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Martin Jekel - One of the best experts on this subject based on the ideXlab platform.
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Cucurbituril for water treatment. Part II: Ozonation and oxidative regeneration of Cucurbituril.
Water research, 2001Co-Authors: Anja Kornmüller, Silke Karcher, Martin JekelAbstract:In Part I it was shown, that Cucurbituril has high sorption capacities for the removal of reactive dyes from textile wastewater; despite the partial dissolution of this sorbent. Ozonation has been suggested as a regeneration step for loaded Cucurbituril. Ozonation of loaded and pure Cucurbituril was therefore evaluated. Dissolved Cucurbituril reacts with ozone forming oxidation products like nitrite, nitrate, formate, acetate and oxalate. Oxidation is enhanced at alkaline pH. Dye-loaded Cucurbituril suspended in water can be decolorized by ozone, but the ozone consumption is tip to seven times higher than for ozonation of the dissolved dyes without Cucurbituril. Loaded columns can be regenerated by ozone gas, but dissolution of Cucurbituril results in a higher DOC content than the initial one to be removed. Therefore oxidative regeneration does not seem to be a feasible approach in this case.
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Cucurbituril for water treatment. Part I: Solubility of Cucurbituril and sorption of reactive dyes.
Water research, 2001Co-Authors: Silke Karcher, Anja Kornmüller, Martin JekelAbstract:Cucurbituril was investigated regarding its potential as a sorbent for the removal of reactive dyes from model solutions and authentic wastewaters. The solubility of Cucurbituril is low in pure water but increases in the presence of salts. When dyes sorbing onto Cucurbituril are present, solubility is drastically decreased compared to dye-free media. Sorption efficiency depends on salt concentration and salt species. Moderate salt concentrations favor sorption, high concentrations lead to Cucurbituril dissolution. Divalent ions have a stronger effect than monovalent ions and larger ions more than smaller ones. In tests with authentic wastewaters Cucurbituril was partially (20-100%) dissolved and contaminant removal was inefficient. Because of its solubility, Cucurbituril is not feasible as a sorbent in wastewater treatment unless it could be covalently fixed onto a suitable support material.
Silke Karcher - One of the best experts on this subject based on the ideXlab platform.
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Cucurbituril for water treatment. Part II: Ozonation and oxidative regeneration of Cucurbituril.
Water research, 2001Co-Authors: Anja Kornmüller, Silke Karcher, Martin JekelAbstract:In Part I it was shown, that Cucurbituril has high sorption capacities for the removal of reactive dyes from textile wastewater; despite the partial dissolution of this sorbent. Ozonation has been suggested as a regeneration step for loaded Cucurbituril. Ozonation of loaded and pure Cucurbituril was therefore evaluated. Dissolved Cucurbituril reacts with ozone forming oxidation products like nitrite, nitrate, formate, acetate and oxalate. Oxidation is enhanced at alkaline pH. Dye-loaded Cucurbituril suspended in water can be decolorized by ozone, but the ozone consumption is tip to seven times higher than for ozonation of the dissolved dyes without Cucurbituril. Loaded columns can be regenerated by ozone gas, but dissolution of Cucurbituril results in a higher DOC content than the initial one to be removed. Therefore oxidative regeneration does not seem to be a feasible approach in this case.
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Cucurbituril for water treatment. Part I: Solubility of Cucurbituril and sorption of reactive dyes.
Water research, 2001Co-Authors: Silke Karcher, Anja Kornmüller, Martin JekelAbstract:Cucurbituril was investigated regarding its potential as a sorbent for the removal of reactive dyes from model solutions and authentic wastewaters. The solubility of Cucurbituril is low in pure water but increases in the presence of salts. When dyes sorbing onto Cucurbituril are present, solubility is drastically decreased compared to dye-free media. Sorption efficiency depends on salt concentration and salt species. Moderate salt concentrations favor sorption, high concentrations lead to Cucurbituril dissolution. Divalent ions have a stronger effect than monovalent ions and larger ions more than smaller ones. In tests with authentic wastewaters Cucurbituril was partially (20-100%) dissolved and contaminant removal was inefficient. Because of its solubility, Cucurbituril is not feasible as a sorbent in wastewater treatment unless it could be covalently fixed onto a suitable support material.
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removal of reactive dyes by sorption complexation with Cucurbituril
Water Science and Technology, 1999Co-Authors: Silke Karcher, Anja Kornmüller, M. JekelAbstract:Color removal is an important task in textile wastewater treatment. Cucurbituril, a cyclic hexamer with internal hydrophobic cavity, has been studied as sorbent for removal of reactive dyes. Loadings as high as 1 g/g and more were obtained, making the method seem interesting for technical application. A minimum of 1 to 5 mmol/L calcium is needed for efficient sorption. However, salt concentrations of 100 mmol/L and above decrease sorption efficiency due to increased solubility of Cucurbituril in salt solutions. The pH has little influence between 4 and 7.5, higher pH-values can result in decreased sorption. The salt influences are similar for most of the tested dyes whereas the pH-effect differs from dye to dye.
Anja Kornmüller - One of the best experts on this subject based on the ideXlab platform.
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Cucurbituril for water treatment. Part II: Ozonation and oxidative regeneration of Cucurbituril.
Water research, 2001Co-Authors: Anja Kornmüller, Silke Karcher, Martin JekelAbstract:In Part I it was shown, that Cucurbituril has high sorption capacities for the removal of reactive dyes from textile wastewater; despite the partial dissolution of this sorbent. Ozonation has been suggested as a regeneration step for loaded Cucurbituril. Ozonation of loaded and pure Cucurbituril was therefore evaluated. Dissolved Cucurbituril reacts with ozone forming oxidation products like nitrite, nitrate, formate, acetate and oxalate. Oxidation is enhanced at alkaline pH. Dye-loaded Cucurbituril suspended in water can be decolorized by ozone, but the ozone consumption is tip to seven times higher than for ozonation of the dissolved dyes without Cucurbituril. Loaded columns can be regenerated by ozone gas, but dissolution of Cucurbituril results in a higher DOC content than the initial one to be removed. Therefore oxidative regeneration does not seem to be a feasible approach in this case.
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Cucurbituril for water treatment. Part I: Solubility of Cucurbituril and sorption of reactive dyes.
Water research, 2001Co-Authors: Silke Karcher, Anja Kornmüller, Martin JekelAbstract:Cucurbituril was investigated regarding its potential as a sorbent for the removal of reactive dyes from model solutions and authentic wastewaters. The solubility of Cucurbituril is low in pure water but increases in the presence of salts. When dyes sorbing onto Cucurbituril are present, solubility is drastically decreased compared to dye-free media. Sorption efficiency depends on salt concentration and salt species. Moderate salt concentrations favor sorption, high concentrations lead to Cucurbituril dissolution. Divalent ions have a stronger effect than monovalent ions and larger ions more than smaller ones. In tests with authentic wastewaters Cucurbituril was partially (20-100%) dissolved and contaminant removal was inefficient. Because of its solubility, Cucurbituril is not feasible as a sorbent in wastewater treatment unless it could be covalently fixed onto a suitable support material.
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removal of reactive dyes by sorption complexation with Cucurbituril
Water Science and Technology, 1999Co-Authors: Silke Karcher, Anja Kornmüller, M. JekelAbstract:Color removal is an important task in textile wastewater treatment. Cucurbituril, a cyclic hexamer with internal hydrophobic cavity, has been studied as sorbent for removal of reactive dyes. Loadings as high as 1 g/g and more were obtained, making the method seem interesting for technical application. A minimum of 1 to 5 mmol/L calcium is needed for efficient sorption. However, salt concentrations of 100 mmol/L and above decrease sorption efficiency due to increased solubility of Cucurbituril in salt solutions. The pH has little influence between 4 and 7.5, higher pH-values can result in decreased sorption. The salt influences are similar for most of the tested dyes whereas the pH-effect differs from dye to dye.
Shiyan Chen - One of the best experts on this subject based on the ideXlab platform.
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white light emission from Cucurbituril based host guest interaction in the solid state new function of the macrocyclic host
ACS Applied Materials & Interfaces, 2018Co-Authors: Yu Xia, Shiyan ChenAbstract:Energy transfer and interchange are central for fabricating white light-emitting organic materials. However, increasing the efficiency of light energy transfer remains a considerable challenge because of the occurrence of “cross talk”. In this work, by exploiting the unique photophysical properties of Cucurbituril-triggered host–guest interactions, the two complementary luminescent colors blue and yellow for white light emission were independently obtained from a single fluorophore dye rather than energy transfer. Further study suggested that the rigid cavity of Cucurbiturils efficiently prevented the aggregation of the dye and improved its thermal stability in the solid state by providing a regular nanosized fence for each encapsulated dye molecule. As a result, a novel macrocycle-assisted supramolecular approach for obtaining solid, white light-emitting organic materials with low cost, high efficiency, and easy scale-up was successfully demonstrated.
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White Light Emission from Cucurbituril-Based Host–Guest Interaction in the Solid State: New Function of the Macrocyclic Host
2018Co-Authors: Yu Xia, Shiyan ChenAbstract:Energy transfer and interchange are central for fabricating white light-emitting organic materials. However, increasing the efficiency of light energy transfer remains a considerable challenge because of the occurrence of “cross talk”. In this work, by exploiting the unique photophysical properties of Cucurbituril-triggered host–guest interactions, the two complementary luminescent colors blue and yellow for white light emission were independently obtained from a single fluorophore dye rather than energy transfer. Further study suggested that the rigid cavity of Cucurbiturils efficiently prevented the aggregation of the dye and improved its thermal stability in the solid state by providing a regular nanosized fence for each encapsulated dye molecule. As a result, a novel macrocycle-assisted supramolecular approach for obtaining solid, white light-emitting organic materials with low cost, high efficiency, and easy scale-up was successfully demonstrated
Zhu Tao - One of the best experts on this subject based on the ideXlab platform.
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Synthesis of a symmetrical octamethyl-substituted Cucurbituril with a dimethyl-substituted glycoluril dimer
Tetrahedron, 2014Co-Authors: Zhou Jiajia, Zhao Yingchun, Xin Xiao, Yun-qian Zhang, Qian-jiang Zhu, Sai-feng Xue, Qian-jun Zhang, Jing-xin Liu, Zhu TaoAbstract:Abstract A symmetrical octamethyl-substituted Cucurbituril has been synthesized in a controlled manner by using a dimer of dimethyl-substituted glycoluril, which was in turn synthesized under formaldehyde-deficient conditions. The dimer of dimethyl-substituted glycoluril and the symmetrical octamethyl-substituted Cucurbituril have been characterized by NMR spectrometry, ESI mass spectrometry and single-crystal X-ray diffraction analysis. The structure of the dimer of dimethyl-substituted glycoluril is notable because it constitutes a useful new building block that could permit the formation of such cucurbit[n]urils with substituents in certain positions or with limited numbers of methine groups on their backbones.
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Cucurbituril-resisted acylation of the anti-tuberculosis drug isoniazidvia a supramolecular strategy
Organic & biomolecular chemistry, 2010Co-Authors: Hang Cong, Qian-jiang Zhu, Sai-feng Xue, Zhu Tao, Gang WeiAbstract:A chemical investigation reveals that the resistance to acylation of an anti-tuberculosis drug, isoniazid is a consequent result of the inclusion or exclusion of cucurbit[n]urils (n = 6 or 7). The 1H NMR spectra analysis shows that the different interaction models of the isoniazid with the two Cucurbiturils are dependent on the cavity size of the hosts. Quantum chemistry calculations with density functional theory method indicate that the interaction of the isoniazid with both Cucurbiturils is through thermodynamic stabilization in both the gas phase and aqueous solution through hydrogen bonding on the portal carbonyls of the Cucurbiturils. Electronic absorption titration spectra suggest the hosts and guest interact in a ratio of 1 : 1 with moderate binding constants. Acylation kinetics of isoniazid with various acylating agents in the presence of the Cucurbiturils revealed that resistance is only dependent on the host–isoniazid ratio, and independent on the size of the Cucurbiturils and the species of acylating agents.
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Exclusion complexes of the HCl salts of benzidine and bis(4-aminophenyl) methane with two methyl-substituted Cucurbiturils
New Journal of Chemistry, 2009Co-Authors: Ying Yan, Yun-qian Zhang, Qian-jiang Zhu, Sai-feng Xue, Hang Cong, Jian-xing Zhang, Zhu TaoAbstract:The interaction between two partially methyl-substituted Cucurbiturils, a sym-tetramethyl-substituted cucurbit[6]uril (TMeQ[6]) and a meta-hexamethyl-substituted Cucurbituril (m-HMeQ[6]), with the hydrochloride salt of benzidine (g1·HCl) and the analogue bis(4-aminophenyl) methane (g2·HCl) was investigated by single crystal X-ray diffraction determination, 1H NMR spectroscopy, electronic absorption spectroscopy and fluorescence spectroscopy. Single crystal X-ray diffraction determination showed the two guest compounds were excluded at the portals of the partial methyl-substituted Cucurbiturils in the solid state. The 1H NMR spectroscopic analysis in aqueous solution supported the crystallographic results in which an excluding or portal interaction occurs between the host and guest. Aqueous absorption spectrophotometric and fluorescence spectroscopic analysis defined the stability of the host–guest exclusion complex at pH 5.6 with a host : guest ratio of 1 : 1, which forms quantitatively as ∼105 L mol−1 for the TMeQ[6]–g1 system. The host : guest ratio of 2 : 1 forms quantitatively as ∼1010 L2 mol−2 for the m-HMeQ[6]–g2 system. The experimental results are in good agreement with HF and B3LYP computational approaches with a moderate-sized basis set.
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Solubility enhancement of kinetin through host–guest interactions with Cucurbiturils
Journal of Inclusion Phenomena and Macrocyclic Chemistry, 2008Co-Authors: Ying Huang, Qian-jiang Zhu, Sai-feng Xue, Zhu Tao, Hong Zhang, Jing-xiang LinAbstract:We explored the use of Cucurbiturils to form inclusion complexes to overcome the solubility problems of kinetin, a plant cytokinin. Inclusion complexes between kinetin and Q[7], TMeQ[6] and HMeQ[6] in aqueous solution and in solid state were investigated by phase solubility studies, 1H NMR and IR. The effects of pH and temperature on complex stability were also investigated. Phase solubility studies showed that kinetin solubility increased in a linear fashion as a function of Q[7] and TMeQ[6] concentrations. However, kinetin solubility increased first, then decreased as the HMeQ[6] concentration increased, and the maximum solubility of kinetin was achieved at 4.95 mM in HMeQ[6]. The solubility of kinetin as well as the stability constant of its complex with Q[7] were affected by the pH of the medium. The thermodynamic parameters of the complex formation were also determined, and it showed that the formation of the inclusion complexes between kinetin and Q[7] was enthalpy controlled, suggesting that hydrophobic and van der Waals interactions were the main driving forces. Moreover, we found that the size of the cavity of Cucurbituril played an important role in the association process. The formation of inclusion complexes between Q[7], TMeQ[6] and HMeQ[6] with kinetin was confirmed by 1H NMR, and IR spectroscopy showed the presence of inclusion complexes in solid state. Our results demonstrated that the complexation of kinetin with Q[n] could be used to improve the solubility of kinetin in aqueous solution.
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solubility enhancement of kinetin through host guest interactions with Cucurbiturils
Journal of Inclusion Phenomena and Macrocyclic Chemistry, 2008Co-Authors: Ying Huang, Qian-jiang Zhu, Sai-feng Xue, Zhu Tao, Hong Zhang, Jing-xiang LinAbstract:We explored the use of Cucurbiturils to form inclusion complexes to overcome the solubility problems of kinetin, a plant cytokinin. Inclusion complexes between kinetin and Q[7], TMeQ[6] and HMeQ[6] in aqueous solution and in solid state were investigated by phase solubility studies, 1H NMR and IR. The effects of pH and temperature on complex stability were also investigated. Phase solubility studies showed that kinetin solubility increased in a linear fashion as a function of Q[7] and TMeQ[6] concentrations. However, kinetin solubility increased first, then decreased as the HMeQ[6] concentration increased, and the maximum solubility of kinetin was achieved at 4.95 mM in HMeQ[6]. The solubility of kinetin as well as the stability constant of its complex with Q[7] were affected by the pH of the medium. The thermodynamic parameters of the complex formation were also determined, and it showed that the formation of the inclusion complexes between kinetin and Q[7] was enthalpy controlled, suggesting that hydrophobic and van der Waals interactions were the main driving forces. Moreover, we found that the size of the cavity of Cucurbituril played an important role in the association process. The formation of inclusion complexes between Q[7], TMeQ[6] and HMeQ[6] with kinetin was confirmed by 1H NMR, and IR spectroscopy showed the presence of inclusion complexes in solid state. Our results demonstrated that the complexation of kinetin with Q[n] could be used to improve the solubility of kinetin in aqueous solution.