Macrocyclic bis(ureas) as ligands for anion complexation

Two macrocyclic bis(ureas) 1 and 2, both based on diphenylurea, have been synthesized. Compound 1 represents the smaller ring with two ethynylene groups as linkers and 2 the larger ring with two butadiynylene groups. On thermal treatment to 130 °C molecule 1 splits up into two dihydroindoloquinolinone (3) molecules. Both compounds 1 and 2 form adducts with polar molecules such as dimethyl sulfoxide (DMSO) and dimethylformamide (DMF) and act as complexing agents towards a series of anions (Cl−, Br−, I−, NO3 −, HSO4 −). The crystal structures of 3, 2·2DMSO, 2·2DMF, and of the complex NEt4[Br·2] have been determined. Quantitative investigations of the complexation equilibria were performed via 1H NMR titrations. While 1 is a rather weak complexing agent, the large ring of 2 binds anions with association constants up to log K = 7.93 for chloride ions.

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Complexation of 2,6-helic[6]arene and its derivatives with 1,1′-dimethyl-4,4′-bipyridinium salts and protonated 4,4'-bipyridinium salts: an acid–base controllable complexation

Beilstein Journal of Organic Chemistry ◽

10.3762/bjoc.15.173 ◽

2019 ◽

Vol 15 ◽

pp. 1795-1804 ◽

Cited By ~ 1

Author(s):

Jing Li ◽

Qiang Shi ◽

Ying Han ◽

Chuan-Feng Chen

Keyword(s):

Association Constants ◽

The Other ◽

Acid Base ◽

Polar Solvents ◽

X Ray ◽

H Nmr ◽

Hydrogen Bonding Interactions ◽

Acids And Bases ◽

Multiple Hydrogen Bonding ◽

Nmr Titrations

2,6-Helic[6]arene and its derivatives were synthesized, and their complexation with 1,1′-dimethyl-4,4′-bipyridinium and protonated 4,4'-bipyridinium salts were investigated in detail. It was found that the helic[6]arene and its derivatives could all form 1:1 complexes with both 1,1′-dimethyl-4,4'-bipyridinium salts and protonated 4,4'-bipyridinium salts in solution and in the solid state. Especially, the helic[6]arene and its derivatives containing 2-hydroxyethoxy or 2-methoxyethoxy groups exhibited stronger complexation with the guests than the other helic[6]arene derivatives for the additional multiple hydrogen bonding interactions between the hosts and the guests, which were evidenced by 1H NMR titrations, X-ray crystal structures and DFT calculations. Moreover, it was also found that the association constants (K a) of the complexes could be significantly enhanced with larger counteranions of the guests and in less polar solvents. Furthermore, the switchable complexation between the helic[6]arene and protonated 4,4'-bipyridinium salt could be efficiently controlled by acids and bases.

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Pollutant Identification by Selected Area Electron Diffraction

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100052675 ◽

1974 ◽

Vol 32 ◽

pp. 532-533

Author(s):

R. E. Ferrell ◽

G. G. Paulson ◽

C. W. Walker

Keyword(s):

Thermal Treatment ◽

Electron Diffraction ◽

Sample Preparation ◽

Crystal Structures ◽

Water Samples ◽

Environmental Samples ◽

Short Review ◽

Selected Area Electron Diffraction ◽

Multiple Component

Selected area electron diffraction (SAD) has been used successfully to determine crystal structures, identify traces of minerals in rocks, and characterize the phases formed during thermal treatment of micron-sized particles. There is an increased interest in the method because it has the potential capability of identifying micron-sized pollutants in air and water samples. This paper is a short review of the theory behind SAD and a discussion of the sample preparation employed for the analysis of multiple component environmental samples.

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Enantioselective Recognition of Chiral Guests by the Water-Soluble Chiral Keplerate {Mo132} Spherical Capsule with 30 Inner Lactate Ligands

10.26434/chemrxiv.8847923.v1 ◽

2019 ◽

Author(s):

Nancy Watfa ◽

Weimin Xuan ◽

Zoe Sinclair ◽

Robert Pow ◽

Yousef Abul-Haija ◽

...

Keyword(s):

Aqueous Solution ◽

Chiral Recognition ◽

Association Constants ◽

Water Soluble ◽

Enantioselective Recognition ◽

H Nmr ◽

Dosy Nmr ◽

Spherical Capsule ◽

Surface Pores ◽

Guest Chemistry

Investigations of chiral host guest chemistry are important to explore recognition in confined environments. Here, by synthesizing water-soluble chiral porous nanocapsule based on the inorganic metal-oxo Keplerate-type cluster, {Mo132} with chiral lactate ligands with the composition [Mo132O372(H2O)72(x-Lactate)30]42- (x = D or L), it was possible to study the interaction with a chiral guest, L/D-carnitine and (R/S)-2-butanol in aqueous solution. The enantioselective recognition was studied by quantitative 1H NMR and 1H DOSY NMR which highlighted that the chiral recognition is regulated by two distinct sites. Differences in the association constants (K) of L- and D-carnitine, which, due to their charge, are generally restricted from entering the interior of the host, are observed, indicating that their recognition predominantly occurs at the surface pores of the structure. Conversely, a larger difference in association constants (KS/KR = 3) is observed for recognition within the capsule interior of (R)- and (S)-2-butanol.

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A multilevel investigation supported by multivariate analysis for tomato product formulation

European Food Research and Technology ◽

10.1007/s00217-021-03794-y ◽

2021 ◽

Author(s):

Fatma Boukid ◽

Elena Curti ◽

Agoura Diantom ◽

Eleonora Carini ◽

Elena Vittadini

Keyword(s):

Thermal Treatment ◽

Color Change ◽

Water Molecules ◽

Thermal Treatments ◽

Industrial Processing ◽

H Nmr ◽

Mobile Populations ◽

Product Formulation ◽

Tomato Product ◽

The Impact

AbstractIndustrial processing of tomato includes its cutting and mincing, thermal treatments, and the addition of ingredients, which might induce changes in physicochemical properties of the final products. In this frame, the impact of texturing/thickening [xanthan gum (X) or potato fiber (F)] on the macroscopic, mesoscopic and molecular properties of tomato double concentrate (TDC) was investigated to determine if F can efficiently substitute X, in association with small solutes (sugar and salt) and thermal treatment (cold and hot). At a macroscopic level, multivariate statistics (MANOVA) underlined that color change (ΔE) was increased by X and F addition contrary to heating and the addition of salt and sugar. MANOVA revealed that texture was greatly enhanced through the use of F over X. 1H NMR molecular mobility changes were more controlled by texturing agents (F and X) than thermal treatment and small solutes. Particularly F increased the more rigid population indicating stronger interaction with water molecules resulting in shear-thinning flow. However, adding X contributed into the increase of the dynamic and mobile populations. Therefore, F can be a valid “clean label” substitute of X in modulating tomato products properties.

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Structural studies of phosphorylation-dependent interactions between the V2R receptor and arrestin-2

Nature Communications ◽

10.1038/s41467-021-22731-x ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Qing-Tao He ◽

Peng Xiao ◽

Shen-Ming Huang ◽

Ying-Li Jia ◽

Zhong-Liang Zhu ◽

...

Keyword(s):

Crystal Structures ◽

Conformational Changes ◽

Nmr Spectrum ◽

H Nmr ◽

Interaction Sites ◽

Receptor Interactions ◽

Remote Sites ◽

Genetic Code Expansion ◽

G Protein Coupled ◽

Interaction Change

AbstractArrestins recognize different receptor phosphorylation patterns and convert this information to selective arrestin functions to expand the functional diversity of the G protein-coupled receptor (GPCR) superfamilies. However, the principles governing arrestin-phospho-receptor interactions, as well as the contribution of each single phospho-interaction to selective arrestin structural and functional states, are undefined. Here, we determined the crystal structures of arrestin2 in complex with four different phosphopeptides derived from the vasopressin receptor-2 (V2R) C-tail. A comparison of these four crystal structures with previously solved Arrestin2 structures demonstrated that a single phospho-interaction change results in measurable conformational changes at remote sites in the complex. This conformational bias introduced by specific phosphorylation patterns was further inspected by FRET and 1H NMR spectrum analysis facilitated via genetic code expansion. Moreover, an interdependent phospho-binding mechanism of phospho-receptor-arrestin interactions between different phospho-interaction sites was unexpectedly revealed. Taken together, our results provide evidence showing that phospho-interaction changes at different arrestin sites can elicit changes in affinity and structural states at remote sites, which correlate with selective arrestin functions.

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The Structural, Magnetic and Optical Properties of Ni-Mg-Zn Ferrite Prepared With Different Complexing Agents via Sol-Gel Method

10.21203/rs.3.rs-263070/v1 ◽

2021 ◽

Author(s):

Yanchun Zhang ◽

Aimin Sun ◽

Zhaxi Suonan

Keyword(s):

Optical Properties ◽

Electron Microscope ◽

Sol Gel ◽

Complexing Agents ◽

Complexing Agent ◽

Gel Method ◽

X Ray ◽

Sol Gel Method ◽

Zn Ferrite ◽

Vis Spectroscopy

Abstract Different complexing agents were used to prepare Ni-Mg-Zn ferrite with the composition formula Ni0.2Mg0.2Zn0.6Fe2O4 via sol-gel method, which included citric acid, oxalic acid, egg white and EDTA. The Ni0.2Mg0.2Zn0.6Fe2O4 ferrite with no complexing agent was also prepared as a comparison. The chemical phases of samples were analyzed by the X-ray diffraction (XRD), which indicated that samples had spinel phase structure. The lattice constants of samples are in the range of 8.3980 ~ 8.4089 Å. The composition and structure were further studied by fourier transform infrared spectroscopy (FTIR). There were two typical characteristic bands related to the stretching vibrations of spinel ferrite in FTIR spectra. Scanning electron microscope (SEM) micrographs and transmission electron microscope (TEM) images showed that the particles have the shape of spherical cube. Energy dispersive spectrometer (EDS) analyzed the elements and ingredients of samples, which included Ni, Mg, Zn, Fe and O. X-ray photoelectron spectroscopy (XPS) is used to examine further the elemental composition and chemical state of sample prepared with EDTA as complexing agent. The optical properties of samples were investigated by photoluminescence spectra and UV-Vis spectroscopy. Vibrating sample magnetometer (VSM) was used to characterize magnetic properties, hysteresis loops revealed the ferrimagnetism behavior of prepared samples.

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Study of the coordination of quinuclidine to a chiral zinc phthalocyanine dimer

Journal of Porphyrins and Phthalocyanines ◽

10.1142/s1088424616500929 ◽

2016 ◽

Vol 20 (08n11) ◽

pp. 1224-1232 ◽

Cited By ~ 1

Author(s):

Nelson Giménez-Agulló ◽

Gemma Aragay ◽

José Ramón Galán-Mascarós ◽

Pablo Ballester

Keyword(s):

Chemical Exchange ◽

Variable Temperature ◽

Exchange Process ◽

Zinc Phthalocyanine ◽

Hydrogen Atoms ◽

Dimerization Constant ◽

H Nmr ◽

Dimerization Process ◽

Nmr Titrations ◽

Millimolar Concentration

We attempted the calculation of an accurate equilibrium constant for the dimerization process of enantiomerically pure Zn-1 using UV-vis dilution experiments. At millimolar concentration Zn-1 is involved in a chemical exchange process between its monomeric and dimeric state that is slow on the 1H NMR timescale. We performed variable-temperature 1H NMR experiments in CDCl3 solution to determine the dimerization constant value at different temperatures and performed a van’t Hoff plot to derive the thermodynamic parameters of the process. The calculated thermodynamic data revealed that the dimerization process is entropy-driven and enthalpically opposed. We also probed the coordination of quinuclidine, 1-azabicyclo[2.2.2]octane, 2, to the Zn-1 using UV-vis and 1H NMR titrations in CDCl3 solution. At micromolar concentration the Zn-1 exclusively exists in solution as a monomer and forms a simple 1:1, [Formula: see text], complex with quinuclidine having a stability constant of [Formula: see text]([Formula: see text]) [Formula: see text] 106 M[Formula: see text]. On the other hand, the 1H NMR titrations carried out at 298 K and at millimolar concentration showed that Zn-1 was present in solution as the dimer and formed 1:2, [Formula: see text], and 2:2, [Formula: see text] complexes by coordination to 2. In addition, the 1:1 complex, [Formula: see text] showed a reduced dimerization constant compared to the uncoordinated parent monomer Zn-1. At high quinuclidine concentration, the 1:1 complex, [Formula: see text], derived from the coordinated dimer dissociation was also detected. The 1H NMR spectra of the titrations displayed separate signals for some hydrogen atoms of the Zn-phthalocyanine in each one of the four species. Remarkably, the chemical exchange processes involving free and bound quinuclidine in the monomeric and dimeric complexes showed different kinetics on the NMR timescale.

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Novel fluorescent probes for the fluoride anion based on hydroxy-substituted perylene tetra-(alkoxycarbonyl) derivatives

RSC Advances ◽

10.1039/c8ra00299a ◽

2018 ◽

Vol 8 (25) ◽

pp. 14084-14091 ◽

Cited By ~ 3

Author(s):

Fengxia Zhang ◽

Yunlong Zhao ◽

Yanhui Chi ◽

Yongshan Ma ◽

Tianyi Jiang ◽

...

Keyword(s):

Fluorescent Probes ◽

Visual Detection ◽

Fluoride Anion ◽

Detection Experiment ◽

H Nmr ◽

Nmr Titrations

The fluoride anion (F−) sensing abilities of two fluorescent probes based on hydroxy-substituted perylene tetra-(alkoxycarbonyl) derivatives were studied through visual detection experiment, UV-Vis, fluorescence, and 1H NMR titrations.

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An Assessment of Olmesartan Medoxomil Tablet by Inclusion Complex Technique

Research Journal of Pharmaceutical Dosage Forms and Technology ◽

10.52711/0975-4377.2021.00034 ◽

2021 ◽

pp. 193-197

Author(s):

Deepak Sarangi ◽

Subhashree Mallick ◽

Anjum Ara ◽

Sanjeeb Kumar Sahoo ◽

Rabinarayan Rana

Keyword(s):

Inclusion Complex ◽

Water Solubility ◽

Olmesartan Medoxomil ◽

Complexing Agents ◽

Complexing Agent ◽

Angiotensin Ii Receptor ◽

Current Effort ◽

Ir Studies ◽

Beta Cyclodextrin ◽

Ft Ir

Olmesartan Medoxomil is an AT1 subtype selected angiotensin-II receptor antagonist approved for the treatment of hypertension. It has low water solubility, so the current effort is being made to enhance the solubility of the Olmesartan by inclusion complex and to incorporate them into tablets by direct compression. Complexing agent like Beta cyclodextrin and polyvinyalpyrrolidone has been used for complexation method. FT-IR studies have shown that there is no link between drugs and complexing agents. Among all methods, the inclusion complex (OLBCD 3) containing the drug: Beta cyclodextrin in a 1: 3 ratio showed rapid drug release (87.41% within 30 minutes) and post compression parameters are within limits. All the values obtained from pre compression and post compression parameters meets the legal requirements for tablets. Stability studies of batch no OLBCD 3 shows no significant change. Therefore, it can be concluded that the structure was stable.

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Synthesis and crystal structures of some bis(3-methyl-1H-indol-2-yl)(salicyl)methanes

Acta Crystallographica Section C Structural Chemistry ◽

10.1107/s2053229618017758 ◽

2019 ◽

Vol 75 (1) ◽

pp. 65-69

Author(s):

Wyatt Cole ◽

Stephanie L. Hemmingson ◽

Audrey C. Eisenberg ◽

Catherine A. Ulman ◽

Joseph M. Tanski ◽

...

Keyword(s):

Hydrogen Bonding ◽

Dimethyl Sulfoxide ◽

Crystal Structures ◽

Double Layer ◽

Acid Catalysis ◽

Double Layers ◽

One Dimensional ◽

Salicylaldehyde Derivatives ◽

Central Carbon ◽

Solvent Molecules

Four 2,2′-bisindolylmethanes (BIMs), a useful class of polyindolyl species joined to a central carbon, were synthesized using salicylaldehyde derivatives and simple acid catalysis; these are 2-[bis(3-methyl-1H-indol-2-yl)methyl]-6-methylphenol, (IIa), 2-[bis(3-methyl-1H-indol-2-yl)methyl]-4,6-dichlorophenol, (IIb), 2-[bis(3-methyl-1H-indol-2-yl)methyl]-4-nitrophenol, (IIc), and 2-[bis(3-methyl-1H-indol-2-yl)methyl]-4,6-di-tert-butylphenol, (IId). BIMs (IIa) and (IIb) were characterized crystallographically as the dimethyl sulfoxide (DMSO) disolvates, i.e. C26H24N2O·2C2H6OS and C25H20Cl2N2O·2C2H6OS, respectively. Both form strikingly similar one-dimensional hydrogen-bonding chain motifs with the DMSO solvent molecules. BIM (IIa) packs into double layers of chains whose orientations alternate every double layer, while (IIb) forms more simply packed chains along the a axis. BIM (IIa) has a remarkably long c axis.

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