Dimethyl Sulfoxide Complexes Research Articles

Curdlan Complexes As a Potential food-grade Delivery System: Genistein Case Study

Complexes of curdlan and genistein were prepared using four different methods. The total amount of genistein in curdlan-genistein complexes prepared at 40 degrees C (system I) was significantly higher (2.3 mg/100 mg dry matter) than that in other systems studied: curdlan-genistein complexes prepared at 60 degrees C (system II; 1.8 mg/100 mg dry matter); curdlan-genistein gel complexes (system III; 1.0 mg/100 mg dry matter); and curdlan-genistein dimethyl sulfoxide complexes (system IV; 1.8 mg/100 mg dry matter). x-ray diffraction results indicate that complexation of curdlan with genistein changes the crystalline nature of the pure components. Particle size analysis, atomic force microscopy and scanning electron microscopy imaging of curdlan-genistein complexes showed strong difference in particle size, surface and distribution in comparison with pure curdlan, confirming our assumption of a molecular interaction between curdlan and genistein and the formation of a new structure, which was revealed at the nanoscale level. All the curdlan-genistein complexes showed prolonged genistein release of up to 72 h, enhanced upon enzymatic digestion of curdlan by lyticase, thus opening the possibility of release regulation by the incorporation of lyticase in the delivery system. It is therefore suggested that the complexes could be used as a delivery system for the protection and slow release of genistein in the digestive tract.

Sub-nanosecond photolysis studies of Fe 2+ protoporphyrin IX solubilized in neat dimethyl sulfoxide

The present study examines the optical properties of the sub-nanosecond photolytic transient of Fe(II)protoporphyrin IX (Fe(II)PPIX) in neat dimethyl sulfoxide (DMSO). Previous nanosecond studies have revealed that photolysis of the (DMSO) 2Fe(II)PPIX complex in neat DMSO results in the formation of a five-coordinate high-spin (DMSO)Fe(II)PPIX complex within ∼100 ns which decayed with a pseudo-first order rate constant of 2 × 10 6 s −1 (Larsen et al. (1995) [19]). The results presented here demonstrate that the five-coordinate (DMSO)Fe(II)PPIX species is generated in <100 ps and that no significant changes occur in the kinetic difference between 100 ps and ∼100 ns. The 100 ps transient spectrum of the (DMSO)Fe(II)PPIX complex was also constructed from the kinetic difference spectrum and the equilibrium spectrum of the (DMSO) 2Fe(II)PPIX. The 100 ps transient spectrum exhibits a Soret maximum at ∼432 nm close to that of deoxyMb (435 nm, imidazole coordination) consistent with S-bonded DMSO occupying the fifth coordination site. Neither base elimination is detected on time scales down to 100 ps nor is there evidence for transient O-bonded DMSO followed by linkage isomerization to the equilibrium S-bonded form. The unusually slow rate of DMSO recombination is attributed to electrostatic interactions between DMSO and the five-coordinate heme iron as well as intermolecular interactions between solvent molecules in the bulk, as has been previously proposed.

Electronic and Steric Effects on the Photoisomerization of Dimethylsulfoxide Complexes of Ru(II) Containing Picolinate

Calculations were performed on [Ru(tpy)(bpy)(dmso)]2+ (tpy = 2,2′:6′,2′′-terpyridine; bpy = 2,2′-bipyridine, dmso = dimethylsulfoxide, 1), cis-[Ru(tpy)(Me-pic)(dmso)]+ (Me-pic = 6-methylpicolinate,...

Syntheses of ruthenium(II)-4,4′-biimidazole complexes and their potential anti-tumour activity

Synthesis and characterization of the RuII complexes, [Ru(N−N)3][CF3SO3]2, where N−N is 4,4′-biimidazole (complex 1a) or 2,2′-dimethyl-4,4′-biimidazole (1b), and the dimethylsulfoxide complexes RuCl2(DMSO)2(N−N) are reported. The air-stable, water-soluble complexes were characterized by elemental analysis, 1H NMR and IR spectroscopies, mass spectrometry, and solution conductivity. Evidence is presented also for the existence of the diruthenium complexes Ru2Cl4(DMSO)4(N−N), but there are insufficient data for elucidation of their structure. The complexes (and cisplatin) were tested against human breast-cancer cells (MDA-MB-435S) using an in vitro MTT assay, a colorimetric determination of cell viability: 1a and 1b exhibit the lowest IC50 values of 18 ± 5 and 36 ± 5 µmol/L, respectively, with cisplatin exhibiting an IC50 value of 35 ± 5 µmol/L. Isolation of DNA from cells treated with a solution of the Ru species showed no evidence of DNA-binding to the metal, although examination of the cells indicated that Ru was being taken up into the cells.

Sulfation of a squid ink polysaccharide and its inhibitory effect on tumor cell metastasis

This paper is the first to report the preparation, characterization, and potential biological activities of a chemically sulfated polysaccharide isolated from the ink of the squid, Ommastrephes bartrami. The squid ink polysaccharides (SIPs) were firstly sulfated with the pyridine–sulfur-trioxide complex in dimethyl sulfoxide. Structural characterization of sulfated SIP using nuclear magnetic resonance indicated that sulfation mainly occurred at the 4,6-position of GalNAc. The effects of the sulfated SIP (TBA-1) on tumor cell growth, invasion, and migration were examined in vitro, and its effects on angiogenesis were measured in vivo using the chick embryo chorioallantoic membrane (CAM) assay. TBA-1 did not have any obvious effects on the proliferation of HepG2 tumor cells, but induced the dose-dependent suppression of cell invasion and migration in HepG2. Moreover, TBA-1 obviously inhibited angiogenesis in a CAM model. Thus, our results indicate that TBA-1 is a potential candidate compound for the prevention of tumor metastasis.

Electrochemical bromination of peracetylated d-glucal: Effect of DMSO on chemoselectivity

Abstract The electrochemical bromination of 3,4,6-tri-O-acetyl- d -glucal (1) has been investigated in dimethyl sulfoxide (DMSO) by cyclic voltammetry and preparative-scale electrolyses. In this solvent, the bromination involves a bromine–DMSO complex of the type [DMSO–Br]+Br− whose reactivity towards 1 was clearly evidenced by cyclic voltammetry. Importantly, only the monobrominated glucose and mannose derivatives were obtained from electrolyses. This specific behavior was attributed to the nucleophilicity of DMSO that may react with the oxocarbenium intermediate preventing thus a possible second bromination of the transient species. The gluco/manno ratio, roughly equal to 30/70, indicated an electrophilic attack by [DMSO–Br]+Br− preferentially from the β side of the starting glycal for steric reasons. The treatment of the crude product obtained after the end of the electrolyses with acetic anhydride allowed the preparation of derivatives in which the anomeric carbon bears an acetoxy group. Based on both the cyclic voltammetry experiments and preparative-scale electrolyses, a mechanism is proposed for the bromination of peracetylated d -glucal in DMSO. These new and original results are of high interest in carbohydrate chemistry and especially for the preparation of new valuable oligosaccharides.

Interaction of dimethylsulfoxide and diethylsulfoxide complexes of platinum(II) with bovine serum albumin

We have used electronic absorption spectroscopy in the UV region to study the interaction of a dimethylsulfoxide complex of platinum(II) (cis-[Pt(DMSO)2Cl2]) and a diethylsulfoxide complex of platinum (II) (cis-[Pt(DESO)2Cl2]) with bovine serum albumin (BSA). We have calculated the physicochemical binding parameters for binding with BSA (the binding constants and the Hill coefficient). We found that sulfoxide ligands promote an increase in the rate of binding of the complexes with BSA. Binding of cis-[Pt(DMSO)2Cl2] and cis-[Pt(DESO)2Cl2] with BSA leads to a decrease in the thermal stability of the protein. The leaving groups in the complexes for binding with BSA are the sulfoxide molecules, and the mechanism for binding between the dialkylsulfoxide complexes and the protein remains unchanged.

Synthesis, photophysical and nonlinear optical properties of microwave synthesized 4-tetra and octa-substituted lead phthalocyanines

This work presents the photophysical and nonlinear optical behaviour of newly synthesized complexes: 2,(3)-tetrakis(4-benzyloxyphenoxyphthalocyaninato) lead ( 5a) and 2,3-octakis(4-benzyloxyphenoxyphthalocyaninato) lead ( 6a). The nonlinear optical behaviour of complexes 5a and 6a are compared with those of 2,(3)-tetraphenoxyphthalocyaninato lead ( 5b), 2,(3)-tetrakis(4-t-butylphenoxyphthalocyaninato) lead ( 5c), 2,3-octaphenoxyphthalocyaninato lead ( 6b) and 2,3-octakis(4-t-butylphenoxyphthalocyaninato) lead ( 6c). The synthesis of 5a and 6a was performed using microwave irradiation. Photophysical properties were studied for these complexes in dimethylsulfoxide, dimethylformamide, toluene, tetrahydrofuran and chloroform. The fluorescence spectra were different from excitation spectra due to demetallation upon excitation. High triplet quantum yields ranging from 0.80 to 0.86 (in DMSO, DMF and toluene) and low triplet lifetimes (20–50 μs in DMSO, and <10 μs in the rest of the solvents) were observed due to the presence of heavy atom. Nonlinear optical properties were studied in dimethylsulfoxide. The optical limiting threshold intensity ( I lim) for the PbPc derivatives were calculated and ranged from 2.1 to 6.6 W/cm 2.

Synthesis and crystal structures of polynuclear complexes of Cu I with 1-methyl-1,3-imidazoline-2-thione

Reactions of equimolar solutions of copper(I) halides with 1-methyl-1,3-imidazoline-2-thione (SC 4H 6N 2) in acetonitrile have yielded a trinuclear complex, {Cu 3(η 1-Br) 3(μ-SC 4H 6N 2) 3} · CH 3CN 1, and 1D polymer, {Cu 2(μ-I) 2(μ-SC 4H 6N 2) 2} n 2. The thio-ligands/halogens adopt μ-S, η 1-X or μ-X modes. There is weak interaction between trinuclear units {Cu···Br, 3.025 Å} and Cu···Cu contacts lie in the range, 2.974(2)–3.650(2) Å. Polymer 2 has alternating Cu 2I 2 and Cu 2S 2 cores involving sulfur/iodine bridging in a twisted ribbon type arrangement with short Cu···Cu distances {2.6912(9) and 2.785(9) Å}, respectively. The polynuclear complexes in dimethyl sulfoxide exhibit intense fluorescent bands { λ em = 319 ( 1) and 322 ( 2)}.

1H NMR spectrum and computational study of firefly luciferin in dimethyl sulfoxide

Experimental and theoretical 1H NMR chemical shift values ( δs) of firefly luciferin (Ln) in dimethyl sulfoxide (DMSO) were studied for the estimation of the detailed structure of Ln and the characteristics of the interaction between Ln and DMSO. The 1H chemical shifts were recorded in DMSO- d 6. The temperature dependence of δ obs.s of Ln of the 1H NMR chemical shifts was also measured. The theoretical NMR chemical shifts ( δ calc.s) were calculated based on the GIAO DFT approach, using the 6-311+G(2d,p) basis set (a total of 544 contracted basis functions), implemented in the Gaussian software package. The solvent effect was obtained by means of the Onsager reaction field model or an Ln···DMSO hydrogen-bonded complex model. The calculated results of the Ln···DMSO complex model are in good agreement with the observed chemical shifts, but all observed 1H peaks could not be reproduced for the optimized structure of Ln using the Onsager reaction field model. The considerably large δ obs.s of –H and –OOH protons of Ln in the observed 1H NMR spectra are probably explained in terms of hydrogen-bonded complex model between protons in Ln and oxygen atoms in DMSO molecules, rather than in the Onsager reaction field model.

Synthesis, photophysical and photochemical properties of octa-substituted antimony phthalocyanines

This work reports on the synthesis and photophysicochemical parameters of unsubstituted [Sb IIIPc] + I 3 - and octa-phenoxy ([Sb IIIOPPc] + I 3 - ) and -4- t-butylphenoxy ([Sb IIIOTBPPc] + I 3 - ) substituted antimony phthalocyanines. Photophysical and photochemical properties were studied for these complexes in dimethylsulfoxide, dimethylformamide and toluene. The excitation spectra of oxidized antimony (Sb(V)Pc) derivates were similar to absorption spectra. Low fluorescence quantum yields, high triplet quantum yields and low triplet lifetimes were observed as the result of heavy atom (antimony ion).

Copper(I) Templated Synthesis of a 2,2´-Bipyridine Derived 2-Catenane: Synthetic, Modelling, and X-ray Studies

Following molecular modelling employing molecular mechanics and semi-empirical (PM3) calculations as an aid to ligand design, a new copper(i)-containing [2]-catenane has been prepared by the reaction of 6,6′-bis[(4″-formylphenoxy)methyl]-2,2′-bipyridyl with 1,6-hexanediamine in the presence of a copper(i) template, followed by in situ sodium borohydride reduction of the tetra-imine species generated. The corresponding [2]-catenane was obtained as a deep orange crystalline solid. The X-ray structure of this product along with that of the corresponding bis-dialdehyde precursor copper(i) complex have been determined. In the latter case, the structure is pre-organized for catenane formation. The new catenane appears to be the first example of a tetrahedral metal template product incorporating a bis-bipyridyl derivative core. Isolation of the metal-free [2]-catenane has also been achieved following treatment of the copper(i) catenane complex in dimethylsulfoxide with tetrabutylammonium cyanide.

Spectroscopic determination of binding between human serum albumin and a platinum(II) dimethylsulfoxide complex

We have used electronic absorption and fluorescence spectroscopy to study binding between a platinum(II) dimethylsulfoxide complex (cis-[Pt(DMSO)2Cl2]) and human serum albumin (HSA), and the effect of complexation on the structure of the protein. We have calculated the binding parameters for binding between cis-[Pt(DMSO)2Cl2] and HSA. We have determined the binding constant KB = (1.2 ± 0.1)·103 M−1 and the Hill coefficient h = 1.03 ± 0.1. We have determined that binding between cis-[Pt(DMSO)2Cl2] and the protein leads to a change in the internal packing of the macromolecule.

Cadmium(II) for zinc(II) exchange reactions in deutero- and hematoporphyrin complexes in dimethyl sulfoxide

The metal-exchange reaction between Cd-deuteroporphyrin or Cd-ematoporphyrin and ZnCl2 in dimethyl sulfoxide (DMSO) was studied spectrophotometrically. The order and activation parameters of the reaction of Cd2+ replacement by zinc ions were calculated. A mechanism of this reaction is suggested. The results are compared with the available data on metal-exchange reactions between Cd-mesoporphyrin and Cdprotoporphyrin and ZnCl2 in DMSO.

Solvent effects on vibrational spectra of hydrogen-bonded complexes of propanedinitrile (malononitrile) and dimethyl sulfoxide (DMSO): Ab initio and DFT studies

The hydrogen-bonded complexes malononitrile–dimethyl sulfoxide (DMSO) ( 1: 1; 1: 2) have been studied extensively by ab initio and DFT (B3LYP) calculations with different basis sets. The most stable structures of the complexes are established. The vibrational spectra of the complexes have been predicted by ab initio and B3LYP calculations and the solvent effects on the vibrational spectrum of malononitrile are evaluated. In agreement with the experiment, the calculations show that the moderately strong O…C–H hydrogen bonds are formed between malononitrile and DMSO that lead to the substantial changes in the vibrational characteristics (vibrational frequencies and IR intensities) for ν sym(CH 2) and ν as(CH 2) in malononitrile. The predicted frequency shift with B3LYP/6-311++G(d,p) calculations for ν sym(CH 2) is −98 cm −1 and for ν as(CH 2) is −53 cm −1, while the experimentally observed shifts are in the range: from −51 to −81 cm −1. The IR intensity for ν sym(CH 2) increases upon hydrogen bonding at the higher extent in comparison with the IR intensity of ν as(CH 2).

Photochemical Properties of Camptothecin in the Presence of Copper(II) Ions: The Role of Radicals as Prospective Species in Photodynamic Therapy

Camptothecin (CPT) is an anticancer drug that inhibits topoisomerase I (Topo I) by forming a ternary DNA-CPT-Topo I complex. However, it has also been shown that UVA-irradiated CPT in the absence of Topo I produces significant DNA damage to cancer cells. In this work, we explored and identified free radicals generated in these processes. From the low-temperature EPR spectrum of Cu(II)-CPT complex, a proximity between Cu(II) ion and 20-hydroxy group of lactone E ring of CPT is proposed. Upon irradiation (lambda = 365 nm) of the Cu(II)-CPT complex in de-oxygenated dimethylsulfoxide (DMSO), the EPR signal of Cu(II) measured in situ at room temperature shows formal first-order exponential decay with a formal half-life of 11 min. By the use of a specific Cu(I) chelating agent, neocuproine, it was shown that, during this process, Cu(II) is reduced to Cu(I). The loss in EPR signal intensity of the Cu(II)-CPT complex upon irradiation is accompanied by the appearance of a new EPR signal at g approximately 2.0022. Application of the spin trap nitrosodurene (ND) revealed that the main radical product formed upon continuous irradiation of CPT in DMSO solutions is the hydroxyl radical (trapped in DMSO as the *CH3 adduct) and superoxide radical. Application of 2,2,6,6-tetramethyl-4-piperidinol has revealed that irradiation of CPT in aerated DMSO solution also leads to formation of singlet oxygen (1O2). Our spectroscopic experiments indicate that CPT is a promising photosensitizer and that radicals and singlet oxygen generated upon illumination play a central role in DNA cleavage and in the induction of apoptosis in cancer cells.

Inclusion Compounds of Dehydrocholic Acid with Solvents

The host-guest inclusion of various organic solvents within dehydrocholic acid has been studied and the selectivity of enclathration determined by competition experiments.

Investigation of molecular association in mixtures of dimethylsulfoxide with trichloromethane by vibrational spectroscopy and ab initio calculations

Vibrational spectroscopy methods (IR absorption and Raman scattering) are employed to investigate molecular association in dimethylsulfoxide (DMSO)-trichloromethane (TCM) mixtures. A spectral manifestation of the interactions between DMSO and TCM molecules are revealed. The ground state geometry of the complexes of DMSO with TCM (dimers and trimers) are calculated by the ab initio MP2 method using the 6-31G** basis set.

Structural Evidence for a Ligand Coordination Switch in Liver Alcohol Dehydrogenase

The use of substrate analogues as inhibitors provides a way to understand and manipulate enzyme function. Here we report two 1 A resolution crystal structures of liver alcohol dehydrogenase in complex with NADH and two inhibitors: dimethyl sulfoxide and isobutyramide. Both structures present a dynamic state of inhibition. In the dimethyl sulfoxide complex structure, the inhibitor is caught in transition on its way to the active site using a flash-freezing protocol and a cadmium-substituted enzyme. One inhibitor molecule is partly located in the first and partly in the second coordination sphere of the active site metal. A hydroxide ion bound to the active site metal lies close to the pyridine ring of NADH, which is puckered in a twisted boat conformation. The cadmium ion is coordinated by both the hydroxide ion and the inhibitor molecule, providing structural evidence of a coordination switch at the active site metal ion. The structure of the isobutyramide complex reveals the partial formation of an adduct between the isobutyramide inhibitor and NADH. It provides evidence of the contribution of a shift from the keto to the enol tautomer during aldehyde reduction. The different positions of the inhibitors further refine the knowledge of the dynamics of the enzyme mechanism and explain how the crowded active site can facilitate the presence of a substrate and a metal-bound hydroxide ion.

Emission switching of ferrocenyl Schiff bases and a representative ruthenium complex in alkaline DMSO: Absorption, electrochemical and microstructural studies

N,N′-Bis(4-ferrocenyl)- p-phenylene/octamethylene-diimines (L 1/L 2) and a representative Ru(II) complex [Ru(DMSO) 2Cl 2L 1]·2H 2O were prepared and characterized which showed many fold enhancement in their luminescence in alkaline dimethylsulfoxide (DMSO) solution. Spectral and electrochemical properties of these compounds have been studied. Microstructure (SEM) of L 1 and its complex showed single-phase porous material of crystal size ∼1 μm.