Crystalline Inclusion Research Articles

Bacillus sphaericus: biocontrolador de vectores que producen malaria, fiebre amarilla y dengue

El aumento en la incidencia de enfermedades de interés en salud pública como malaria, dengue y fiebre amarilla asociado a los efectos secundarios del uso de plaguicidas químicos y la resistencia generada, ha impulsado a la búsqueda de nuevas alternativas para la erradicación de sus vectores. Una opción viable como bacteria entomopatógena es el Bacillus sphaericus, descrita por primera vez en 1904 por Neide y Meyer, quienes descubrieron una bacteria formadora de esporas, que existe en la naturaleza y que crece fácilmente tanto in vitro como en el cadáver de las larvas.Su actividad larvicida se debe a la producción de una inclusión cristalina denominada toxina binaria A y B de 41,9 y 51,4 kDa, respectivamente, las cuales, al ser liberadas en el intestino de los insectos susceptibles en su fase larvaria y tras ser solubilizada por el pH alcalino en la porción media del intestino, activan las proteasas causando deshidratación y muerte a los vectores. Es considerada como un biolarvicida altamente potencial y eficaz para el control biológico de Anopheles spp., Aedes spp. y Culex spp. Comercialmente puede producirse por fermentación sumergida a pequeña escala con materiales proteínicos de desecho. Este producto ha sido utilizado y registrado en numerosos países de América Latina, donde se han obtenido buenos resultados después de su aplicación.

Physical properties of hydrate‐bearing sediments

Methane gas hydrates, crystalline inclusion compounds formed from methane and water, are found in marine continental margin and permafrost sediments worldwide. This article reviews the current understanding of phenomena involved in gas hydrate formation and the physical properties of hydrate‐bearing sediments. Formation phenomena include pore‐scale habit, solubility, spatial variability, and host sediment aggregate properties. Physical properties include thermal properties, permeability, electrical conductivity and permittivity, small‐strain elastic P and S wave velocities, shear strength, and volume changes resulting from hydrate dissociation. The magnitudes and interdependencies of these properties are critically important for predicting and quantifying macroscale responses of hydrate‐bearing sediments to changes in mechanical, thermal, or chemical boundary conditions. These predictions are vital for mitigating borehole, local, and regional slope stability hazards; optimizing recovery techniques for extracting methane from hydrate‐bearing sediments or sequestering carbon dioxide in gas hydrate; and evaluating the role of gas hydrate in the global carbon cycle.

Stereoregular Methacrylate-POSS Hybrid Polymers: Syntheses and Nanostructured Assemblies

This contribution reports the first examples of stereoregular (isotactic, it-, and syndiotactic, st-) methacrylate-POSS (polyhedral oligomeric silsesquioxane) hybrid polymers and their derived nanostructured assemblies. The polymerization of methyl methacrylate (MMA) by isospecific and syndiospecific living metallocene catalysts, when end-capped with methacrylisobutyl POSS (MA-POSS) or simultaneously copolymerized with MA-POSS at ambient temperature, readily produces highly stereoregular (94% it- and st-) MA-POSS end-capped PMMA (PMMA-POSS) or statistical copolymers PMMA-co-P(MA-POSS). The MA-POSS incorporation in the it-copolymers ranges from a low 2.6 mol % (20 wt %) to a high, maximum 24 mol % (75 wt %), whereas the incorporation in the st-copolymers is relatively lower with the same comonomer feed ratio due to the formation of a crystalline inclusion complex in which the POSS nanocages are encapsulated within the helical st-PMMA cavity. The it-copolymers with high POSS contents (>20 mol %) show evidence for interchain association through POSS aggregation and display a ∼20 °C Tg enhancement over the pristine it-PMMA. MA-POSS end-capped diastereomeric PMMAs exhibit versatile nanostructured assemblies, including micelle-like core−shell nanostructures (Rh up to 186 nm derived from the 5.7 nm it-PMMA-POSS unimer) through POSS inorganic collapse in selective solvents, helical stereocomplexes (Rh = 11 nm) between two or three polymer chains through organic self-organization of the diastereomeric PMMAs, and large core−shell nanospheres (Rh up to 636 nm) through synergistic organic PMMA self-organization and inorganic POSS nanocluster aggregation. Thermal annealing of the it-/st-PMMA-POSS blend in a 1:2 ratio also generates the crystalline stereocomplex with a high Tm of 213 °C.

Constrained/Directed Crystallization of Nylon-6. I. Nonstoichiometric Inclusion Compounds Formed with Cyclodextrins

Noncovalently bonded crystalline inclusion compounds (ICs) have been formed by threading host cyclic starches, cyclodextrins (CDs), onto guest nylon-6 (N-6) chains. When excess N-6 is employed, nonstoichiometric (n-s)-N-6-CD-ICs, with partially uncovered and “dangling” N-6 chains, result. While the host crystalline CD lattice is stable to ∼300 °C, the uncovered, yet constrained, portions of the N-6 chains emanating from the CD-IC surfaces may crystallize below or be molten above ∼225 °C. We have been studying the constrained crystallization of the unthreaded N-6 chains “dangling” from (n-s)-N-6-CD-ICs, with comparison to bulk N-6 samples, as functions of N-6 molecular weights, lengths of uncovered N-6 chains (N-6:CD stoichiometry), and the CD host used. In the IC channels formed with host α- and γ-CDs containing 6 and 8 glucose units, respectively, single and pairs of side-by-side N-6 chains are threaded and included. In α-CD-ICs, the ∼0.5 nm channels produced by stacked α-CDs are separated by ∼1.4 nm, wh...

Investigation of the inclusion of the herbicide metobromuron in native cyclodextrins by powder X-ray diffraction and isothermal titration calorimetry

We report the formation of inclusion complexes between the phenylurea herbicide metobromuron [3-( p-bromophenyl)-1-methoxy-1-methylurea] and β- and γ-cyclodextrin in the solid state. Formation of crystalline inclusion complexes by the kneading method was confirmed by powder X-ray diffraction and further structural characterization using the principles of isostructurality followed. In addition, Δ H°, Δ S°, Δ G° and the association constants ( K) at 298 K were determined for complex formation in solution using isothermal titration calorimetry. The magnitudes of K for the formation of 1:1 complexes between metobromuron and α-, β- and γ-CD were estimated as 598, 310 and 114, respectively.

Organizational stabilities of bulk neat and well‐mixed, blended polymer samples coalesced from their crystalline inclusion compounds formed with cyclodextrins

AbstractCyclodextrins (CDs) are cyclic starches containing α‐1,4‐linked glucose units. Commonly available α‐, β‐, and γ‐CDs have six, seven, and eight glucose units, respectively. They are well known for forming noncovalent inclusion complexes (ICs) with a variety of guest molecules, including many polymers, by threading and inclusion into their relatively hydrophobic interior cavities, which are roughly cylindrical, with diameters of ∼0.5–1.0 nm. Warm water washing of crystalline CD‐ICs containing polymer guests insoluble in water or treatment with amylase enzymes serve to remove the host CDs and result in the coalescence of the guest polymers into solid bulk samples. When guest polymers are coalesced from their CD‐ICs by carefully removing the host CD lattices, they are observed to solidify with structures, morphologies, and even conformations that are distinct from bulk samples made from their solutions and melts. In addition, molecularly mixed, intimate blends can be obtained upon coalescence of two or more normally immiscible polymer guests from their common CD‐ICs. Not only are the organizations and behaviors of bulk polymer samples significantly modified on coalescence from their CD‐ICs, but both are also maintained for significant periods of time even when heated above their Tgs and Tms, where their chains are mobile. Here, we discuss the long‐time, high temperature stabilities of the organizations and properties of bulk polymers coalesced from their crystalline CD‐ICs. While random‐coiling of their initially coalesced, largely extended, separated, and unentangled chains may be relatively rapid, we conclude that the subsequent slow establishment of homogeneous melts or phase‐segregated blends results from the extremely sluggish center‐of‐mass diffusion that must accompany full entanglement of their chains. Apparently, the process of entangling the largely separated and not fully interpenetrating randomly coiled chains initially coalesced from their CD‐ICs is particularly slow, much slower in fact than the center‐of mass diffusion of polymer chains in their fully entangled melts. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 1543–1553, 2009

Structural effects on the solid-state photodimerization of 2-pyridone derivatives in inclusion compounds

The structures of six crystalline inclusion compounds between various host molecules and three guest molecules based on the 2-pyridone skeleton are described. The six compounds are 1,1'-biphenyl-2,2'-dicarboxylic acid-2-pyridone (1/2), C(14)H(10)O(4).2C(5)H(5)NO, (I-a), 1,1'-biphenyl-2,2'-dicarboxylic acid-4-methyl-2-pyridone (1/2), C(14)H(10)O(4).2C(6)H(7)NO, (I-c), 1,1'-biphenyl-2,2'-dicarboxylic acid-6-methyl-2-pyridone (1/2), C(14)H(10)O(4).2C(6)H(7)NO, (I-d), 1,1,6,6-tetraphenyl-2,4-hexadiyne-1,6-diol-1-methyl-2-pyridone (1/2), C(30)H(22)O(2).2C(6)H(7)NO, (II-b), 1,1,6,6-tetraphenyl-2,4-hexadiyne-1,6-diol-4-methy-2-pyridone (1/2), C(30)H(22)O(2).2C(6)H(7)NO, (II-c), and 4,4',4''-(ethane-1,1,1-triyl)triphenol-6-methyl-2-pyridone-water (1/3/1), C(20)H(18)O(3).3C(6)H(7)NO.H(2)O, (III-d). In two of the compounds, (I-a) and (I-d), the host molecules lie about crystallographic twofold axes. In two other compounds, (II-b) and (II-c), the host molecules lie across inversion centers. In all cases, the guest molecules are hydrogen bonded to the host molecules through O-H...O=C hydrogen bonds [the range of O...O distances is 2.543 (2)-2.843 (2) A. The pyridone moieties form dimers through N-H...O=C hydrogen bonds in five of the compounds [the range of N...O distances is 2.763 (2)-2.968 (2) A]. In four compounds, (I-a), (I-c), (I-d) and (II-c), the molecules are arranged in extended zigzag chains formed via host-guest hydrogen bonding. In five of the compounds, the guest molecules are arranged in parallel pairs on top of each other, related by inversion centers. However, none of these compounds underwent photodimerization in the solid state upon irradiation. In one of the crystalline compounds, (III-d), the guest molecules are arranged in stacks with one disordered molecule. The unsuccessful dimerization is attributed to the large interatomic distances between the potentially reactive atoms [the range of distances is 4.027 (4)-4.865 (4) A] and to the bad overlap, expressed by the lateral shift between the orbitals of these atoms [the range of the shifts from perfect overlap is 1.727 (4)-3.324 (4) A]. The bad overlap and large distances between potentially photoreactive atoms are attributed to the hydrogen-bonding schemes, because the interactions involved in hydrogen bonding are stronger than those in pi-pi interactions.

Formation of Diquinoline Molecular Bricks and Their Assembly into Lattice Inclusion Compounds

The dibromodiquinoline derivative 2 yields crystalline lattice inclusion compounds with a wide range of guest molecules. The solvent-free crystal structure is also formed. In all these, pairs of dibromodiquinoline molecules form centrosymmetric brick-like dimers by means of three different aromatic edge−face (EF) interactions. The resultant (EF)6 building blocks, which are virtually identical across the series of 13 crystal structures described, act as tectons that pack into layers. Guest molecules occupy interlayer spaces near the corners of the tectons, with the host−guest attractions acting as molecular mortar and allowing variation of the inclusion structures dependent on guest size, shape, and functionality. The apohost crystal structure demonstrates that guest-free packing of these molecular bricks (analogous to the dry stone construction method) is also favorable. The molecular substitution of a dibromodiquinoline unit required to ensure dimeric (EF)6 tecton formation is explained.

Preparation of borneol–methyl-β-cyclodextrin inclusion complex by supercritical carbon dioxide processing

In this work, the complex of borneol–methyl-β-cyclodextrin was prepared both by supercritical carbon dioxide processing and by the sealed heating treatment at mild pressure and temperature. An amorphous complex was obtained by the sealed heating treatment. A crystalline inclusion complex was obtained by the supercritical carbon dioxide processing. The crystalline complex is more stable than the amorphous complex. The apparent aqueous solubility of borneol could be enhanced about 70 times by complexation with methyl-β-cyclodextrin. In this work, a 1:1 crystalline inclusion complex between borneol and methyl-β-cyclodextrin was obtained by supercritical carbon dioxide processing at temperature about 100 °C and pressure about 100 bar. This inclusion complex is more stable than the amorphous complex prepared by the sealed heating method. The apparent aqueous solubility of borneol could be enhanced about 70 times by complexation with methyl-β-cyclodextrin. The possible complex structure is shown below:

Flexible host frameworks with diverse cavities in inclusion crystals of bile acids and their derivatives

We have systematically investigated structures and properties of inclusion crystals of bile acids and their derivatives. These steroidal compounds form diverse host frameworks having zero-, one- and two-dimensional cavities, causing various inclusion behaviors towards many organic compounds. The diverse host frameworks exhibit the following guest-dependent flexibility. First, the frameworks mainly depend on the included guests in size and shape. The size-dependence is quantitatively estimated by the parameter PCcavity, which is the volume ratio of a guest molecule to a host cavity. The resulting values of PCcavity lie in the range of 42-76%. Second, each of the host frameworks has its own range of the values. Some guests can employ two different frameworks with the boundary values, explaining formation of polymorphic crystals. Third, the host frameworks are selected by host-guest interactions through weak hydrogen bonds, such as NH/pi and CH/O. The weak hydrogen bonds play an important role for various selective inclusion processes. Fourth, the host frameworks are dynamically exchangeable, resulting in intercalation and polymerization in the cavities. These static and dynamic structures of the frameworks demonstrate great potential of crystalline organic inclusion compounds as functional materials.

Guest-dependent self-assembly of (R,R)-2,3-diphenylsuccinic acids : formation of a cyclotetrameric chiral square

A chiral crystalline inclusion complex containing four molecules of (+)-(R,R)−1 and one molecule of diethyl ether was grown from diethyl ether with a diffusion of hexane, and its structure was determined by X-ray diffraction. Since this guest-dependent self-assembled cage was presumed to be chiral with D4 symmetry, its potential as an enantiomer separator was examined.

Bidirectional Transport of Guest Molecules through the Nanoporous Tunnel Structure of a Solid Inclusion Compound

Confocal Raman microspectrometry is used to probe, for the first time, the transport of guest molecules along the one-dimensional tunnels in a crystalline urea inclusion compound under conditions of guest exchange in which new guest molecules are introduced simultaneously at both ends of the urea tunnel structure. We focus on the system comprising 1,8-dibromooctane as the original type of guest and pentadecane as the new type of guest, and results are presented for experiments in which the guest exchange process is probed both ex situ and in situ. The Raman data, recorded as a function of position along the tunnel direction and, in the case of the in situ experiments, as a function of time, demonstrate that pentadecane guest molecules enter the tunnels at both ends of the crystal and that transport of guest molecules occurs in both directions along the crystal. Mechanistic aspects of this bidirectional transport process are discussed, particularly in relation to the corresponding process for unidirectional transport of guest molecules in urea inclusion compounds reported previously.

Crystalline inclusion compounds of lower rim propyl substituted calix[4]arenes featuring different number and positions of the modifying groups

Three lower rim n-propyl substituted calix[4]arenes (1–3) with varied number and position of the modifying groups have been prepared. Inclusion compounds (five species) involving different kinds of guest solvents have been isolated. Their X-ray crystal structures were determined and comparatively discussed using isostructurality calculations. Two of the inclusion compounds obtained (1a and 1b) are polymorphs containing the same host and guest molecules in equal stoichiometric ratio but different Z′ values caused by a phase transition around 140 K. The inclusion compounds 2a and 2b refer to the interesting case of a mixed solvent complex while 3a allows studying the effect of full lower rim n-propyl substitution.

Release characteristics of the non-toxic insect repellant 2-undecanone from its crystalline inclusion compound with α-cyclodextrin

2-Undecanone (methyl nonyl ketone), a natural non-toxic insect repellant compound, was recently isolated from the trichomes of wild tomatoes, and is currently being introduced as a replacement for insect repellants containing N,N-diethyl-meta-toluamide or DEET, which are permitted for use on children older than 2 months. In an effort to improve the delivery of the somewhat volatile 2-undecanone, we have successfully formed the crystalline inclusion compound (IC) between 2-undecanone and α-cyclodextrin (α-CD), using a coprecipitation method. Employing WAXD, DSC, FT-IR, and NMR observations, we have confirmed that 2-undecanone is included as a guest inside the host α-CD cavities, and forms a channel-type crystalline IC. The release characteristics of 2-undecanone insect repellant from its α-CD-IC were studied using TGA either at a heating rate of 20 °C/min in nitrogen, and air atmospheres or at constant temperatures of 25, and 40 °C over a period of 24 h. The release/loss of 2-undecanone insect repellant from its α-CD-IC was ~60% after 24 h at 40 °C. By comparison, ~97% of pure 2-undecanone was volatilized, and lost over 24 h at 40 °C. In addition, insecticidal activity of 2-undecaonone from its α-CD complex against German cockroaches was evaluated. The results show an excellent repellency that 100% of the cockroaches were repelled for the first 2 days after application. These results suggest that the gradual, long-term delivery of the insect repellant 2-undecanone can be significantly improved through employment of its crystalline α-CD-IC.

Construction of different supramolecular polymer systems by combining the host–guest and hydrogen‐bonding interactions

AbstractPoly(ethylene glycol) (PEG) can form either the inclusion complex with α‐cyclodextrins (α‐CDs) through host–guest interactions or the interpolymer complex with poly(acrylic acid) (PAA) through hydrogen‐bonding interaction. Mixing α‐CD, PEG, and PAA ternary components in an aqueous solution, the competition between host–guest and hydrogen‐bonding interactions occurs. Increasing feed ratio of α‐CD:EG:AA from 0:1:1 to 0.2:1:1 (molar ratio), various interesting supramolecular polymer systems, such as hydrogen‐bonding complex, dynamic polyrotaxane, crystalline inclusion complex, and thermoresponsive hydrogel, are successively obtained. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 1114–1120, 2008

Molecular Pacman: Folding, Inclusion, and X‐ray Structures of Tri‐ and Tetraamino Piperazine Cyclophanes

Reaction of piperazine and 1,3-bis(bromomethyl)-2-nitrobenzene under high-dilution conditions yields cyclic trimeric trinitro, tetrameric tetranitro, and pentameric pentanitro piperazine cyclophanes. Reduction of the nitro groups with SnCl(2) under acidic conditions produces the corresponding triamino and tetraamino piperazine cyclophanes. The solution studies of both nitro and amino piperazine cyclophanes at 30 degrees C by (1)H NMR spectroscopy shows symmetrical structures owing to the fast conformational exchange, whereas the low temperature studies of the tetraamino piperazine cyclophane reveals interesting dynamic behavior that indicates additional intramolecular interactions. Careful crystallizations of the trimeric trinitro and triamino and the tetrameric tetraamino cyclophanes resulted in crystals suitable for X-ray diffraction studies. In the crystalline state the amino-functionalized cyclophanes manifest an extraordinary circular intramolecular hydrogen-bonding network that leads to a fixed 3D structure. Hydrogen bonding in the triamino trimer leads to orientation of all three of the amino groups on the same side of the macrocycle, namely, the rcc conformation, whereas the tetraamino tetramer folds into a more compact shell-like conformation. During the crystallization process one acetonitrile guest is enclosed into the cavity of the tetraamino cyclophane, which gives a crystalline inclusion complex with remarkable resemblance to the famous Pacman motif. The folding, which mimics the behavior of some cyclic peptides and pyrroles, is induced by intramolecular hydrogen bonding from the amino groups to the tertiary amine groups of the piperazines. The cavity of the tetraamino tetramer is markedly smaller than in the corresponding, but nonfolded, tetranitro tetramer and the guest/host volume ratio (packing coefficient) for the acetonitrile and the cavity is approximately 50 %, which indicates a good size match for acetonitrile inclusion.

Fanconi-Syndrom des Erwachsenen bei Frühmyelom mit monoklonaler Gammopathie IgG, Typ kappa*

First description of a case of early myeloma with monoclonal IgG, type kappa, anomaly plus Bence-Jones proteinuria and Fanconi's syndrome in a 67-year-old woman. Characteristic crystalline inclusion bodies were found in plasma cells of bone marrow and renal tissue.

Bacillus thuringiensis: applications in agriculture and insect resistance management. A review

Bacillus thuringiensis (Bt) is a sporulating, Gram-positive facultative-aerobic soil bacterium. Its principal characteristic is the synthesis, during sporulation, of a crystalline inclusion containing proteins known as δ-endotoxins or Cry proteins. These proteins have insecticidal properties. The considerable diversity of these toxins, their efficacy and their relatively cheap production have made Bt the most widely used biopesticide in the world. It is used in the fight against many agricultural crop pests – mostly lepidopteran and coleopteran larvae – notably in the creation of new plant varieties expressing Bt cry genes. For human health, Bt can be used for the effective control of populations of several dipteran disease vectors. The aim of this review is to provide an overview of the use of Bt for crop protection and to deal with the problem of the emergence of insects resistant to this biopesticide. We will begin by presenting various aspects of the biology of this entomopathogenic micro-organism, focusing on the diversity and mode of action of the insecticidal toxins it produces. We will then present several examples of utilization of commercially available Bt products used as sprays or as transgenic crops. Finally, we will describe the principal strategy for the use of Bt transgenic plants, developed so as to prevent or delay the emergence of resistance in target insect populations.

Supramolecular end-group separation of linear polymers with different terminals through host–guest interaction

By increasing the hydrophobicity of end group, the complexation rate between α-cyclodextrin (α-CD) and poly(ethylene glycol) (PEG) derivative speeds up greatly. Based on such a huge difference of complexation kinetics, the PEG derivative with palmityloxy terminal (PEG-C16) can be successfully separated from a carboxylic acid end-functionalized analogue (PEG-COOH) by once supramolecular purification. Adding α-CD into the aqueous solution of PEG-C16/PEG-COOH mixture, PEG-C16 is encapsulated into α-CD cavity to form the crystalline inclusion complex in a very short time, while almost all of PEG-COOH molecules are still reserved in the aqueous solution. After dichloromethane extraction, the pure PEG-C16 is obtained. Moreover, the host CD can be recycled. Thus, it is an efficient green way to separate and purify the linear polymers with different terminal functionality.

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.