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21.
The ability of β-cyclodextrin (β-CD), γ-CD, hydroxypropyl-β-CD (HP-β-CD), trimethyl-β-CD (TM-β-CD), sulfurbutylether-β-CD (SBE-β-CD) and carboxymethyl-β-cyclodextrin (CM-β-CD) to break the aggregate of the meso-tetrakis(4-N-trimethylaminobenzyl)porphyrin (TAPP) and to form 2:1 inclusion complexes has been studied by absorption and fluorescence spectroscopy. The formation constants are calculated, respectively, by fluorimetry, from which the inclusion capacity of different CDs is compared and the inclusion mechanism of charged-β-CD (SBE-β-CD and CM-β-CD) is quite different from that of the parent β-CD. At lower pH, the complexation between TM-β-CD and H2TAPP2+ (the form of the diprotonated TAPP) hampers the continuous protonation of the pyrrole nitrogen of TAPP and the hydrophobic cavity may prefer to bind an apolar neutral porphyrin molecule. 1HNMR data support the inclusion conformation of the porphyrin–cyclodextrin supramolecular system, indicating the interaction of the meso-phenyl groups of TAPP with the cavity of CDs. For this host–guest inclusion model, cyclodextrin being regarded as the protein component, which acts as a carrier enveloping the active site of heme prosthetic group within its hydrophobic environment, provides a protective sheath for the porphyrin, creating artificial analogues of heme-containing proteins. However, for TAPP, encapsulated within this saccharide-coated barrier, its photophysical and photochemical properties changed strongly. 相似文献
22.
Interactions of cucurbit[7]uril (Q[7] host) with guest adenine (g1), adenosine (g2) and 2′,3′-o-isopropylideneadenosine (g3) were studied in details by 1H NMR, UV absorption spectroscopy, fluorescence spectroscopy and high performance liquid chromatography (HPLC) methods. We found that the suitable pH range for interaction was between 1 and 7, and the optimal pH range was between 2 and 4. The 1H NMR analysis indicated that Q[7] selectively interacted with the adenine moiety of the guests g1 and g2, while Q[7] selectively interacted with the D-ribose sugar ring moiety of the guest g3. Moreover, 1H NMR spectra showed that the exchange between the bound guest and the free guest was fast on the NMR time scale for the Q[7]-g1 and Q[7]-g2 systems. However, an obvious equilibrium between the bound host/guest and the unbound host/guest were observed in the Q[7]-g3 complex. Several methods were used to determine quantitatively the stability of the three host–guest inclusion complexes formed between Q[7] and the guests. The formation constants by UV and fluorescence were 1.90 × 105 L mol? 1 and 1.34 × 105 L mol? 1 for Q[7]-g1, 9.41 × 104 L mol? 1 and 4.24 × 104 L mol? 1 for Q[7]-g2, 4.50 × 104 L mol? 1 and 3.62 × 104 L mol? 1 for Q[7]-g3, respectively. HPLC method was also introduced to explore the interactions between Q[7] and the adenine and its derivatives. The formation constants of the host–guest inclusion complexes, as determined by HPLC, were 6.76 × 104 L mol? 1 for Q[7]-g1, 1.80 × 104 L mol? 1 for Q[7]-g2, 3.01 × 104 L mol? 1 for Q[7]-g3 respectively. Our study suggested that Q[7] could be a suitable host for the delivery of bioactive molecules, such as the adenine and its derivatives. 相似文献
23.
A novel supramolecular graft copolymer(SGP) composed of viologen-containing copolymer(P(DMA-co-diEV)) as the main chain and Np ended PNIPAM(Np-PN1PAm) as the grafts is prepared(DMA:N,N- dimethylacryamide,diEV:ethylviologen dimer,Np:naphthalene,PNIPAM:poly(N-isopropylacrylamide)). The grafting is based on the triple complexation among a host of cucurbit[8]uril(CB[8])and two guests of diEV and Np,which is characterized by UV-vis spectra and ITC.Temperature sensitive property of PNIPAm moiety allows SGP to self-assemble into non-covalently connected micelle(NCCM) at high temperature. The micelles are sensitive to reducing agents,for example Na2S2O3,which breaks the current inclusion complex pair and induces aggregation. 相似文献
24.
Macrocycles consisting of two tris(phenylene ethynylene) (or tri-PE) units connected via two flexible linkers adopt an ‘unfolded’ conformation that is converted into a folded conformation upon introducing intramolecular hydrogen bonding interaction. These foldable macrocycles are capable of forming inclusion charge transfer (CT) complex with electron-deficient small aromatics. 相似文献
25.
Ameer Ghuzlaan Mahmoud M. Al Omari Khaldoun A. Al-Sou’od 《Journal of solution chemistry》2009,38(1):83-94
Guest–host interaction of prednisone (PN) with cyclodextrins (CDs) have been investigated using phase solubility diagrams
(PSD), differential scanning calorimetry (DSC), X-ray powder diffractometry (XRPD), scanning electron microscopy (SEM) and
molecular mechanical modeling (MM). Estimates of the complex formation constant (K
11) show that the tendency of PN to complex with CDs follows the order: β-CD>γ-CD>HP-β-CD>α-CD. At the same pH of 7.0, β-CD forms soluble 1:1 and insoluble 1:2 PN/CD complexes (BS-type PSDs). The thermodynamic functions for 1:1 PN/β-CD estimated at pH = 7.0 (ΔG
11o=−20.8 kJ⋅mol−1) show that complexation is driven by enthalpy (−30.7 kJ⋅mol−1) but retarded by entropy (ΔS
11o=−33.1 J⋅mol−1⋅K−1) changes. The MM modeling study indicates the formation of different isomeric 1:1 complexes with CDs. PSD, DSC, XRPD, SEM
and MM studies established the formation of inclusion complexes in solution and the solid state. 相似文献
26.
Marlin Opałło Nagao Kobayashi Tetsuo Osa 《Journal of inclusion phenomena and macrocyclic chemistry》1989,7(4):413-422
The complexation of 2,3-anthracenedicarboxylate (ADC) by- and-cyclodextrins in water containing an organic solvent has been studied by induced circular dichroism. It has been shown that an increase of organic solvent ratio causes the degradation of the 1:1 ADC:-CD complex and the liberation of one guest molecule from the 2:1 ADC:-CD complex in water. The higher the hydrophobicity of the cosolvent, the weaker the complexation of ADC by-CD. 相似文献
27.
Dávid Szegvári Romána Zelkó Péter Horváth András Gergely 《Journal of inclusion phenomena and macrocyclic chemistry》2007,57(1-4):169-172
Enantioselective solubility of rac-norgestrel was found in the presence of γ-cyclodextrin or hydroxypropyl-γ-cyclodextrin.
In both cases the efficacious enantiomer was dissolved in greater extent. Calculating the molar absorptivity and molar ellipticity
spectra of the γ- and hydroxypropyl-γ-cyclodextrin aqueous complexes, a simple and rapid direct circular dichroism (CD) spectrometric
method was obtained for the determination of the enantiomer ratio in aqueous solutions. 相似文献
28.
GAO Jie MENG Ye ZHAO Weiwei JIANG Daofa JIN Yanmei ZHENG Jun YANG Xinan MA Peihua 《高等学校化学研究》2021,37(3):674-678
The host-guest interactions between cyclopentanocucurbit-[6]uril(CyP6Q[6]) as host and six alkyl imidazolium hydrochloride as guests(g1, g2, g3, g4, g5, and g6) have been studied by various techniques, such as 1H NMR spectroscopy, isothermal titration calorimetry, mass spectrometry, and single-crystal X-ray diffraction analysis. The experimental results showed that CyP6Q[6] formed 1:1 inclusion complexes with each of guests g1-g6. The part of the guest entered the cavity of CyP6Q[6] changes as the alkyl chain increases in length. It can be seen that the length of the alkyl chain plays a key role in determining the mode of host-guest interactions. 相似文献
29.
Juan Gu Shao‐Ming Chi Yong Zhao Ping Zheng Qiong Ruan Yan Zhao Hong‐You Zhu 《Helvetica chimica acta》2011,94(9):1608-1617
The inclusion‐complexation behavior of coenzyme Q10 (CoQ10) with the three polyamine‐modified β‐cyclodextrins (CDs) 1 – 3 was investigated in both solution and the solid state by means of NMR, XRD, and FT‐IR spectroscopy. The results showed that the apparent solubility of CoQ10 increased linearly upon addition of hosts 1 – 3 , giving AL‐type phase‐solubility curves. These hosts 1 – 3 were able to solubilize CoQ10 to high levels, up to 1.35, 1.52, and 1.44 mg/ml (calculated as CoQ10), respectively. The host 2 with a moderate‐length chain is the most suitable for inclusion complexation of CoQ10. Accroding to the ROESY experiments, the MeO groups of CoQ10 and the tether of 2 can be co‐included into the cavity of β‐CD through the induced‐fit interaction between host and guest. The binding ability of modified β‐CDs 1 – 3 upon complexation with CoQ10 are discussed from the viewpoints of the size/shape‐matching relationship and the induced‐fit concept between host CDs and guest CoQ10 molecule. 相似文献
30.
Arantzazu Zabala?Ruiz Dominik?Brühwiler Takayuki?Ban Gion?CalzaferriEmail author 《Monatshefte für Chemie / Chemical Monthly》2005,136(1):77-89
Summary. A convenient synthesis of zeolite L is presented. The size of the crystals can be tuned between 30 and 6000nm, spanning a volume range of seven orders of magnitude. The zeolite L crystals, which typically feature a cylindrical morphology, are synthesized with various aspect ratios ranging from elongated to disc-shaped. The importance of obtaining zeolite crystals with well-defined size and morphology is discussed in view of potential applications of zeolite L containing organic dye molecules as guests.This revised version was published online in February 2005. In the previous version the issue was not marked as a special issue, and the issue title and the editor was missing 相似文献