Synthesis,crystal structure,and photoluminescence of zinc complex [Zn(Qina)<Subscript>2</Subscript>(DMSO)<Subscript>2</Subscript>] · 2DMSO

A novel complex [Zn(Qina)₂(DMSO)₂] · 2DMSO (I) (Qina = quinaldic acid, DMSO = dimethyl sulfoxide) has been synthesized and characterized by X-ray diffraction, elementary analysis, and IR spectrum. The unit cell parameters for complex I: a = 8.2884(11), b = 22.015(3), c = 9.0685(12) Å, β = 100.61(0)°, V = 1626.41(40) ų, Z = 2, space group, P2₁/n. In the complex I, the Zn(II) atom was six-coordinated to form a distorted octahedral geometry by two Qina ligands and two dimethyl sulfoxide molecules. The crystal structure is stabilized by hydrogen bonds, C - H... π, π-π stacking interaction between adjacent complexes. The binding of the complex I with calf thymus DNA has been investigated by fluorescence spectroscopic studies. The result suggested that the complex intercalates into DNA base pairs.     

Improved Fluorometric DNA Determination Based on the Interaction of the DNA/Polycation Complex with Hoechst 33258

When DNA is mixed with the cationic polyelectrolyte poly(diallyldimethyl ammonium chloride) (PDDA), the DNA/PDDA complex is formed instantaneously at room temperature. This complex is much more efficient in enhancing the fluorescence of Hoechst 33258 (H 33258) than DNA alone. Based on the interaction of H 33258 with the DNA/PDDA complex, a new fluorescence assay for DNA is described. At pH 7.3 in Tris-HCl buffered solution, the DNA/PDDA complex causes a sharp enhancement in fluorescence intensity of H 33258. Simultanously, the emission maximum wavelength of H 33258 blueshifts from 490nm to 450nm, while the excitation redshifts from 345 to 350nm. The calibration graphs for calf thymus DNA (ctDNA) and herring sperm DNA (hsDNA) are both linear up to 5.0µgmL^–1 when the concentration of H 33258 and PDDA are fixed at 1.5×10^–6 and 1.6×10^–5molL^–1, respectively. The method is specific for native DNA. The 3 detection limits for ctDNA and hsDNA are 1.8 and 5.6ngmL^–1, respectively, i.e. much lower than in the presence of H 33258 alone. Four synthetic samples were determined satisfactorily. This method can also be developed to investigate the formation and the nature of the complexes between DNA and polycations, which have recently been widely applied in some fields such as genetic engineering and gene therapy.     

Synthesis of monolithic columns based on poly(styrene-co-divinylbenzene) with the capillary-like flow-through pore diameter by template method

Poly(styrene-co-divinylbenzene) (PSt-DVB) is one of the most important kinds of organic polymeric monolithic columns. In order to improve its efficiency, it is necessary that the column has regular microstructure. In this research, hollow and ordered PSt-DVB columns were successfully prepared through radical polymerization using crystal structure of dimethyl sulfoxide as template. Different initiation types, times and storing temperatures were mainly investigated. The results showed PSt-DVB prepared at a temperature lower than the melting point of DMSO had regular and oriented structure. And longer initiating time and higher storing temperature helped polymer forming.     

DNA Interaction with PtCl<Subscript>2</Subscript>(LL) (LL = Chelating Diamine Ligand: <Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>-Dimethyltrimethylendiamine) Complex

The [PtCl₂(LL)] complex, as a cisplatin derivative, which LL is diamine chelate ligand (N,N-dimethyltrimethylendiamine), was synthesized and characterized by elemental analysis (CHN) mass, ¹H, and ¹³C nuclear magnetic resonance techniques. Then the binding of this complex to calf thymus DNA was investigated by various physicochemical methods such as spectrophotometric, circular dichroism, spectrofluorometric, melting temperature, and viscosimetric techniques. Upon addition of the complex, important changes were observed in the characteristic UV–Vis bands (hypochromism) of calf thymus DNA, increase in melting temperature and some changes in specific viscosity. Also, the fluorescence spectral characteristics showed an increase in the fluorescence intensity of methylene blue–DNA solutions in the presence of increasing amounts of metal complex, indicating PtCl₂(LL) is able to displace the methylene blue bound to DNA but not as complete as intercalative molecules. The experimental results showed that the platinum complex is bound to DNA non-intercalatively, and an outside binding is the preferred mode of interaction.     

Complex formation of halogenated alcohols with various electron donors

The results are reported of a study, by the near i.r. spectroscopic method, of the hydrogen bonding between 2-bromoethanol, 2-chloroethanol and 2-fluoroethanol, and hexamethylphosphortriamide, dimethyl sulfoxide, dibenzyl sulfoxide, di-p-tolyl sulfoxide and diphenyl sulfoxide in carbon tetrachloride at 288.15, 298.15, 308.15 and 318.15 K.The K₁₁, ΔH°, ΔG° and ΔS° values for the complex formation show that the complex formation ability of the 2-halogen substituted ethanols is weak towards the selected electron donors and much weaker than found earlier for the corresponding 2,2,2-trihalogen substituted ethanols. The basicity order of the electron donors decreases in the order hexamethylphosphortriamide ⪢ dimethyl sulfoxide ⪢ dibenzyl sulfoxide ⪢ di-p-tolyl sulfoxide ⪢ diphenyl sulfoxide, while the proton donating ability of the halogenated alcohols is in the order 2-bromoethanol ⪢ 2-chloroethanol ⪢ 2-fluoroethanol. The pK_a values of the alcohols determined in water are in the same order. Therefore the order of the complex formation ability is opposite to the acidity order in water.     

Alkylation of methyl 4,6-O-benzylidene-α-D-galactopyranoside

The partial alkylation of methyl 4,6-O-benzylidene-α-D-galactopyranoside in dimethylformamide and dimethyl sulfoxide in the presence of barium oxide and hydroxide is described. It has been shown that methylation and benzylation lead predominantly to the 3-alkyl derivatives with yields of 30–40%, benzylation taking place more selectively than methylation. The compounds synthesized have been characterized by their melting points and specific rotations.     

Volume properties of reverse micellar systems AOT/n-heptane/DMSO-water

The volume properties of reverse micellar systems bis(2-ethylhexyl) sulfosuccinate sodium salt/n-heptane/dimethyl sulfoxide-water are studied via densitometry. The presence of dimethyl sulfoxide and the increase in its amount in a dimethyl sulfoxide-water mixed solvent raise the apparent volume of the polar phase. This increase is also observed when the degree of hydration of the polar core and the temperature are raised.     

Thermosensitive PNIPAAm cryogel with superfast and stable oscillatory properties

Through copolymerization/crosslinking in dimethyl sulfoxide (DMSO) at temperature below the melting point of DMSO, we demonstrated a novel poly(N-isopropylacrylamide) (PNIPAAm) hydrogel with regularly oriented micromatrix; the superfast/stable oscillatory hydration-dehydration character of this hydrogel would find wide applications in biomedical field.     

Influence of Excitation of the Lanthanide 4 fShell on Complexation with Organic Substrates in Solutions: 2. Isotope Effects in Complexation of Tris(heptafluorodimethyloctanedionato)europium(III) with Dimethyl Sulfoxide in Benzene Solutions

The effect of deuteration of dimethyl sulfoxide on the fluorescence quantum yield, temperature quenching of fluorescence, and its complexation with tris(heptafluorodimethyloctanedionato)europium(III) (Eu(fod)₃) in the ground and excited states was studied. It was found that excitation of f–ftransitions in Eu(III) increases the stability of Eu(fod)₃complexes with sulfoxides but has a very insignificantly influence on isotope effects. The deuterium effect is displayed to a small extent in altering the quantum yield and is accompanied by a decrease in the efficiency of temperature quenching of Eu(fod)^* ₃fluorescence.     

A Novel Cobalt(III) Mixed-polypyridyl Complex: Synthesis, Characterization and DNA Binding

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Change in the reactivity of N-vinylsuccinimide after complexation with dimethyl sulfoxide

The influence of dimethyl sulfoxide on the copolymerization kinetics and the reactivity parameters of N-vinylsuccinimide was studied. It was shown that, owing to the complexation of monomer molecules with dimethyl sulfoxide molecules, the relative activities of monomers are changed. The electron structures of N-vinylsuccinimide and dimethyl sulfoxide molecules and the molecule geometry was considered, and a complexation mechanism was proposed. The Alfrey–Price Q-e parameters of N-vinylsuccinimide during the complexation were analyzed. The causes of the change in the reactivity of monomer were revealed.     

Synthesis and characterization of ruthenium(ii) complexes of 5-hydroxyflavones

Bis(dimethyl sulfoxide)bis(flavonato)ruthenium(II) complexes, RuL₂(DMSO)₂, were synthesized by the reaction of dichlorotetrakis(dimethyl sulfoxide)ruthenium(II) with the sodium salts of 5-hydroxyflavone, 5-hydroxy-4′-methoxyflavone and 5-hydroxy-3′,4′,5′,7-tetramethoxyflavone, ( L ). The complexation was followed by ¹H nmr spectroscopy. The 1:1 kinetically favoured tris(dimethyl sulfoxide)chloroflavonatoruthenium(II) complexes, RuLCl(DMSO)₃, were initially formed and then transformed into the thermodynamically more stable ones. Each one of these complexes, by reacting with another equivalent of lig-and L, also gave rise to a mixture of 1:2 kinetic species, from which the 1:2 thermodynamically more stable bis(dimethyl sulfoxide)bis(flavonato)ruthenium(II) complexes, RuL₂(DMSO)₂, were formed. The complexes were characterized by extensive studies involving ¹H, ¹³C nuclear magnetic resonance, infrared and ultraviolet-visible spectroscopy, mass spectrometry, cyclic voltammetry and elemental analysis. Such 1:2 complexes exhibited properties of two nonequivalent flavonate ligands and also of two non-equivalent dimethyl sulfoxide ligands; one of these dimethyl sulfoxide ligands is considered to be S-bonded and the other O-bonded. Also two quasireversible one-electron redox steps were observed at 0.53 to 0.57 and 0.44 to 0.41 V (vs Saturated Calomel Electrode). The spectroscopic results obtained allow for the discussion of stereochemistry of each bis(dimethyl sulfoxide)bis(flavonato)ruthenium(II) complex and to postulate its possible structure as one corresponding to the more anisochronous species.     

How and how much can Hoechst 33258 cause unwinding in a DNA duplex?

The effect of Hoechst 33258 binding on the geometry of a DNA duplex (plasmid pBR322) has been examined using topoisomerase II relaxation followed by gel electrophoresis. Of this drug-DNA system, fluorescence, optical absorption, and calorimetric measurements were also made at various drug and DNA concentrations and in the same buffer as that for the topoisomerase reaction. It has been confirmed that there are two modes of drug-DNA interaction. When the drug concentration is much lower than the DNA base pair concentration, the Hoechst 33258 molecule binds in the minor groove of the DNA duplex and occupies a site formed of five continuous base pair sequences that contain no G.C pair. Here, the equilibrium constant K1 is 1.8 x 10(7) M-1 (at 37 degrees C), and the enthalpy of binding delta H1 is -865 cal/mol. When the drug concentration is much higher, on the other hand, it shows another binding mode which is much weaker, so that K2 = 2.25 x 10(4) M-1 and delta H2 is -464 cal/mol, which gives fluorescence quenching, which has no base pair preference, and which causes an unwinding of the duplex by 1 degree.     

[Ni(qina)2(H2O)2]·2DMSO配合物的合成、结构及其催化性能

在常温下, 通过溶剂置换法制备了[Ni(qina)2(H2O)2]·2DMSO单晶, 其中qina-为喹哪啶酸根, DMSO为二甲亚砜. 配合物属于单斜晶系, C2/m空间群. 2个qina-配体以氮原子和氧原子与Ni(Ⅱ)离子反式螯合配位, 2个H2O分子则以氧原子与Ni(Ⅱ)离子轴向配位, 形成八面体配合物. 配合物分子之间通过氢键和π-π堆积等弱相互作用构筑成三维超分子结构. 该配合物能显著提高乙酸-1-萘酯的水解反应速率, 当配合物浓度为1.0×10-4 mol/L时, 在pH=8.44的乙酸-1-奈酯体系中, 酯的水解速率提高了365倍.     

DNA interaction with Al-N,N'-bis(salicylidene)2,2'-phenylendiamine complex

The Al(III) complex, [Al(salophen)2H2O]NO3, was synthesized and characterized by spectroscopic (NMR and FT-IR) techniques. Then the binding of Schiff base complex of [Al(salophen)]+ type, where salophen denotes N,N'-bis(salicylidene) 2,2-phenylendiamine to calf thymus DNA, has been investigated by spectrophotometric, circular dichroism, spectrofluorometric, melting temperature and viscosimetric techniques. This Al(III) complex showed absorption hyperchromism in the range of 310-390 nm, increase in melting temperature, some structural changes in specific viscosity, when bound to calf thymus DNA. The binding constant has been determined using absorption measurement and found to be 1.82 x 10(3)M(-1) and 1.31 x 10(3)M(-1) in HEPES and Tris-HCl buffers, respectively. Also the fluorescence spectral characteristics and interaction of Al-salophen complex with DNA have been studied. Al-salophen bound to DNA showed a marked increase in the fluorescence intensity along with a bathochromic shift (5 nm). The intersection point of the binding isotherm indicated a binding site size of 12 bp per bound complex molecule in both HEPES and Tris-HCl buffers. The experimental results showed that the Al-salophen complex bound to DNA by non-intercalative mode and major groove binding was the preferred mode of interaction.     

Mixed ligand cobalt(II) picolinate complexes: synthesis, characterization, DNA binding and photocleavage

Complexes of the type [Co(pic)(2)(NN)], where pic = picolinate, NN = dipyrido[3,2-d:2',3'-f]quinoxaline (dpq) (4) and 4b,5,7,7a-tetrahydro-4b,7a-epiminomethanoimino-6H-imidazo[4,5-f][1,10]-phenanthroline-6,13-dione (bipyridyl-glycoluril) (bpg) (6) have been synthesized and characterized by elemental analysis, IR, UV-vis, NMR and ESI-MS spectroscopy and thermogravimetic analysis (TGA). Their physicochemical properties are compared with previously synthesized complexes, where NN = (H(2)O)(2) (1), 2,2'-bipyridine (bpy) (2), 1,10-phenanthroline (phen) (3) and dipyrido[3,2-a:2',3'-c]phenazine (dppz) (5). The crystal structures of the complexes 4-6 were solved by single-crystal X-ray diffraction. The complexes 4 and 5 crystallize from a mixture of chloroform and methanol in monoclinic and orthorhombic crystal systems, respectively, whereas complex 6 crystallizes from dimethyl sulfoxide (DMSO) in a tetragonal crystal system. The coordination sphere consists of two oxygen atoms and two nitrogen atoms from the two picolinates and two nitrogen atoms from the dpq, dppz or bpg ligand, respectively. Co(ii)/Co(iii) oxidation potentials have been determined by cyclic voltammetry. The DNA binding of complexes 1-5 has been investigated using thermal melting, fluorescence quenching and viscosity measurements, which indicate the partial intercalation of complex 5 with an apparent binding constant (k(app)) of 8.3 × 10(5) M(-1). DNA cleavage studies of complexes 1-5 have been investigated using gel electrophoresis in the presence of H(2)O(2) as an oxidizing agent and also by photoirradiation at 365 nm. The mechanistic investigations suggest that singlet oxygen ((1)O(2)) is the major species involved in the DNA cleavage by these complexes. The structures of complexes 2-6 were optimized with density functional theory (DFT) method (B3LYP/6-31G(d,p)). The low vertical ionization potential values indicate photoredox pathways for the DNA cleavage activity by complexes 4 and 5, which is corroborated by DNA cleavage experiments.     

Studies of interaction of emodin and DNA in the presence of ethidium bromide by spectroscopic method

Emodin interacting with deoxyribonucleic acid (DNA) has been studied by different spectroscopic techniques, such as fluorescence, ultraviolet and visible (UV-vis), and fourier transform infared (FT-IR) spectroscopies, using ethidium bromide (EB) as a fluorescence probe of DNA. The decrease in the fluorescence of DNA-EB system on addition of emodin shows that the fluorescence quenching of DNA-EB complex by emodin occurs. The binding constants of emodin with DNA in the presence of EB are 6.02x10(4), 9.20x10(4) and 1.17x10(5)Lmol(-1) at 20, 35 and 50 degrees C, respectively. FT-IR spectrum further suggests that both the phosphate groups and the bases of DNA react with emodin. The reaction of DNA with emodin in the presence of EB is affected by ionic strength and temperature. The values of melting temperature (T(m)) of DNA-EB complex and emodin-DNA-EB complexes were determined, respectively. From the experiment evidences, the major binding mode of emodin with DNA should be the groove binding.     

A FLUORESCENCE STUDY OF THE BINDING OF HOECHST 33258 and DAPI TO HALOGENATED DNAs

We have studied the time-resolved and the steady-state fluorescence of the DNA groove binders 4',6-diamidino-2-phenylindole (DAPI) and Hoechst 33258 with the double stranded DNAs poly(dA-dU) and poly(dI-dC) and their halogenated analogs, poly(dA-I5dU) and poly(dI-Br5dC). These studies were prompted by earlier observations that steady-state fluorescence of Hoechst 33258 is quenched on binding to halogenated DNAs (presumably due to an intermolecular heavy atom effect involving the halogen atom in the major groove), and recent studies which clearly point to a binding-site in the minor groove of DNA. Measurements of the time resolved fluorescence decay demonstrate that the fluorescence of Hoechst 33258 is quenched on binding to the halogenated DNAs, in agreement with previous observations. However, quenching studies carried out using the free halogenated bases IdUrd and BrdCyd in solution yielded bimolecular rate constants more than one order of magnitude larger than those expected for an intermolecular heavy atom effect. Moreover, the quenching of the Hoechst 33258 fluorescence was accompanied by an accelerated photochemical destruction of Hoechst 33258. We therefore conclude that the fluorescence quenching observed with halogenated DNAs is probably due to a photochemical reaction involving Hoechst 33258, rather than direct contact of Hoechst 33258 with the halogen substituents in the major groove of the DNA. The fluorescence decay measurements however, do provide clear evidence for at least two different modes of binding. Taking into account the alternating sequences used in this study and the possibility of two different conformations for bound dye, at least four different modes of binding are plausible. Our present data do not allow us to distinguish between these alternatives. The time-resolved fluorescence decays and fluorescence quantum yields of DAPI are not affected by the presence of the heavy atom substituents in the DNA major groove. Based on this observation and earlier reports that DAPI binds in one of the DNA grooves, we conclude that the high affinity sites for DAPI on DNA are located in the minor groove.     

Thermodynamic Study of Poly(vinyl pyrrolidone) in Water/Dimethyl Sulfoxide Solutions by Viscometry

In this work, the intrinsic viscosities of poly(vinyl pyrrolidone) with a molar mass of 58?kg?mol^?1 were measured in water?Cdimethyl sulfoxide solutions at temperatures from (298.15 to 318.15)?K. The expansion factors of the polymer chains were calculated from the intrinsic viscosity data. The thermodynamic parameters (entropy of dilution parameter, the heat of dilution parameter, theta temperature, polymer?Csolvent interaction parameter and second osmotic virial coefficient) were derived by the temperature dependence of the polymer chain expansion factor. The thermodynamic parameters indicate that mixtures of water/dimethyl sulfoxide become poorer solvents for poly(vinyl pyrrolidone) as the temperature is increased. Also, the thermodynamic parameters indicate that water/dimethyl sulfoxide mixtures become better solvents for poly(vinyl pyrrolidone) by increasing the volume fractions of dimethyl sulfoxide.     

Molecular complexes of dimethyl sulfoxide with tri‐ and dichloromethane

Crystals of molecular complexes of dimethyl sulfoxide with trichloromethane (chloroform), (CH₃)₂SO·2CHCl₃, (I), and dichloromethane, (CH₃)₂SO·CH₂Cl₂, (II), have been grown in situ. In both compounds, the components are linked together by (Cl)C—H...O interactions. The dimethyl sulfoxide molecules in (I) are bound into chains by C—H...O interactions. In (II), pairs of the components form centrosymmetric rings, linked into a three‐dimensional network by C—H...O contacts and dipole–dipole interactions between dimethyl sulfoxide molecules.