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Aude Bouchet Thierry Brotin Dr. Dominique Cavagnat Dr. Thierry Buffeteau Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(15):4507-4518
We report the synthesis of the water‐soluble cryptophanol derivative 1 and the study of the chiroptical properties of its two enantiomers (>99 % ee) by polarimetry, electronic circular dichroism (ECD), and vibrational circular dichroism (VCD). We show that cryptophanol 1 exhibits unusual chiroptical properties in water under basic conditions (pH>12). For instance, the shapes of the ECD and VCD spectra of 1 in water were strongly dependent on the nature of the alkali metal ions (Li+, Na+, K+, Cs+) surrounding the cryptophane and whether or not a guest molecule is present inside the cavity of the host. To the best of our knowledge, this is the first example in which the nature of these counterions governs the chiroptical properties of a host molecule. Moreover, specific ECD spectra were obtained depending on the size of the guest molecules. This makes 1 a good sensor for small neutral molecules in aqueous solvent. Finally, VCD experiments associated with DFT calculations show that the chiroptical changes can be directly correlated to the presence of charges close to the aromatic rings and with a conformational change of the alkyl chains upon encapsulation. 相似文献
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Back Cover: Molecular Sensing with Hyperpolarized 129Xe Using Switchable Chemical Exchange Relaxation Transfer (ChemPhysChem 11/2015)
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Dr. Léa Delacour Dr. Naoko Kotera Dr. Ténin Traoré Sébastien Garcia‐Argote Céline Puente Dr. François Leteurtre Dr. Edmond Gravel Dr. Nawal Tassali Dr. Céline Boutin Estelle Léonce Dr. Yves Boulard Dr. Patrick Berthault Dr. Bernard Rousseau 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(19):6089-6093
We describe the synthesis of a highly water‐soluble cryptophane 1 that can be seen as a universal platform for the construction of 129Xe magnetic resonance imaging (MRI)‐based biosensors. Compound 1 is easily functionalized by Huisgen cycloaddition and exhibits excellent xenon‐encapsulation properties. In addition, 1 is nontoxic at the concentrations typically used for hyperpolarized 129Xe MRI. 相似文献
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Keunhong Jeong Clancy C. Slack Dr. Christophoros C. Vassiliou Phuong Dao Muller D. Gomes Dr. Daniel J. Kennedy Ashley E. Truxal Dr. Lindsay J. Sperling Prof. Dr. Matthew B. Francis Prof. Dr. David E. Wemmer Prof. Dr. Alexander Pines 《Chemphyschem》2015,16(17):3573-3577
Recent work has shown that xenon chemical shifts in cryptophane‐cage sensors are affected when tethered chelators bind to metals. Here, we explore the xenon shifts in response to a wide range of metal ions binding to diastereomeric forms of 1,4,7,10‐tetraazacyclododecane‐1,4,7,10‐tetraacetic acid (DOTA) linked to cryptophane‐A. The shifts induced by the binding of Ca2+, Cu2+, Ce3+, Zn2+, Cd2+, Ni2+, Co2+, Cr2+, Fe3+, and Hg2+ are distinct. In addition, the different responses of the diastereomers for the same metal ion indicate that shifts are affected by partial folding with a correlation between the expected coordination number of the metal in the DOTA complex and the chemical shift of 129Xe. These sensors may be used to detect and quantify many important metal ions, and a better understanding of the basis for the induced shifts could enhance future designs. 相似文献
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Inside Cover: Investigation of DOTA–Metal Chelation Effects on the Chemical Shift of 129Xe (ChemPhysChem 17/2015)
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Versatile Syntheses of Hemi‐Cryptophanes and a Metallo‐Cryptophane from a Hexa‐Functionalized C3v‐Symmetrical Tribenzotriquinacene (TBTQ) Derivative
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Jun Wei Zhi‐Min Li Xiao‐Jie Jin Prof. Xiao‐Jun Yao Prof. Xiao‐Ping Cao Prof. Hak‐Fun Chow Prof. Dietmar Kuck 《化学:亚洲杂志》2015,10(5):1150-1158
A number of three‐fold C3v‐symmetrical tribenzotriquinacene (TBTQ) cavitands were synthesized by a “metamorphosis‐to‐half” strategy, employing six‐fold etherification reactions between the hexakis(chloromethyl)‐TBTQ intermediate 2 a and various 5‐functionalized resorcinols. X‐ray structure analyses of single crystals of the cavitands revealed limited rotational flexibility of the resorcinol bridging units, which enables an apical, nearly co‐axial orientation of the three functional groups and, as a consequence, the construction of nanoscale cage‐like molecules via covalent or coordination bonding. On this basis, two TBTQ‐based hemicryptophanes were prepared from the TBTQ cavitands via covalent bond formation in good yields. A dumbbell‐shaped TBTQ‐based metallo‐cryptophane was also synthesized in 34 % yield by a solvothermal reaction between cadmium nitrate and two equivalents of the TBTQ‐cavitand triacid, as confirmed by single‐crystal X‐ray diffraction and MALDI‐ToF mass spectrometry. 相似文献
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Molecular Sensing with Hyperpolarized 129Xe Using Switchable Chemical Exchange Relaxation Transfer
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Dr. Nicola J. Rogers James L. Krupa Dr. Galina E. Pavlovskaya Prof. Dr. Neil R. Thomas Dr. Henryk M. Faas Prof. Dr. Thomas Meersmann 《Chemphyschem》2015,16(11):2294-2298
An approach for hyperpolarized 129Xe molecular sensors is explored using paramagnetic relaxation agents that can be deactivated upon chemical or enzymatic reaction with an analyte. Cryptophane encapsulated 129Xe within the vicinity of the paramagnetic center experiences fast relaxation that, through chemical exchange of xenon atoms between cage and solvent pool, causes accelerated hyperpolarized 129Xe signal decay in the dissolved phase. In this proof‐of‐concept work, the relaxivity of Gadolinium III‐DOTA on 129Xe in the solvent was increased eightfold through tethering of the paramagnetic molecule to a cryptophane cage. This potent relaxation agent can be ′turned off′ specifically for 129Xe through chemical reactions that spatially separate the GdIII centre from the attached cryptophane cage. Unlike 129Xe chemical shift based sensors, the new concept does not require high spectral resolution and may lead to a new generation of responsive contrast agents for molecular MRI. 相似文献
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Michael J. Potter Paul D. Kirchhoff Heather A. Carlson J. Andrew McCammon 《Journal of computational chemistry》1999,20(9):956-970
Time scales currently obtainable in explicit–solvent molecular dynamics simulations are inadequate for the study of many biologically important processes. This has led to increased interest in the use of continuum solvent models. For such models to be used effectively, it is important that their behavior relative to explicit simulation be clearly understood. Accordingly, 5 ns stochastic dynamics simulations of a derivative of cryptophane-E alone, and complexed with tetramethylammonium and neopentane were carried out. Solvation electrostatics were accounted for via solutions to the Poisson equation. Nonelectrostatic aspects of solvation were incorporated using a surface area-dependent energy term. Comparison of the trajectories to those from previously reported 25 ns explicit–solvent simulations shows that use of a continuum solvent model results in enhanced sampling. Use of the continuum solvent model also results in a considerable increase in computational efficiency. The continuum solvent model is found to predict qualitative structural characteristics that are similar to those observed in explicit solvent. However, some differences are significant, and optimization of the continuum parameterization will be required for this method to become an efficient alternative to explicit–solvent simulation. ©1999 John Wiley & Sons, Inc. J Comput Chem 20: 956–970, 1999 相似文献
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