Diversely Responsive Turn-On Fluorescent Cyclodextrin Chemosensors: Guest Selectivities and Mechanism Insights

Chemosensors have attracted considerable attention among the numerous strategies for detecting organic molecules in water. A turn-off mechanism was previously employed for the construction of a cyclodextrin (CD) chemosensor. This mechanism is greatly effective but has several shortcomings. In order to overcome these shortcomings, new fluorescent chemosensors NC0αCD, NC0βCD, and NC0γCD, which were (7-nitrobenz-2-oxa-1,3-diazol-4-yl)amine-modified α-CD, β-CD, and γ-CD, respectively, were prepared. Their guest selectivities were different from those of previously reported CD chemosensors. Here, the mechanism of new CD chemosensors was investigated using nuclear magnetic resonance (NMR) spectroscopy and molecular mechanics calculations. The fluorescence intensity of NC0βCD and NC0γCD slightly decreased and largely increased, respectively, upon the addition of ursodeoxycholic acid as a guest. This is due to the fact that the fluorophore of NC0βCD moved away to the hydrophilic bulk water to form hydrogen bonds between the host and the guest, while the fluorophore of NC0γCD remained located at the primary hydroxy side of the γ-CD unit to form a stable inclusion complex with hydrogen bonds between the fluorophore and the guest. NC0αCD also acted as a turn-on chemosensor for small guests, which could not be detected by the previous CD chemosensors. The motion restriction of the fluorophore through the generation of inclusion complexes could also contribute to increase in fluorescence intensity.

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Characterization of germinating and non-viable soybean seeds by nuclear magnetic resonance (NMR) spectroscopy

Seed Science Research ◽

10.1079/ssr2004189 ◽

2004 ◽

Vol 14 (4) ◽

pp. 355-362 ◽

Cited By ~ 17

Author(s):

P. Krishnan ◽

D.K. Joshi ◽

Shantha Nagarajan ◽

A.V. Moharir

Keyword(s):

Nuclear Magnetic Resonance ◽

Nmr Spectroscopy ◽

Magnetic Resonance ◽

Phase Ii ◽

Water Status ◽

Free Water ◽

Bulk Water ◽

Water Proton ◽

Soybean Seeds ◽

Nuclear Magnetic

The changes in water status of germinating and non-viable soybean (Glycine max L. Merr.) seeds were characterized by nuclear magnetic resonance (NMR) spectroscopy. There were distinct changes in water status between viable and non-viable soybean seeds. In dry seeds, there were only two components, bound and bulk water, as revealed by component analysis of NMR (T2) data. On the contrary, a three-component water proton system (bound, bulk and free water) was observed in both germinating and non-viable soybeans during Phase I of hydration. The bulk water component of non-viable seeds disappeared completely during the lag phase (Phase II) of hydration, resulting in a two-component water proton system. In contrast, the three-component water proton system in Phase II was observed in the germinating seeds. Rapid hydration (Phase III), following Phase II, was observed in germinating soybean seeds only. Due to reorganization of water protons, there was a concomitant increase in bulk and free water, but a decrease in bound water. The physical state of water in these seeds (analysed by NMR spectroscopy) and the measurements of tissue leachate conductivity suggest that non-viable soybean seeds were more affected by the disorganized cell structure in the seed membrane system. The present study also provides evidence that physical reorganization of water is essential in germinating soybean seeds during hydration.

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Hydrogen Bonds between Sexual Hormones and Nucleobases: NMR Investigations *§

Zeitschrift für Naturforschung C ◽

10.1515/znc-1973-9-1003 ◽

1973 ◽

Vol 28 (9-10) ◽

pp. 494-498 ◽

Cited By ~ 3

Author(s):

Wolfgang Schimmack ◽

Wolfgang Lohmann

Keyword(s):

Nuclear Magnetic Resonance ◽

Nmr Spectroscopy ◽

Magnetic Resonance ◽

Chemical Shift ◽

Hydrogen Bonds ◽

Ethinyl Estradiol ◽

Hydroxyl Group ◽

Kcal Mole ◽

Sexual Hormones ◽

Nmr Parameters

Abstract The hydrogen-bonded complexes of 17 α-ethinyl-estradiol, progesterone, and testosterone with adenine- and uracil-derivatives have been investigated by means of nuclear magnetic resonance (NMR) spectroscopy using deutero-chloroform as a solvent. The thermodynamic and NMR-parameters (equilibrium constant K, enthalpy ΔH, entropy ΔS, and relative chemical shift of the complexes ΔδC) for selfassociation and mixed association have been determined. The strongest complex was formed by the phenolic hydroxyl group of estradiol with dimethyl-adenine (K = 14 mole- 1 , - ΔH = i kcal/mole, - ΔS = 8 cal/m ole-grad). The values were considerably less for the OH-17 group of estradiol and testosterone. The interaction of the keto groups of progesterone and testo sterone with nucleobases was very weak: K < 1 .0 mole- 1 . The biological importance of these results is discussed.

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Conductivity Studies of Schiff Base Ligands Derived from O-Phenylenediamine and Their Co(II) and Zn(II) Complexes

Scientific Research Journal ◽

10.24191/srj.v12i2.5427 ◽

2015 ◽

Vol 12 (2) ◽

pp. 13

Author(s):

Muhamad Faridz Osman ◽

Karimah Kassim

Keyword(s):

Nuclear Magnetic Resonance ◽

Fourier Transform ◽

Schiff Base ◽

Nmr Spectroscopy ◽

Magnetic Resonance ◽

Impedance Spectroscopy ◽

Ftir Spectroscopy ◽

Coordination Complexes ◽

Frequency Range ◽

Schiff Base Ligands

The coordination complexes of Co(II) and Zn(II) with Schiff bases derived from o-phenylenediamine and substituted 2-hydroxybenzaldehyde were prepared All compounds were characterized by Fourier transform infrared (FTIR) spectroscopy and Nuclear magnetic resonance (NMR) spectroscopy elemental analyzers. They were analyzed using impedance spectroscopy in the frequency range of 100Hz-1 MHz. LI and L2 showed higher conductivity compared to their metal complexes, which had values of 1.3 7 x 10-7 and 6.13 x 10-8 S/cm respectively.

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Biological NMR Spectroscopy

10.1093/oso/9780195094688.001.0001 ◽

1997 ◽

Keyword(s):

Nuclear Magnetic Resonance ◽

Nmr Spectroscopy ◽

Magnetic Resonance ◽

Magnetic Resonance Spectroscopy ◽

State Of The Art ◽

Critical Assessment ◽

Resonance Spectroscopy ◽

History Of ◽

Structure Of Proteins

This book presents a critical assessment of progress on the use of nuclear magnetic resonance spectroscopy to determine the structure of proteins, including brief reviews of the history of the field along with coverage of current clinical and in vivo applications. The book, in honor of Oleg Jardetsky, one of the pioneers of the field, is edited by two of the most highly respected investigators using NMR, and features contributions by most of the leading workers in the field. It will be valued as a landmark publication that presents the state-of-the-art perspectives regarding one of today's most important technologies.

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A Metabolomic Approach to Beer Characterization

Molecules ◽

10.3390/molecules26051472 ◽

2021 ◽

Vol 26 (5) ◽

pp. 1472

Author(s):

Nicola Cavallini ◽

Francesco Savorani ◽

Rasmus Bro ◽

Marina Cocchi

Keyword(s):

Nuclear Magnetic Resonance ◽

Nmr Spectroscopy ◽

Magnetic Resonance ◽

Analytical Methods ◽

Nmr Spectra ◽

Full Spectrum ◽

The Past ◽

Beer Consumption ◽

Metabolomic Approach ◽

Chemometric Tools

The consumers’ interest towards beer consumption has been on the rise during the past decade: new approaches and ingredients get tested, expanding the traditional recipe for brewing beer. As a consequence, the field of “beeromics” has also been constantly growing, as well as the demand for quick and exhaustive analytical methods. In this study, we propose a combination of nuclear magnetic resonance (NMR) spectroscopy and chemometrics to characterize beer. 1H-NMR spectra were collected and then analyzed using chemometric tools. An interval-based approach was applied to extract chemical features from the spectra to build a dataset of resolved relative concentrations. One aim of this work was to compare the results obtained using the full spectrum and the resolved approach: with a reasonable amount of time needed to obtain the resolved dataset, we show that the resolved information is comparable with the full spectrum information, but interpretability is greatly improved.

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