Compounds In Dimethylsulfoxide Research Articles

Highly soluble 3,4-(dimethoxyphenylthio) substituted phthalocyanines: Synthesis, photophysical and photochemical studies

The synthesis of a new 3,4-(dimethoxyphenylthio) substituted phthalonitrile ( 1) and its soluble metal free ( 2), zinc (II) ( 3), oxo-titanium (IV) ( 4) and nickel (II) ( 5) phthalocyanine derivatives are reported for the first time. The new compounds have been characterized by elemental analysis, FT-IR, 1H NMR, UV–Vis, fluorescence spectroscopies and mass spectra. General trends are described for fluorescence, photodegradation and singlet oxygen quantum yields and fluorescence lifetimes of oxo-titanium (IV) and zinc (II) phthalocyanine compounds in dimethylsulfoxide (DMSO). The effects of the metal ion on the photophysical and photochemical parameters for these phthalocyanines ( 3 and 4) are also reported.

Synthesis and binding properties of guanidinium biscarboxylates

The ammonium ion binding site of the enzyme glutaminase HisF inspired us to design guanidinium biscarboxylates as potential self-organized ionophores in molecular recognition. The syntheses of the title compounds based on aliphatic and aromatic building blocks, along with a general method for the preparation of δ-aminoethoxyacetic acids, are presented in this work. Investigation of the binding properties of the title compounds in dimethyl sulfoxide (DMSO) and methanol solution revealed no ammonium ion affinity, but interaction of the guanidinium moiety with acetate ions.

Thermophysical properties of dimethylsulfoxide with ionic liquids at various temperatures

In this article, we present densities ( ρ), ultrasonic sound velocities ( u) and viscosities ( η) for the binary systems of the highly polar compound dimethylsulfoxide (DMSO) with ionic liquids (ILs) over the whole composition range at temperature ranging from 298.15 to 328.15 K under atmospheric pressure. The ILs investigated in the present study included diethyl ammonium hydrogen sulfate ([Et 2NH][HSO 4], DEAS) is an ammonium salt (protic IL) and 1-butyl-3-methylimidazolium chloride ([Bmim][Cl]) is an imidazolium salt (aprotic IL). Further, to gain some insight into the several aggregations of molecular interactions present in these mixed solvents, we predicted the excess molar volume ( V E), the deviation in isentropic compressibilities (Δ K s ) and deviation in viscosity (Δ η) as a function of the concentration of IL using the measured properties of ρ, u and η, respectively. Redlich–Kister polynomial was used to correlate the results. The intermolecular interactions and structural effects were analyzed on the basis of the measured and the derived properties. A qualitative analysis of the results is discussed in terms of the ion–dipole, ion-pair interactions, and hydrogen bonding between ILs and DMSO molecules and their structural factors. Comparison of these properties of DMSO with ILs explicitly elucidates the influence of ions and also the temperature effects on the thermophysical properties.

ChemInform Abstract: Synthesis, Characterization, and Solution Properties of New Heterocyclic Tellurium Compounds Based on 5,6-Dimethyl-1,3-dihydro-2-telluraindene.

The synthesis and characterization of a new range of heterocyclic tellurium compounds based on 5,6-dimethyl-1,3-dihydro-2-telluraindene are reported. Conductivity measurements of most compounds in dimethylsulfoxide (DMSO) and N,N-dimethylformamide (DMF) showed considerable ionic character in both solvents. 1H and 13C NMR studies indicated that the telluronium salts are stable to reductive elimination and no reaction between solute and solvent was observed. Benzyl and allyl telluronium salts are exceptional. Infrared and mass spectral data are reported and discussed.

Synthesis, photophysics, photochemistry and fluorescence quenching studies on highly soluble substituted oxo-titanium(IV) phthalocyanine complexes

The synthesis, photophysical and photochemical properties of soluble 3,4-(methylendioxy)-phenoxy substituted oxo-titanium(IV) phthalocyanines ( 4– 6) are reported for the first time. The new compounds have been characterized by elemental analysis, FT-IR, 1H NMR spectroscopy, electronic spectroscopy and mass spectra. General trends are described for fluorescence lifetimes and fluorescence, photodegradation and singlet oxygen quantum yields, of these compounds in dimethylsulfoxide (DMSO) and toluene. The effects of the position of the substituents and solvent effect on the photophysical and photochemical parameters of the oxo-titanium(IV) phthalocyanines ( 4– 6) are also reported. The fluorescence of the substituted oxo-titanium(IV) phthalocyanine complexes ( 4– 6) is effectively quenched by 1,4-benzoquinone (BQ) in both DMSO and toluene.

Solution Speciation, Kinetics, and Observing Reaction Intermediates in the Alkylation of Oxidovanadium Compounds

Contact with environmental alkylating agents brings about modification of DNA bases, mispairing, mutations, and cancer. Nucleophilic compounds may be able to consume these toxins, thereby providing an alternative reaction pathway and preventing DNA damage. Owing to promising results from animal trials, oxidovanadium compounds present a potential class of nucleophilic complexes for preventing cancer. We are studying the reactivity of alkylating toxins with oxidovanadium-ligand compounds. The complexes K[VO(2)(salhyph(R)(2))], where salhyph is the salicylidenehydrazide ligand, are the focus of this study. By changing the electron donating or withdrawing ability of the -R substituents upon the salhyph(R)(2) ligand (R = -NO(2), -H, -CH(3), -OCH(3)), a family of compounds is obtained to investigate. Conductivity measurements reveal significant ion-pairing of all compounds in dimethyl sulfoxide (DMSO) solutions. Kinetic analysis shows that this ion-pairing causes a reduction in reaction rates. Reactivity of K[VO(2)(salhyph(R)(2))] is attributed exclusively to the non-ion-paired "free" [VO(2)(salhyph(R)(2))](-) anion in solution. Both (1)H and (51)V NMR spectroscopic studies show that direct alkylation of K[VO(2)(salhyph(H)(2))].CH(3)OH generates a VO(OCH(2)CH(3))(salhyph(H)(2)) intermediate which then protonates to release CH(3)CH(2)OH and a proposed [VO(salhyph(H)(2))](+) compound. Upon hydrolysis the dinuclear {[VO(salhyph(H)(2))](2)O} end product is formed. This mechanistic understanding and ability to exert control over reactions between inorganic compounds and alkylating toxins may aid in the future development of pharmaceuticals for preventing DNA damage.

Synthesis, photophysical and photochemical studies of novel liquid crystalline phthalocyanines

Ni(II) and Zn(II) phthalocyanines carrying four or eight branched oligo(ethyleneoxy)-thia groups on peripheral positions have been synthesized from new phthalonitrile derivatives. The new compounds have been characterized by elemental analysis, IR, NMR, mass spectra and electronic spectroscopy. The aggregation behaviors of the phthalocyanine complexes were studied in different solvents and concentrations. General trends are described for photodegradation, singlet oxygen and fluorescence quantum yields, and fluorescence lifetimes of these compounds in dimethylsulfoxide (DMSO). The effects of the substitution on the photophysical and photochemical parameters of the nickel(II) (3a and 4a) and zinc(II) phthalocyanines (4b) are also reported. The octasubstituted zinc(II) complex (3b) is not stable for these measurements. Preliminary investigation of the photophysical and photochemical properties of phthalocyanine complexes are very useful for further PDT applications. The mesogenic properties of these new materials were studied by differential scanning calorimetry (DSC), optical polarized microscopy and X-ray investigations.

Mutations Define Cross-talk between the N-terminal Nucleotide-binding Domain and Transmembrane Helix-2 of the Yeast Multidrug Transporter Pdr5

The yeast Pdr5 multidrug transporter is an important member of the ATP-binding cassette superfamily of proteins. We describe a novel mutation (S558Y) in transmembrane helix 2 of Pdr5 identified in a screen for suppressors that eliminated Pdr5-mediated cycloheximide hyper-resistance. Nucleotides as well as transport substrates bind to the mutant Pdr5 with an affinity comparable with that for wild-type Pdr5. Wild-type and mutant Pdr5s show ATPase activity with comparable K(m)((ATP)) values. Nonetheless, drug sensitivity is equivalent in the mutant pdr5 and the pdr5 deletion. Finally, the transport substrate clotrimazole, which is a noncompetitive inhibitor of Pdr5 ATPase activity, has a minimal effect on ATP hydrolysis by the S558Y mutant. These results suggest that the drug sensitivity of the mutant Pdr5 is attributable to the uncoupling of NTPase activity and transport. We screened for amino acid alterations in the nucleotide-binding domains that would reverse the phenotypic effect of the S558Y mutation. A second-site mutation, N242K, located between the Walker A and signature motifs of the N-terminal nucleotide-binding domain, restores significant function. This region of the nucleotide-binding domain interacts with the transmembrane domains via the intracellular loop-1 (which connects transmembrane helices 2 and 3) in the crystal structure of Sav1866, a bacterial ATP-binding cassette drug transporter. These structural studies are supported by biochemical and genetic evidence presented here that interactions between transmembrane helix 2 and the nucleotide-binding domain, via the intracellular loop-1, may define at least part of the translocation pathway for coupling ATP hydrolysis to drug transport.

Synthesis, Photophysical and Photochemical Properties of Poly(oxyethylene)‐Substituted Phthalocyaninato Oxotitanium(IV) Complexes

AbstractThe synthesis, photophysical and photochemical properties of tetra‐ and chlorotetrapoly(oxyethylene)‐substituted oxotitanium(IV) phthalocyanines are reported for the first time. The new compounds were characterized by elemental analysis, IR, 1H and 13C NMR spectroscopy, electronic spectroscopy and mass spectra. These complexes showed monomeric behaviour in solution. General trends are described for photodegredation, singlet oxygen, triplet state and fluorescence quantum yields, and triplet and fluorescence lifetimes of these compounds in dimethyl sulfoxide (DMSO). Photophysical and photochemical properties of phthalocyanine complexes are very useful for PDT applications. The complexes showed high triplet quantum yields and triplet lifetimes in DMSO. The singlet oxygen quantum yields (ΦΔ), which give an indication of the potential of the complexes as photosensitizers in applications where singlet oxygen is required (Type II mechanism), were 0.72 and 0.78 for 3a and 5a, respectively. Thus, these complexes show potential as Type II photosensitizers. These complexes were also quenched by benzoquinone for fluorescence quenching studies.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

Synthesis, photophysical and photochemical properties of tetra- and octa-substituted gallium and indium phthalocyanines

The synthesis, photophysical and photochemical properties of the tetra- and octa-[4-(benzyloxyphenoxy)] substituted gallium(III) and indium(III) phthalocyanines are reported for the first time. The new compounds have been characterized by elemental analysis, IR, 1H NMR spectroscopy and electronic spectroscopy. General trends are described for quantum yields of photodegredation, fluorescence quantum yields and lifetimes, triplet lifetimes and triplet quantum yields as well as singlet oxygen quantum yields of these compounds in dimethylsulfoxide (DMSO). Substituted indium phthalocyanine complexes ( 7b– 9b) showed much higher quantum yields of triplet state and shorter triplet lifetimes, compared to the substituted GaPc derivatives due to enhanced intersystem crossing (ISC) in the former. The gallium and indium phthalocyanine complexes showed phototransformation during laser irradiation due to ring reduction. The singlet oxygen quantum yields ( Φ Δ), which give an indication of the potential of the complexes as photosensitizers in applications where singlet oxygen is required (Type II mechanism) ranged from 0.51 to 0.94. Thus, these complexes show potential as photodynamic therapy of cancer.

Synthesis, photophysical and photochemical properties of substituted zinc phthalocyanines

The synthesis, photophysical and photochemical properties of the 4-({3,4,5-tris-[2-(2-ethoxyethoxy)ethyloxy]benzyl}oxy) and 4-({3,4,5-tris-[2-(2-ethoxyethoxy)ethyloxy]benzyl}thio) zinc(ii) phthalocyanines are reported for the first time. The new compounds have been characterized by elemental analysis, IR, (1)H and (13)C NMR spectroscopy, electronic spectroscopy and mass spectra. General trends are described for photodegradation, singlet oxygen, fluorescence and triplet excited state quantum yields, and triplet state and fluorescence lifetimes of these compounds in dimethylsulfoxide (DMSO). The fluorescence of the complexes was quenched by benzoquinone (BQ). The effects of the substitution on the photophysical and photochemical parameters of the zinc(II) phthalocyanines (6, 7 and 8) are also reported. Photophysical and photochemical properties of phthalocyanine complexes are very useful for PDT applications. The substituted Zn(II) phthalocyanines showed high triplet and singlet oxygen quantum yields. High singlet oxygen quantum yields are very important for Type II mechanism. Thus, these complexes show potential as Type II photosensitizers.

Synthesis, photophysical and photochemical properties of poly(oxyethylene)-substituted zinc phthalocyanines

The synthesis, photophysical and photochemical properties of the tetra- and octa-poly(oxyethylene)substituted zinc (II) phthalocyanines are reported for the first time. The new compounds have been characterized by elemental analysis, IR, 1H and 13C NMR spectroscopy, electronic spectroscopy and mass spectra. General trends are described for photodegradation, singlet oxygen, triplet state and fluorescence quantum yields, and triplet and fluorescence lifetimes of these compounds in dimethylsulfoxide (DMSO). Photophysical and photochemical properties of phthalocyanine complexes are very useful for PDT applications. The effects of the substituents on the photophysical and photochemical parameters of the zinc(II) phthalocyanines (3a, 5a and 6a) are also reported. The singlet oxygen quantum yields (Phi(Delta)), which give an indication of the potential of the complexes as photosensitizers in applications where singlet oxygen is required (Type II mechanism) ranged from 0.60 to 0.72. Thus, these complexes show potential as Type II photosensitizers. The fluorescence of the complexes was quenched by benzoquinone (BQ).

Radioprotective−Antimutagenic Effects of Rosemary Phenolics against Chromosomal Damage Induced in Human Lymphocytes by γ-rays

The radioprotective effects of carnosic acid (CA), carnosol (COL), and rosmarinic acid (RO) against chromosomal damage induced by gamma-rays, compared with those of L-ascorbic acid (AA) and the S-containing compound dimethyl sulfoxide (DMSO), were determined by use of the micronucleus test for antimutagenic activity, evaluating the reduction in the frequency of micronuclei (MN) in cytokinesis-blocked cells of human lymphocytes before and after gamma-ray irradiation. With treatment before gamma-irradiation, the most effective compounds were, in order, CA > RO > or = COL > AA > DMSO. The radioprotective effects (antimutagenic) with treatment after gamma-irradiation were lower, and the most effective compounds were CA and COL. RO and AA presented small radioprotective activity, and the sulfur-containing compound DMSO lacked gamma-ray radioprotection capacity. Therefore, CA and COL are the only compounds that showed a significant antimutagenic activity both before and after gamma-irradiation treatments. These results are closely related to those reported by other authors on the antioxidant activity of the same compounds, and the degree of effectiveness depends on their structure. Furthermore, the results for treatments before and after gamma-ray irradiation suggest the existence of different radioprotective mechanisms in each case.

A global but stable change in HeLa cell morphology induces reorganization of DNA structural loop domains within the cell nucleus

DNA of higher eukaryotes is organized in supercoiled loops anchored to a nuclear matrix (NM). The DNA loops are attached to the NM by means of non-coding sequences known as matrix attachment regions (MARs). Attachments to the NM can be subdivided in transient and permanent, the second type is considered to represent the attachments that subdivide the genome into structural domains. As yet very little is known about the factors involved in modulating the MAR-NM interactions. It has been suggested that the cell is a vector field in which the linked cytoskeleton-nucleoskeleton may act as transducers of mechanical information. We have induced a stable change in the typical morphology of cultured HeLa cells, by chronic exposure of the cells to the polar compound dimethylsulfoxide (DMSO). Using a PCR-based method for mapping the position of any DNA sequence relative to the NM, we have monitored the position relative to the NM of sequences corresponding to four independent genetic loci located in separate chromosomes representing different territories within the cell nucleus. Here, we show that stable modification of the NM morphology correlates with the redefinition of DNA loop structural domains as evidenced by the shift of position relative to the NM of the c-myc locus and the multigene locus PRM1 --> PRM2 --> TNP2, suggesting that both cell and nuclear shape may act as cues in the choice of the potential MARs that should be attached to the NM.

Enthalpies of solution of aliphatic compounds in dimethyl sulfoxide

Enthalpies of solution of aliphatic alcohols {CH 3(CH 2) n OH, n=0–10} and aliphatic nitriles {CH 3(CH 2) n CN, n=0–12} in dimethyl sulfoxide (DMSO) have been determined at 298.15 K for the mole fraction range 5×10 −5 to 0.002. In all cases enthalpies of solution were found to be positive. Partial molar enthalpies of solution at infinite dilution were derived. Linear relations between the limiting excess partial molar enthalpies and the number of methylene groups were found for both groups of compounds investigated. McMillan–Mayer’s parameters, h xx and h xxx , showed unfavorable and favorable interactions, respectively.

The resonance Raman effect of UO2L2 (L = NO3, CH3COO or Cl) type uranyl compounds in dimethyl sulfoxide

The resonance Raman scattering spectra of UO2L2 (L = NO3, CH3COO or Cl) type uranyl compounds in dimethyl sulfoxide ((CH3)2SO) have been measured under laser excitation of the UO22+ ion in resonance with the 1Σg+ -->1Φg Laport-forbidden f-f electronic transition. The resonance Raman excitation profiles of the totally symmetric stretching vibrational mode of uranyl are presented and analyzed in terms of transform theory within the non-Condon model It is found that, in the 1Σ+g -->1Φg electronic transition, elongation of the U-O equilibrium bond length is related to the magnitude of the change in the excitation profile and has a linear correlation with the increase in the charge transferred from the ligand to the uranium atom.

Cyclic Voltammetry of Two Analogue K-Group Vitamin Compounds in Dimethylsulfoxide

The electrochemical reduction of two analogue K-group vitamin compounds, menadione and phthiocol, was studied by cyclic voltammetry in DMSO on glassy carbon electrodes. The reduction process of the more biologically active of these compounds (menadione), is associated with the formation of the semiquinone anion radical and the dianion. Two separated reversible one-electron peaks were observed. In contrast, the less biologically active phthiocol exhibits a single irreversible 2/3-electron peak which is explained by an ECE-DISP1 self-protonation mechanism. In the presence of a donor proton such as benzoic acid, menadione and phthiocol are reduced both through a sequence of consecutive electron transfer and protonation reactions occurring via an irreversible two-electron ECE-DISP1 mechanism.

New long-wavelength perylenequinones. The reaction between hypocrellin B and mercapto compounds

Certain new mercapto-substituted hypocrellin B (HB) derivatives have been synthesized and characterized. The possible mechanism for this reaction, and the properties of the resulting compound, are discussed. Interaction of HB with mercapto compounds in dimethyl sulfoxide containing ammonium hydroxide proceeded very quickly, and the mono- or di-substituted HB derivatives were formed. Their significantly enhanced red absorptivities and strong 1O 2-generating functions may qualify them as promising PDT agents. In addition, the semiquinone radical anion of HB (HB −.) was one of the reaction intermediates detected by ESR and Uv-vis spectrum. Moreover, the effect of free radical quenchers on this reaction have also been investigated. On the basis of the experimental evidence, the mechanism of free radical addition and nucleophilic addition are proposed.

Relationship between cooling rates, cryoprotectant concentrations and salinities in the cryopreservation of marine microalgae

The viability of the marine microalgae Rhodomonas baltica Karsten, Isochrysis affinis galbana (Strain T-ISO) Parke, Chaetoceros gracilis Schutt, Tetraselmis chuii Butcher, Nannochloropsis gaditana Lubian and Nannochloris atomus Butcher, cryopreservec employing different cooling rates, either with or without the addition of the cryoprotective compounds dimethyl sulfoxide (DMSO) and methanol was studied at two exposure salinities. A viability index, which considered both cell recovery and the growth capacity of microalgae after thawing, was developed. The growth of thawed algae was compared to that obtained for unfrozen algae grown in liquid medium under the same conditions. Viability (V) was calculated according to the equation: V=(C 0/C i)x(C 7/(a·C 0 b ))x100, where C 0 and C 7 are, respectively, the initial and final cell densities measured in the cultures after thawing from-196°C, C i is the maximum initial cell density (complete cell recovery), and a, b are the regression coefficients obtained for C 7 as a function of C 0 in the unfrozen controls. R. baltica was the only species that showed an improved viability when salinity was reduced from 36‰ (average viability 13.7% for 15% DMSO) to 20‰ (average viability 36.2% for 15% DMSO). The other five species displayed better viability only at the higher salinity at all tested cooling rates and cryoprotectant levels. T. chuii, Nannochloropsis gaditana, and Nannochloris atomus Butcher could be cryopreserved without cryoprotectant. However, their respective viabilities (32.7, 30.8 and 65.8%) at 36‰ S were progressively improved on addition of 5% DMSO (70.9, 48.2 and 93.5, respectively) and 15% DMSO (91.9, 57.0 and 94.2%, respectively). Similar improvements were found for Nannochloropsis gaditana and Nannochloris atomus when cryopreserved using methanol concentrations of 1% (average viabilities of 46.9 and 91.8, respectively) and 5% (average viablities of 48.7 and 95.3, respectively). Methanol was completely ineffective in cryopreserving the other four species and caused a lethal effect on T. chuii during freezing. C. gracilis could be cryopreserved with 5% DMSO only at 36‰ S. This resulted in a similar viability (11.7%) to that obtained using 15% DMSO in 20‰ S (13.7%). Keeping cryoprotectant concentration at 15% DMSO and raising salinity to 36‰ significantly improved the mean viability of C. gracilis to 21.6%. A low mean viability of 2.1% was obtained for I. galbana when 15% DMSO was used in full-strength seawater (36‰ S). Within the range of cooling rates tested (0.25 to 16 C° min-1), cryopreserved microalgae showed higher viabilities at faster rates in the absence of cryoprotectants at both salinities. Generally, the dependence on cooling rate decreased proportionally to the concentration of DMSO or methanol, as demonstrated by the lack of significance for the slope of the regressions. Only C. gracilis appeared to depend on faster cooling rates in the presence of 15% DMSO.

Aggregation of amphiphilic compounds in dimethyl sulfoxide: example of non-ionic alkyl–fluoroalkyl lipopeptides

The surface-active properties and association in dimethyl sulfoxide (DMSO) of two non-ionic alkyl–fluoroalkyl lipopeptides have been studied up to the limit of solubility (0.15–0.25) mol dm–3) by combined use of surface tension, 19F NMR, and small-angle neutron scattering (SANS) experiments. Various models of aggregation have been tested using least-squares procedures on both NMR and SANS data. The conclusion is a progressive and very limited aggregation of these surfactants in DMSO with a structure where the hydrophobic chains tend to gather together. Equilibrium constants for a multistep equilibrium are clearly weaker for the primary step of dimerization, thus showing the existence of weak cooperative solvophobic effects in higher aggregates.