electron microscopy verified the planarity of this macrocyclic system. Properties such as polymorphism, absorption spectra, magnetic and catalytic characteristics, oxidation and reduc-... 

The examples given in Figure 1 illustrate not only the persisting problems to identify the structure of supramolecular complexes, but at the same time represent an interesting piece of history. The complex of a benzidino-cyclophane with a benzene guest molecule inside the macrocycle is likely the oldest published picture of such a supramolecular complex/31... 

Again at the beginning of the 1970 s, other classes of synthetic macrocycles were being investigated, not necessarily in connection with biological problems. For instance, the rich chemistry of Schiff base derivatives (Fig. 4.8) was being developed and yielded the first macrocyclic complexes in 1979 (Fig. 4.9). Another type of interesting macrocyclic molecules are the calixarenes (Fig. 4.8) the history of which can be traced back to the first experiments, in Berlin in 1872, of Adolf von Baeyer (Nobel prize in chemistry in 1905) who treated p-substituted phenols with formaldehyde in the presence of acid or base. 

History of ligand substitution in Co111 complexes Coordination Chemistry of Macrocyclic Compounds (book) Template synthesis of macrocycles... 

The binding of ammonium ion, NH4+, by 18-crown-6 was demonstrated early in the history of macrocycle chemistry. The O-H-N in crowns or N-H-N interaction in azacrowns has been characterized by a variety of techniques, including NMR, calorimetry, and X-ray crystal structure analysis. Recent studies in this area have shown that both quaternary and secondary ammonium salts can form complexes with crowns. In the latter case, a rotaxane molecule was prepared by treatment of a dibenzylammonium salt with dibenzo-24-crown-8 and other macrocycles, including pyrido-24-crown-8. The solid-state structure of the pseudo-rotaxane structure obtained with pyrido-24-crown-8 is shown in the left panel of Figure 23. 

Cobalt Inorganic Coordination Chemistry Coordination Chemistry History Macrocyclic Ligands Mixed Valence Compounds Nitrogen Inorganic Chemistry. 

In the vast majority of ionic polymerizations reported in the literature the counterion is ionically bound to the polymer chain. When the counterion is covalently bound to the chain, the polymerization is termed macroz witterionic. This review surveys what is known about this relatively unexplored area of polymer chemistry. A brief history of the topic is followed by a summary of the literature. The evidence presented in each report for the formation of macrozwitterions is critically assessed. Then an attempt is made to draw out features common to all monomerlinitiator combinations which can thus be considered characteristic of macrozwitterion polymerization. These are contrasted to what would be thought typical of an ion pair polymerization. Macroz witterionic polymerization offers a convenient route to macrocyclic ligands and, when polymeric initiators are used, a range of novel graft copolymers. 

Already in the beginning of the history of concave reagents, the template effect of metal cations was utilized, but also organic molecules can be applied. Sanders for instance used the interaction of pyridines with zinc porphyrins in the construction of macrocyclic oligomeric porphyrins, and recently, the interaction between polyols and boronic acids has been used in order to synthesize new mdo-fimctionalized macrocycles (Figure 7.14) ... 

Crossed and hnked histories of tetrapyrrohc macrocycles and their use for engineering pores within sol—gel matrices 13MOL588. 

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