Narrow Results

The formation of β- and γ-cyclodextrin (CD) nanotubes induced by the molecule 4,4′-bis(2-benzoxazolyl) stilbene (BOS) was investigated by fluorescence anisotropy. Using the Perrin–Webber formula, the average number of cyclodextrin (n_CD) in each nanotube was estimated and the results suggested that the n_CD value in the γ-CD system is larger than that in the β-CD system. Hydrogen-bonding between the hydroxyl groups of neighboring CDs was found to be an important contribution to the formation of cyclodextrin nanotube on the basis of the pH effect study. The temperature effect study showed that this nanotube was thermostable at T ≤ 303 K, while it was gradually collapsed at higher temperature.

The inclusion process of β-cyclodextrin (β-CD) with Acetovanillone (Ace) was studied by using PM3 method, and the single-point energy of the inclusion complex was calculated at the level of B3LYP/6-31G*. The calculated data suggest that (1) the inclusion complex formed by Ace entering into the cavity of β-CD from its wide side (the secondary hydroxyl group side) is more stable than that from its narrow side (the primary hydroxyl group side); (2) the formation of the inclusion complex is probably an enthalpy-driven process; (3) the more the charge transfers, the more unstable the inclusion complex is. In addition to the inclusion schemes, other seven interaction schemes of the Ace with β-CD were also investigated and the results suggest that all these schemes should exist in actual experiment.

The geometries of the –CH₃ and –CH₂OH modified β-cyclodextrin {i.e. (β-CD(R)_m (R = –CH₃, –CH₂OH; m = 0, 1, …, 7)} and the energetical behaviors of one trans-Resveratrol (TR) molecule including inside their cavities were studied by using ONIOM (B3LYP/6-31G*:PM3) method. The most outstanding geometrical characteristic of the β-CD(R)_m is that their inside radius (r) are varied with different chemical modifications. The released energies for one TR molecule passing through or rotating inside the cavities of β-CD(R)_m are predicted to be related with the inclusion schemes (from narrow side or wide side of the cavity), the values of the inside radius r, and the types (–CH₃ or –CH₂OH) and number (m) of the substituted R groups. Our calculations also suggest that the formation of H-bonds in the inclusion interaction is the main factor to stabilize the formed inclusion complexes, i.e. the TR@β-CD(R)_m(R = –CH₃, –CH₂OH; m = 0, 1, …, 7).

The photodynamic sensitizers zinc(II)- and palladium(II)-5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrins and 5,10,15,20-tetrakis(4-carboxyphenyl)porphyrin form 1:1 and/or 1:2 supramolecular complexes with native cyclodextrins (CD) and 2-hydroxypropyl cyclodextrins (hpCD) in aqueous neutral solutions. The formation of these assemblies causes a bathochromic shift of the porphyrin Soret band in the UV-vis spectra and a red shift of the fluorescence emission bands. The binding constants span over three orders of magnitude, from 8.1 × 10²M⁻¹ to 5.4 × 10⁵M⁻¹ (or 1.1 × 10⁶M⁻²) depending on the size of the CD cavity and on the functionalization by adding 2-hydroxypropyl groups. The highest binding constants were obtained for hpβCD and hpγCD. The Nuclear Overhauser spectroscopy signals (ROESY) revealed three binding modes: i) inclusion of the porphyrin 4-sulfonatophenyl or 4-carboxyphenyl groups via the secondary face of βCD and hpβCD with sulfonic or carboxylic groups oriented towards the primary hydroxyl groups. ii) inclusion of the porphyrin groups via the primary face of γCD and hpγCD. iii) non-specific binding of the porphyrin monomers or aggregates on the cyclodextrin exterior. The inclusion host-guest complexation via i) or ii) does not influence the inherent photophysical properties of the monomeric porphyrins such as the quantum yields of fluorescence, the triplet states, and the singlet oxygen formation. Due to the deaggregation effect of cyclodextrins, the inclusion complexes remain efficient supramolecular sensitizers of singlet oxygen even under conditions of extensive aggregation in aqueous solutions.

The effects of formation of cyclodextrin inclusion complexes on the photochemical and photophysical properties of zinc phthalocyanine (ZnPc) and various peripherally substituted zinc phthalocyanines as well as zinc naphthalocyanine (ZnNPc) are investigated. The cyclodextrins employed were the hydroxypropyl-γ-cyclodextrin and unsubstituted β-cyclodextrin. Job's plots were employed to confirm the stoichiometry of the inclusion complexes and showed 2:1 and 4:1 (cyclodextrin:phthalocyanine) inclusion behavior. The phthalocyanine inclusion complexes showed larger singlet oxygen quantum yield (ϕ_Δ) values when compared to the free phthalocyanines before inclusion, for complexes 1 (zinc naphthalocyanine), 2 (zinc tetranitrophthalocyanine) and 4 (zinc tetra-tert-butylphenoxyphthalocyanine). The fluorescence quantum yields generally remained unchanged following inclusion.

In this report, the interaction of iron(III) meso-tetrakis(p-sulfonatophenyl)porphyrin, TPPS₄FeCl, and 2-hydroxypropyl-β-cyclodextrin, HP-β-CD as a model of cytochrome P-450 enzyme, has been investigated by UV-vis and ¹H NMR spectroscopy, in different pHs. The formation of a 1:1 inclusion complex has been confirmed by spectroscopic methods. Equilibrium constants (K₁) for the formation of the inclusion complexes have been estimated from the absorbance changes in neutral, basic and acidic phosphate buffer solutions. The K₁ values show that the inclusion behavior of HP-β-CD depends upon pH. The inclusion ability of the inclusion complex for the TPPS₄FeCl/HP-β-CD system is strongest (K₁ = 678.4 m⁻¹) in a neutral solution. In the second part, these inclusion complexes have been examined for the aqueous-catalytic oxidation of styrene under different reaction conditions. The effect of imidazole as an axial ligand and the effect of pH on the catalytic behavior of TPPS₄FeCl/HP-β-CD were also investigated. This data suggests that the addition of HP-β-CD to the porphyrin solution increases catalytic activity and selectivity of the system.

The diversity of hexaphyrin-cyclodextrin hybrids (HCD), previously formed from the covalent assembly of regular hexaphyrin and $\alpha$-cyclodextrin subunits, has been increased following two main directions: enlarging the confined space provided by the cyclodextrin and tuning the N-core of the hexaphyrin aiming at bimetallic complexes. The larger $\beta$-cyclodextrin unit was selectively functionalized with aldehyde linkers on its primary rim which were further reacted with 2 eq. of pentafluorophenyl tripyrrane in acidic conditions, followed by DDQ oxidation. Doubly-linked HCD hybrids were obtained with structural variations in the hexaphyrin macrocycles depending on the MSA concentration (2 vs. 200 mM) producing either regular ([26] rectangular/[28] Möbius) or doubly N-confused dioxo ([26] rectangular) scaffolds. For the latter, two isomers were isolated featuring mirror transoid skeletons and long-side meso-linking patterns, giving rise to planar chirality at the origin of intense and opposite electronic circular dichroism (ECD) spectra. Zn(II) complexation was then investigated leading to two main findings. (i) The regular [28] Möbius HCD afforded a mixture of monometallic Möbius Zn(II) complexes in the presence of acac ligand. ECD spectroscopy indicated a chirality transfer from the $\beta$-cyclodextrin favoring a $P$ Möbius twist, but opposite to that arising from the narrower $\alpha$-cyclodextrin congener ($M$ twist favored). (ii) Owing to N₃O coordination boxes, dissymmetric bimetallic Zn(II) complexes were readily formed with the doubly N-confused dioxo HCDs through a positive cooperative process. Both metal centers bind a DMAP ligand in axial positions, which is of interest for the

The functionalization of multiwalled carbon nanotubes (MWNTs) with β cyclodextrin (β-CD) is described. The functionalization using β-CD treatment is an environmentally friendly and nondestructive method to modify carbon nanotubes. It was observed that the degree of functionalization increases with increasing ratios of β-CD as seen from the Raman analysis. The Raman spectra also indicated that the nanotubes walls were not damaged. The presence of functional groups associated with β-CD on the functionalized MWNTs indicated that the cyclodextrin groups were found to be adsorbed at the surface of the nanotubes walls. Mixed matrix membrane (MMM) was prepared by a phase inversion process. Enhanced selectivity and permeability for CO₂ over CH₄ was observed for MMM prepared using functionalized MWNTs.

Magnetic field-assisted drug delivery is a fascinating strategy to transport chemotherapeutic drugs. Ferrite nanoparticles (NPs) of the form MFe₂O₄ are a good choice for utilization as magnetic nanocarriers. Although many ferrite NPs have been tested for their function as nanocarriers, their nonspecific toxicity must be minimized. In this work, calcium–nickel ferrite nanoparticles (CNF MNPs) coated with dextran–$\beta$-cyclodextrin and dextran–$\beta$-cyclodextrin–dextran polymers are reported. The synthesized NPs are characterized using XRD, TEM, EDX and XPS. The magnetic properties are investigated by vibrating sample magnetometry. The 20 nm-sized CNF MNPs fall in the size range suitable for cancer drug transport. The magnetic nanocarriers containing the polymers are superparamagnetic. The camptothecin (CPT) loading efficiency is observed as 88%. The in vitro CPT release profiles are sustained, displaying a continuous release for a period of above 45 h. The cytotoxicity studies on A549 cell lines reveal that the CPT-loaded CNF MNPs are active against them and can be used as an anticancer drug carrier.

This chapter will briefly introduce the molecular design, synthesis, structure and properties, characterisation method and applications of adaptive polymers. There are many smart and functional materials, and adaptive polymers are one such example. This book mainly focuses on adaptive polymers and textiles. First, some concepts will be suggested and definitions of adaptive polymers and textiles are reviewed. Following that, the characteristics, structures and potential applications of adaptive polymers will be summarised. Developing novel smart adaptive polymers and textiles are challenging, and some future trends are suggested at the end.

The hydrophobic cavity of cyclodextrin contributes to the wide applications in medicine, pharmaceutical, food, cosmetic industries, agriculture and environmental protection. Cyclodextrin glycosyltransferase (cgt) gene was able to be amplified from Paenibacillus polymyxa and inserted into vectors of pWB980. The recombinant vectors were transformed to Bacillus subtilis WB600. The results showed that cgt gene was expressed in Bacillus subtilis successfully. The optimum conditions for maximum enzyme activity were obtained at a temperature 35°C, pH 7 and quantity of inoculum 6%. Corn starch and soybean meal were chosen as carbon source and nitrogen source in the process of production. A maximum activity of the CGTase activity reached 9.2 U/mL, which is about 15-fold to that of the original strain Paenibacillus polymyxa. β-cyclodextrin is 0.104 mg/mL from 1% (m/m) soluble starch in 10 min (pH 7.0 50 oC). Cyclodextrins can form inclusion complexes with different molecules with the aid of their special chemical (molecular) structures. Physical and chemical properties of molecules can be changed after the formation of complex. This special feature enables the usage of cyclodextrins in different industry areas.