Aqueous DMSO Research Articles

A comparative study of aqueous DMSO mixtures by computer simulations and integral equation theories

ABSTRACTSeveral computer simulation studies of aqueous-dimethylsulfoxide with different force field models, and conducted by different authors, point out to an anomalous depressing of second and third neighbour correlations of the water–water radial distribution functions. This seemingly universal feature can be interpreted as the formation of linear water clusters. We test here the ability of liquid state integral equation theories to reproduce this feature. It is found that the incorporation of the water bridge diagram function is required to reproduce this feature. These theories are generally unable to properly reproduce atom–atom distribution functions. However, the near-ideal Kirkwood–Buff integrals are relatively well reproduced. We compute the X-ray scattering function and compare with available experimental results, with the particular focus to explain why these data do not reproduce the cluster pre-peak observed in the water–water structure factor.

Structure elucidation, DNA binding, DFT, molecular docking and cytotoxic activity studies on novel single crystal (E)-1-(2-fluorobenzylidene)thiosemicarbazide

Compound 3 {(E)-1-(2-fluorobenzylidene)thiosemicarbazide} – a new Schiff base of thiosemicarbazide has been synthesized, characterized and reported for crystal structure. Planer side chain in the crystal structure was observed co-planer with aromatic ring plane and molecules were connected into centrosymmetric dimmers via intermolecular hydrogen bonding. DFT geometry optimization and the relevant quantum parameters indicated unstable and reactive nature of compound 3. Experimental and theoretical findings for DNA binding by UV–visible, cyclic voltammetry and molecular docking studies showed consistency in kinetic (Kb) and thermodynamic (ΔG) parameters and that compound 3 significantly interacted with DNA via intercalation. Viscometric analysis further comprehended intercalation as possible binding mode of the compound with DNA and non-denaturing of DNA in the presence of 10% aqueous DMSO. Docked parameters further assured the drug like characteristics of the investigated compound as fit in Lipinski’s criteria. Dose dependant cytotoxic activity of compound 3 against human Huh-7 cell line indicated its anti-cancer potential at 100 µg/ml concentration.

A novel Schiff base derivative of pyridoxal for the optical sensing of Zn2+ and cysteine.

An easy to prepare novel vitamin B6 cofactor derivative 3-hydroxy-N'-((3 hydroxy-5-(hydroxymethyl)-2-methylpyridin-4-yl)methylene)-2-naphthohydrazide (NPY) was synthesized by a one pot condensation reaction of pyridoxal with 3-hydroxy-2-naphthoic hydrazide and applied for the optical detection of Zn2+ and cysteine in the aqueous DMSO medium. The addition of Zn2+ ions leads to a selective blue-shift in the fluorescence emission spectrum of NPY from 530 nm to 475 nm, which allowed ratiometric detection of Zn2+ ions down to 8.73 × 10-7 M without any interference from other tested metal ions. This system was also successfully applied to detect intracellular Zn2+ ions in live HeLa cells. Further, when the in situ generated NPY·Zn2+ complex was interacted with various amino acids, the addition of cysteine resulted in an instantaneous colour change from light yellow to colourless and the absorbance at 435 nm of the complex was quenched selectively. Also, the fluorescence of the NPY·Zn2+ complex was quenched, which allowed the detection of cysteine down to 6.63 × 10-7 M.

Influence of rhodamine B on interaction behaviour of lanthanide nitrates with 1st tier dendrimer in aqueous DMSO: A physicochemical, critical aggregation concentration and antioxidant activity study

Density, viscosity, sound velocity, and molar conductivity for hexahydrate nitrates of gadolinium, samarium and neodymium from (0.0012–0.0072) mol∙kg−1 in (a) 40% (v/v) aq. DMSO (b) Trimesoyl 1,3,5-tridimethyl malonate (TTDMM) from (0.00010–0.00030) mol∙kg−1+40% (v/v) aq. DMSO (c) Rhodamine B (RB)+40% (v/v) aq. DMSO (d) RB+TTDMM from (0.00010–0.00030) mol∙kg−1+40% (v/v) aq. DMSO at 298.15K and atmospheric pressure are reported. By using these primary parameters; the apparent molar volume, limiting apparent molar volume, apparent molar isentropic compressibility, viscosity B-coefficient, and limiting molar conductivity have been calculated. The trends of these physicochemical parameters are discussed in terms of solute-solvent and solute-solute interactions. The trends inferred weaker solute-solvent interactions in presence of RB with TTDMM+aq. DMSO, causing structural changes. The aggregation tendency of TTDMM was studied using conductivity measurements, well supported by RB based UV–visible absorption spectroscopy through the L-form to Z-form shifting dynamics. To the best of our knowledge, this is the first attempt reporting the impact of trivalent lanthanide ions on the critical aggregation concentration of a 1st tier dendrimer (TTDMM) in aq. DMSO. This work is the first report, as far as we know, on the influence of Ln(NO3)3 towards the antioxidant activity of dendrimer, wherein the IC50 value of TTDMM was found in range with ascorbic acid. Our study with such significant outcomes may hold great promise for various biological applications.

Broad-Spectrum Antibacterial Activity of Proteolytically Stable Self-Assembled αγ-Hybrid Peptide Gels.

Bacterial infections pose a serious threat to mankind, and there is immense interest in the design and development of self-assembled peptide gels using ultrashort peptides for antibacterial applications. The peptide gels containing natural amino acids suffer from poor stability against proteolytic enzymes. Therefore, there is a need to design and develop peptide gels with improved stability against proteolytic enzymes. In the present work, we report the synthesis and characterization of α/γ hybrid peptides Boc-D-Phe-γ4-L-Phe-PEA (NH007) and Boc-L-Phe-γ4-L-Phe-PEA (NH009) to improve the proteolytic stability. Both of the dipeptides were found to self-assemble into gels in aqueous DMSO (3-5% w/v), and the self-assembly process was studied using FTIR and CD, which indicated antiparallel β-sheet formation with random coils in NH007 gels and random or unordered conformation in NH009. The rheological studies indicated viscoelastic characteristics for both gels; the storage modulus ( G') for NH007 and NH009 gels (3% w/v) was estimated as 0.2 and 0.5 MPa, higher than the loss modulus ( G''). Also, both gels demonstrated self-healing characteristics for six consecutive cycles when subjected to varying strains of 0.1 and 30% (200 s each). The peptide gels were incubated with a mocktail of proteolytic enzymes, proteinase K, pepsin, and chymotrypsin, and stability was monitored using RP HPLC. Up to 23 and 40% degradation was observed for NH007 (3%, w/v) in 24 and 36 h, and 77 and 94% degradation was observed for NH009 (3%, w/v), within the same period. Thus α/γ hybrid peptide gels containing D-Phe exhibited higher stability than gels fabricated using L-Phe. The use of D-residue in α/γ hybrid peptide significantly enhanced the stability of peptides against proteolytic enzymes, as the stability data reported in this work are possibly the best in class. Both peptide gels exhibited broad-spectrum antibacterial activity against Gram-negative and Gram-positive bacteria, such as Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis, and Staphylococcus aureus. The Pseudomonas aeruginosa and Staphylococcus aureus, in particular, are known to develop resistance. The NH007 (3%, w/v) demonstrated 65% inhibition, whereas NH009 (3%, w/v) showed 78% inhibition, with potent activity against Pseudomonas aeruginosa. Mechanistic studies, using SEM, HR-TEM, and bacterial live-dead assay, indicated entrapment of bacteria in gel networks, followed by interaction with cell membrane components and lysis. Cell viability (MTT assay) and toxicity (LDH assay) studies showed that both gels are not toxic to NIH 3T3 mouse embryonic fibroblast cells (mammalian). MTT assay showed >85% cell viability, and LDH assay exhibited not more than 15% cytotoxicity, even at higher concentrations (5%, w/v) and prolonged exposures (48 h). Overall, studies indicate the potential application of gels developed from the α/γ hybrid peptides in preventing biomaterial-related infections.

Selective Detection of 2,4,6‐Trinitrophenol Based on In Situ‐generated Fluorescent Zn2+–Anthracene Ensembles in 80% Aqueous Dimethyl Sulfoxide

Novel in situ‐generated highly fluorescent chelated Zn2+–anthracene (Zn2+•P: 1:1) complex detected 2,4,6‐trinitrophenol (TNP) more selectively by a “switch‐off” response with a very high Stern–Volmer quenching constant (Ksv = 3.75 × 106 M−1) at a 1:2 stoichiometry in 80% aqueous DMSO. The selective quenching response that occurred with TNP is due to the effective destruction of the chelated complex by efficient protonation at secondary amines, which created an effective resonance energy transfer (RET) from the anthracene unit to the TNP. Formation of a stable P2+•(TNP)−2 ionic charge‐transfer complex showed that the anthracene monomer band quenching resulted from efficient RET, accompanied by synergistic multiple hydrogen bonding, electron‐rich–electron‐deficient πAn–πTNP interactions, and columbic interactions. An application was demonstrated using the biocompatible ensemble‐coated hydrogel for ultraviolet‐assisted naked eye sensing, and its sensing mechanism was postulated. The lowest detection limit for TNP was 3.01 × 10−10 M in 80% aqueous DMSO.

Efficient copper-catalyzed amination of DNA-conjugated aryl iodides under mild aqueous conditions.

Herein, we describe the development of copper-catalyzed cross-coupling of DNA-conjugated aryl iodides with aliphatic amines. This protocol leverages a novel ligand, 2-((2,6-dimethoxyphenyl)amino)-2-oxoacetic acid, to effect the transformation in aqueous DMSO, under mild conditions and in air, making it an ideal candidate for the synthesis of DNA-encoded libraries.

Synthesis, Characterization, and Antimicrobial Studies of Novel Series of 2,4-Bis(hydrazino)-6-substituted-1,3,5-triazine and Their Schiff Base Derivatives

The present work represents the synthesis, characterization, and antimicrobial studies of novel series of 2,4-bis(hydrazino)-6-substituted-1,3,5-triazine and their Schiff base derivatives. IR, NMR (H1 and C13), elemental analysis, and LC-MS characterized the prepared compounds. The biological activity of the target products was evaluated as well. Twenty-two of the prepared compounds were selected according to their solubility in aqueous DMSO. Only eight compounds showed good activity against the selected pathogenic bacteria and did not show antagonistic effect against fungus Candida albicans. Two compounds 4k and 5g have wide-range effect presently in Gram-positive and Gram-negative bacteria while other compounds (4f, 4i, 4m, 5d, 6i, and 6h) showed specific effect against the Gram-negative or Gram-positive bacteria. The minimum inhibitory concentration (MIC, μg/mL) of 4f, 4i, 4k, and 6h compounds against Streptococcus mutans was 62.5 μg/mL, 100 μg/mL, 31.25 μg/mL, and 31.25 μg/mL, respectively. The MIC of 4m, 4k, 5d, 5g, and 6h compounds against Staphylococcus aureus was 62.5 μg/mL, 31.25 μg/mL, 31.25 μg/mL, 100 μg/mL, and 62.5 μg/mL, respectively. The MIC of 4k, 5g, and 6i compounds against Salmonella typhimurium was 31.25 μg/mL, 100 μg/mL, and 62.5 μg/mL, respectively. The MIC of 6i compound against Escherichia coli was 62.5 μg/mL.

Synthesis of novel phosphonium betaines and bis-betaines derived from hexafluoro-1,4-naphthoquinone

Reactions of hexafluoro-1,4-naphthoquinone with phosphorus-centered bis-phenylphosphanes with structure Ph2P(CH2)nPPh2 (where n=1–5) and Et2P(CH2)2PEt2 in various solvents (anhydrousC6H6, aq. C6H6, aq. dioxane, aq. DMSO, or MeOH) were investigated. It was shown that the use of aqueous dioxane and DMSO leads to target products of phosphanodefluorination (i.e., phosphorus-containing betaines and bis-betaines) with high yields. We found that the betaines upon purification by thin-layer chromatography underwent various transformations such as a ring contraction (thus yielding novel polyfluorinated indenones) or addition of an acetone molecule at the CO bond of the fluorinated 1,4-naphthoquinone. According to X-ray diffraction analysis, there were intermolecular F⋯π interactions in the crystal packing of all the obtained betaines. The interactions are characterized by short distances F⋯Cg from 3.151(5) to 3.831(2) Å (where Cg is a centroid of π-system).

Highly Sensitive Bifunctional Probe for Colorimetric Cyanide and Fluorometric H2S Detection and Bioimaging: Spontaneous Resolution, Aggregation, and Multicolor Fluorescence of Bisulfide Adduct.

A 4-methylbenzothiazole linked maleimide-based single molecular bifunctional probe 1 has been synthesized for the colorimetric and fluorometric detection of highly competitive H2S and cyanide ion in aqueous DMSO media. The probe 1 selectively detected CN- under the UV-vis spectroscopy through the rapid appearance of deep pink color. The bright pink color developed due to ICT in the moderately stable cyano substituted enolate intermediate. The absorbance titration of 1 with CN- revealed a new band at 540 nm and the nonlinear curve fitting analysis showed good fit with 1:1 model. In fluorescence channel, 1 was found to be highly selective to H2S in 50% aqueous buffer (pH 7). It exhibited ∼16-fold fluorescence intensity enhancement at 435 nm after reaction with 1 equiv of H2S due to the inhibition of PET. The 1-SH adduct showed TICT phenomenon and behaved like molecular rotor. It further displayed aggregation behavior at higher concentration and excitation wavelength dependent multicolor emission properties. Most interestingly, the spontaneous resolution of chiral S-isomer of the 1-SH adduct occurred during crystallization. The cell imaging study revealed the staining of the cell and multicolor emission in the presence of H2S.

Green ultrasound-assisted three-component click synthesis of novel 1H-1,2,3-triazole carrying benzothiazoles and fluorinated-1,2,4-triazole conjugates and their antimicrobial evaluation.

The present study describes an efficient and ecofriendly, ultrasound, one-pot click cycloaddition approach for the construction of a novel series of 1,4-disubstituted-1,2,3-triazoles tethered with fluorinated 1,2,4-triazole-benzothiazole molecular conjugates. It involved three-component condensation of the appropriate bromoacetamide benzothiazole, sodium azide and 4-alkyl/aryl-5-(2-fluorophenyl)-3-(prop-2-ynylthio)-1,2,4-triazoles 4a-e through a Cu(I)-catalyzed 1,3-dipolar cycloaddition reaction. This approach involves in situ generation of azidoacetamide benzothiazole, followed by condensation with terminal alkynes in the presence of CuSO4/Na-ascorbate in aqueous DMSO under both conventional and ultrasound conditions. Some of the designed 1,2,3-triazole conjugates 6a-o were recognized for their antimicrobial activity against some bacterial and fungal pathogenic strains.

ESIPT‐Based Nanomolar Zn2+ Sensor for Human Breast Cancer Cell (MCF7) Imaging

AbstractA single crystal X‐ray structurally characterized probe (L), derived from 2‐amino‐1‐phenylpropan‐1‐ol and 2‐hydroxy‐1‐napthaldehyde selectively recognizes nano‐molar Zn2+ both by fluorescence and colorimetric method. Inhibition of excited‐state intra‐molecular proton transfer (ESIPT) and ‐CH=N isomerization along with chelation‐enhanced fluorescence (CHEF) collectively contribute to Zn2+ recognition. L exhibits excellent sensitivity (2×10−9 M) and selectivity for Zn2+ in aqueous DMSO (1:1, v/v) media and useful for intra‐cellular Zn2+ imaging in human breast cancer cells (MCF7).

Anion and sugar recognition by 2,6-pyridinedicarboxamide bis-boronic acid derivatives

AbstractTwo 2,6-pyridinedicarboxamide derivatives containing arylboronic acid fragments were prepared and fully characterized including X-ray crystal diffraction analysis of a pinacol ester. These compounds are potential bifunctional receptors for sugars and anions. Acid dissociation and stability constants for complexation of both receptors with glucose and fructose were determined by potentiometric titrations in aqueous DMSO. Also, binding of alizarin red S indicator was studied spectrophotometrically and a highly sensitive detection of fructose by an indicator displacement assay was proposed. Complexation with anions was studied by1H NMR titrations in DMSO-d6. Binding of acetate anion occurs only via hydrogen bonding to OH groups of boronic acid fragments and does not affect signals of NH protons but chloride anion induces large shift of the signals of NH protons and small shifts of the signals of OH groups. This behavior makes possible anion discrimination based on preference in the type of binding site rather than simply on anion basicity as is typical for majority of neutral hydrogen bonding anion receptors.

Alkyl-malonate-substituted thiacalix[4]arenes as ligands for bottom-up design of paramagnetic Gd(III)-containing colloids with low cytotoxicity

The present work introduces thiacalix[4]arene adopting 1,3-alternate conformation with alkyl-malonate terminal substituents as ligands for Gd(III) ions. pH-dependent complex formation of Gd(III) ions via alkyl-malonate substituents in aqueous DMSO solutions results in a precipitation. The precipitated complexes were converted into hydrophilic colloids of “plum-pudding” morphology, where the Gd(III) complexes form hard small (1.5–4nm) cores included into larger (about 180nm) soft PSS shells. The precipitate-to-colloid transformation is facilitated by polystyrolsulfonate (PSS) for Gd(III) complexes with thiacalix[4]arene bearing propyl-malonate groups, while the presence of PSS triggers a dissolution of the precipitated complexes for thiacalix[4]arenes with pentyl-malonate substituents. To a lesser extent the similar tendency disturbs the formation of PSS-stabilized colloids on the basis of butyl-malonate substituted thiacalix[4]arene. The PSS-stabilized colloids exhibit high longitudinal and transverse relaxivities (r1=23.8 and r2=29.4mM−1s−1 at 0.47T, respectively), while the recoating of the PSS-stabilized colloids with polyethyleneimine is accompanied by the dissolution of the hard cores. High relaxivity along with low cytotoxicity of PSS-stabilized colloids indicates their applicability as contrast agents in MRI.

Highly efficient fluorescence switching of carbon nanodots by CO2

In recent years, carbon nanodots (CDs) have attracted increasing attention in many applications because of their superior optical and chemical properties. To manipulate CDs properties for their smart applications, CDs with CO2 switchable luminescence property have been designed and prepared in the present work. It is found that fluorescence of the polyamine-functionalized CDs can be switched “off” and “on” in DMSO-water mixture by alternatively bubbling and removal of CO2. 13C NMR spectra suggest that the mechanism behind the fluorescence “on-off” results involves the reversible acid-base reaction of the functionalized CDs with CO2 and the formation of hydrophilic polyammonium bicarbonates. Due to the poor solubility of polyammonium bicarbonates in DMSO-water mixture, the formation of the polyammonium bicarbonates precipitation, by CO2 bubbling, decreases the concentration of the functionalized CDs in aqueous DMSO, leading to the switch off of the fluorescence. When CO2 is removed by N2 bubbling, the precipitation is returned to the DMSO-water mixture, and thereby the fluorescence is switched on again. Based on this novel CO2-switchable photoluminescence property, the functionalized CDs have been used for the quantitative detection of CO2 and SO2 in aqueous solution and in the air.

Efficient Selenium‐Catalyzed Selective C(sp3)−H Oxidation of Benzylpyridines with Molecular Oxygen

AbstractAn efficient selenium‐catalyzed direct oxidation of benzylpyridines in aqueous DMSO has been successfully developed by using molecular oxygen as the oxidant. A variety of benzoylpyridines with broad functional group tolerance were obtained in modest to excellent yields and with exclusive chemoselectivity.magnified image

Synthesis of 3-(2-hydroxyphenyl)-1,5-dialkyl-1H-1,2,4-triazoles and their Zn(II) complexes

It has been demonstrated by 13C NMR and quantum-chemical calculations that alkylation of 5-(2-hydroxyphenyl)-3-methyl(vinylphenyl)-1H-1,2,4-triazoles with dialkyl sulfates in aqueous DMSO in the presence of alkali occurs exclusively in the 2-position of the triazole ring to give 3-(2-hydroxyphenyl)-1,5-dialkyl(alkylvinylphenyl)-1H-1,2,4-triazoles. Emission spectra of these compounds show two weak bands (λmaxfl = 317–346 and 430–447 nm, φ = 0.002–0.007), whereas their zinc complexes emit in the violet range of the visible spectrum (λmaxfl= 373–377 nm, φ = 0.20–0.25).

A Single and Simple Receptor as a Multifunctional Chemosensor for the Al3+/Cu2+ ions and Its Live Cell Imaging Applications.

AbstractA simple and smart chemosensor (DSA) has been developed using Schiff base ligand for highly sensitive and selective colorimetric detection of Al3+/ Cu2+ in partial aqueous DMSO mixture (1:1) as a solvent medium. It showed a rapid fluorescence response (∼ 10 Sec) with Al3+ as greenish yellow from weak orange fluorescence while, Cu2+ ions affords yellow colour from fade orange colour and it can be sensed even by naked eyes. Besides showing great selectivity, the probe gives a lower sensitivity of 20 nM for Al3+ and 0.27 μM for Cu2+ in the fluorescence and UV‐vis. spectral studies respectively. The solid state colorimetric and fluorescence changes of the probe were examined in silica supported TLC plates. The sensing mechanism of the proposed probe in the presence of Al3+ and Cu2+ was determined with the support of a job's plot, 1H‐NMR, ESI‐Mass and theoretical (DFT) analysis. Based on the observed results from the absorbance and fluorescence spectroscopic studies, a logic circuit was designed with the combination of OR, NOT and AND logic gates. Moreover, the probe DSA has been employed for live cell imaging to detect Al3+ ions in C6 glioma cells and it showed a good cell permeability and efficiency in the detection of Al3+ ions.

Solvation state of iron(III) in aqueous solutions of dimethyl sulfoxide. Complex formation ability of iron(III) with respect to derivatives of sym-triazine and bis(hydrazinocarbonylmethyl) sulfoxide

Parameters of the solvation equilibria \({\left[ {Fe{{\left( {{H_2}O} \right)}_6}} \right]^{3 + }} + nDMSO \rightleftarrows {\left[ {Fe{{\left( {{H_2}O} \right)}_{6 - n}}{{\left( {DMSO} \right)}_n}} \right]^{3 + }} + n{H_2}O\) have been determined in aqueous-dimethyl sulfoxide solutions (0–90 vol% DMSO) by means of spectrophotometry and mathematical modeling of equilibria. Iron(III) is not involved in the complex formation with derivatives of sym-triazine: 2,4-diamino-6-(carbamoylmethylsulfinylmethyl)-1,3,5-triazine and 2,4-diamino-6-(acetohydrazidomethylsulfinylmethyl)-1,3,5-triazine in aqueous DMSO medium (40 vol % DMSO). Bis(hydrazinocarbonylmethyl) sulfoxide forms two complexes with iron(III), with 1: 1 and 1: 2 compositions; in contrast to the Cu(II) and Ni(II) complexes, in the iron complexes the ligand exists in the amide form. The most probable structures of the complexes have been revealed by molecular mechanics simulation and (in selected cases) using the DFT/B3LYP/6-31++G(d,p) density functional theory method.

Two-Component Self-Assembly: Hierarchical Formation of pH-Switchable Supramolecular Networks by π-π Induced Aggregation of Ion Pairs.

Two-component self-assembly is a promising approach to construct functional nanomaterials. Interaction of a flexible guanidiniocarbonyl pyrrole tetra-cation (1) with naphthalene diimide dicarboxylic acid (NDIDC) in aqueous DMSO leads to the formation of supramolecular networks. First, the carboxylate groups of NDIDC bind to the guanidiniocarbonyl pyrrole cations of 1 in a 1:2 stoichiometry. Further π-π induced aggregation then leads to 3D networks, as established by dynamic light scattering studies (DLS), NMR, fluorescence titration, viscosity measurements, AFM, and TEM microscopy. Due to ion pairing, the resulting aggregates can be switched between the monomers and the aggregates reversibly using external stimuli like protonation or deprotonation. At high concentration, a stable colloidal solution is formed, which shows an extensive Tyndall effect. Increasing the concentrations even further leads to formation of a supramolecular gel.