Studies of the interaction between daidzein and 3′-daidzein sulfonic sodium with bovine serum albumin by spectroscopic methods

The interaction between daidzein and 3′-daidzein sulfonic sodium with bovine serum albumin (BSA) in physiological buffer (pH = 7.4) is investigated by fluorescence quenching technique and UV/vis absorption spectra. The results reveal that both daidzein and 3′-daidzein sulfonic sodium could strongly quench the intrinsic fluorescence of BSA. The quenching mechanism of both the daidzein and 3′-daidzein sulfonic sodium for BSA is static quenching procedure. The apparent binding constants K _a and number of binding sites n of daidzein and 3′-daidzein sulfonic sodium with BSA are obtained by fluorescence quenching method. The thermodynamic parameters, enthalpy change (Δ_r H ^m ), and entropy change (Δ_r S ^m ), are calculated, respectively, which indicate that the interaction of daidzein with BSA is driven mainly by hydrogen bonding and van der Waals, and 3′-daidzein sulfonic sodium with BSA is driven mainly by hydrophobic forces. The distance r between BSA with daidzein and 3′-daidzein sulfonic sodium are calculated to be 4.02 nm and 3.08 nm, respectively, based on F?rster’s non-radiative energy transfer theory. The results of synchronous fluorescence spectra show that binding of daidzein and 3′-daidzein sulfonic sodium with BSA cannot induce conformational changes in BSA.     

Electrospray mass spectrometric studies of a potential antitumor drug and its analogous platinum(II) and platinum(IV) complexes with the ethylenediamine-N,N′-di-3-propanoato ligand and its dibutyl ester

Abstract  The electrospray mass spectrometric (ESI–MS) behavior of the complexes trans-dichloro(ethylenediamine-N,N′-di-3-propionato)platinum(IV), trans-dibromo(ethylenediamine-N,N′-di-3-propionato)platinum(IV), dichloro(ethylenediamine-N,N′-di-3-propionic acid)platinum(II), tetrachloro(O,O′-di-n-butyl-ethylenediamine-N,N′-di-3-propanoate)platinum(IV), chlorotribromo(O,O′-di-n-butyl-ethylenediamine-N,N′-di-3-propanoate)platinum(IV), and dichloro(O,O′-di-n-butyl-ethylenediamine-N,N′-di-3-propanoate)platinum(II), with the formulae trans-[PtCl₂(eddp)] (1), trans-[PtBr₂(eddp)] (2), [PtCl₂(H₂eddp)] (3), [PtCl₄(Bu₂eddp)] (4), [PtBr₃Cl(Bu₂eddp)] (5), and [PtCl₂(Bu₂eddp)]·H₂O (6), is reported. The deprotonated molecular ions or halide adducts are usually observed. ESI–MS data demonstrate the usefulness of the method for efficient characterization of metal complexes in solution. Graphical Abstract        

Mass Spectrometric Determination of Association Constants of Bovine Serum Albumin (BSA) with para-Sulphonato-Calix[n]arene Derivatives

Electrospray Ionization Mass Spectrometry (ESI/MS) has been used to determine the association constants (K_As) and binding stoichiometries for parent para-Sulphonato-calix[n]arenes and their derivatives with bovine serum albumin (BSA). K_A values were determined by titration experiments using a constant concentration of protein. K_A measurements were carried out in a methanol–formic acid solution. 5,11,17,23–tetra-Sulphonato-calix[4]arene (1a) and 25-mono-(2-aminoethoxy)-5,11,17,23-tetra-Sulphonato-calix[4]arene (1d) interact strongly with BSA showing 3 non-equivalent binding sites with K_A1 = 7.69 × 10⁵ M⁻¹, K_A2 = 3.85 × 10⁵ M⁻¹, K_A3 = 0.33 × 10⁵ M⁻¹ and K_A1 = 1.69 × 10⁵ M⁻¹, K_A2 = 2.94 × 10⁵ M⁻¹, K_A3 = 0.60 × 10⁵ M⁻¹, respectively. The strength of the interactions between the calixarene and BSA is inversely proportional to the size of macrocyclic ring: n = 4 > n=6>>n=8.     

Fluorescence study on the interaction of bovine serum albumin with two coumarin derivatives

The interactions between bovine serum albumin (BSA) and two substituted hydroxychromone derivatives of coumarin, 3-hydroxy-7,8,9,10-tetrahydro-6H-benzo[c]chromen-6-on (C₃) and 1,3-dihydroxy-7,8,9,10-tetrahy-dro-6H-benzo[c]chromen-6-on (C_1.3), were investigated by fluorescence quenching spectra and UV-vis absorption spectra. It was proved that the fluorescence quenching of BSA by C₃ and C_{1, 3} was mainly a result of the formation of C₃ and C_1.3-BSA complexes. The Stern-Volmer quenching constants, binding constants, binding sites and the corresponding thermodynamic parameters ΔH ^o, ΔS ^o and ΔG ^o at different temperatures were calculated. The results indicated that van der Waals interactions and hydrogen bonds were the predominant intermolecular forces in stabilizing each complex. The detection limits of C₃ and C_1.3 were 5.08 × 10⁻⁷ and 1.11 × 10⁻⁷ M in the presence of BSA, respectively.     

Mesogenic and magnetic behavior in cobalt(II) and iron(II) compounds with long alkyl chains

Abstract  

Metal complexes with long alkyl chains [Co(C16-terpy)₃](BF₄)₂ (1), [Fe(C16-terpy)₂](BF₄)₂ (2), [Co(C16-terpy)₂](BPh₄)₂ (3), [Co(C14-terpy)₂](BF₄)₂ (4), and [Fe(C12C10C5-terpy)₂](BF₄)₂ (5) were synthesized and their physical properties characterized, where C16-terpy, C14-terpy, and C12C10C5-terpy are 4′-hexadecyloxy-2,2′:6′,2′′-terpyridine, 4′-tetradecyloxy-2,2′:6′,2′′-terpyridine, and 4′-5′′′-decyl-1′′′-heptadecyloxy-2,2′:6′,2″-terpyridine, respectively. Complexes 1, 2, and 5 exhibited liquid–crystal properties in the temperature ranges of 371–528 K and 466–556 K, and 88–523 K, respectively. Variable-temperature magnetic susceptibility measurements revealed that the Co(II) complexes 1 and 4 exhibited unique spin transitions (T _1/2↓ = 217 K and T _1/2↑ = 260 K for 1 and T _1/2↓ = 250 K and T _1/2↑ = 307 K for 4), so-called ‘reverse spin transition,’ induced by structural phase transitions. Complex 3 exhibited gradual spin-crossover behavior (T _1/2 = 160 K.), and complex 5 exhibited spin transitions (T _1/2↑ = 288 K and T _1/2↓ = 284 K) at the liquid crystal transition temperature. Compounds with multifunction, i.e., magnetic and liquid–crystal properties, are important in the development of molecular materials.     

Spectrophotometric determination of total protein in serum using a novel near-infrared cyanine dye, 5,5′-dicarboxy-1,1′-disulfobutyl-3,3,3′,3′-tetramethylindotricarbocyanine

The application of near-infrared (NIR) dyes (λ _em > 750 nm) to the analysis of biological samples shows much promise, because the long emission wavelengths of such dyes allow interferences from biomolecule matrices to be minimized. In this paper, a novel NIR dye, 5,5′-dicarboxy-1,1′-disulfobutyl-3,3,3′,3′-tetramethylindotricarbocyanine (DCDSTCY) has been developed for the spectrophotometric determination of total protein in serum. Under acidic conditions, the binding of DCDSTCY to proteins caused a new peak at 878 nm, the height of which was proportional to the concentration of protein. The linear range of the method was found to be 0.04–0.5 μg mL⁻¹ for bovine serum albumin (BSA) and human serum albumin (HSA), and detection limits of 5 ng mL⁻¹ were obtained for these substances. The maximum binding number of BSA with DCDSTCY was measured to be 133. The method proposed here has been applied to the quantitation of total protein in serum, and recoveries of 96.6–104% were achieved. Figure Near-infrared probe for protein determination     

Synthesis of azoles from 3,3′-[(4-alkoxyphenyl)imino]bis(propanoic acid hydrazides)

Abstract  

Reaction of 3,3′-[(4-alkoxyphenyl)imino]bis(propanoic acid hydrazides) with CS₂ in alkaline solution and subsequent acidification gave 5,5′-[[(4-alkoxyphenyl)imino]diethane-2,1-diyl]bis(1,3,4-oxadiazole-2(3H)-thiones). The same dihydrazides on reaction with phenyl isocyanates or phenyl isothiocyanates were converted to bis[N′-(phenylaminocarbonyl)propanoic acid hydrazides] and bis[N′-(phenylaminocarbonothioyl)propanoic acid hydrazides], which underwent cyclization in alkaline medium to produce 5,5′-[[(4-alkoxyphenyl)imino]diethane-2,1-diyl]bis(4-phenyl-2,4-dihydro-3H-1,2,4-triazol-3-ones) and their 3-thio analogues, whereas in sulfuric acid or POCl₃ 5,5′-[[(4-alkoxyphenyl)imino]diethane-2,1-diyl]bis(N-phenyl-1,3,4-oxadiazol-2-amines) and 5,5′-[[(4-alkoxyphenyl)imino]diethane-2,1-diyl]bis(N-phenyl-1,3,4-thiadiazol-2-amines) were obtained.     

Effects of Temperature and Common Ions on Binding of Puerarin to BSA

The effects of temperature and common ions on binding of puerarin to bovine serum albumin (BSA) are investigated. The binding constants (K _a) between puerarin and BSA are 1.13×10⁴ L⋅mol⁻¹ (20 °C) and 1.54×10⁴ L⋅mol⁻¹ (30 °C), and the number of binding sites (n) is (0.95±0.02). However, at a higher temperature (40 °C) the stability of the puerarin–BSA system decreases, which results in a lower binding constant (1.58×10³ L⋅mol⁻¹) and number of binding sites (n=0.73) of the puerarin–BSA system. However, the presence of Cu²⁺ and Fe³⁺ ions increases the binding constants and the number of binding sites in the puerarin–BSA complex.     

Theoretical study of substituent and solvent effects on the thermodynamics for <Emphasis Type="Italic">cis</Emphasis>/<Emphasis Type="Italic">trans</Emphasis> isomerization and intramolecular rearrangements of 2,2′-diphenoquinones

Enthalpies (Δ_isom H _(g)^o), Gibbs free energies (Δ_isom G _(g)^o), and equilibrium constants (log K _isom) for the trans → cis isomerization of various 3,3′-, 4,4′-, and 5,5′- disubstituted 2,2′-diphenoquinones with a range of electron withdrawing and releasing moieties (methyl, fluoro, chloro, bromo, trifluoromethyl, and amino) were calculated in the gas phase and in the solvent phase (n-hexane, benzene, n-octanol, acetonitrile, and water). In the gas phase, the trans isomer of the parent and all substituted 2,2′-diphenoquinones is predicted to be more thermodynamically stable than the cis configuration, with log K _isom ranging from −2.8 to −7.0. For all compounds, increasing solvent polarity/proticity progressively favors shifting the cis/trans equilibrium towards greater contributions of the cis configuration and substantially increases the log K _isom by up to 5.1 units relative to the gas phase. In polar protic and polar aprotic solvents, the estimated log K _isom ranges as low as −0.4, indicating significant populations of the cis isomers should be present. The findings support the polar solvent phase mechanistic predictions for a cis configuration of 2,2′-diphenoquinones participating in the thermal transformation of trans-2,2′-diphenoquinones to oxepino[2,3-b]benzofurans. With limited exceptions for some amino derivatives, the cis-2,2′-diphenoquinone to oxepino[2,3-b]benzofuran isomerization is expected to be thermodynamically favorable for all substituents/phases under consideration. The cis-2,2′-diphenoquinone to oxepino[2,3-b]benzofuran rearrangement is predicted to become less thermodynamically favored with increasing solvent polarity/proticity.     

Binding equilibrium of I? to serum albumin with resonance Rayleigh scattering

The binding equilibrium between l⁻ and human serum albumin (HSA) or bovine serum albumin (BSA) has been studied by means of the resonance Rayleigh scattering (RRS) and equilibrium dialysis. It has been found for the first time that RRS and multiple frequency scattering (MFS) are enhanced as the l⁻ binding to the HSA and BSA, but fluorescence quenches. The equilibrium dialysis results suggest that the binding of l⁻ to HSA and BSA fits a phase-distribution model other than Scatchard model, and that the order of magnitude of its phase-distribution constant was found to be 10⁴. It is most probable that Cl⁻ or other anion ions influence the binding of l⁻ by changing the ionic strength in the solution. The dialysis at different pH indicates that the binding mechanism is due to the electrostatic forces between the l⁻ and protonated basic amino-acid residues.     

A kinetic investigation into the rate of chloride substitution from chloro terpyridine platinum(II) and analogous complexes by a series of azole nucleophiles

The substitution kinetics of the complexes [Pt(terpy)Cl]Cl·2H₂O (PtL1), [Pt(^tBu₃terpy)Cl]ClO₄ (PtL2), [Pt{4′-(2′′′-CH₃-Ph)terpy}Cl]BF₄ (PtL3), [Pt{4′-(2′′′-CF₃-Ph)terpy}Cl]CF₃SO₃ (PtL4), [Pt{4′-(2′′′-CF₃-Ph)-6-Ph-bipy}Cl] (PtL5) and [Pt{4′-(2′′′-CH₃-Ph)-6-2′′-pyrazinyl-2,2′-bipy}Cl]CF₃SO₃ (PtL6) with the nucleophiles imidazole (Im), 1-methylimidazole (MIm), 1,2-dimethylimidazole (DIm), pyrazole (Pyz) and 1,2,4-triazole (Trz) were investigated in a methanolic solution of constant ionic strength. Substitution of the chloride ligand from the metal complexes by the nucleophiles was investigated as a function of nucleophile concentration and temperature under pseudo first-order conditions using UV/Visible and stopped-flow spectrophotometric techniques. The reactions follow the rate law k_\textobs = k₂ [ \textNu ] + k _{- 2} k_{\text{obs}} = k_{2} \left[ {\text{Nu}} \right] + k_{ - 2} . The results indicate that changing the nature or distance of influence of the substituents on the terpy moiety affects the π-back-donation ability of the chelate. This in turn controls the electrophilicity of the metal centre and hence its reactivity. Electron-donating groups decrease the reactivity of the metal centre, while electron-withdrawing groups increase the reactivity. Placing a strong σ-donor cis to the leaving group greatly decreases the reactivity of the complex, while the addition of a good π-acceptor group significantly enhances the reactivity. The results indicate that the metal is activated differently by changing the surrounding atoms even though they are part of a conjugated system. It is also evident that substituents in the cis position activate the metal centre differently to those in the trans position. The kinetic results are supported by DFT calculations, which show that the metal centre is less electrophilic when a strong σ-donor is cis to the leaving group and more electrophilic when a good π-acceptor group is part of the ring moiety. The temperature dependence studies support an associative mode of activation. An X-ray crystal structure of Pyz bound to PtL3 was obtained and confirmed the results of the DFT calculations as to the preferred N-atom as a binding site.     

Mesogenic and magnetic behavior in cobalt(II) and iron(II) compounds with long alkyl chains

Abstract  Metal complexes with long alkyl chains [Co(C16-terpy)₃](BF₄)₂ (1), [Fe(C16-terpy)₂](BF₄)₂ (2), [Co(C16-terpy)₂](BPh₄)₂ (3), [Co(C14-terpy)₂](BF₄)₂ (4), and [Fe(C12C10C5-terpy)₂](BF₄)₂ (5) were synthesized and their physical properties characterized, where C16-terpy, C14-terpy, and C12C10C5-terpy are 4′-hexadecyloxy-2,2′:6′,2′′-terpyridine, 4′-tetradecyloxy-2,2′:6′,2′′-terpyridine, and 4′-5′′′-decyl-1′′′-heptadecyloxy-2,2′:6′,2″-terpyridine, respectively. Complexes 1, 2, and 5 exhibited liquid–crystal properties in the temperature ranges of 371–528 K and 466–556 K, and 88–523 K, respectively. Variable-temperature magnetic susceptibility measurements revealed that the Co(II) complexes 1 and 4 exhibited unique spin transitions (T _1/2↓ = 217 K and T _1/2↑ = 260 K for 1 and T _1/2↓ = 250 K and T _1/2↑ = 307 K for 4), so-called ‘reverse spin transition,’ induced by structural phase transitions. Complex 3 exhibited gradual spin-crossover behavior (T _1/2 = 160 K.), and complex 5 exhibited spin transitions (T _1/2↑ = 288 K and T _1/2↓ = 284 K) at the liquid crystal transition temperature. Compounds with multifunction, i.e., magnetic and liquid–crystal properties, are important in the development of molecular materials. Graphical Abstract  

ESR study of paramagnetic derivatives of sterically hindered di-<Emphasis Type="Italic">o</Emphasis>-quinone with the tetrathiafulvalene bridge

The paramagnetic derivatives of 4,4′,7,7′-tetra-tert-butyl-2,2′-bis-1,3-benzodithiol-5,5′,6,6′-tetraone (1), viz., radical anion salts of the alkali metals (Li, Na, K) and cobaltocenium cations, chelated mono-o-semiquinone complexes with different metal fragments (Tl, TlMe₂, SnPh₃, Mn(CO)₄, Mn(PPh₃)(CO)₃), a number of copper(I) complexes with sterically hindered phosphines as well as binuclear heterometallic derivatives of triphenylantimony(V) o-semiquinone-catecholate with the analogous paramagnetic centers, were studied by ESR spectroscopy. The reaction of di-o-quinone 1 with sodium amalgam resulted in the formation of all reduced forms including quinone-semiquinone, disemiquinone, semiquinone-catecholate, and dicatecholate. A radical cation with the unpaired electron localized on the tetrathiafulvalene (TTF) fragment, which resulted from the oxidation of di-o-quinone 1, was detected by ESR spectroscopy.     

A theoretical investigation on structures of tripodal thiourea derivatives and their anion recognition

The structural geometries of three tripodal thiourea receptors, i.e. 1,3,5-triethyl-2,4,6-tris[(N′-methylthioureido)methyl]benzene (1), tris[N′-methyl-N-(2-aminoethyl)thiourea]methane (2), tris[N′-methyl-N-(2-aminoethyl)thiourea]amine (3), and their complexes with F⁻, Cl⁻, Br⁻, I⁻, NO₃ ⁻, CO₃ ²⁻, SO₄ ²⁻, HSO₄ ⁻, PO₄ ³⁻, HPO₄ ²⁻ and H₂PO₄ ⁻ were obtained using the density functional theory calculations. Electronic and thermodynamic properties of anion binding complexes of the receptors 1, 2 and 3 were investigated. Recognition abilities of all the receptors in terms of selectivity coefficients are reported. Intermolecular interactions in all the studied complexes occurring via multi-point hydrogen bonding were found. The receptors 1, 2 and 3 were found to be excellent selectivity for phosphate ion and their binding free energy for the phosphate ion are −292.57, −291.77 and −295.01 kcal/mol, respectively.     

Studies of the interaction between apigenin and bovine serum albumin by spectroscopic methods

The interaction between apigenin (Ap) and bovine serum albumin (BSA) in physiological buffer (pH = 7.4) is investigated by fluorescence quenching technique and UV-vis absorption spectra. The results reveal that Ap could strongly quench the intrinsic fluorescence of BSA. The quenching mechanism of Ap for BSA varies with the change of Ap concentration. when Ap concentration is lower, it is a static quenching procedure, when Ap concentration is higher, a combined quenching (both static and dynamic) would operate. The apparent binding constants Ka and number of binding sites n of Ap with BSA are obtained by fluorescence quenching method. The thermodynamic parameters, enthalpy change (Δ_r H ^m and entropy change (Δ_r S ^m ), are calculated to be −15.382 kJ mol⁻¹ K⁻¹ < 0 and 104.888 J mol⁻¹ K⁻¹ > 0, respectively, which indicate that the interaction of Ap with BSA is driven mainly by hydrogen bonding and hydrophobic interactions. The distance r between BSA and Ap is calculated to be 1.89 nm based on F?rster’s non-radiative energy transfer theory. The results of synchronous fluorescence spectra show that binding of Ap with BSA cannot induce conformational changes in BSA.     

Synthesis of macrocyclic polyethers and polyether diesters and preparation of their cationic complexes

New macrocyclic polyethers, 2,3,5,6-bis-[5′(5′)-chlorobenzo]-1,7,10-trioxacyclododeca-2,5-diene (I), 2,3,5,6-bis-[5′(5′)-chlorobenzo]-1,7,10,13-tetra oxacyclo pentadeca-2,5-diene (II), and 2,3,5,6-bis-[5′(5′)-chlorobenzo]-1,7,10,13,16-penta oxa cyclo octadeca-2,5-dien (III), and macrocylic lactones 2,3,5,6-bis-[5′(5′)-chlorobenzo]-1,7,10,13-tetraoxacyclopentadeca-2,5-diene-8,15-dione (IV) and 2,3,5,6-bis[5′(5′)-chlorobenzo]-1,7,10,13,16-pentaoxacyclooctadeca-2,5-diene-8,18-dione (V) were synthesized. Complexes of ligands III and V with metal cations were prepared. Furthermore, their metal-picrate extraction with some metal salts was attempted. Structures of the ligands and complexes were confirmed using spectroscopic techniques.     

Synthesis,structure and DNA-binding studies of tetranuclear copper(II) complexes bridged by asymmetrical<Emphasis Type="Italic"> N</Emphasis>,<Emphasis Type="Italic">N′</Emphasis>-bis(substituted)oxamides

Two tetranuclear copper(II) complexes bridged by asymmetrical N,N′-bis(substituted)oxamides have been synthesized and characterized as [Cu₄(dmapob)₂(Me₂bpy)₂](pic)₂·6H₂O (1) and [Cu₄(oxbe)₂(dabt)₂](pic)₂ (2), where H₃dmapob and H₃oxbe denote N-benzoato-N′-[3-(dimethylamino)propyl]oxamido and N-benzoato-N′-(2-aminoethyl)oxamide, respectively; and Me₂bpy, dabt, and pic represent 4,4′-dimethyl-2,2′-bipyridine 2,2′-diamino-4,4′-bithiazole, and 2,4,6-trinitrophenol, respectively. Complex 1 was characterized by elemental analyses, IR and electronic spectra, and single-crystal X-ray diffraction. Its structure consists of two asymmetrical binuclear copper(II) units linked by carboxyl bridges into a circular tetranuclear copper(II) complex with an embedded center of inversion. The copper(II) centers are in square-planar and distorted square-pyramidal environments. Hydrogen bonds and aromatic stacking interactions link the tetranuclear copper(II) fragments into a 3D supramolecular structure. The interactions of complexes 1 and 2 with herring sperm DNA (HS-DNA) were investigated by electronic and fluorescence spectra and viscosity measurements. Both complexes bind to HS-DNA via the intercalative mode, and complex 2 displays a significant binding propensity to HS-DNA.     

Probing the Interaction Between a Surfactant–Cobalt(III) Complex and Bovine Serum Albumin

The mechanism of binding of the surfactant–cobalt(III) complex, cis-[Co(phen)₂(C₁₄H₂₉NH₂)Cl](ClO₄)₂⋅3H₂O (phen = 1,10-phenanthroline, C₁₄H₂₉NH₂ = tetradecylamine) with bovine serum albumin (BSA) was investigated by UV–vis absorption, circular dichroism (CD) and fluorescence spectroscopic techniques. The results of fluorescence titration revealed that the surfactant–cobalt(III) complex quenched the intrinsic fluorescence of BSA through a combination of static and dynamic quenching. The apparent binding constant (K _a) and number of binding sites (n) were calculated below and above the critical micelle concentration (CMC). The thermodynamic parameters determined by the van’t Hoff analysis of the constants (ΔH ^∘=14.87 kJ⋅mol⁻¹; ΔS ^∘=152.88 J⋅mol⁻¹⋅K⁻¹ below the CMC and 25.70 kJ⋅mol⁻¹ and 243.14 J⋅mol⁻¹⋅K⁻¹, respectively, above the CMC) clearly indicate that the binding is entropy-driven and enthalpically disfavored. Based on F?rster’s theory of non-radiation energy transfer, the binding distance, r, between donor (BSA) and the acceptor (surfactant–cobalt(III) complex) was evaluated. UV–vis, CD and synchronous fluorescence spectral results showed that the binding of the surfactant–cobalt(III) complex to BSA induced conformational changes in BSA.     

1,3-diallyl-5-[ω-(diphenylphosphino)alkyl] isocyanurates in reactions of complex formation with palladium(ii) dichloride

The reactions of phosphine derivatives of diallyl isocyanurates with palladium(ii) dichloride lead to the formation of complexes, whose structure, composition, and stability depend on the length of the methylene chain between the isocyanurate and diphenylphosphine fragments in the ligand. 1,3-Diallyl-5-[5′-(diphenylphosphino)pentyl and 10′-(diphenyl-phosphino)decyl] isocyanurates with PdCl₂ form monomeric L₂PdCl₂ trans-complexes in which P atoms of the ligands participate in coordination with the metal. 1,3-Diallyl-5-[2′-(diphenylphosphino)ethyl] isocyanurate with PdCl₂ forms a dimeric (LPdCl₂)₂ complex, which decomposes in a solution to the monomer including solvent molecule into the coordination sphere of the metal. The reactions of 1,3-diallyl-5-[4′-(diphenylphosphino)butyl] isocyanurate and 1,3-diallyl-5-[6′-(diphenylphosphino)hexyl] isocyanurate with PdCl₂ give monomeric chelate LPdCl₂ complexes in which one of the allyl groups of the isocyanurate cycle participates in coordination with the central ion along with the phosphorus atom. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1859–1865, September, 1998.     

Comparative study on interaction of bovine serum albumin with dissymmetric and symmetric gemini surfactant by spectral method

The interaction between bovine serum albumin (BSA) with N, N′-bis(dimethylalkyl) ethylammonium dibromide (C₁₂C₂C_m, m = 8, 12) was investigated by spectral methods. It can be seen that C₁₂C₂C₈ and C₁₂C₂C₁₂ mainly interact with tryptophan residues of BSA from synchronous fluorescence spectra. Fluorescence, far-UV, and near-UV circular dichrosim spectra of BSA are changed by addition of dissymmetric and symmetric gemini surfactant. For surfactant solution, the polarity of the microenvironment surrounding pyrene is lower while the fluorescence lifetime of it is longer and the microviscosity is higher in the presence of BSA than those in the absence of BSA. But compared with C₁₂C₂C₁₂, C₁₂C₂C₈ has lower binding ability with BSA due to the shorter hydrophobic tail and lower symmetry.