Cyclodextrins assembled structures

A further contribution from this group, in collaboration with Pikramenou, deals with energy transfer processes in self-assembled structures of multin-uclear complexes. Each ligand of a Ru(bpy)32+ unit is connected to the rim of a /1-cyclodextrin receptor to form Ru(/J-CD-mbpy), which can complex in a polar medium the biphenyl (or adamathyl) tail of an Ir(III)-terpyridine complex, Fig. 24c [131]. In order to provide complexation of the Ir guest and because of the low association constant, a consistent excess of the Ru(/J-CD-mbpy) host is required, (80-90% of host relative to guest). Under these... 

Lin Y-C, Wang P-1, Kuo S-W. Water-soluble, stable helical polypeptide-grafted cyclodextrin bioconjugates synthesis, secondary and self-assembly structures, and inclusion complex with guest compounds. Soft Matter 2012 8 9676-84. 

Investigating the assembled structures of macrocyclic compounds in the solid state is very important because such studies reveal the optical properties, mechanical and thermal stabilities in macrocyclic-based bulk materials, and the complexation ability of macrocyclic compounds. Assembled structures of macrocyclic compounds, such as cyclodextrins (CDs), calix[ ]arenes and cucutbit[ ]urils in the crystal state have... 

Recently, we have also prepared nanosized polymersomes through self-assembly of star-shaped PEG-b-PLLA block copolymers (eight-arm PEG-b-PLLA) using a film hydration technique [233]. The polymersomes can encapsulate FITC-labeled Dex, as model of a water-soluble macromolecular (bug, into the hydrophilic interior space. The eight-arm PEG-b-PLLA polymersomes showed relatively high stability compared to that of polymersomes of linear PEG-b-PLLA copolymers with the equal volume fraction. Furthermore, we have developed a novel type of polymersome of amphiphilic polyrotaxane (PRX) composed of PLLA-b-PEG-b-PLLA triblock copolymer and a-cyclodextrin (a-CD) [234]. These polymersomes possess unique structures the surface is covered by PRX structures with multiple a-CDs threaded onto the PEG chain. Since the a-CDs are not covalently bound to the PEG chain, they can slide and rotate along the PEG chain, which forms the outer shell of the polymersomes [235,236]. Thus, the polymersomes could be a novel functional biomedical nanomaterial having a dynamic surface. 

Braun, T. (1997) Water soluble fullerene-cyclodextrin suframolecular assemblies preparation, structure, properties (an annotated bibliography). Fullerene Sci. Technol. 5, 615-626. 

Cyclodextrin-substituted molecular channel approaches have now been extended to include acyl substituents through a covalent bond formation. Stearoyl and methyl cholate-substituted cyclodextrins 10 and 11, respectively, have been synthesized. It may be worthwhile commenting on the molecular design of methyl cholate-substituted a-cyclodextrin. All of the ether groupings are convergent at the inner side of the steroidal backbone of a bent structure to make the molecule amphiphilic. Once the cyclodextrin derivative is incorporated into the membrane phase, it may easily be expected that the ether parts are assembled inside the channel in the sea of hydrophobic lipid molecules and the hydrophobic steroidal skeletons cover its outside to stabilize the inner hydrophilic pore (Figure 13). 

Figure 7-19. Three examples of supramo-lecules formed from the assembly of two molecular species. In 7.33, the 1,4-butane-dioic acid is specifically hydrogen bonded to the bisamide. In 7.34, rc-stacking interactions between the cationic cyclophane and the host 1,4-dimethoxybenzene stabilise the structure, whilst in 7.35 the cavity of the ct-cyclodextrin host is the correct size for the benzaldehyde guest. In each case, hydrogen atoms have been omitted for clarity carbon atoms are grey, nitrogen atoms white and oxygen atoms black.

Summary The analysis of supramolecular structures containing polymers, and the discussion about the effect of polymeric materials with different chemical structures that form inclusion complexes is extensively studied. The effect of the inclusion complexes at the air-water interface is discussed in terms on the nature of the interaction. The entropic or enthalpic nature of the interaction is analyzed. The description of these inclusion complexes with different cyclodextrines with several polymers is an interesting way to understand some non-covalent interaction in these systems. The discussion about the generation and effect of supramolecular structures on molecular assembly and auto-organization processes is also presented in a single form. The use of block copolymers and dendronized polymers at interfaces is a new aspect to be taken into account from both basic and technological interest. The effect of the chemical structure on the self-assembled systems is discussed. 

The results obtained by Fujita, Lichtenthaler, and co-workers show that cyclooligosaccharides with sugar units other than glucose do not necessarily have to assemble as tubes. Via the 2,3 an-hydro compound as intermediate, a- and / -cyclo-altrin were obtained from the corresponding cyclodextrins (Scheme 4) [19]. The X-ray structure analysis of the a-cycloaltrin revealed a highly unusual structure with alternating chair... 

The formation of hydrophilic molecular capsules by self-assembly of two cyclodextrin entities in the presence of a guest has been investigated. A system of this type was demonstrated to self-assemble from per-6-amino P-cyclodextrin (34) and per-6-thioglycolic P-cyclodextrin (35) in 50 mmol dm KCl solution at neutral pH. The structure of the resulting dimer has been investigated using a... 

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