2D NOESY Research Articles

Trikoramide A, a Prenylated Cyanobactin from the Marine Cyanobacterium Symploca hydnoides.

A new cyclic decapeptide, trikoramide A (1), has been isolated from samples of the marine cyanobacterium Symploca hydnoides, collected from Bintan Island, Indonesia. Trikoramide A (1) is a C-prenylated cyclotryptophan-containing cyanobactin. Its planar structure was deduced by 1D and 2D NMR spectroscopy as well as HR-MS/MS data. In addition, its absolute configuration was determined by Marfey's method and 2D NOESY NMR spectroscopic analysis. Compound 1 possessed cytotoxicity against the MOLT-4 and AML2 cancer cell lines with IC50 values of 4.8 and 8.2 μM, respectively.

Backbone and methyl assignment of bacteriorhodopsin incorporated into nanodiscs

Resonance assignments are challenging for membrane proteins due to the size of the lipid/detergent-protein complex and the presence of line-broadening from conformational exchange. As a consequence, many correlations are missing in the triple-resonance NMR experiments typically used for assignments. Herein, we present an approach in which correlations from these solution-state NMR experiments are supplemented by data from 13C unlabeling, single-amino acid type labeling, 4D NOESY data and proximity of moieties to lipids or water in combination with a structure of the protein. These additional data are used to edit the expected peaklists for the automated assignment protocol FLYA, a module of the program package CYANA. We demonstrate application of the protocol to the 262-residue proton pump from archaeal bacteriorhodopsin (bR) in lipid nanodiscs. The lipid-protein assembly is characterized by an overall correlation time of 44 ns. The protocol yielded assignments for 62% of all backbone (H, N, Cα, Cβ, C′) resonances of bR, corresponding to 74% of all observed backbone spin systems, and 60% of the Ala, Met, Ile (δ1), Leu and Val methyl groups, thus enabling to assign a large fraction of the protein without mutagenesis data. Most missing resonances stem from the extracellular half, likely due intermediate exchange line-broadening. Further analysis revealed that missing information of the amino acid type of the preceding residue is the largest problem, and that 4D NOESY experiments are particularly helpful to compensate for that information loss.

Regio‐ and Stereoselective Synthesis of Enynyl Boronates via Ruthenium‐Catalyzed Hydroboration of 1,4‐Diaryl‐Substituted 1,3‐Diynes

AbstractA facile ruthenium‐catalyzed regio‐ and stereoselective hydroboration of symmetrical, aromatic 1,3‐diynes with pinacolborane towards 2‐boryl‐1,4‐diaryl‐buta‐1‐en‐3‐ynes and their further transformation into potassium trifluoroborate salts is presented. The reaction proceeded efficiently for 1,4‐diphenylbutadiynes with various substituents on the phenyl rings and heterocyclic 1,4‐di(thiophen‐3‐yl)buta‐1,3‐diyne. The resulting products were isolated and fully characterized (1H, 13C, 11B and 1D NOESY NMR, IR, GC‐MS, HRMS or elemental analysis). Moreover, the crystal structure of an enynyl boronate was determined, proving the addition of boryl moiety at the internal carbon in the diyne, according to the anti‐Markovnikov rule. The results presented here are the first examples of selective catalytic monohydroboration of conjugated diynes. The products obtained due to the presence of the boryl group and the unsaturated bonds are potential synthons in the synthesis of natural compounds or active pharmaceutical ingredients (API). The model Suzuki coupling of 2‐boryl‐1,4‐diphenyl‐buta‐1‐en‐3‐ynes with iodobenzene was carried out to illustrate the utility of the resulting compounds.magnified image

Autonomous Shrinking/Swelling Phenomenon Driven By Macromolecular Interchain Cross-Linking via β-Cyclodextrin–Triazole Complexation

Molecular recognition-induced autonomous dynamic motions, which feature in living systems, have been attracting much interest because such biological functions can promote the consequent development of sophisticated functional materials. To realize molecular recognition-induced autonomous dynamic motions using synthetic materials and manipulate them, herein, we designed poly(NIPAM-co-triaz–CD), which bears a cyclodextrin (CD) host and a triazole guest in the side chains of the polymer itself; subsequently, we investigated its phase transition behavior. 2D NOESY NMR analysis evidenced that triazole in the polymer side chains was included into the CD cavity, and DLS measurements indicated that the CD–triazole complexation resulted in the formation of interchain cross-linking. Poly(NIPAM-co-triaz–CD) exhibited autonomous shrinking/swelling of the polymer chains that occurred by itself in water due to the interchain cross-linking via the CD–triazole complexation. Thus, this study enabled the poly(NIPAM) itself to generate the artificial molecular recognition-induced autonomous phenomenon. These findings not only present a unique methodology for polymer phase transition phenomena but also provide a new platform for designing molecular recognition polymeric materials.

The rheological behavior of organic salt/Gemini surfactant mixed systems: Effect of isomerization of additives

The effect of isomerization of organic salts (2-hydroxybenzoic acid monosodium salt (o-ph-ONa), 3-hydroxybenzoic acid monosodium salt (m-ph-ONa), and 4-hydroxybenzoic acid monosodium salt (p-ph-ONa)) on the formation and properties of wormlike micelles in 2-hydroxyl-propanediyl-α,ω-bis(dimethyldodecylammonium bromide) (abbreviated as 12-3(OH)-12) aqueous solutions were investigated using rheological methods, surface tension, and 1H–1H 2D NOESY NMR. The results indicate that the addition of organic salts can promote the formation of wormlike micelles. However, the effect of o-ph-ONa is the strongest and that of p-ph-ONa is the weakest. These are attributed to the occupying area of molecules. The hydroxyl and carboxylate groups in o-ph-ONa molecules are on the micelle interface and can interact with the hydroxyl group in the spacer of 12-3(OH)-12 by electrostatic interaction and/or hydrogen bonding associations, inducing a closer micelle arrangement than the other two kinds of salts so that the occupying area of molecules may be the smallest. The hydroxyl group in m-ph-ONa is located at the meta-position of carboxylate groups, which widens the gap of surfactant molecules and increases the occupying area of molecules. The whole p-ph-ONa molecule is located within the micelle interior and shows low viscosity owing to the high molecular occupying area.

Asymmetric Synthesis of 2'-C-Methyl-4'-selenonucleosides as Anti-Hepatitis C Virus Agents.

In search of a new template for anti-hepatitis C virus (HCV) agents, we designed and synthesized the 2'-C-methyl-4'-selenopyrimidine and -purine nucleosides and their phosphoramidate prodrugs to replace a furanose oxygen of anti-HCV nucleos(t)ides with a selenium atom on the basis that selenium is a chemical isostere of oxygen. These nucleosides are expected to show different physicochemical properties such as better lipophilicity which might enhance the penetration across cell membranes and the conformational constraint induced by a bulky selenium atom in the sugar ring. The 2'-C-methyl-4'-selenopyrimidine and -purine nucleosides 8 and 9 were synthesized from 2-C-methyl-d-ribono-γ-lactone (14) via construction of 2-C-methyl-d-selenosugar 18 through C-4 epimerization and SN2 cyclization with Se2- as key steps. The key 4'-selenosugar was converted to the 2'-C-methyl-4'-selenopyrimidine and -purine nucleosides using Pummerer-type rearrangement and Vorbrüggen glycosylation, respectively. In addition, the ProTide strategy has been applied to synthesize the adenine and uracil phosphoramidate derivatives 10a and 10b to overcome the limitations associated with parent nucleosides such as inefficient conversion to their corresponding 5'-monophosphate form and poor cellular uptake. The regio- and stereochemistry of 4'-selenonucleosides were confirmed by 2D NOESY NMR spectroscopy and X-ray crystallography. None of the final pyrimidine and purine nucleosides and their prodrugs exhibited significant anti-HCV activity up to 100 μM.

Light-responsive vesicles based on azobenzene containing imidazolium surfactants and sodium oleate

In this work, three light responsive imidazolium surfactants containing azobenzene moiety (CmAZOCnIMB, m = 0, 2, 4 and m + n = 6), namely, 1-[2-(4-phenylazo-phenoxy)-ethyl]-7-methylimidazolium bromide (C0AZOC6IMB), 3-[2-(4-phenylazo-phenoxy)-ethyl]-7-methylimidazolium bromide (C2AZOC4IMB), and 5-[2-(4-phenylazo-phenoxy)-ethyl]-7-methylimidazolium bromide (C4AZOC2IMB), were developed. These surfactants showed strong micellization tendency in the aqueous solution with their critical micelle concentrations (cmc) highly depending on the location of azobenzene moiety. Moreover, they also showed innate light response with excellent reversibility attributing to the trans-and cis-isomerization of azobenzene moiety under UV- and visible-light irradiation, respectively. Phase behavior showed that the addition of CmAZOCnIMB in the sodium oleate (NaOA) aqueous solution could induce the apparent growth of aggregates from spherical micelles to vesicles via wormlike micelles. Moreover, the presence of CmAZOCnIMB also endowed the catanionic systems with excellent light response, i.e., the typically reversible vesicle to multi-connected wormlike micelle network transitions. Static light scattering and dynamic rheological measurements were employed to characterize the turbidity and viscosity variation during the transitions. The morphological changes between vesicles and wormlike micelles were demonstrated by cryogen transmission electron microscopy (cryo-TEM) observation. Moreover, the transition mechanism was illustrated by 1H NMR and 2D Noesy spectra.

Diastereoselective synthesis of 3-tert-butyl-3,4-dihydropyrazolo[5,1-c][1,2,4]triazine-3,4-diyl dicarboxylates

The reactions of 3-tert-butyl-7-R1-8-R2-pyrazolo[5,1-c][1,2,4]triazines (R1 = H, Br; R2 = Me, n-Bu) with N-bromosuccinimide in the presence of R3CO2H (R3 = Me, t-Bu, Ph) afforded novel diastereomerically pure 3-tert-butyl-7-R1-8-R2-3,4-dihydropyrazolo[5,1-c][1,2,4]triazine-3,4-diyl dicarboxylates. The structures of the isolated products were established on the basis of IR, 1H, 13C, 2D NOESY NMR, high resolution mass spectrometry and X-ray single-crystal analysis. The steric and mechanistic origins of the observed regio- and stereoselectivity were also discussed.

Crystal Engineering for Intramolecular π–π Stacking: Effect of Sequential Substitution of F on Molecular Geometry in Conformationally Flexible Sulfonamides

A small library of ten sulfonamide derivatives comprising two aromatic rings was synthesized to investigate the effect of chronological positioning of the F-atom on the intramolecular π-stacking assembly. The sequential positioning of F-atoms was carried out on one of the aromatic rings that is linked to the sulfonamide moiety directly while the other aromatic ring (phenyl or pyridine) is linked by an ethyl spacer with the sulfonamide moiety. The ethyl spacer is provided to achieve the required flexibility so that both aromatic rings can bend to acquire syn conformation facilitated π-stacking between electron-deficient and electron-rich aromatic rings. The idea was to study the interplay between hydrogen bonding and π-stacking synthons in the conformationally flexible sulfonamide derivatives. The solid-state conformation of all the derivatives was investigated using the single-crystal X-ray diffraction technique. Crystal structure analysis revealed that the syn conformation was achieved only in trifluoro and pentafluoro sulfonamide derivatives with benzene substitution while in all other derivatives the molecules take either midway or anti conformations. None of the sulfonamide molecules with a pyridine moiety showed syn conformation. It could be because of the involvement of the pyridine N-atom in the hydrogen bonding dimeric synthon. The molecular conformation study in solution state using 2D NOESY and HOESY NMR experiments also substantiated syn conformation in a pentafluoro sulfonamide molecule with benzene substitution. The conformational analysis carried out employing density functional theory (DFT) calculations confirmed higher stability for the syn conformation over midway and anti orientations.

Importance of time-ordered non-uniform sampling of multi-dimensional NMR spectra of Aβ1-42 peptide under aggregating conditions.

Although the order of the time steps in which the non-uniform sampling (NUS) schedule is implemented when acquiring multi-dimensional NMR spectra is of limited importance when sample conditions remain unchanged over the course of the experiment, it is shown to have major impact when samples are unstable. In the latter case, time-ordering of the NUS data points by the normalized radial length yields a reduction of sampling artifacts, regardless of the spectral reconstruction algorithm. The disadvantage of time-ordered NUS sampling is that halting the experiment prior to its completion will result in lower spectral resolution, rather than a sparser data matrix. Alternatively, digitally correcting for sample decay prior to reconstruction of randomly ordered NUS data points can mitigate reconstruction artifacts, at the cost of somewhat lower sensitivity. Application of these sampling schemes to the Alzheimer's amyloid beta (Aβ1-42) peptide at an elevated concentration, low temperature, and 3 kbar of pressure, where approximately 75% of the peptide reverts to an NMR-invisible state during the collection of a 3D 15N-separated NOESY spectrum, highlights the improvement in artifact suppression and reveals weak medium-range NOE contacts in several regions, including the C-terminal region of the peptide.

Single-handed supramolecular double helix of homochiral bis(N-amidothiourea) supported by double crossed C\u2212I\xb7\xb7\xb7S halogen bonds

The natural DNA double helix consists of two strands of nucleotides that are held together by multiple hydrogen bonds. Here we propose to build an artificial double helix from fragments of two strands connected by covalent linkages therein, but with halogen bonding as the driving force for self-assembling the fragments to the double helix. We succeed in building such a double helix in both solution and solid state, by using a bilateral N-(p-iodobenzoyl)alanine based amidothiourea which in its folded cis-form allows double and crossed C−I···S halogen bonds that lead to right- or left-handed double helix when the two alanine residues are of the same L,L- or D,D-configuration. The double helix forms in dilute CH3CN solution of the micromolar concentration level, e.g., 5.6 μM from 2D NOESY experiments and exhibits a high thermal stability in solution up to 75 °C, suggesting cooperative and thereby strong intermolecular double crossed halogen bonding that makes the double helix stable. This is supported by the observed homochiral self-sorting in solution.

From Simplicity to Complexity in Grafting Dawson-Type Polyoxometalates on Porphyrin, Leading to the Formation of New Organic-Inorganic Hybrids for the Investigation of Third-Order Optical Nonlinearities.

Four new organic-inorganic hybrids, [N(C4H9)4]5H[{HNC2O(CH2O)3P2V3W15O59}C44N4H29O3] (TPPOH-1POM), [N(C4H9)4]10H2[{HNC2O(CH2O)3P2V3W15O59}2C44N4H28O2] (TPPOH-2POM trans), [N(C4H9)4]10H2[{HNC2O(CH2O)3P2V3W15O59}2C44N4H28O2] (TPPOH-2POM cis), and [N(C4H9)4]15H3[{HNC2O(CH2O)3P2W15V3O59}3C44N4H27O] (TPPOH-3POM), have been synthesized by covalently grafting the Dawson-type polyoxometalate (POM) [N(C4H9)4]5[H4P2W15V3O62] onto new porphyrins N-[1,3-dihydroxy-2-(hydroxymethyl)propan-2-yl]-4-[10,15,20-tris(4-hydroxyphenyl)porphyrin-5-yl]benzamide (TPPOH-1Tris), 4,4'-[5,15-bis(4-hydroxyphenyl)porphyrin-10,20-diyl]bis[ N-[1,3-dihydroxy-2-(hydroxymethyl)propan-2-yl]benzamide] (TPPOH-2Tris trans), 4,4'-[10,15-bis(4-hydroxyphenyl)porphyrin-5,20-diyl]bis[ N-[1,3-dihydroxy-2-(hydroxymethyl)propan-2-yl]benzamide] (TPPOH-2Tris cis). and 4,4',4″-[20-(4-hydroxyphenyl)porphyrin-5,10,15-triyl]tris[ N-[1,3-dihydroxy-2-(hydroxymethyl)propan-2-yl]benzamide] (TPPOH-3Tris), respectively, in N, N-dimethylacetamide under nitrogen. The hybrid compounds were thoroughly characterized by elemental analysis, FT-IR, NMR (1H, 2D NOESY, 31P, and 51V), ESI-MS, MALDI-TOF-MS, UV-vis, and fluorescence spectroscopy. All porphyrins and their corresponding hybrids exhibited remarkable third-order nonlinear-optical responses under laser irradiation, with the intensity of light at focus E0 being 4.2 μJ at wavelength 532 nm, pulse duration τ = 6 ns, and repetition rate 10 Hz. The molecular second hyperpolarizability (γ) values of the hybrids (TPPOH-1POM, TPPOH-2POM trans, TPPOH-2POM cis, TPPOH-3POM) were calculated to be 8.48 × 10-28 esu, 8.94 × 10-28 esu, 10.16 × 10-28 esu, and 8.93 × 10-28 esu, while the molecular second hyperpolarizability (γ) of their corresponding porphyrin precursors (TPPOH-1Tris, TPPOH-2Tris trans, TPPOH-2Tris cis, and TPPOH-3Tris) were 7.19 × 10-28 esu, 8.09 × 10-28 esu, 9.07 × 10-28 esu, and 7.24 × 10-28 esu, respectively. The γ values of the cis forms were found to be superior to those of all other compounds, indicating the significant role of the greater dipole moment and low symmetry of the cis form compared to other compounds. It was also found that the fluorescence intensity was decreased by 81.52%, 90.37%, 93.93%, and 84.62% for the hybrids TPPOH-1POM, TPPOH-2POM trans, TPPOH-2POM cis, and TPPOH-3POM with respect to their corresponding precursors, respectively, which reveals the Dawson-type POM as a strong quencher. This quenching phenomenon not only indicates again unequivocally the formation of hybrid compounds but also may imply a photoinduced electron/energy-transfer process favored from a porphyrin moiety to a Dawson-type POM moiety.

Effect of Steric Hindrance on the Aggregation Behavior of Cationic Silicone Surfactants in Aqueous Solutions

To study the effect of steric hindrance on the surface activities and thermodynamics of cationic silicone surfactants, the adsorption and aggregation behavior of cationic silicone surfactants with different siloxane hydrophobic groups and headgroups, bis(trimethylsiloxy)methylsilylpropylpyridinium chloride (Si3pyrCl), N,N,N-triethyl-3-[tri(trimethylsiloxy)]silylpropylammonium chloride (Si4AEtCl), and 3-[tri(vinyldimethylsiloxy)methyl]silylpropylpyridinium chloride (Vi–Si4pyrCl), were investigated by surface tension, electrical conductivity, DLS, TEM, and 2D NOESY NMR measurements. All the three cationic silicone surfactants have excellent surface activity. Owing to the steric hindrance of hydrophobic groups and headgroups, the CMC values increase following the order Vi–Si4pyrCl < Si4AEtCl < Si3pyrCl. The micellization process of Si3pyrCl and Si4AEtCl in aqueous solution is enthalpy-driven, while Vi–Si4pyrCl is entropy-driven at low temperature and enthalpy-driven at high temperature and the degree of counterion binding of Vi–Si4pyrCl increases as the temperature increases, caused by the intermolecular interaction between the pyridinium group and vinyldimethylsiloxy hydrophobic region of the micelles. Moreover, the results obtained in this paper can be useful in understanding the structure-properties relationship of cationic silicone surfactants and the design of novel silicone surfactants.

Responsive Polypseudorotaxane Hydrogels Triggered by a Compatible Stimulus of CO2

AbstractRealizing the reversible transformation of the supramolecular hydrogels is essential for their application as smart materials. The reversible sol‐gel transition of the polypseudorotaxane (PPR) hydrogels is achieved through adding a CO2‐switchable guest molecule into the PPR hydrogel of poly(ethylene glycol) (PEG) and α‐cyclodextrins (α‐CDs). Alternating treatments with CO2 and heating drive such reversible transition due to the competitive complexation as evidenced by 2D NOESY 1H NMR and isothermal titration calorimetry as well as X‐ray diffraction. The present work describes a straightforward way to obtain switchable PPR hydrogels triggered by a compatible stimulus of CO2. These stimuli‐responsive PPR hydrogels have potential applications as biomaterials.

Mussel‐Glue Inspired Adhesives: A Study on the Relevance of l‐Dopa and the Function of the Sequence at Nanomaterial‐Peptide Interfaces

AbstractMussel glue‐proteins undergo structural transitions at material interfaces to optimize adhesive surface contacts. Those intriguing structure responses are mimicked by a mussel‐glue mimetic peptide (HSY*SGWSPY*RSG (Y* = l‐Dopa)) that was previously selected by phage‐display to adhere to Al2O3 after enzymatic activation. Molecular level insights into the full‐length adhesion domain at Al2O3 surfaces are provided by a divergent‐convergent analysis, combining nuclear Overhauser enhancement based 2D NOESY and saturation transfer difference NMR analysis of submotifs along with molecular dynamics simulations of the full‐length peptide. The peptide is divided into two submotifs, each containing one Dopa “anchor” (Motif‐1 and 2). The analysis proves Motif‐1 to constitute a dynamic Al2O3 binder and adopting an “M”‐structure with multiple surface contacts. Motif‐2 binds stronger by two surface contacts, forming a compact “C”‐structure. Taking these datasets as constraints enables to predict the structure and propose a binding process model of the full‐length peptide adhering to Al2O3.

Construction of [1]rotaxanes with pillar[5]arene as the wheel and terpyridine as the stopper

The condensation reaction of ω-aminoalkyleneamide-functionalized pillar[5]arenes with 2-(4-([2,2′:6′,2′′-terpyridin]-4′-yl)phenoxy)acetic acid or 4-(4-([2,2′:6′,2′′-terpyridin]-4′-yl)phenoxy)butanoic acid in dry chloroform at room temperature under the catalysis of HOBT/EDCl resulted in novel pillar[5]arene diamido-bridged terpyridine derivatives. 1H NMR and 2D NOESY spectra clearly indicated that the interesting [1]rotaxanes were formed by longer alkylene such as propylene, butylene and hexylenediamido chains threading into the cavity of the pillar[5]arene and with larger terpyridine acting as the stopper. However, the shorter ethylenediamido chain only exists outer of cavity of pillar[5]arene and the molecule exist on free form.

Supramolecular hydrogel-based AIEgen: Construction and dual-channel recognition of negative charged dyes

It is noteworthy that highly selective molecular recognition endows host-guest gels, especially hydrogel, with valuable properties. Therefore, in pure water, a supramolecular hydrogel (SH-α-CD) was constructed by using benzimidazolium-based positive charged guest molecule (J2) assembled with cyclodextrin (α-CD) through host-guest interaction, and accompanied an aggregation-induced emission (AIE). The self-assemble process of the hydrogel-based AIEgen was investigated using 1H NMR titration, 2D NOESY, XRD and SEM. In particular, the hydrogel-based AIEgen was investigated as a good candidate for fluorescent quenching and gel state destruction dual-channel recognizing negative charged dye molecule methyl orange (MO). The competitive inclusion interaction triggered the dissolution of aggregate, which induced the gel to transform into sol, with disappearance of the AIE of SH-α-CD. However, the addition of the competitive dye molecules methylene blue (MB) and xylenol orange (XO) only made the fluorescence quenching of hydrogel-based AIEgen. Meanwhile, the hydrogel-based AIEgen also exhibited an excellent thermal responsiveness under temperature transition. Such a performance is highly beneficial for potential applications in probe material for organic dye molecules.

Mapping Local Conformational Landscapes of Proteins in Solution

The ability of proteins to adopt multiple conformational states is essential to their function, and elucidating the details of such diversity under physiological conditions has been a major challenge. Here we present a generalized method for mapping protein population landscapes by NMR spectroscopy. Experimental NOESY spectra are directly compared with a set of expectation spectra back-calculated across an arbitrary conformational space. Signal decomposition of the experimental spectrum then directly yields the relative populations of local conformational microstates. In this way, averaged descriptions of conformation can be eliminated. As the method quantitatively compares experimental and expectation spectra, it inherently delivers an R factor expressing how well structural models explain the input data. We demonstrate that our method extracts sufficient information from a single 3D NOESY experiment to perform initial model building, refinement, and validation, thus offering a complete de novo structure determination protocol.

Ambient Stabilization of Few Layer Phosphorene via Noncovalent Functionalization with Surfactants: Systematic 2D NMR Characterization in Aqueous Dispersion

Phosphorene suffers from instability under ambient condition, despite its potential to bridge the gap between graphene and two-dimensional (2D) metal chalcogenides. We report effective exfoliation and stabilization of few layer phosphorene (FLP) in the presence of strongly interacting surfactants. Surfactants containing long hydrophobic chain and nonbulky charged headgroups (CTAB) effectively exfoliate and stabilize FLP in water, which is consistent with our density functional theory prediction. Nuclear magnetic resonance measurements are systematically employed to probe the interaction between surfactants and FLP. Retarded diffusion rate measured by 2D DOSY spectroscopy revealed the presence of noncovalently bonded CTAB over phosphorene. 2D NOESY spectroscopy further suggests the interdigitated arrangement of surfactants. Such a tight interaction impedes the ambient degradation rate of phosphorene by 70–80%. This work proposes a new insight into the control over ambient degradation of phosphorene without...

Protic ionic liquid + water interactions studied by 1D NOESY NMR spectroscopy

The interactions between ionic liquids and water are very important for the chemical industry. The advancement of research between levels of interactions and the presence of clustering can boost the pharmaceutical industry and of polymers. The aim of this work was to use different protic ionic liquids to observe the formation of aggregated using the NMR 1D NOESY. The results reveal the presence of Nuclear Overhauser Effect in some systems and the behavior of the NOE effect does not seem to be so linear, that is, the increase in the size of the alkyl chain lengths ranging does not guarantee the presence of supra molecular aggregates.