Changes in motion vs. bonding in positively vs. negatively cooperative interactions

From a consideration of the interactions between non-covalent bonds, it is concluded that positively cooperative binding will occur with a benefit in enthalpy and a cost in entropy, and that negatively cooperative binding will occur with a cost in enthalpy and a benefit in entropy; experimental data support these conclusions.     

A theoretical study of conformational aspects and energy transfer between terthiophene and quinquethiophene in perhydrotriphenylene inclusion compounds

A theoretical study of models with supramolecular architecture of co-inclusion compounds based on the host perhydrotriphenylene and guests terthiophene and quinquethiophene (PHTP:T3,T5) is carried out to elucidate in detail the conformational aspects of the oligomeric guest species in the PHTP matrix host. The factors that direct the geometry, location and separation of terthiophene and quinquethiophene within the channels of the PHTP host have been studied using semi-empirical and ab initio calculations. The movement of the guests inside the channel is subject to constraints preventing free rotations or axial displacements along the nanochannel. Optimal arrangement and the general trend of the relative order between T3 and T5 in the (PHTP:T3,T5) co-inclusion compound is obtained. Furthermore, excited state calculations allow the explanation of the spectral shifts of the included species in terms of the planarization of their geometries. An analysis of the energy transfer processes between the T3-T5 donor-acceptor pair based on the configurational details of the co-inclusion compound conclude that efficient transfer proceeds only through two different and perpendicular windows for the T3 --> T5 transfer. The results emphasize the importance for better understanding of the directional details of the energy transfer mechanisms in this kind of one-dimensional systems.     

Photometric determination of palladium with the inclusion complex 1,2-Diaminoanthraquinone-β-cyclodextrin as ligand

1,2-Diaminoanthraquinone forms a 11 inclusion complex with-cyclodextrin in aqueous media and at different pH. This can be employed to solubilize the anthraquinone in water for use as a ligand for metal ions. This ligand can be used to determine palladium at trace levels spectrophotometrically. The limit of detection is 11 ng/ml and the R.S.D. is 2.1%. The performance can be improved by using derivative spectrometry.     

Characterization of polyethylene with partially random chlorine substitution

A series of chlorine‐containing polymers were prepared by ring‐opening metathesis polymerization (ROMP) followed by hydrogenation. This synthesis route was chosen specifically so that chain microstructures would be obtained that resembled copolymers of ethylene and vinyl chloride. The chlorine content was varied by the copolymerization of 5‐chlorocyclooctene and cyclooctene. Differential scanning calorimetry, light microscopy, tapping‐mode atomic force microscopy, wide‐angle X‐ray diffraction (WAXD), and density were employed to characterize the polymers. The copolymers had certain restrictions on the length of the methylene sequence between substituted carbons, however, ROMP copolymerization introduced enough variation in the methylene sequence length that model copolymers with the equivalent of 14 mol % vinyl chloride or less closely resembled random copolymers of ethylene and vinyl chloride. These materials organized as spherulites and exhibited the orthorhombic crystal form. Constraints on the placement of chlorine atoms strongly affected the crystallization of polymers with more than the equivalent of 14 mol % vinyl chloride. More regular chlorine substitution along the polyethylene chain translated into better ordered crystal structures with sharp melting peaks. The granular morphology of these materials at ambient temperature was interpreted as fringed micellar crystals. The WAXD patterns provided definitive evidence that chains in the fringed micelle took the hexagonal crystal form. The lower density hexagonal form facilitated the crystallization of short ethylene sequences and accommodated chlorine atoms more easily than the orthorhombic form. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 2062–2070, 2003     

Partially-methylated amyloses as effective hosts for inclusion complex formation with polymeric guests

Partially 2,3-O-methylated amyloses efficiently form inclusion complexes with polytetrahydrofuran and poly(epsilon-caprolactone) by simply mixing them in DMSO-H(2)O (1 : 9) solution, in contrast to the case of the parent amylose in which the corresponding inclusion complexes are only slightly formed.     

Molecular ozone-water complex.ab initio calculation with inclusion of electron correlation

The geometrical and electronic structure of different molecular O₃–H₂O complexes has been calculated by the ab initio method in the 4–31G (d, p) basis set with inclusion of electron correlation according to the Möller-Plesset fourth-order perturbation theory (MP4). It has been shown that the geometrical structure of the experimentally observed hydrogen-bonded complex is mainly determined by the entropy (rather than energy) effect, and is characterized by an almost free internal rotation of the H₂O molecule.Boreskov Institute of Catalysis, Siberian Branch, Russian Academy of Sciences. Ruberzhansk Department of Dnepropetrovsk Chemical Technological Institute. Translated fromZhurnal Strukturnoi Khimii, Vol. 34, No. 3, pp. 26–30, May–June 1993.Translated by L. Smolina     

Efficient resolution of naproxen by inclusion crystallization with N-octyl-glucamine and structure characterization of the inclusion complex

(S)-(+)-Naproxen was directly resolved from the racemate with high enantiopurity (>95% e.e.) by inclusion crystallization using N-octyl-d-(−)-glucamine as the chiral host. The crystal structure of the inclusion complex was determined.     

Crystalline inclusion complex of a calixarene with a nitroxide

The first capsular crystalline inclusion complex of para-hexanoyl calix[4]arene with stable nitroxyl radical DEPN has been isolated and showed a low mobility of the radical in the capsule.     

Self-trapping vs. non-trapping of electrons and holes in organic insulators: polyethylene

We show, by electronic structure based molecular dynamics simulations, that an extra electron injected in crystalline polyethylene should fall spontaneously into a self-trapped state, a shallow donor with a large novel distortion pattern involving a pair of trans-gauche defects. Parallel calculations show instead that a hole will remain free and delocalized. We trace the difference of behavior to the intrachain nature of the hole, as opposed to the interchain one of the electron, and argue that applicability of this concept could be more general. Thus electrons (but not holes) should tend to self-trap in saturated organic insulators, but not for example in aromatic insulators, where both carriers are intrachain.     

Spectrofluorimetric determination of beryllium based on the inclusion complex of 1-amino-4-hydroxyanthraquinone with β-cyclodextrin as ligand

The use of the inclusion complex of 1-amino-4-hydroxyanthraquinone (AHA) in the internal cavity of β-cyclodextrin is compared with AHA alone as a ligand for the spectrofluorimetric determination of beryllium. The organizing ability of the cyclodextrin medium and the protection of the ligand from the micro-environment confers increased sensitivity, selectivity and detection limit, and allows the determination of 10–70 ng ml^?1 beryllium, compared to 60–500 ng ml^?1 in the absence of the cyclodextrin.     

Study on the inclusion behavior and solid inclusion complex of 5-amino-6-methyl-2-benzimidazolone with cyclodextrins

The inclusion behaviors of three native or modified CDs including p-CD,2-hydroxypropyl-β-CD(2-Hp-β-CD) and 2,6-dimethyl-β-CD(Me-β-CD) toward 5-amino-6-methyl-2-benzimidazolone(AMBI) were comparatively investigated by NMR and fluorescence titration in combination with IR spectra,X-ray diffractometry and scanning electron microphotographs.The experimental results jointly demonstrated that the phenyl ring of AMBI entered into the cavity of the CDs and located close to the narrow rims accompanied by the formation of the 1:1 inclusion complex with large stability constant in aqueous solution.The introduction of the hydroxypropyl unit to the host improved the solubility,ultimately effecting an obvious promoting in the fluorescence intensity and the stability constant     

Preparation and study on the solid inclusion complex of ciprofloxacin with beta-cyclodextrin

The interaction of ciprofloxacin with beta-cyclodextrin (betaCD) has been studied by several analytical techniques, including 1H-NMR (nuclear magnetic resonance),13C-NMR, fluorescence spectroscopy, infrared (IR) spectroscopy, thermal analysis, and scanning electron microscope. In this paper, solid inclusion complex of ciprofloxacin with beta-CD was synthesized by the coprecipitation method. In addition, the characterization of the inclusion complex has been proved by fluorimetry, IR, differential scanning calorimetry and 1D, 2D NMR. The experimental results confirmed the existence of 1:1 inclusion complex of ciprofloxacin with beta-CD. The formation constant of complex was determined by fluorescence method and 1H-NMR. Spatial configuration of complex has been proposed on two dimensional NMR technique.     

Preparation and study on the solid inclusion complex of sparfloxacin with HP-beta-cyclodextrin

The interaction of sparfloxacin with HP-beta-cyclodextrin (HP-beta-CD) has been studied by several analytical techniques, including 1H NMR, fluorescence spectroscopy, infrared spectroscopy, thermal analysis and scanning electron microscopy. In this paper, solid inclusion complex of sparfloxacin with HP-beta-CD was synthesized by the coprecipitation method. In addition, the characterization of the inclusion complex has been proved by fluorimetry, infrared, differential scanning calorimetry and 1D, 2D NMR. The experimental results confirmed the existence of 1:1 inclusion complex of sparfloxacin with HP-beta-CD. The formation constant of complex was determined by the fluorescence method and 1H NMR. Spacial configuration of complex has been proposed on 2D NMR technique.     

NMR spectroscopic study of the inclusion complex of desloratadine with β-cyclodextrin in solution

Desloratadine (DES) is an antihistamine used in the treatment of allergies and chronic urticaria. ¹H NMR spectroscopic study of varying ratios of DES and β-Cyclodextrin (β-CD) in D₂O suggests the formation of a 1:1 inclusion complex formed by the penetration of Cl-substituted aromatic ring into the β-CD cavity. The stoichiometry and binding constant of the complex were determined by Scott’s method.     

Preparation and characterization of theβ-cyclodextrin inclusion complex with phenylpropiolic acid

The preparation of a 1:1 complex involving-cyclodextrin (-CD) and phenylpropiolic acid (PPA) is reported. The new inclusion complex of-CD has been characterized on the basis of its chemical analysis, thermal behavior, infrared spectrum, X-ray powder pattern and¹³C-NMR spectrum in DMSO solution.     

Preparation and study on the solid inclusion complex of sparfloxacin with beta-cyclodextrin

The interaction of sparfloxacin with beta-cyclodextrin (beta-CD) has been studied by several analytical techniques, including 1H-NMR, 13C-NMR, fluorescence spectroscopy, infrared spectroscopy, thermal analysis, and scanning electron microscope. In this paper, solid inclusion complex of sparfloxacin with beta-CD was synthesized by the coprecipitation method. In addition, the characterization of the inclusion complex has been proved by fluorimetry, Infrared, differential scanning calorimetry and 1D, 2D NMR. The experimental results confirmed the existence of 1:1 inclusion complex of sparfloxacin with beta-CD. The formation constant of complex was determined by fluorescence method and 1H-NMR. Spacial configuration of complex has been proposed on 2D NMR techniques.     

Peculiarities of inclusion complex formation in the 1,4-benzodiazepine-benzene system

5-Phenyl-1-methyl-7-bromo-3-hydroxy-1,2-dihydro-3H-1,4-benzodiazepin-2-one and its 5-(o-chloro)-phenyl analog form 2:1 (host:guest) inclusion compounds with benzene. The crystal structures of the compounds were studied by the single-crystal XRD method and were interpreted as host (H) (benzodiazepine) — guest (G) (benzene solvent molecule) complexes. The studied structures, revealing H-H and H-G interactions as both typical hydrogen bonds and π-π, C-H?π weak interactions, may serve as models for ligand-receptor binding.