Reaction Of Dimethyl Sulfoxide Research Articles

X-ray Absorption Spectroscopy of a Quantitatively Mo(V) Dimethyl Sulfoxide Reductase Species

Molybdenum K-edge X-ray absorption spectroscopy (XAS) has been used to probe the structure of a Mo(V) species that has been suggested to be a catalytic intermediate in the reaction of dimethyl sulfoxide (DMSO) reductase with the alternative substrate trimethylamine N-oxide (Bennet et al. Eur. J. Biochem. 1994, 255, 321-331; Cobb et al. J. Biol. Chem. 2005, 280, 11007-11017; Mtei, et al. J. Am. Chem. Soc. 2011, 133, 9672-9774). The oxidized Mo(VI) state of DMSO reductase has previously been structurally characterized as being six coordinate, with four sulfurs from pyranopterin dithiolene molybdenum cofactors, a terminal oxygen ligand, and an additional oxygen coordination from a serine residue. We find the most plausible structure for the Mo(V) active site is a five-coordinate species with four sulfur donors from the two pyranopterin dithiolene ligands, with an average Mo-S bond-length of 2.35 Å, plus a single oxygen donor at 1.99 Å, very likely from an Mo-OH ligand. Our results thus suggest that the oxygen of the serine residue has dissociated from the metal ion, suggesting hitherto unsuspected flexibility of the active site, and calling into question whether this putative intermediate is catalytically relevant. The relevance to previous Mo(V) electron paramagnetic resonance and other spectroscopic studies on DMSO reductase is discussed. XAS of an extensively studied Mo(V) form of Rhodobacter sphaeroides DMSO reductase (the high-g split species) shows that previously suggested structures for the active site are likely incorrect.

Theoretical study on the gas phase reaction of dimethyl sulfoxide with atomic chlorine in the presence of water

We have investigated theoretically the gas phase reactions of dimethyl sulfoxide (DMSO) with atom Cl in the absence and presence of a single water molecule. The calculations of the potential energy surfaces in the water-free and water-assisted along the different channels are performed at the CCSD(T)/6-311++G(2df,2p)//MP2/6-31G(d) level. The calculated results show that energy barriers of the Hc-abstraction reaction are reduced due to one water molecule added. The computed rate constants of Hc-abstraction reaction indicate that the reaction with water is faster than the value of the naked reaction. However, Ha-abstraction reaction, path2, path3, and path4 are slower without water than hydrous channels.

Enhancing collagen stability through nanostructures containing chromium(III) oxide

Stabilization of collagen for various applications employs chemicals such as aldehydes, metal ions, polyphenols, etc. Stability against enzymatic, thermal and mechanical degradation is required for a range of biomedical applications. The premise of this research is to explore the use of nanoparticles with suitable functionalization/encapsulation to crosslink with collagen, such that the three dimensional architecture had the desired stability. Collagen solution prepared as per standard protocols is treated with chromium(III) oxide nanoparticules encapsulated within a polymeric matrix (polystyrene-block-polyacrylic acid copolymer). Selectivity towards encapsulation was ensured by the reaction in dimethyl sulfoxide, where the PS groups popped out and encapsulated the Cr2O3. Subsequently when immersed in aqueous solution, PAA units popped up to react with functional groups of collagen. The interaction with collagen was monitored through techniques such as CD, FTIR, viscosity measurements, stress analysis. CD studies and FTIR showed no degradation of collagen. Thermal stability was enhanced upon interaction of nanostructures with collagen. Self-assembly of collagen was delayed but not inhibited, indicating a compete binding of the metal oxide encapsulated polymer to collagen. Metal oxide nanoparticles encapsulated within a polymeric matrix could provide thermal and mechanical stability to collagen. The formed fibrils of collagen could serve as ideal material for various smart applications such as slow/sustained drug release. The study is also relevant to the leather industry in that the nanostructures can diffuse through the highly networked collagen fibre bundles in skin matrix easily, thus overcoming the rate limiting step of diffusion.

A kinetic study of dimethyl sulfoxide reductase based on density functional theory

We present a density functional theory study on the oxygen atom transfer (OAT) reaction of dimethyl sulfoxide (DMSO) with model complexes resembling a functional synthetic analogue of the molybdoenzyme DMSO reductase. The good agreement between our calculated Gibbs free energy profile and data derived from experimental kinetic parameters supports the reaction mechanisms of the oxygen atom transfer proposed in this study. When the mechanism involves the formation of a DMSO-bound intermediate, the calculations on the free energy surface provide valuable information that explains the origin of the apparent contradiction between the experimental findings and previous theoretical calculations with respect to the rate-limiting step of the reaction mechanism. The enzymatic mechanism of the OAT reaction is more complex than the mechanism of any synthetic analogue, mainly due to the formation of an enzyme-substrate adduct prior to the appearance of the substrate-bound intermediate. This study also presents a possible mechanism for the formation of such an adduct and the subsequent oxygen atom transfer. The mechanism involves a proton transfer to and from the substrate.

Synthesis of water-soluble poly(vinyl alcohol)-grafted multi-walled carbon nanotubes

A facile method for preparing waster-soluble poly(vinyl alcohol)-grafted multi-walled carbon nanotubes (PVA-grafted MWNTs) was developed. Well-defined poly(vinyl acetate) chains end-capped by a cobalt(II) acetylacetonate (Co(acac)2) complex [PVAc-Co(acac)2] were synthesized by the cobalt-mediated radical polymerization (CMRP) of vinyl acetate. PVAc macroradicals generated by the homolytic cleavage of the carbon-cobalt (C-Co) bonds of PVAc-Co(acac)2 chains were then grafted directly to the MWNTs via radical addition reactions in dimethyl sulfoxide (DMSO) at 50 °C. The amount of the PVAc grafted onto the surface of the MWNTs decreased with increasing molecular weight of PVAc-Co(acac)2. Hydrolysis of the grafted PVAc finally yielded PVA-grafted MWNTs, which showed good solubility in water. Surface functionalization of the MWNTs was confirmed by 1H NMR spectroscopy, FTIR spectroscopy and TEM.

ChemInform Abstract: Reaction of Dimethyl Sulfoxide with 4‐Acyloxycoumarins.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

PEGylation of Melittin: Structural Characterization and Hemostatic Effects

To promote and understand the structure—property relationship for hemostasis, we modified melittin (MLT) using a four-arm poly(ethylene glycol) (PEG) with N-hydroxysuccinimide ester. The PEGylation was characterized by FTIR, MALDI-MS, NMR, a bicinchoninic acid assay, circular dichroism, hemolysis assay, and thromboelastography. Changes in the reaction conditions affected the extent of the modification, the numbers of MLT conjugated to PEG arms, and possible PEGylation sites. The reaction at pH 9.2 with a high MLT/PEG ratio, resulted in the highest modification. Reactions in dimethylsulfoxide (DMSO) resulted in more multi-arm coupled MLT, reaching a maximum of four MLT per PEG. The helicity of the modified peptide, relative to the native peptide, was essentially maintained in DMSO, but substantially lost at pH 9.2. PEGylation reduced the hemolytic effects of MLT and subsequently changed its coagulation profiles. The overall hemostatic effects of MLT modified in DMSO indicate that this may be a convenient approach to the PEGylation of biomolecules for biomedical applications.

Reaction of Dimethyl Sulfoxide with 4-Acyloxycoumarins

Dimethyl sulfoxide converts 4-acetoxycoumarin (1) exclusively to 2-(2-hydroxybenzoyl)-2-[(methylthio)methyl]-2,3-dihydro-4 H-furo[3,2-c]chromen-4-one (3) at 180°C under a nitrogen atmosphere, but in the absence of nitrogen, the products obtained are dicoumarol and its dehydrative cyclization products 7 H-bis[1]benzopyrano[4,3-b: 3′,4′-c]pyran-6,8-dione (9) and (3). Under similar conditions, 4-benzoyloxycoumarin (1a) affords benzoic acid, 4-hydroxy-3-({2-[(methylthio)methyl]-3-oxo-2,3-dihydro-1-benzofuran-2-yl}methyl)-2H-chromen-2-one (7), and 3-(2-hydroxybenzoyl)-3,4-dihydro-2H,5H-pyrano[2,3-b] chromen-5-one (8).

Kinetics and Products of the Gas-Phase Reactions of Divinyl Sulfoxide with OH and NO3 Radicals and O3

Using relative rate methods, rate constants for the gas-phase reactions of divinyl sulfoxide [CH 2CHS(O)CHCH 2; DVSO] with NO 3 radicals and O 3 have been measured at 296 +/- 2 K, and rate constants for the reaction with OH radicals have been measured over the temperature range of 277-349 K. Rate constants obtained for the NO 3 radical and O 3 reactions at 296 +/- 2 K were (6.1 +/- 1.4) x 10 (-16) and (4.3 +/- 1.0) x 10 (-19) cm (3) molecule (-1) s (-1), respectively. For the OH radical reaction, the temperature-dependent rate expression obtained was k = 4.17 x 10 (-12)e ((858 +/- 141)/ T ) cm (3) molecule (-1) s (-1) with a 298 K rate constant of (7.43 +/- 0.71) x 10 (-11) cm (3) molecule (-1) s (-1), where, in all cases, the errors are two standard deviations and do not include the uncertainties in the rate constants for the reference compounds. Divinyl sulfone was observed as a minor product of both the OH radical and NO 3 radical reactions at 296 +/- 2 K. Using in situ Fourier transform infrared spectroscopy, CO, CO 2, SO 2, HCHO, and divinyl sulfone were observed as products of the OH radical reaction, with molar formation yields of 35 +/- 11, 2.2 +/- 0.8, 33 +/- 4, 54 +/- 6, and 5.4 +/- 0.8%, respectively, in air. For the experimental conditions employed, aerosol formation from the OH radical-initiated reaction of DVSO in the presence of NO was minor, being approximately 1.5%. The data obtained here for DVSO are compared with literature data for the corresponding reactions of dimethyl sulfoxide.

Dibromido(dimethyl sulfoxide-κO)(1,10-phenanthroline-κ2N,N′)copper(II)

The solvent effect on the molecular structures of copper(II) complexes produced from the reaction between CuBr(2) and 1,10-phenanthroline is evident. The monomeric title compound, [CuBr(2)(C(12)H(8)N(2))(C(2)H(6)OS)], which consists of discrete units, is produced from this reaction in dimethyl sulfoxide (DMSO), whereas a polymeric copper(II) compound is known to be produced from the same reaction in the poor coordinating solvent ethanol. The geometry around the copper(II) ion in the title compound is best described as trigonal-bipyramidal distorted square-based pyramidal, with a tau value of 0.37. The two phenanthroline N atoms, the DMSO O atom and one of the Br atoms occupy the four basal positions, while the second Br atom occupies the axial position. The magnetic susceptibility data also indicate that the title compound is monomeric, but there is still a weak antiferromagnetic interaction between paramagnetic copper(II) centers via the intermolecular 'Cu-Br...Br-Cu' contact pathway.

A systematic computational study on the reactions of dimethyl sulfoxide with XO (X = NO 2, Cl, Br and I)

The reactions of dimethyl sulfoxide (DMSO) with XO (X = NO 2, Cl, Br, I) have been studied at CCSD/6-311G(d,p)//B3LYP/6-311G(d,p) level. Two reaction channels have been considered: (1) the oxygen-atom transfer (OAT) from XO (X = NO 2, Cl, Br, I) to DMSO and (2) the hydrogen-abstraction by XO (X = NO 2, Cl, Br, I). The reaction mechanisms of DMSO with NO 3, ClO and BrO are similar: the OAT channel is the dominant channel and DMSO 2 is the primary product; the hydrogen-abstraction channel is not likely to be competitive with the OAT channel. The DMSO + IO reaction, because two reaction channels have the overall negative reaction activation energies and Gibbs free energies, the reaction could occur on both reaction channels. Furthermore, the formation of the stable complex may vary the yield rate of DMSO 2.

Reactions of metal iodides as a simple route to heterometallics: synthesis, structural transformations, thermal and luminescent properties of novel hybrid iodoargentate derivatives templated by [YL8]3+ or [YL7]3+ cations (L = DMF or DMSO)

A 1 : 3 molar reaction of YI3 and AgI in dimethylformamide (DMF) in the presence of NH4I afforded [Y(DMF)8][Ag3(mu3-I)(mu-I)3I2] (1) with good yield, whereas the similar reaction in dimethylsulfoxide (DMSO) gave complexes [Y(DMSO)8][Ag2(mu-I)3I2] (2) and/or [Y(DMSO)8]2[Ag4(mu3-I)2(mu-I)4I2][I]2 (3), depending on the reaction and crystallization conditions. These discrete heterometallic hybrid compounds 1-3 undergo solid- and solution-state transformations via condensation of iodoargentate anions. So in the confined and solvent-free environment of paratone, crystals of 1 transformed into a 1D zig-zag structure [Y(DMF)8]3+[Ag6(mu4-I)2(mu3-I)2(mu-I)5]1infinity(3-) (4), whereas those of 2 were first converted into 3 and finally into [Y(DMSO)7]4[Ag4(mu3-I)4I4]3 (5). In solution phase, re-crystalization of 1 or 2 from DMSO-toluene gave 3 as an exclusive species, whereas reaction of 1 with 3 equiv of AgI in DMF afforded 4 with good yield. Alternatively, 4 could also be synthesized with excellent yield from a 1 : 6 molar reaction of YI3 and AgI. The above transformations suggest that, for a given metal-organic cation, an iodometallate cluster with higher nuclearity is thermodynamically more stable. Single crystal X-ray structures are reported for all the compounds and a mechanism for the structural transformation of 2 to 3 is proposed. In addition, spectroscopic, thermo-gravimetric and luminescent properties of the complexes 1, 3 and 4, which were obtained exclusively and in pure form, are also described.

Rate-limiting proton-transfer in the σ-adduct forming reactions of 1,3,5-trinitrobenzene and 4-nitrobenzofuroxan with substituted anilines in dimethyl sulfoxide

Kinetic and equilibrium results are compared for the reactions in dimethyl sulfoxide of 1,3,5-trinitrobenzene, 1, and 4-nitrobenzofuroxan, 4, with a series of substituted anilines in the presence of Dabco or in, some cases, quinuclidine. pKa values for the corresponding anilinium ions are reported. The reactions of 1and 4 are likely to proceed through nucleophilic attack by the aniline to yield zwitterionic intermediates which may transfer an acidic proton to the bases present to yield the anionic adducts 9 or 12 respectively. In the formation of 9 from 1 the proton transfer step is rate-limiting; however, the slower interconversion of 4 and its zwitterion leads to only partial rate-limiting proton transfer in the formation of 12. Results with substituted anilines including 2-substituted and N-methyl aniline indicate that steric effects are not a major factor in determining rates of proton-transfer in these systems. Contrary to previous reports no evidence was found for a strong interaction between 1 and Dabco in DMSO.

Cd(II) and Cu(II) complexes of polydentate Schiff base ligands: synthesis, characterization, properties and biological activity

We report the synthesis of the Schiff base ligands, 4-[(4-bromo-phenylimino)-methyl]-benzene-1,2,3-triol (A 1), 4-[(3,5-di- tert-butyl-4-hydroxy-phenylimino)-methyl]-benzene-1,2,3-triol (A 2), 3-( p-tolylimino-methyl)-benzene-1,2-diol (A 3), 3-[(4-bromo-phenylimino)-methyl]-benzene-1,2-diol (A 4), and 4-[(3,5-di- tert-butyl-4-hydroxy-phenylimino)-methyl]-benzene-1,3-diol (A 5), and their Cd(II) and Cu(II) metal complexes, stability constants and potentiometric studies. The structure of the ligands and their complexes was investigated using elemental analysis, FT-IR, UV–Vis, 1H and 13C NMR, mass spectra, magnetic susceptibility and conductance measurements. In the complexes, all the ligands behave as bidentate ligands, the oxygen in the ortho position and azomethine nitrogen atoms of the ligands coordinate to the metal ions. The keto-enol tautomeric forms of the Schiff base ligands A 1–A 5 have been investigated in polar and non-polar organic solvents. Antimicrobial activity of the ligands and metal complexes were tested using the disc diffusion method and the strains Bacillus megaterium and Candida tropicalis. Protonation constants of the triol and diol Schiff bases and stability constants of their Cu 2+ and Cd 2+ complexes were determined by potentiometric titration method in 50% DMSO–water media at 25.00 ± 0.02 °C under nitrogen atmosphere and ionic strength of 0.1 M sodium perchlorate. It has been observed that all the Schiff base ligands titrated here have two protonation constants. The variation of protonation constant of these compounds was interpreted on the basis of structural effects associated with the substituents. The divalent metal ions of Cu 2+ and Cd 2+ form stable 1:2 complexes with Schiff bases. The Schiff base complexes of cadmium inhibit the intense chemiluminescence reaction in dimethylsulfoxide (DMSO) solution between luminol and dioxygen in the presence of a strong base. This effect is significantly correlated with the stability constants K CdL of the complexes and the protonation constants K OH of the ligands; it also has a nonsignificant association with antibacterial activity.

Carbocation-forming reactions in dimethyl sulfoxide.

Mesylate derivatives of 3-aryl-3-hydroxy-beta-lactams and thiolactams react in DMSO-d(6) by first-order processes to give alcohol products. Substituent effect studies implicate carbocation intermediates (ion-pairs) that are captured by DMSO-d(6) to give transient oxosulfonium ions. Rapid reaction of the oxosulfonium ions with trace amounts of water leads to the alcohol product and regenerates DMSO-d(6). H(2)(17)O labeling studies show that (17)O is incorporated into the DMSO. The mesylate derivatives of endo- and exo-2-hydroxy-2-phenylbicyclo[2.2.1]heptan-3-one also react in DMSO-d(6) to give the alcohol products. Ion-pair intermediates that capture DMSO giving unstable oxosulfonium ions are again proposed. Exo-2-phenyl-endo-bicyclo[2.2.1]heptyl trifluoroacetate readily eliminates trifluoroacetic acid in DMSO-d(6) via a cationic mechanism involving loss of the endo-trifluoroacetate leaving group as well as an exo-hydrogen. The O-methyl oxime derivative of alpha-chloro-alpha,alpha-diphenylacetophenone reacts in DMSO-d(6) to give 1-methoxy-2,3-diphenylindole, a product derived from cyclization of a cationic intermediate. A common ion rate suppression provides further evidence for a cationic mechanism. The triflate derivative of pivaloin reacts by a cationic mechanism in DMSO-d(6) to give rearranged products. The rate is even faster than in highly ionizing solvents such as trifluoroethanol or trifluoroacetic acid. 1-Adamantyl mesylate reacts in DMSO-d(6) by a first-order process (Y(OMs) = -4.00) to give a long-lived oxosulfonium ion, 1-Ad-OS(CD(3))(2)(+), which can be characterized spectroscopically. This oxosulfonium ion reacts only slowly with water at elevated temperatures to give 1-adamantanol. DMSO is therefore a viable solvent for k(s), k(C), and k(Delta) cationic processes.

Peri-Naphthylenediamines. 36. 5,6-Bis(dimethylamino)acenaphthylene in [4+2] cycloaddition reactions. Synthesis and characteristic features of protonation of “proton sponges” with the 8,9-diazafluoranthene structure

5,6-Bis(dimethylamino)acenaphthylene is readily involved in [4+2] cycloaddition reactions with symm-tetrazine derivatives to form new “proton sponges” with the diazafluoranthene skeleton. Under analogous condition, 1,8-bis(dimethylamino)-4-vinylnaphthalene gave 4-pyridazinyl derivatives. The relative reactivities of 5,6-bis(dimethylamino)acenaphthylene, 1,8-bis(dimethylamino)-4-vinylnaphthalene, 5-dimethylaminoacenaphthylene, and acenaphthylene in the reactions with 3,6-diphenyl-symm-tetrazine are in a ratio of 32 : 17 : 14 : 1. The site of protonation of 3,4-bis(dimethylamino)-7,10-diphenyl-8,9-diazafluoranthene is controlled by the basicity of the solvent. The reaction in acetonitrile afforded the cation stabilized by an intramolecular hydrogen bond, whereas the reaction in dimethyl sulfoxide gave rise to the resonance-stabilized cation. 6,7-Bis(dimethylamino)phenalen-1-one was protonated only at the carbonyl group.

Carotenoids as antioxidants: spin trapping EPR andoptical study

The role of several natural and synthetic carotenoids as scavengers of free radicals was studied in homogeneous solutions. A set of free radicals: OH, OOH, and •CH 3 were generated by using the Fenton reaction in dimethyl sulfoxide. It was shown that the spin trapping technique is more informative than optical methods for the experimental conditions under study. 5,5-Dimethyl-pyrroline- N-oxide (DMPO) and N-tert-butyl-α-phenylnitrone (PBN) were used as spin traps for the EPR studies. The results show that the scavenging ability of the carotenoids towards radical OOH correlates with their redox properties.

The Complexation Reactions of N-methylated Polyamines with Silver(I) in Dimethylsulfoxide

The thermodynamic parameters for the complex formation reactions in dimethylsulfoxide (dmso) between Ag(I) and the following polyamines: N,N′-dimethylethylenediamine (dmen), N,N,N′,N′-tetramethylethylenediamine (dmen), N,N″-dimethyl-diethylenetriamine (dmdien) and N,N,N′,N″, N″-pentamethyldiethylenetriamine (pmdien) have been determined by potentiometric and calorimetric techniques at 298 K and 0.1 mol dm−3 ionic strength (NEt4ClO4). Only mononuclear complexes are formed (AgLj + j = 1,2) where the ligands act prevalently as chelate agents. All the complexes are enthalpy stabilized whereas the entropy changes counteract the complex formation. The results are discussed in terms of different basicities and steric requirements of both the ligands and the complexes formed.

Synthesis and properties of thermotropic liquid crystalline polyurethane elastomers

High molecular weight thermoplastic polyurethane elastomers (TPEs), which consist of crystalline polycaprolactone soft segment and hexamethylene diisocyanate (HDI)/4,4′-dihydroxy biphenyl (DHBP) based mesogenic hard segment, were effectively synthesized by polyaddition reaction in dimethyl sulfoxide. These TPEs had an enantiotropic mesophase in the hard domain, when the content of hard segment was 40wt.% or higher. Differential scanning calorimetry, polarizing microscopy, X-ray scattering analysis, dynamic mechanical test, tensile test were carried out to examine liquid crystalline, thermal, and mechanical properties and shape memory effect of these TPEs. The results were discussed and compared with those of previous articles, where low molecular weight HDI/DHBP based polyurethane or polycaprolactone diol/4,4′-diphenylmethane diisocyanate/1,4-butanediol based TPEs were examined.

Syntheses, crystal structures and autoreduction behavior of antiferromagnetically coupled dicopper(II) oximato complexes

Four dicopper(II) oximato complexes of 2-[2-(α-pyridyl)methyl]imino-3-butanone oxime (pmiboH) and 2-[2-(α-pyridyl)ethyl]imino-3-butanone oxime (peiboH), [Cu 2(pmibo) 2](ClO 4) 2 ( 1), [Cu 2(pmibo) 2](NO 3) 2·CH 3OH ( 2), [Cu 2(peibo) 2](ClO 4) 2·CH 3OH ( 3) and [Cu 2(peibo) 2(H 2O) 2](ClO 4) 2 ( 4), were prepared and characterized structurally and magnetically. All the dicopper(II) oximato complexes have a common cationic structure in which the two Cu atoms are bridged through two NO bridges of the oximato ligand to afford a dinuclear structure. The cation moieties of 1 and 2 consist of one six-membered Cu 2N 2O 2 chelate ring and four five-membered (CuN 2C 2 and CuNC 2N) chelate rings, providing a planar configuration. The cation moieties of 3 and 4 are also composed of three six-membered (Cu 2N 2O 2 and CuNC 3N) chelate rings and two five-membered CuN 2C 2 chelate rings, giving a twisted-boat configuration. The −2 J values ( H=−2 JS 1 S 2) are 835, 825, 550 and 510 cm −1 for 1, 2, 3 and 4, respectively, indicative of a strong antiferromagnetic interaction in the solid state. All the dicopper(II) oximato complexes show seven 1H NMR signals at 23°C in the range of −0.5 to 30 ppm with the linewidths at half-height, Δ ν 1/2 of 60–1500 Hz, which is characteristic of antiferromagnetic species and indicates that the dinuclear structure is kept in solution. The −2 J values reflect the degree of distortion from the planarity of the Cu 2 framework. The −2 J values roughly correlate with the 1H NMR parameters; the larger the −2 J values, the smaller the chemical shifts and linewidths. Complexes 1 and 2 were found to undergo an autoreduction reaction in dimethyl sulfoxide (DMSO), N, N-dimethylformamide (DMF) and N, N-dimethylacetamide (DMA), and their behaviors were first monitored by UV–Vis and 1H NMR methods.