Molecular conformation of orotidine, a naturally occurring nucleoside, in the syn conformation in aqueous solution

1971 ◽  
Vol 93 (7) ◽  
pp. 1795-1797 ◽  
Author(s):  
Frank E. Hruska
Keyword(s):  
Aqueous Solution ◽  
Molecular Conformation ◽  
Naturally Occurring

Fluorescence of the Complexes of 2-Methylnaphthoate and 2-Hydroxypropyl-α-, -β-, and -γ-Cyclodextrins in Aqueous Solution

2002 ◽  
Vol 56 (12) ◽  
pp. 1579-1587 ◽  
Author(s):  
Antonio Di Marino ◽  
Franscisco Mendicuti
Keyword(s):  
Aqueous Solution ◽  
Fluorescence Anisotropy ◽  
Intensity Ratio ◽  
Driving Forces ◽  
Emission Spectra ◽  
Formation Constants ◽  
Dielectric Constants ◽  
Additional Information ◽  
Fluorescence Techniques ◽  
Naturally Occurring

Fluorescence techniques were employed to study the inclusion complexes of 2-methylnaphthoate (MN) with 2-hydroxypropyl-α-cyclodextrin (αHPCD), 2-hydroxypropyl-β-cyclodextrin (βHPCD), and 2-hydroxypropyl-γ-cyclodextrin (γHPCD). Emission spectra of MN show two vibronic bands whose intensity ratio R is very sensitive to the polarity of the medium. The stoichiometry and formation constants of these complexes were investigated by obtaining R as a function of the cyclodextrin (CD) concentration. Results showed identical stoichiometry (1/1) for the three MN/αHPCD, MN/β-HPCD, and MN/γHPCD complexes. Formation constants at 25 °C were 780 ± 15, 2700 ± 130, and 165 ± 10 M−1, respectively. ΔH0 and ΔS0 were obtained from linear van't Hoff plots. Results reveal that the complexation of MN with αHPCD is enthalpy driven. With βHPCD, both the entropy and enthalpy terms favor the process, whereas the formation of the complex with γHPCD is entropically governed. The extrapolation of R at infinite CD concentration allows us to estimate the effective dielectric constants of the inner CD cavities, which are around 50, but which differ from their counterparts, the naturally occurring α-, β-, and γ-CDs. Fluorescence anisotropy, quencher lifetimes, and average lifetimes can also give additional information about the structure and driving forces accompanying the formation of such complexes.

scholarly journals Stabilisation of Natural Colourants and Lignocellulosic Textiles

2021 ◽  
Author(s):  
◽  
Ying Tang
Keyword(s):  
Reactive Oxygen Species ◽  
Aqueous Solution ◽  
Textile Fibre ◽  
Oxygen Species ◽  
Blue Fluorescence ◽  
Esi Ms ◽  
Naturally Occurring ◽  
Antifungal Effects ◽  
Fluorescent Whitening Agents ◽  
Cyclobutane Ring

<p>The lignocellulosic fibres extracted from the leaves of New Zealand flax, Phormium tenax, have been used as the principal textile fibre by Maori since pre- European times. Variations of antifungal activity were observed in Phormium fibres of different cultivars. The most resistant cultivars of P. tenax in an aqueous antifungal assay also possessed the greatest variety of naturally-occurring 7-hydroxycoumarins as identified by mass spectroscopy, ESI-MS. In addition to antifungal effects, coumarins function as fluorescent whitening agents in Phormium fibres and play a role in the fibre’s photodegradation. Ultraviolet irradiation (350 – 400 nm) of the fibre resulted in a substantial loss of the blue fluorescence originating from a number of 7-hydroxycoumarins present, together with the formation of new fluorophores absorbing and emitting at longer wavelengths, which contribute to the photoyellowing of the fibre. The photolysis of two standard 7-hydroxycoumarins in aqueous solution was examined and two primary photoproducts were elucidated by ESI-MS: a photodimer containing a linking cyclobutane ring and a monomeric photooxidation product. The formation of at least some of the photoproducts is associated with the coumarin-sensitised generation of reactive oxygen species, hydrogen peroxide and superoxide. The fluorescence properties and photodegradation of Chinese handmade papers were also investigated. Papers manufactured by traditional methods were found to be more photostable than that produced from chemically-facilitated techniques.</p>

Molecular Conformation of 4-Thiouridine in Aqueous Solution

1971 ◽  
Vol 49 (14) ◽  
pp. 2449-2452 ◽  
Author(s):  
F. E. Hruska ◽  
K. K. Ogilvie ◽  
A. A. Smith ◽  
H. Wayborn
Keyword(s):  
Aqueous Solution ◽  
Long Range ◽  
Crystalline State ◽  
Molecular Conformation ◽  
Spin Coupling ◽  
Pyrimidine Nucleoside ◽  
Coupling Interaction ◽  
X Ray ◽  
Anti Conformation ◽  
Spin Spin Coupling

β-4-Thiouridine is a component of several tRNA molecules. A recent X-ray study has shown that this pyrimidine nucleoside favors the syn conformation in the crystalline state. The 100 and 220 MHz p.m.r. data and a comparison with those of uridine are presented here. A long-range five-bond spin–spin coupling interaction between the H-5 and -1′ hydrogens is noted. The results are consistent with an anti conformation for 4-thiouridine in an aqueous solution.

Ribo-2′-deoxyribo hybrid dinucleoside monophosphates. Proton magnetic resonance studies of 3′,5′- and 2′,5′-uridylyl-2′-deoxythymidine

1978 ◽  
Vol 56 (4) ◽  
pp. 522-529 ◽  
Author(s):  
James Peeling ◽  
Frank E. Hruska ◽  
Peter C. Loewen
Keyword(s):  
Aqueous Solution ◽  
Magnetic Resonance ◽  
Proton Magnetic Resonance ◽  
Molecular Conformation ◽  
The Other ◽  
Magnetic Resonance Studies ◽  
Dinucleoside Monophosphates ◽  
Standard Techniques

This 1Hmr study initiates our examination of the conformations of dinucleoside monophosphates possessing ribo 2′- or 3′-nucleotidyl units linked to 5′-nucleotidyl units possessing the 2′-deoxyribo sugar. The syntheses of uridylyl-3′,5′-2′-deoxythymidine (3′,5′-UpdT) and its 2′,5′-isomer, 2′,5′-UpdT, were carried out with standard techniques. The 1Hmr data were obtained at frequencies up to 270 MHz and used to derive the dominant conformation of the dimers in aqueous solution. Comparison with data for the component mononucleotides reveals that dimerization does not lead to drastic changes in the molecular conformation. Literature data for dimers possessing only the ribo sugar (3′,5′-UpU) and the 2′-deoxyribo sugar (3′,5′-d(TpT)) are also presented. The results indicate that, at least for our dipyrimidine dimers, the molecular conformation of a particular fragment is not critically dependent on the nature (ribo or 2′-deoxyribo) of the other nucleotide unit.

Molecular Conformation-Controlled Vesicle/Micelle Transition of Cationic Trimeric Surfactants in Aqueous Solution

Langmuir ◽  
2010 ◽  
Vol 26 (11) ◽  
pp. 7922-7927 ◽  
Author(s):  
Chunxian Wu ◽  
Yanbo Hou ◽  
Manli Deng ◽  
Xu Huang ◽  
Defeng Yu ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Molecular Conformation ◽  
Trimeric Surfactants

The chemical stability of mimetite and distribution coefficients for pyromorphite–mimetite solid-solutions

1989 ◽  
Vol 53 (371) ◽  
pp. 363-371 ◽  
Author(s):  
Adedayo I. Inegbenebor ◽  
John H. Thomas ◽  
Peter A. Williams
Keyword(s):  
Solid Solution ◽  
Aqueous Solution ◽  
Solid Phase ◽  
Distribution Coefficients ◽  
Solid Solution Series ◽  
Solution Series ◽  
Ph Values ◽  
Naturally Occurring ◽  
Phosphate Species ◽  
End Members

AbstractThe equilibrium solubility of mimetite has been determined in aqueous solution at 298.2K. For the reaction Pb5(ASO4)3Cl(s,mimetite)+6H+(aq)⇌5Pb2+(aq)+3H2AsO4−(aq)+Cl−(aq) at this temperature log KH+, extrapolated to zero ionic strength, is equal to −27.9(4). This value is equal, within experimental error, to that corresponding to pyromorphite, Pb5(PO4)3Cl, derived from the literature, and redetermined here under analogous conditions. Distribution coefficients in terms of both HXO42− and H2XO4−(aq) ions (X = P,As) have also been determined for solid phases of the pyromorphite-mimetite solid solution series containing from 5 to 95 mol. % mimetite. Although the two end-members are isostructural without being strictly isomorphous, the solid solution series behaves ideally over the whole compositional range; that is, the composition of the solid phase reflects the ratio of arsenate to phosphate species in aqueous solution at pH values corresponding to naturally-occurring aqueous solutions generally associated with the oxidized zones of base metal orebodies. Some relationships between mimetite and other secondary lead(II) and copper(II) arsenate minerals have been explored.

scholarly journals The Removal Performance and Mechanisms of Tetracycline Over Mn-rich Limonite

2021 ◽  
Author(s):  
Luyao Wang ◽  
Hanlin Wang ◽  
Haibo Liu ◽  
Xuehua Zou ◽  
Dong Chen ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Physicochemical Properties ◽  
Active Sites ◽  
Manganese Oxides ◽  
Mesoporous Structure ◽  
High Specific Surface Area ◽  
Solution Ph ◽  
Natural Mineral ◽  
Naturally Occurring ◽  
Ft Ir

Abstract Naturally occurring Mn-rich limonite mainly composed of goethite and manganese oxides was used to remove tetracycline (TC) from the aqueous solution. The physicochemical properties of limonite were illustrated by various characterization techniques such as XRD, FE-TEM, XPS and FT-IR. The effects of dosage, initial solution pH, temperature and coexisting anions on TC removal were investigated. The results showed that TC could be efficiently adsorbed by limonite with high specific surface area and mesoporous structure through electrostatic interaction and complexation. The co-existence of PO43- inhibited the adsorption of TC by limonite due to the competition with TC for active sites. In addition, manganese oxides exhibited oxidative properties to TC, and the singlet oxygen (1O2) generated during the redox reaction was responsible for TC degradation. Furthermore, the regenerated limonite displayed an efficient recycling performance after four cycles. This study revealed that the Mn-rich limonite was a promising adsorbent for TC removal from aqueous solutions and promoted the application of natural mineral material in the environmental field.

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