Showing papers on "Stability constants of complexes published in 2008"
TL;DR: Determining the individual binding parameters of organic matter components with metals represents a significant advance over current approaches that utilize fluorescence quenching at a single excitation-emission wavelength pair to characterize organic matter-metal interactions.
Abstract: Organic matter−metal complexes in soil solution and aquatic systems are involved in important environmental and ecological processes such as plant nutrient availability and the solubilization and transport of metals Our work presented here extends the use of fluorescence spectrometry for determining conditional stability constants for such complexes We combine the use of excitation–emission matrix (EEM) fluorescence spectrometry and parallel factor analysis (PARAFAC) to determine the stability constants of the chemically meaningful components modeled by PARAFAC Water-soluble organic matter (WSOM) from O-horizon soils of deciduous and coniferous forest stands were extracted and titrated at pH = 47 with iron(III) (Fe) and aluminum (Al) which are important metals in acid soil systems The EEM spectra were then recorded and PARAFAC analysis showed that the WSOM contained three humic-substance-like components Fe titration led to fluorescence quenching of the three components, while Al titration enhanced f
201 citations
TL;DR: Spectrophotometric and 1H NMR titrations of N-methoxyethyl-N'-(4-nitrophenyl)thiourea by Bu(4-)NOAc show that in DMSO deprotonation of the receptor and formation of a hydrogen-bonded complex with anion proceed simultaneously but in MeCN deproTONation requires the participation of the second acetate anion.
Abstract: Spectrophotometric and 1H NMR titrations of N-methoxyethyl-N‘-(4-nitrophenyl)thiourea (3) by Bu4NOAc show that in DMSO deprotonation of the receptor and formation of a hydrogen-bonded complex with anion proceed simultaneously but in MeCN deprotonation requires the participation of the second acetate anion. The formation constants of hydrogen-bonded complexes were determined from titrations in the presence of added acetic acid, which suppressed deprotonation. These constants together with independently measured stability constants of (AcO)2H- complexes were employed for a rigorous numerical analysis of titration results in the absence of added acid, which allowed us to determine the equilibrium deprotonation constants as well as pKa values for 3 in both solvents. Although 3 appeared to be a weaker acid than AcOH in both solvents, it can be deprotonated by acetate in dilute solutions when the concentration of liberated acetic acid is low enough. With disubstituted N,N-bis(methoxyethyl)-N‘-(4-nitrophenyl)thi...
138 citations
TL;DR: HypΔH as discussed by the authors is a general-purpose Windows® application designed to derive equilibrium constants and/or formation enthalpies of complexes from solution calorimetric data.
Abstract: The computer program HypΔH is a general-purpose Windows® application designed to derive equilibrium constants and/or formation enthalpies of complexes from solution calorimetric data. Least-squares minimization is used with the analytically determined derivatives. The efficacy of the program is demonstrated by application to the calculation of formation constants and enthalpies for the formation of AgPy+ and AgPy2+, and also of CH3HgGly+, CH3HgGlyH and (CH3Hg)2Gly2+. The results are compared with published data.
122 citations
TL;DR: The experimental results have shown that for a given aqueous two-phase system, the extraction behaviour of metal ions in presence of inorganic extractants is mainly dependent on the stability of extracted species.
89 citations
TL;DR: The proposed membrane electrode revealed good selectivity for Al(III) ions over a wide variety of other cations, and was used in non-aqueous solvents and also as indicator electrode in potentiometric determination of Al( III) ions in some real samples.
86 citations
TL;DR: The pH dependence of the complexes was determined by both potentiometric and spectrophotometric studies and stability constants and stoichiometries of the formed complexes were determined using slope ratio method.
84 citations
TL;DR: Uranium sorption results are consistent with an equivalent anion exchange reaction between NO3- and UO2(CO3)3(4-) species to retain charge neutrality regardless of Mg concentration, and stability constants for aqueous Mg-UO2-CO3 complexes were determined.
Abstract: The formation of and stability constants for aqueous Mg−UO2−CO3 complexes were determined using an anion exchange method. Magnesium concentration was varied (up to 20 mmol/L) at constant ionic stre...
81 citations
TL;DR: The structure-activity correlation in Schiff bases and their metal(II) complexes are discussed, and it is observed that the activity enhances upon complexation and the order of activity is in accordance with stability order of metal ions.
74 citations
01 Jan 2008
TL;DR: In this article, the authors focus on aqueous actinide chemistry, reflecting the wide variety of studies on actinides reactions in non-aqueous solvents.
Abstract: The solution chemistry of the actinide elements has been explored in aqueous and organic solutions. While the relative stabilities of the actinide oxidation states and the types of complexes formed with the actinide cations in these states vary between solvents, the fundamental principles governing their redox reactions and their complexation strengths are the same regardless of the solvent. This chapter focuses on aqueous actinide chemistry, reflecting the wide variety of studies on actinide reactions in aqueous solutions. However, three factors that are important for actinides in non–aqueous solvents should be noted. First, in non–aqueous solvents, the formation of neutral cation–anion ion pairs is often dominant due to the lower (as compared to water) dielectric constants of the solvents. Second, non–aqueous conditions also allow the formation of complexes between actinide cations and ligands containing soft Lewis base groups, such as sulfur. Third, non–aqueous solvents are often useful for stabilizing redox–sensitive actinide complexes, as oxidation states that are unstable in aqueous solution may be stable in non–aqueous solutions (Mikheev et al., 1977; Hulet et al., 1979).
69 citations
TL;DR: Encapsulation with alpha-cyclodextrin improves the chemical stability of FA against UVB stress, and the bioavailability of FA on the skin, slowing its delivery (Strainer cell model).
66 citations
TL;DR: While the enthalpy of the UO2(SO4)2(2-) formation reaction is in good agreement with calorimetric data, that for UO 2SO4 (aq) is higher than other values by a few kilojoules per mole, in line with recent structural data, incomplete knowledge of the speciation may have led to an underestimation of Delta r H1.
Abstract: The formation constants of UO2SO4 (aq), UO2(SO4)2(2-), and UO2(SO4)3(4-) were measured in aqueous solutions from 10 to 75 degrees C by time-resolved laser-induced fluorescence spectroscopy (TRLFS). A constant enthalpy of reaction approach was satisfactorily used to fit the thermodynamic parameters of stepwise complex formation reactions in a 0.1 M Na(+) ionic medium: log 10 K 1(25 degrees C) = 2.45 +/- 0.05, Delta r H1 = 29.1 +/- 4.0 kJ x mol(-1), log10 K2(25 degrees C) = 1.03 +/- 0.04, and Delta r H2 = 16.6 +/- 4.5 kJ x mol(-1). While the enthalpy of the UO2(SO4)2(2-) formation reaction is in good agreement with calorimetric data, that for UO2SO4 (aq) is higher than other values by a few kilojoules per mole. Incomplete knowledge of the speciation may have led to an underestimation of Delta r H1 in previous calorimetric studies. In fact, one of the published calorimetric determinations of Delta r H1 is here supported by the TRLFS results only when reinterpreted with a more correct equilibrium constant value, which shifts the fitted Delta r H1 value up by 9 kJ x mol(-1). UO2(SO 4) 3 (4-) was evidenced in a 3 M Na (+) ionic medium: log10 K3(25 degrees C) = 0.76 +/- 0.20 and Delta r H3 = 11 +/- 8 kJ x mol(-1) were obtained. The fluorescence features of the sulfate complexes were observed to depend on the ionic conditions. Changes in the coordination mode (mono- and bidentate) of the sulfate ligands may explain these observations, in line with recent structural data.
TL;DR: The results suggest that the UV absorbance titration can be used to study the binding capacities of HSs and/or dissolved organic matter (DOM) with trace metals.
TL;DR: The analysis of the natural bond orbitals indicate that the Pb(ii) lone-pair is polarized by a substantial 6p contribution, which results in a hemi-directed coordination geometry around the metal ion.
Abstract: Herein, we report the coordination properties towards Zn(II), Cd(II) and Pb(II) of two hexadentate ligands containing pyridinecarboxylate groups with ethane-1,2-diamine (bcpe) or cyclohexane-1,2-diamine (bcpc) backbones. The X-ray crystal structures of [Zn(bcpe)], [Cd(bcpe)] and [Cd(bcpc)] show hexadentate binding of the ligand to the metal ions, with the coordination polyhedron being best described as a severely distorted octahedron. The X-ray crystal structure of the Pb(II) analogue shows the presence of tetrameric structural units [Pb4(bcpe)4] in which the four Pb(II) ions are bridged by carboxylate oxygen atoms. While in the Zn(II) and Cd(II) complexes the bcpe ligand adopts a twist–wrap (tw) conformation in which the ligand wraps around the metal ion by twisting the pyridyl units relative to each other, for the Pb(II) complex a twist–fold (tf) conformation, where a slight twisting of the pyridyl units is accompanied by an overall folding of the two pyridine units relative to each other is observed. Theoretical calculations performed at the DFT (B3LYP) level on the [Pb(bcpe)] and [Pb(bcpc)] systems indicate that the tf conformation is more stable than the tw form both in the solid state and in aqueous solution. The analysis of the natural bond orbitals (NBOs) indicate that the Pb(II) lone-pair is polarized by a substantial 6p contribution, which results in a hemi-directed coordination geometry around the metal ion. Potentiometric studies have been carried out to determine the protonation constants of the ligands and the stability constants of the complexes with Zn(II), Cd(II), Pb(II) and Ca(II). The replacement of the ethylene backbone of bcpe by a cyclohexylene ring causes a very important increase in the stability constant of the Pb(II) complex (ca. 2.3 logK units), while this effect is less important for Cd(II) (ca. 1.4 logK units). However, the introduction of the cyclohexylene ring does not substantially affect the stability of the Zn(II) and Ca(II) complexes. The ligand bcpc shows Pb/Ca and Cd/Ca selectivities [108.9 and 109.8, respectively] superior to those of extracting agents, such as EDTA, already used in Pb(II) and Cd(II) removal from contaminated water and soils.
TL;DR: A series of octadentate ligands featuring the 2-hydroxyisophthalamide (IAM) antenna chromophore to sensitize Tb(III) and Eu-III luminescence has been prepared and characterized in this article.
Abstract: A series of octadentate ligands featuring the 2-hydroxyisophthalamide (IAM) antenna chromophore to sensitize Tb(III) and Eu(III) luminescence has been prepared and characterized. The length of the alkyl amine scaffold that links the four IAM moieties has been varied to investigate the effect of the ligand backbone on the stability and photophysical properties of the Ln(III) complexes. The amine backbones utilized in this study are N,N,N′,N′-tetrakis-(2-aminoethyl)-ethane-1,2-diamine [H(2,2)-], N,N,N′,N′-tetrakis-(2-aminoethyl)-propane-1,3-diamine [H(3,2)-], and N,N,N′,N′-tetrakis-(2-aminoethyl)-butane-1,4-diamine [H(4,2)-]. These ligands also incorporate methoxyethylene [MOE] groups on each of the IAM chromophores to increase their water solubility. The aqueous ligand protonation constants and Tb(III) and Eu(III) formation constants were determined from solution thermodynamic studies. The resulting values indicate that at physiological pH the Eu(III) and Tb(III)complexes of H(2,2)-IAM-MOE and H(4,2)-IAM-MOE are sufficiently stable to prevent dissociation at nanomolar concentrations. The photophysical measurements for the Tb(III) complexes gave overall quantum yield values of 0.56, 0.39, and 0.52 respectively for the complexes with H(2,2)-IAM-MOE, H(3,2)-IAM-MOE, and H(4,2-IAM-MOE, while the corresponding Eu(III)complexes displayed significantly weaker luminescence, with quantum yield values of 0.0014, 0.0015, and 0.0058, respectively. Analysis of the steady state Eu(III) emission spectra provides insight into the solution symmetries of the complexes. The combined solubility, stability, and photophysical performance of the Tb(III) complexes in particular make them well suited to serve as the luminescent reporter group in high sensitivity time-resolved fluoroimmunoassays.
TL;DR: A rapid, simple and sensitive determination of the apparent formation constant of trans-resveratrol/CD complexes by HPLC in aqueous medium has been investigated for first time and it can be observed that trans- Resver atrol forms a 1:1 complex with α-, β- and γ-CD.
TL;DR: The strategy of caging copper is promising for applications where light could be used to trigger release of copper as a pro-oxidant to increase oxidative stress or as a tool to release copper intracellularly to study mechanisms of copper trafficking.
Abstract: A photosensitive caged copper complex has been prepared from a tetradentate ligand (H2cage) composed of two pyridyl-amide arms connected by a photoreactive nitrophenyl group. H2cage binds Cu2+ in aqueous solution with a stability constant (log beta) of 10.8, which corresponds to a KD of 16 pM at pH 7.4. The neutral Cu2+ complex, [Cu(OH2)(cage)], crystallizes as a distorted trigonal bipyramid coordinated by two amide and two pyridyl N atoms, with a water molecule bound in the trigonal plane. Photolysis with 350 nm UV light cleaves the ligand backbone to release photoproducts with significantly diminished affinity for Cu2+, thereby uncaging the metal ion. When coordinated as the caged complex, copper has diminished reactivity to produce hydroxyl radicals from Fenton-like reaction mixtures containing hydrogen peroxide and ascorbic acid. Postphotolysis, uncaged copper promotes hydroxyl radical formation under the same conditions. The strategy of caging copper is promising for applications where light could be used to trigger release of copper as a pro-oxidant to increase oxidative stress or as a tool to release copper intracellularly to study mechanisms of copper trafficking.
TL;DR: The molar absorptivity curves of the mono and bis nickel(II) complexes of 2,2'-bipyridine and 1,10-phenanthroline have been deduced from the composite absorbance data of a series of equilibrium solutions in methanol using equilibrium-restricted factor analysis, a technique for extracting spectral and thermodynamic information for component species involved in solution equilibria.
Abstract: The molar absorptivity curves of the mono and bis nickel(II) complexes of 2,2‘-bipyridine and 1,10-phenanthroline have been deduced from the composite absorbance data of a series of equilibrium solutions in methanol using equilibrium-restricted factor analysis, a technique for extracting spectral and thermodynamic information for component species involved in solution equilibria. The solutions achieve equilibrium slowly (t1/2 ≈ 100 min) as the amounts of the tris and methanolato complexes are initially in excess. The relative formation constants at 293 K have been determined with a high degree of accuracy, especially for the bipyridine complexes: log(K1/K2) = 0.340(4) and log(K2/K3) = 1.091(6). Solubility limitations compromised the accuracy of the thermodynamic results for the phenanthroline complexes.
TL;DR: The interaction of the alkaline earth ions Mg(2+), Sr (2+) and Ba(2+) with the uranyl tricarbonato complex has been studied by time-resolved laser-induced fluorescence spectroscopy to determine the stoichiometry and complex stabilities of the formed compounds.
TL;DR: The solution coordination environments of pentavalent and hexavalent Np are studied by high-energy X-ray scattering to determine a stability constant of Keq=0.74(9) M(-1) for the dimeric complex.
Abstract: The solution coordination environments of pentavalent and hexavalent Np are studied by high-energy X-ray scattering. Np5+ and Np6+ both exist as the neptunyl moiety coordinated with five equatorial waters at Np−O distances of 2.46(2) and 2.37(2) A, respectively. NpO22+ also has a second coordination sphere of 6−10 waters at 4.37(3) A. The NpO2+ scattering is complicated by the presence of scattering at about 4.2 A that is attributed to Np−Np cation−cation interactions. The analysis of changing intensity of this peak as a function of Np concentration is used to determine a stability constant of Keq = 0.74(9) M−1 for the dimeric complex.
TL;DR: In this article, a nano-electrospray mass-spectrometer was used to directly quantify polymeric metal hydroxide complexes in solution, i.e., the degrees of polymerization, the number of Th 4+ ions and the numbers of hydride ligands, and as a consequence also the charges of the complexes.
Abstract: Polynuclear hydroxide complexes play an important role for the hydrolysis of tetravalent thorium ions in aqueous solution, in particular for Th(IV) concentrations exceeding some [Th(IV)] =10 -4 M. Consequently, these polymers must be considered when describing hydrolysis of Th(IV) or dissolution processes of Th(IV) solids. In the past, considerable efforts were made to obtain equilibrium formation constants of these polymers and different stoichiometries for dimers, tetramers and hexamers have been suggested. However, most information was obtained from indirect methods, in particular, from potentiometric titrations. In the present work, we present an approach of directly quantifying polymeric metal hydroxide complexes in solution. By nano-electrospray mass-spectrometry the degrees of polymerization, i.e. the numbers of Th 4+ ions and the numbers of hydroxide ligands, and as a consequence, also the charges of the complexes are measured. All mono-and polynuclear species which are present in solution are quantified simultaneously down to species contributing less than 0.1% of the total [Th(IV)] concentration. Solutions of [Th(IV)] = 6 x10 -6 -10 -1 M are investigated in HCl at [H + ] =10 -4 -0.1 M. More than 30 different polymeric complexes are observed with the general trend of increasing number of hydroxide ligands with decreasing acidity. A surprising finding is the presence of the pentamer Th 5 (OH) y z+ , which was not described in the literature before. With decreasing Th(IV) concentration the stability field of polymers narrows continuously until polymers can no longer be detected below [Th(IV)] = 10 -5 M.
TL;DR: The thermodynamic measurements suggest that the inclusive process of brilliant cresyl blue with beta-cyclodextrin with heptakis(2,6-di-methyl) -beta-CD was enthalpic favor and the release of high-energy water molecules and Van der Waals force played an important role in the inclusion process.
TL;DR: The possible intermediate for the hydrolysis of BNPP, BNPC, and NA catalyzed by ZnL is proposed on the basis of kinetic and thermodynamic analysis and was found to be 9.9x10(-4) M(-1) s(-1), which is comparatively higher than most other reported Zn(II)-based systems.
Abstract: A novel beta-cyclodextrin dimer, 1,10-phenanthroline-2,9-dimethyl-bridged-bis(6-monoammonio-beta-cyclodextrin) (phenBisCD, L), was synthesized. Its zinc complex (ZnL) has been prepared, characterized, and applied as a new catalyst for diester hydrolysis. The formation constant (logK(ML)=9.56+/-0.01) of the complex and deprotonation constant (pK(a)=8.18+/-0.04) of the coordinated water molecule were determined by a potentiometric pH titration at (298+/-0.1) K. Hydrolytic kinetics of carboxylic acid esters were performed with bis(4-nitrophenyl) carbonate (BNPC) and 4-nitrophenyl acetate (NA) as substrates. The obtained hydrolysis rate constants showed that ZnL has a very high rate of catalysis for BNPC hydrolysis, giving a 3.89x10(4)-fold rate enhancement over uncatalyzed hydrolysis at pH 7.01, relative to only a 42-fold rate enhancement for NA hydrolysis. Moreover, the hydrolysis second-order rate constants of both BNPC and NA greatly increases with pH. Hydrolytic kinetics of a phosphate diester catalyzed by ZnL was also investigated by using bis(4-nitrophenyl) phosphate (BNPP) as the substrate. The pH dependence of the BNPP cleavage in aqueous buffer shows a sigmoidal curve with an inflection point around pH 8.11, which was nearly identical to the pK(a) value from the potentiometric titration. The k(cat) of BNPP hydrolysis promoted by ZnL was found to be 9.9x10(-4) M(-1) s(-1), which is comparatively higher than most other reported Zn(II)-based systems. The possible intermediate for the hydrolysis of BNPP, BNPC, and NA catalyzed by ZnL is proposed on the basis of kinetic and thermodynamic analysis.
TL;DR: An inclusion complex model has been established for explaining the observed enhancement of solubility of danazol in water by BCD, and in mouse model, danzol-beta-cyclodextrin complex showed 100% anovulation when given orally.
TL;DR: The results of the first serious effort to find a realistic surface complexation model thatfits both adsorption and total proton concentration data for PMG on the common soil mineral, goethite are presented.
Abstract: N-(phosphonomethyl)glycine (glyphosate, PMG) is the most widely used herbicide, and its adsorption onto soil minerals plays a significant role in its mobility and rate of degradation. In this work, we present the results of the first serious effort to find a realistic surface complexation modelthatfits both adsorption and total proton concentration data for PMG on the common soil mineral, goethite. Special attention was focused on making sure that the final model was in good semiquantitative agreement with previously reported X-ray photoelectron spectroscopy and Fourier-transform infrared spectroscopic measurements. Electrostatic effects were accounted for using the Basic Stern model, and the charges of the PMG-containing surface complexes were assumed to be distributed across the 0- and beta-planes. The reactions for the protonation of the goethite surface were described using the 1 pK model. We optimized on the intrinsic formation constants and the charge distributions of the complexes, as well as the initial total proton concentration (I = 0.1 M Na(NO3), 25.0 degrees C), and the following model was obtained. triple bond FeOH(0.5-) + H3L triple bond FeHL(1.5-) + H(+) + H2O Log10beta = 4.70 +/- 0.08, Q0 = -0.18 +/- 0.02 triple bond FeOH(0.5-) + H3L FeL(2.5-) + 2H(+) + H2O Log10beta = -3.9 +/- 0.1, Q0 = -0.7 +/- 0.1 Here, beta is the intrinsic formation constant, Q0 is the charge at the 0-plane, and the errors are reported as one standard deviation. The charge distributions of the complexes are rationalized by considering intramolecular hydrogen bonding between the protons of the amine group and both the phosphonate and carboxylate groups.
TL;DR: The complexation-induced chemical shift changes in the guest proton resonances, coupled with energy-minimization calculations, suggest that the guests are located such that their dipole moment is aligned perpendicular with the quadrupole moment of the CB[7] host.
Abstract: The host–guest stability constants for the inclusion of a series of small neutral polar organic guests in cucurbit[7]uril (CB[7]) have been determined in aqueous solution by 1H NMR titrations. The dependence of the stability constant on the nature of the guests indicates that hydrophobic and dipole–quadrupole interactions are responsible for the binding. The complexation-induced chemical shift changes in the guest proton resonances, coupled with energy-minimization calculations, suggest that the guests are located such that their dipole moment is aligned perpendicular with the quadrupole moment of the CB[7] host. The stability constants for acetone and acetophenone decrease in the presence of Na+ or K+ cations as a result of cation capping of the CB[7] portals.
TL;DR: In this article, the stability constant of 1,3-alternate-25,27-bis(1-octyloxy)calix in nitrobenzene saturated with water was determined.
Abstract: From extraction experiments in the two-phase water-nitrobenzene system and γ-activity measurements, the stability constant of protonated 1,3-alternate-25,27-bis(1-octyloxy)calix[4]arene-crown-6 in nitrobenzene saturated with water was determined. By using DFT calculations, the most probable structure of the 1,3-alternate-25,27-bis(1-octyloxy)calix[4]arene-crown-6 · H3O+ complex species was derived.
TL;DR: Potentiometric determination of the overall formation constant and three successive pKas for the complex, suggest the formation of stable hydroxo complexes which could be the catalytically active species.
TL;DR: In this article, the formation of 1:1 charge transfer complexes in the reactions of 2,9-dimethyl-1,10-phenanthroline (Me2phen) with some acceptors such as chloranil (Chl), picric acid (HPA) and chloranilic acid (Ch2CA) was studied in the defined solvent at room temperature.
TL;DR: Characterization of ternary complexes of meloxicam-HPβCD and PVP or L-arginine prepared by the spray-drying technique indicated the presence of strong interactions between the components.
Abstract: Ternary complexes of meloxicam (ME) (a poorly water soluble anti-inflammatory drug) with hydroxypropyl-beta-cyclodextrin (HPbetaCD) and either a hydrophilic polymer, namely, polyvinyl pyrrolidone (PVP) or a basic amino acid such as L-arginine, were prepared by the spray-drying technique. The solubilizing efficiency, physical properties and dissolution behaviour of each ternary system of ME-HPbetaCD with either PVP or L-arginine were compared with those of the corresponding binary system of ME-HPbetaCD. Tablets compressed from the ternary system of ME-HPbetaCD-L-arginine were compared with plain and commercial tablets. Phase solubility experiments suggested the formation of an inclusion complex of AL type. Ternary system of ME-HPbetaCD-L-arginine exhibited a stability constant 30.3 times higher than the binary system of ME-HPbetaCD, while the ternary system of ME-HPbetaCD-PVP increased the stability constant 2.2 times only. The prepared complexes were characterized by scanning electron microscopy, differential scanning calorimetry and infra red spectroscopy. Ternary solid complexes indicated the presence of strong interactions between the components. The dissolution behaviour of ME from different ternary complexes was higher than its dissolution from the binary system. Tablets compressed from ternary complexes of ME-HPbetaCD-L-arginine highly improved drug release compared to plain and commercial tablets.
TL;DR: Results showed that the host-guest stoichiometries in the inclusion complexes were all 1:1 both in solid state and in aqueous solution, indicating that the introduction of an extra o-methoxyl group on DOB further stabilized the CD inclusion complexes.
Abstract: Four fanlike organic compounds, 1-ethoxybenzene (EOB), 1-butoxybenzene (BOB), 1-dodecyloxybenzene (DOB), and 1-(dodecyloxy)-2-methoxybenzene (DOMB), were chosen as guests, and β-cyclodextrin (β-CD) and its two derivatives, mono(2-O-2-methyl)-β-CD and mono(2-O-2-hydroxy-propyl)-β-CD, were chosen as hosts. Energy changes involved in host−guest inclusion processes were clearly obtained by applying semiempirical PM3 calculations. According to this, probable structures of the host−guest inclusion complexes were proposed. The inclusion systems in aqueous solution were investigated by UV−vis spectroscopy and nuclear magnetic resonance (1H NMR) titration, and the formation constants (K) of the inclusion complexes were determined using the Benesi−Hildebrand equation. Moreover, two solid inclusion complexes of β-CD with EOB and DOB were prepared and characterized by Fourier transform infrared spectra, X-ray powder diffraction, 1H NMR, electrospray ionization mass spectrometry, and thermogravimetric analyses. Result...