Using PVP/SDS Complex as a Probe to Study the Inclusion Complex of β-cyclodextrin with SDS in Aqueous Solution

PVP/SDS complex was applied as a probe to study the interaction between β-cyclodextrin （β-CD） and sodium dodecyl sulfate （SDS） in aqueous solution. It has been found that a critical concentration, namely cs, exists in the relative viscosity of solution containing PVP/SDS complex versus β-CD concentration plot. As the β-CD concentration is less than cs, the relative viscosity of solution decreases sharply by adding β-CD into solution successively. On the other hand, as the β-CD concentration is greater than cs, the relative viscosity of solution increases gradually by adding β-CD into solution. The decrease of the relative viscosity of solution containing PVP/SDS in the presence of β-CD is just due to the inclusion complex of β-CD with the guest molecule SDS. And, this inclusion interaction takes down SDS from the PVP chains in solution. The ratio of the host molecule β-CD to the guest molecule SDS can be calculated from Cs. In our experiment the inclusion ratio of β-CD to SDS is 1/1. The further experimental results indicate that cs is associated with SDS but free from PVP in PVP/SDS complex. However, the inclusion ratio of β-CD to SDS has proved to be independent of either SDS or PVP in PVP/SDS complex.     

Inclusion of (aminostyryl)-1-methylpyridinium dyes byβ-cyclodextrin and its use for fluorescent-probe studies on association of cationic and neutral molecules withβ-cyclodextrin

An inclusion complex between TRIMEB and (S)-naproxen has been crystallised and characterised by physicochemical methods including X-ray analysis. The complex crystallises in the orthorhombic crystal system, space groupP2₁2₁2₁, witha=15.179(4),b=21.407(5),c=27.67(1) Å andZ=4. The structure was solved using published coordinates for the skeleton atoms of TRIMEB in an isomorphous complex. Refinement by full-matrix least-squares analysis yieldedR=0.0571 for 6573 unique observed reflections. Hydrophobic forces are responsible for the inclusion of the drug, which has its methoxy group buried in the cavity of the host and its propionic acid moiety protruding from the O(2), O(3) side of the TRIMEB molecule. Both host and guest undergo conformational changes on complexation relative to their conformations observed in the TRIMEB monohydrate and naproxen crystal structures respectively. Complex units pack in a screw-channel mode in a head-to-tail fashion with their axes almost parallel to theb-axis.     

Liquid chromatographie separation of penicillamine enantiomers derivatized with OPA/2-ME on aβ-cyclodextrin bonded phase

A high performance liquid Chromatographic method has been developed for the resolution of penicillamine enantiomers on a -cyclodextrin (-CD) column. Fluorogenic derivatives of the D,L-penicillamine were first formed by usingo-phthaldehyde/2-mercaptoethanol (OPA/2-ME) as derivatizating reagent. These chiral derivatives were then chromatographed on a commercially available chiral stationary phase of -CD with 50/50 ethanol/1% triethylammonium acetate (pH 4.5) as a mobile phase, and detected fluorimetrically at 450 nm (_ex = 355 nm). After careful optimization of the classical Chromatographic parameters good resolution was achieved between the d and l enantiomers. The method proposed here is simple and rapid and can detect the presence of 0.5% of the L-enantiomer in D-penicillamine pharmaceutical preparations (tablets).     

Molecular Recognition Studies on Supramolecular Systems. Part 38. Inclusion Complexation of Organic Dyes by Organoselenium Bridged Bis(β-cyclodextrin)s with a Short Linker

In order to further explore the inclusion complexation behavior with -cyclodextrin dimers, the binding constants (K_S) of three organoselenium bridged bis(-cyclodextrin)s (2ndash;4) tethered with a short linker were determined with some representative dye molecules in aqueous phosphate buffer solution (pH 7.20) at 25 °C by fluorescence and UV-vis spectrometry. As compared with the parent -cyclodextrin (1), the bridged bis(-cyclodextrin)s (2ndash;4) can not only significantly enhance the original binding affinity of the parent -cyclodextrin by the cooperative binding of one guest molecule in the closely located two -cyclodextrin cavities but also remarkably extend its molecular recognition abilities towards the different size/shape or substituent of model substrates. The higher binding ability and selectivity of dye molecules by bridged bis(-cyclodextrin)s (2ndash;4) are discussed from the viewpointof the size/shape-fit concept and multiple recognition mechanism.     

Investigation of the Effect of Inclusion of Eriochrome Black T with β-Cyclodextrin on Its Complexation Reaction with Ca2+ and Mg2+ Using Rank Annihilation Factor Analysis

Rank annihilation factor analysis (RAFA) was used to investigate the effects of inclusion of eriochrome black T (EBT) on its complexation reaction with Ca²⁺ and Mg²⁺ at different pH values. Addition of β-cyclodextrin (β-CD) to Ca-EBT or Mg-EBT caused decomposition of the 1:1 metal complex and increase in EBT concentration in solution due to the formation of EBT-β-CD inclusion complex. In order to perform RAFA, concentration profiles were calculated by optimizing the value of the conditional stability constant and inclusion constant. The rank of original data matrix reduces by one by removing the information from the complex form (Ca-EBT or Mg-EBT). The performance of the method was evaluated by using synthetic data as well as experimental data and good results were obtained. The proposed method is capable of the simultaneous spectrophotometric determination of formation constant of a complex and the equilibrium constant of the competing reaction in solution.     

Polymorphism of Inclusion Complexes and Unsolvated Hosts. V. Crystal Structure of the α-Dimorph of the 1 : 2 Dianilinegossypol–DMSO Complex and a 1 : 1 : 1 Inclusion Complex Based on a Mixed Dianilinegossypol/1,4-Dioxane Host Matrix and 1,2-Dichloroethane Guest

Dianilinegossypol forms a 1 : 2 host-guest complex with DMSO:monoclinic, space group P2₁/n, a = 8.522(3), b = 18.034(4), c= 28.462(6) , = 94.14(2)°, V = 4362³, Z = 4, D x = 1.26 g cm^-3, T = 295 K.Final R value is 0.102 for 1793 observed reflections. A 1 : 1 : 1 adduct ofdianilinegossypol with 1,4-dioxane and 1,2-dichloroethane is found to beisostructural with the dianilinegossypol complex with DMSO: monoclinic,space group P2₁/n, a = 8.281(2), b = 19.245(3), c = 27.970(7), = 95.18°, V = 4439 ³, Z = 4, D x =1.28 g cm^-3, T = 295 K. Final R value is 0.114 for 2458observed reflections.The host molecules are associated by O(4)—H ...O(3) H-bonds toinfinite chains running in the direction of the c-axis The chains areincorporated into layers through 1,4-dioxane or DMSO molecules havingH-bonds with dianilinegossypol molecules. Another DMSO or 1,2-dichloroethanemolecule is included as a guest in the channels formed between the layers.At 60 °C a cryptate-type inclusion complex of dianilinegossypol isformed with DMSO or 1,4-dioxane. It is isostructural with the acetonecomplex reported in Part IV of the present series.     

Comparison between Roesy and 13C NMR Complexation Shifts in Deriving the Geometry of Inclusion Compounds: A Study on the Interaction between Hyodeoxycholic Acid and 2-Hydroxypropyl-β-Cyclodextrin

Abstract

The formation and geometry of the hyodeoxycholic acid (HDCA)/2-hydroxypropyl-β-cyclodextrin (HPβCD) complex in methanol-d₄ solution was determined through a rotating frame nuclear Overhauser (ROESY) experiment. The reported results confirmed those independently and previously obtained though the use of ¹³C complexation shifts in the same solvent. The ¹³C approach, which needs shorter experimental times and is currently used in the study of HPβCD/bile acid systems, was then substantiated.     

Molecular Recognition of Bridged Bis(β-cyclodextrin)s Linked by Phenylenediseleno Tether on the Primary or Secondary Side with Fluorescent Dyes

A Novel β-cyclodextrin dimer,2,2′-o-phenylenediseleno-bridgedbis(β-cyclodextrin)(2),has been synthesized by reaction ofmono-[2-O-(p-tolylsulfonyl)]-β-cyclodextrin and poly(o-phenylenediselenide).The complexation stability constants(K_s)and Gibbs free energy changes(-ΔG°)of dimer 2 with fourfluorescence dyes,that is,ammonium 8-anilino-1-naphthalene-sulfonate(ANS),sodium 6-(p-toluidino)-2-naphthalenesul-fonate(TNS),Acridine Red(AR)and Rhodamine B(RhB)have been determined in aqueous phosphate buffer solution(pH=7.2,0.1 mol·L~(-1)at 25℃ by means of fluorescence spec-     

Generator of an H2Se–H2 Mixture,Based on Packing with Selenium Reflux. Part 1. Development of the Design and Experimental Study of the Generator

Russian Journal of Applied Chemistry - Generators of an H2Se–H2 mixture, based on a packing with liquid selenium reflux and addition of selenium from an external source, are considered....     

Development of a Liquid–Liquid Microextraction Method Based on a Switchable Hydrophilicity Solvent for the Simultaneous Determination of 11 Drugs in Urine by GC–MS

A new and green liquid–liquid microextraction method based on a switchable hydrophilicity solvent for the determination of 11 drugs in urine is presented for the first time. The protonated N,N-dimethylcyclohexylamine was used as an extraction solvent and sodium hydroxide was injected as a trigger for organic-phase separation. The extraction procedure has been optimized and investigated in this study. The intraday and interday recovery ranged from 73.8 to 103.0% and the relative standard deviations were in the range from 2.2 to 13.5% (n?=?5). The linear range was from 5.0 to 2000.0 µg L^?1, and R² was greater than 0.99, and the limit of detection was in the range from 0.36 to 12.50 µg L^?1. The proposed method may be a useful procedure for the determination of 11 drugs in urine, and easily incorporated into routine testing for a laboratory.

Graphical Abstract

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Inclusion compounds of plant growth regulators in cyclodextrins, part VII: study of the crystal structures of 2-naphthylacetic acid encapsulated in β-cyclodextrin and heptakis(2,3,6-tri-O-methyl)-β-cyclodextrin complexes by X-ray crystallography

The crystal structures of the β-naphthylacetic acid (2NAA)/β-cyclodextrin (β-CD) and the 2NAA/heptakis(2,3,6-tri-O-methyl)-β-CD (TMβCD) complexes are reported. The 2NAA/β-CD complex crystallizes in the triclinic system forming a dimer inside the cavity of which two 2NAA molecules disordered over two sites are located. The dimers are stacked along the c axis according to the channel packing mode forming a nanotube which resembles a wireway as it contains guest molecules linked by π–π interactions inside each dimeric cavity and by H-bonds between the adjacent dimers. The 2NAA/TMβCD complex crystallizes in the orthorhombic space group P2₁2₁2₁. Its asymmetric unit contains one host, one guest distributed over two sites and one water molecule having a low occupancy factor. The complexes are packed in a head-to-tail mode forming a screw channel along the b axis. The carboxyl group of the guest protrudes towards the “free” space between the complexes and is H-bonded to the water molecule which in turn is H-bonded to the O5n atom of the host of the subsequent complex. The orientation of the guest molecule in the 2NAA/β-CD complex has been found opposite to that of the guest in the 2NAA/TMβCD complex probably due to the formation of dimers and the π–π interactions between the naphthalene moieties of the encapsulated molecules inside the dimeric cavity.     

Synthesis,Crystal Structure and Redox Property of a Copper(Ⅱ) Complex Based on 1,1-Bis(1H-benzoimidazol-2-ylmethyl)cyclohexane

A novel mononuclear copper(Ⅱ) complex [Cu(bbmc)Cl_2]·DMF,where bbmc is 1,1-bis(1H-benzoimidazol-2-ylmethyl)cyclohexane,was synthesized and characterized by X-ray single-crystal structure analysis.The complex crystallizes in triclinic,space group P1 with a = 9.1088(5),b = 11.0075(4),c = 14.2326(6) ?,α = 97.188(3),β = 96.394(4),γ = 111.430(4)°,V = 1298.73(10) ?~3,Z = 2,D_c = 1.409 g/cm~3,μ(Mo Kα) = 1.074 mm~(-1),F(000) = 572,S = 1.078,R = 0.0381 and w R = 0.0876 for 5593 observed reflections with I 2σ(I).The central Cu(Ⅱ) ion adopts a distorted tetrahedral geometry coordinated by two nitrogen atoms of the ligand and two chloride ions.The complex showed its thermal decomposition temperature up to 226 ℃ and exhibited an irreversible one-electron transfer process involving Cu~(Ⅱ)/Cu~I couple.     

Formation of a Stable Cationic Hydridodimethylplatinum(IV) Complex by the Reaction of Bis(μ-dimethyl sulfido)tetramethyldiplatinum(II) with Protonated 1,4,7-Triisopropyl-1,4,7-triazacyclononane. A First Example of Oxidative N-H Addition to a Platinum(II) Complex

The complex bis(-dimethyl sulfido)tetramethyldiplatinum(II) reacts with 1,4,7-triisopropyl-1,4,7-triazacyclopropanone (L) over the course of 24 h at room temperature in THF-d ₈ to give [PtMe₂(L)] and PtMe₂(SMe₂)₂. Subsequent addition of 1 mol of trifluoromethanesulfonic acid results in immediate formation of a previously unknown stable cationic complex [PtMe₂H(L)]⁺SO₃CF₃ ^-. This product can also be prepared by oxidative addition of the N-H bond of LH⁺SO₃CF₃ ^- to the starting complex, which points to a higher basicity of the platinum atom in [PtMe₂(L)] compared with the nitrogen atom in the ligand L. The pK _a of the cationic hydride of platinum(IV) was estimated.     

Detection of a β-Chlorovinyl Complex of Platinum(IV) (an Intermediate of Hydrochlorination of Acetylene by HCl Gas) on the Surface of the Mechanically Activated Salt K2PtCl6

We have used NMR spectroscopy to detect an intermediate of catalytic hydrochlorination of acetylene on the surface of the mechanically activated solid salt K₂PtCl₆: a -chlorovinyl complex of platinum(IV).     

Influence of Dab2 and Pro3 configuration of [Leu]-enkephalins on the interactions with β-cyclodextrin studied by fluorescence spectroscopy, microcalorimetry and 1H NMR spectroscopy

Natural enkephalins and their analogues are very important as potential therapeutic agents (analgetics). Herein we describe the influence of Dab and Pro chirality of cyclic [Leu]enkephalins (X¹-c[Dab²-Pro³-βNal(2)⁴-Leu⁵], where X = Tyr or Phe) on the binding constant with β-cyclodextrin and spatial and mutual orientation of guest and host molecules. The formation of complexes is enthalpy driven for all cyclic [Leu]enkephalins studied as well as for Nal and AcNalNH₂. Moreover, change of Dab residue configuration has a greater influence on changes of the binding constant of cyclic enkephalin with β-CD than change of Pro chirality has. Also, the replacement of Tyr¹ residue by Phe¹ substantially changes the peptide chain conformation. An analysis of 2D NMR spectra reveals that, apart from inclusion complex formed by penetration of cyclodextrin cavity from wider and narrow rims by Nal, Tyr or Phe or Leu residue, a side and/or bottom association complexes are formed.     

A New Approach to 2,3-Dihydro-1H-1,5-Benzodiazepines from the Reaction of o-Nitrophenylazide with α,β-Unsaturated Ketones Promoted by Samarium Diiodide

Applications of samarium diiodide as a mild, neutral, selective and versatile single-electron transfer reducing and coupling reagent in organic synthesis have grown significantly in the last decade1. It is well known that both nitro compounds2a and azide compounds2b can be easily reduced by SmI2 to the corresponding amines. Little attention has been given to the intermediates derived from nitro or azide groups by treatment of SmI2, which may lead to reactions difficult to accomplish by other …     

Synthesis, Crystal Structure and Ferromagnetic Properties of a New Dicyanamide Bridged Dicopper(Ⅱ) Complex with IM-1'-MeBzIm-κ2 N, O Mode

A new dinuclear copper(Ⅱ) complex with imino nitroxide radicals [Cu2(NO3)2(IM-1'-MeBzlm)2(dca)2] (IM-1'-MeBzlm = 2-{2'-[(1'-methyl)benzimidazolyl]}-4,4,5,5-tetramethylimi-dazoline-1-oxyl, dca = dicyanamide anion) has been prepared and structurally characterized by single-crystal X-ray diffraction. The complex crystallizes in triclinie, space group P1, with a =9.440(5), b = 10.124(6), c = 11.603(7)(A°), α= 102.904(7),β = 94.033(6), γ= 104.299(7)°,C34H40Cu2N16O8, Mr= 927.90, V= 1038.2(10) (A°)3, Z = 1, Dc=1.484 g/cm3,μ(MoKα) = 1.093 mm-1,F(000) = 478, R = 0.0609 and wR = 0.1512 for 2889 observed reflections with I > 2σ(I). X-ray analysis reveals that two Cu(Ⅱ) atoms are bridged by two dicyanamides to form a centrosymmetric Cu(Ⅱ)-Cu(Ⅱ) dinuclear entity. Every Cu(Ⅱ) ion is five-coordinated with a distorted square pyramidal coordination geometry and IM-1'-MeBzlm ligand coordinates to the metal ion with the κ2 N(1'-MeBzlm), O(IM) mode to avoid steric hindrance with the methyl group in the complex. Meanwhile, the molecules are linked by intermolecular hydrogen bonds, leading to a 1-D chain structure. Moreover, such chains are further linked by π-π stacking interactions to form a 2-D network structure. Magnetic measurement demonstrates that the intramolecular exchange couplings between Cu(Ⅱ) ion and the IM-1'-MeBzlm are ferromagnetic with J = 12.46 cm-1, where the spin Hamitonian is defined as H= -2JS1S2 within the complex.