Structures of macrocyclic

Macrocycle 16, containing three equivalent DMN electroactive units, shows three distinct oxidation processes (Fig. 13.17). Such a contrasting behavior between 16 and the tetracationic cyclophanes, in which the two incorporated bipyridinium units undergo simultaneous first and second reductions, can be interpreted considering that, in the cyclophanes, the rigidity of the structure prevents interaction between the two bipyridinium units, whereas the flexible structure of macrocycle 16 allows the three DMN units to approach one another. 

Asakawa Y, Toyota M, Tori M, Hashimoto T (2000) Chemical Structures of Macrocyclic Bis(bibenzyls) Isolated from Liverworts (Hepaticae). Spectroscopy 14 149... 

Structure of Macrocyclic Complexes - Solution vs. Solid State... 

Structures of macrocyclic systems will be labeled with consecutive bold numbers, e.g., 1, 2, 3, each number corresponding to a specific ring system. Bold numbers will additionally discriminate between related structures containing different heteroatoms or metal ions, and between different protonation/oxidation levels of the same structure. 

J. H. Horner, P. J. Squatritto, N. McGuire, J. P. Riebenspies, and M. Newcomb, Organometallics, 10, 1741 (1991). Macrocycles Containing Tin. Crystal Structures and Molecular Mechanics Calculated Structures of Macrocyclic Lewis Acidic Hosts. 

Figure 4.13 Molecular structures of macrocyclic metal complexes metal bis(glyoximate), metal tetraazaanulene and metal phthalocyanine complexes...

Asymmetric total synthesis of terpenoids possesing novel structure of macrocyclic ethers with two bibenzyl fragments 00YGK1167. 

The single-crystal X-ray structures of macrocyclic Ni species showing square-planar coordination at the metal center have been reported. The complexes (37) and (38) both show Ni bound to four aza N-donors of a saturated macrocycle to give square-planar coordination at the metal center. The electrochemistry of a wide range of Ni - porphyrin complexes... 

Figure 20, Structures of macrocyclic complexes with iron and other metal ions...

The structure of macrocyclic (129) has been reported. The mono-, di-, and tri-cyclic complexes (54), (55X and (56) have been reported (see Scheme 3). 

Fig.1 X-ray crystal structure of macrocycle 4 highlighting the two chloride anions (solid spheres) bound to the macrocycle...

Mass spectrometry has been widely used for the elucidation of the structures of macrocycles with both oxygen and sulfur as heteroatoms. However, in most cases only molecular compositions are reported and detailed fragmentation patterns are scarce. The mass spectra of macrocyclic polyethers have been evaluated and fragmentation patterns compared <76JCS(P2)206>. Within the series of compounds studied, molecular ion peaks were always observed. Only small differences in the mass spectra of compounds with different aromatic ring substitutions were observed. A protonated... 

Slow crystallization of 1-trifluoroacetoxybenziodoxaborole 188 from methanol afforded the tetrameric macrocyclic structure 192 resulting from self-assembly of the initially formed 4-fluoro-l,3-dimethoxy-l//-lX -benzoM[l,2,3]iodoxoborole (191) (Scheme 2.59). The structure of macrocycle 192 was established by a single-crystal X-ray analysis [243]. The driving force for formation of the eight-membered cyclic system 192 is the transformation of initial trigonal-planar sp hybrid boron atoms in 191 into tetrahedral sp hybridized atoms. Indeed, each boron atom in tetramer 192 forms one covalent bond with carbon and three covalent... 

Sulok CD, Bauer JL et al (2012) A detailed investigation into the electronic structures of macrocyclic iron (Il)-nitrosyl compounds and their similarities to ferrous heme-nitrosyls. Inorg Chim Acta 380 148-160... 

Scheme 1 Basic structure of macrocyclic cyclen ligands...

In spite of a very significant progress achieved with heat-treated macrocyclic compounds as ORR catalysts since the early 1970s, the activity and durability of that family of catalysts are stiU insufficient for replacing platinum at the fuel cell cathode and in other applications. Furthermore, the complex structure of macrocyclic compounds makes their synthesis expensive and potentially noncompetitive with precious-metal-based catalysts also from the materials cost point of view. For those reasons, much effort has been invested by the electrocatalysis research community in recent years into finding less expensive and catalytically more active non-precious metal ORR catalysts that would not rely on macrocylic compounds as either catalysts or catalyst precursors. In the past decade, there has been a significant improvement both in the activity and of non-macrocyclic catalysts, expected to be manufactured at a fraction of the cost of their macrocyclic counterparts. In this section, we review the precursors, synthesis routes, and applications of this relatively new family of catalysts. 

Figure 5 Structures of macrocycle isomers with nitrogen donors at different positions. (Reproduced from Ref. 14. Wiley-VCH, 1998.)...

Figure 21 Chemical structures of macrocyclic bisbenzylisoquinoline alkaloids and some semisynthetic derivatives.

Figure 1 X-ray crystal structure of macrocyclic compound 1. One molecule of DABCO (diazabicyclooctane) is encapsulated inside the macrocycle.

Figure 2 Representative structures of macrocyclic receptors, (a) Crown ethers and derivatives, (b) a- CDs, (c) calixarenes w = 4, 6, 8.

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