Chemical structures of macrocyclic

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

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

Fig. 18 Chemical structure of macrocycle 33 and STM image at the 1,2,4-trichlorobenzene-graphite interface. (Reproduced with permission from Ref. [100])...

The first consideration when investigating HPLC method development protocols is the chemical structure of the analyte, in particular, the presence of functional groups capable of interacting with the stationary phase and containing or in the vicinity of the stereogenic elements [79]. Since the natural target of macrocyclic antibiotics is the A-acyl-D-alanyl-D-alanine terminus (see Section 2.1), the early choice of suitable substrates for this kind of CSPs was that of amino acids [45]. However, it turned out that the macrocyclic CSPs were very successful not only in amino acids enantioresolution, but also in the separation of a wide variety of different structures. 

Different classifications for the chiral CSPs have been described. They are based on the chemical structure of the chiral selectors and on the chiral recognition mechanism involved. In this chapter we will use a classification based mainly on the chemical structure of the selectors. The selectors are classified in three groups (i) CSPs with low-molecular-weight selectors, such as Pirkle type CSPs, ionic and ligand exchange CSPs, (ii) CSPs with macrocyclic selectors, such as CDs, crown-ethers and macrocyclic antibiotics, and (iii) CSPs with macromolecular selectors, such as polysaccharides, synthetic polymers, molecular imprinted polymers and proteins. These different types of CSPs, frequently used for the analysis of chiral pharmaceuticals, are discussed in more detail later. 

Chemical structure of a tetra amido macrocyclic ligand... 

Figure 11. (a) The chemical structure of a 24-membered macrocyclic molecule composed of alternating D- and L-amino acids, cyclo(Gln-(D-Leu-Trp)4-D-Leu 7. (b)A self-assembled tubular structure spanned across the bilayer lipid membrane. Flat ring-shaped units in the antiparallel configuration stack to form a tubular structure through extensive inter subunit hydrogen bonding and peptide side chain-lipid interactions. ... 

Fig. 4.7 Chemical structures of commonly used macrocyclic lactones.

The chemical structures of [2]catenane 19 and the related [3]catenane 20 (Fig. 8) were conceived as an extension of their work on molecular shuttles. The larger macrocycle in 19 comprises two fumaramide stations with differing macro cycle binding affinities. In station B (red) the methyl groups on the fumaramide motif cause it to have lower affinity than the standard fumaramide station. The non-methylated fumaramide station (station A, green) is located next to a benzophenone unit. This allows selective, photosensitized isomerization of station A by irradiation at 350 nm. Station B (red) can be photoisomerized by direct irradiation at 254 nm. The third station, a succinic amide ester (station C, orange), is not photoactive and is intermediate in macrocycle binding affinity between the two fu-... 

Fig. 9. Chemical structures of different trichothecenes. MC = Macrocyclic ISV = isovalerate OH-ISV = hydroxyisovalerate.

All of the examples selected here to illustrate the utility of MCD spectroscopy are based on systems that may be formally derived from a AN3- 2)-electron perimeter. For such systems the MCD effect is most simply and lucidly connected through the quantities AHOMO and ALUMO with the form and the ordering of the molecular orbitals. It can therefore be used to draw conclusions regarding the electronic and chemical structure of the system under investigation. A structural class for which the perimeter model analysis has been particularly fruitful is that of the porphyrins (Goldbeck, 1988) and related macrocycles (Waluk et al., 1991 Waluk and Michl, 1991). 

Figure 5. Chemical structures of norot (a), fumrot (b) and of macrocycle (c)...

Figure 1 Chemical structures of the macrocyclic calixarenes synthesised and studied in this research work.

Figure 4.16 Chemical structures of the macrocyclic glycopeptide antibiotics (a) vancomycin, (b) teicoplanin, (c) avoparcin, (d) ristocetin A, that have been used as chiral selectors in CSPs for HPLC. Reproduced from Ward and Farris, J. Chromatogr. A 906 (2001), copyright (2001), with permission from Elsevier.

Fig. 27. Chemical structures of PPE and its derivatives (a) molecular unit structure of PPE, (b) macrocycles, (c) dendrimers, and (d) nanoarchitecture.

FIGURE 12.11 Chemical structure of supramolecular macrocyclic heterodimer Mn catalyst. 

Fig. 37.1 Schematic representation of a macrocyclic amphiphilic molecule (a) and chemical structures of the native caiix[4]arene (b) and resorcin[4]arene (c). The caiix[4]arene macrocycle, composed of four phenolic units, forms a fairly rigid truncated cone-shaped molecule when adequately modified to lock the structure to avoid conformational changes to partial cone conformations. The aromatic alcohol functions are exposed at the narrow rim, and the para phenolic positions at the wide rim. Applying different chemistries, the macrocycle can be selectively modified either on one rim or on the other. The regio-selectivity of the chemical modifications is not restricted to the selection of the modified rim the number and the position within a rim could also be controlled...

Fig. 37.9 (a) Graphical representation of the monolayer stabilization by organic clips. Each organic clip (red) binds two macrocycles (blue) at the air-water interface through electrostatic interactions (b) Chemical structure of the guanidinocalix[4]arene derivative (Reproduced with permission from Ref. [58], Copyright 2013, The Royal Society of Chemistry)... 

Fig. 37.17 Chemical structure of the calixarene-phosphine ligand (a) and graphical representation of the macrocycle capped Au nanoparticle with the Au core diameter of 0.9 nm and five calixarenes bound to metal surface (b). Two calixarenes bind the metal core with two phosphines while the other three with only one phosphine. The monodentate ligand possesses one phosphine bound to the metal surface and one unbounded phosphine oxide (Reproduced with permission from Ref. [106], Copyright 2010, Nature Publishing Group)...

Fig. 16.16 (a) Examples of macrocyclic compounds used to modify CPEs. (b) Example highlighting the chemical structure of a simple calixarene from which it is easy to see the cup shape of the molecule likely to act as a host for guest species. The symbol R is not a single element but represents a group of atoms. The structure of the R group can be varied to give the basic calixarene structure a more selective action rather than simply working on the basis of size... 

Konig, B., Fricke, T., Dix, I. and Jones, P.G. (1997) Synthesis and structure of macrocyclic diaza-bis-enediynes. Journal of Chemical Research, Synopses, (2), 68-69. 

Figure 1 Generation of phage-encoded combinatorial chemical libraries and an isolated molecule, (a) A phage-encoded peptide with three cysteine residues is tethered to the trifunctional compound TBMB in a nucleophilic substitution reaction (see refs. 18-20 for the chemical reaction). The resulting chemical entities could optionally be further modified through enzymatic reactions such as proteolysis, (b) Chemical structure of a macrocyclic plasma kallikrein inhibitor isolated by phage display (PK15).

The chemical structure of the initiator used determines the type of the active centers of the polymerization, which not only serve as the centers for the growth of polymer chains but also participate in cyclization reactions. The extent of reactivity of the active centers is directly responsible for the content and distribution of macrocycles during the course of the polymerization. The most important reactions leading to cyclic oligomers are mutual reactions of the end-groups of linear molecules ( end-biting ) (Equation 7.23)... 

---