Paul Jara

Ordered arrangement of gold nanoparticles on an α-cyclodextrin–dodecanethiol inclusion compound produced by magnetron sputtering

An ordered self-assembly of gold nanoparticles (AuNPs) onto microcrystal faces of a 2α-cyclodextrin–dodecanethiol (2αCD–DDT) inclusion compound (IC) by means of a magnetron sputtering technique was obtained. The preferential deposition on the (001) plane of the αCD IC crystal occurs because –SH groups from the guest molecules found within the αCD protrude into that plane. These –SH groups form a two-dimensional hexagonal lattice that interacts with the metal NPs, arranging them in an ordered way.

INCLUSION COMPOUNDS OF α-CYCLODEXTRIN WITH ALKYLTHIOLS

ABSTRACT We report the formation of α-cyclodextrin (αCD) inclusion compounds with octanethiol (OT), decanethiol (DT) and dodecanethiol (DDT). Elemental Microanalysis, 1 H-NMR solution, Scanning Electronic Microscopy (SEM) and Powder X-ray Diffraction analysis (PXRD) confirm the inclusion process of the alkylthiols in to the α-cyclodextrin molecules. The basic host structure of the products is similar to that of typical channel type structure cyclodextrin inclusion compounds. The guest presents extended linear (zig-zag) conformation. The presence of the –SH groups located in the (001) plane of the α-cyclodextrins-alkylthiol crystal, is evidenced by Energy dispersive X-ray (EDX) analysis. 13 C CP-MAS NMR spectra of new α-cyclodextrin host-guest inclusion compounds are described.Keywords: Inclusion compound, Cyclodextrin, Thiol INTRODUCTION α, β or γ-cyclodextrins are cyclic oligosaccharides consisting in 6, 7 and 8 glucopyranose units, respectively. These compounds have relatively rigid doughnut-shaped structures, and constitute very useful monomolecular hosts in supramolecular chemistry

UNVEILING THE STRUCTURE OF NI/NI OXIDE NANOPARTICLES SYSTEM

This report shows the structural analysis study of the 30-50 nm Ni/Ni oxide nanoparticles obtained by displacement of a nickel-organometallic complex. So using techniques as electron diffraction (ED), and X-ray diffraction it was shown the presence of Ni2O3, NiO, NiO2, and nickel phases on it.

Dicyclohexylamine-Thiourea Clathrate

Abstract The reaction of dicyclohexylamine (DCHA) with thiourea leads to the formation of the inclusion compound DCHA(6 Thiourea). Room temperature, single crystal X-ray diffraction analysis shows the product has a trigonal structure, α=β=90°, γ=120°, a=b=15.801(2)A, c=12.451(3)A, which may be described as a thiourea matrix defining hexagonal cavities where the di-cyclohexylamine molecules are accommodated. 13C-cross polarization magic angle spinning (CP-MAS) NMR study indicates the guest inside the cavities has a relatively free rotation and that the channels are, concerning this amine, perfect van der Waals cavities. Thermal studies indicates that the structural identity of the thiourea matrix endures after a partial loss of amine.

SYNTHESES AND STRUCTURAL ASPECTS OF CYCLODEXTRIN/DIALKYLAMINE INCLUSION COMPOUNDS

We report the syntheses and structural aspects of cyclodextrin host–guest inclusion compounds containing linear secondary alkylamines (dipropyl, dibutyl, dipentyl, dihexyl, and dioctyl) at 25 °C. Elemental analysis, 13C CP-MAS NMR spectroscopy, and powder X-ray diffraction analysis confirm the inclusion process. The basic host structure of the products is similar to that of typical cyclodextrin inclusion systems. 13C MAS NMR experiments show a different resonance pattern for the confined guest molecules with respect to the amine in the liquid phase. The presence of different resonance signals for the homologous carbon atoms of both dialkylamine branches is evidence for the non-symmetric location of the amine in the cyclodextrin channels.

Synthesis and structural aspects of urea/dialkylamine inclusion compounds

The synthesis and structural aspects of urea host-guest inclusion compounds containing linear secondary alkylamines (dibutyl-,dipentyl-, dihexyl-, dioctyl-) at 25°C are reported. Elemental analysis,13C CP-MAS NMR and1H-NMR Spectroscopy, and Powder X-ray Diffraction Analysis confirm the inclusion process. The basic host structure of the products is similar to that of urea-hydrocarbon systems.13C MAS-NMR experiments show chemical shift differences for the confined guest molecule with respect to the liquid phase. Stoichiometry and |cg| values for the inclusion compounds with dipentyl-and dihexylamine suggest a commensurate structure.

Gold Nanoparticles Interacting with β-Cyclodextrin–Phenylethylamine Inclusion Complex: A Ternary System for Photothermal Drug Release

We report the synthesis of a 1:1 β-cyclodextrin-phenylethylamine (βCD-PhEA) inclusion complex (IC) and the adhesion of gold nanoparticles (AuNPs) onto microcrystals of this complex, which forms a ternary system. The formation of the IC was confirmed by powder X-ray diffraction and NMR analyses ((1)H and ROESY). The stability constant of the IC (760 M(-1)) was determined using the phase solubility method. The adhesion of AuNPs was obtained using the magnetron sputtering technique, and the presence of AuNPs was confirmed using UV-vis spectroscopy (surface plasmon resonance effect), which showed an absorbance at 533 nm. The powder X-ray diffractograms of βCD-PhEA were similar to those of the crystals decorated with AuNPs. A comparison of the one- and two-dimensional NMR spectra of the IC with and without AuNPs suggests partial displacement of the guest to the outside of the βCD due to attraction toward AuNPs, a characteristic tropism effect. The size, morphology, and distribution of the AuNPs were analyzed using TEM and SEM. The average size of the AuNPs was 14 nm. Changes in the IR and Raman spectra were attributed to the formation of the complex and to the specific interactions of this group with the AuNPs. Laser irradiation assays show that the ternary system βCD-PhEA-AuNPs in solution enables the release of the guest.

Metallic nanoparticle tropism of alkylthiol guest molecules included into α-cyclodextrin host

The migration of octanethiol, decanethiol and dodecanethiol guest molecules included in the cavities of the channel-type structure of α-cyclodextrin matrix in the presence of gold nanoparticles (AuNPs) was studied by powder X-ray diffraction. This behaviour has been called metallic nanoparticle tropism. The phenomena behaviour can be associated to the guest (thiol group)–AuNP interaction. This is evidenced by an increase of the lattice parameters, especially the c-axis, because to that AuNPs induce a shift of the guest molecule left outside the (001) plane, stabilising the nanoparticle and arranging them in an ordered way. First evidence of gold nanoparticles tropism of alkylthiol guest molecules included into the cavities of α-cyclodextrin matrix, determined by powder X-ray diffraction.

Single-crystal Anisotropic Proton Conductivity in the Clathrate of the Hydrogen-diquinuclidine Ion Inserted in a Polyanionic Thiourea–chloride Matrix

The anisotropic proton conductivity of a large-sized single crystal of the supramolecular, commensurate host–guest inclusion compound constituted by a polyanionic thiourea–chloride matrix defining channels in which the diquinuclidinium cations [Q2H]+ are hosted is reported. Specimens in the millimetre scale display an anisotropy factor of about 100, with electrical conductivities along molecular channels of the order of 10-4 S cm-1 at room temperature.

Selective nanodecoration of modified cyclodextrin crystals with gold nanorods

Gold nanorods (AuNRs) stabilized by cetyltrimethylammonium bromide (CTAB) were deposited onto crystals of α-cyclodextrin (α-CD) inclusion compounds (ICs) that contained octanethiol (OT) as guest molecules. The nanodecoration was produced specifically at the {001} crystal planes through interaction between the -SH groups of the ICs and the AuNRs.