Nonpolar Organic Solvents Research Articles

Identification of a Novel Selenium-containing Compound, Selenoneine, as the Predominant Chemical Form of Organic Selenium in the Blood of Bluefin Tuna

A novel selenium-containing compound having a selenium atom in the imidazole ring, 2-selenyl-N(alpha),N(alpha),N(alpha)-trimethyl-L-histidine, 3-(2-hydroseleno-1H-imidazol-5-yl)-2-(trimethylammonio)propanoate, was identified from the blood and other tissues of the bluefin tuna, Thunnus orientalis. The selenium-containing compound was purified from the tuna blood in several chromatographic steps. High resolution mass spectrometry and nuclear magnetic resonance spectroscopy showed that the exact mass of the [M+H](+) ion of the compound was 533.0562 and the molecular formula was C(18)H(29)N(6)O(4)Se(2). Its gross structure was assigned as the oxidized dimeric form of an ergothioneine selenium analog in which the sulfur of ergothioneine is replaced by selenium. Therefore, we named this novel selenium-containing compound "selenoneine." By speciation analysis of organic selenium compounds using liquid chromatography inductively coupled plasma mass spectrometry, selenoneine was found widely distributed in various tissues of the tuna, with the highest concentration in blood; mackerel blood contained similar levels. Selenoneine was measurable at 2-4 orders of magnitude lower concentration in a limited set of tissues from squid, tilapia, pig, and chicken. Quantitatively, selenoneine is the predominant form of organic selenium in tuna tissues.

J-Aggregation of Zinc 31,131-Dihydroxychlorins by Exclusive Coordination Bonding between 31-Hydroxy Group and Central Zinc Atom

Abstract Zinc 31,131-dihydroxychlorin lacking an exo-five-membered E-ring was prepared as a model of natural bacteriochlorophyll-d possessing 31-OH and 13-C=O groups. The synthetic zinc complex has the 13-CH2OH instead of the 13-C=O and self-aggregated in a nonpolar organic solvent, giving slipped and π-overlapped molecular stackings (J-aggregates) with red-shifted and broadened electronic absorption bands. For the intermolecular interactions among the J-aggregates, coordination bonding of the 31-OH (not 131-OH) with the central Zn was utilized.

Columnar Organization of Head-to-Tail Self-Assembled Pt4 Rings

Coordination of Pt(2+) to a family of tunable Schiff base proligands directs the 12-component self-assembly of disk-shaped Pt(4) rings in a head-to-tail fashion. Aggregation of these S(4) symmetric Pt(4) macrocycles into columnar architectures was investigated by dynamic and static light scattering, NMR spectroscopy, powder X-ray diffraction, and transmission electron microscopy. Data from these experiments support the formation of columnar architectures for all of the structures studied except when bulky tris(4-tert-butylphenyl)methyl substituents were present. In this case, aggregation was limited to dimers in CHCl(3) (K(dim) = 3200 +/- 200 L mol(-1) at 25 degrees C) and a thermodynamic analysis revealed that dimerization is an entropy driven process. Columnar architectures of Pt(4) rings with branched 2-hexyldecyl substituents organize into lyotropic mesophases in nonpolar organic solvents. These new self-assembled supramolecules are promising candidates to access nanotubes with multiple linear arrays of Pt(2+) ions.

Ab Initio Modeling of Organolithium Equilibria

Experimental ion pair pK's of monomeric contact ion pair lithium salts in THF from our previous studies give good correlations with ab initio calculations at the Hartree-Fock 6-31+g(d) level. PCM methods were found to be inadequate in nonpolar organic solvents, and dielectric solvation was not used in the correlations. Specific coordination of two or three ether solvent molecules with lithium was found to be satisfactory. These correlations include carboxamides, amines, dithianes, sulfones, and sulfoxides, as well as some ketones, beta-diketones, and the lithium salts of dianions.

Reduction of functionalized graphite oxides by trioctylphosphine in non-polar organic solvents

Graphene, functionalized with oleylamine (OA) and soluble in non-polar organic solvents, was produced on a large scale with a high yield by combining the Hummers process for graphite oxidation, an amine-coupling process to make OA-functionalized graphite oxide (OA-GO), and a novel reduction process using trioctylphosphine (TOP). TOP acts as both a reducing agent and an aggregation-prevention surfactant in the reduction of OA-GO in 1,2-dichlorobenzene (DCB). The reduction of OA-GO is confirmed by X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, and Raman spectroscopy. The exfoliation of GO, OA-GO, and OA-functionalized graphene (OA-G) is verified by atomic force microscopy. The conductivity of TOP-reduced OA-G, which is deduced from the current–voltage characteristics of a vacuum-filtered thin film, shows that the reduction of functionalized GO by TOP is as effective as the reduction of GO by hydrazine.

Self-diffusion in supercritical water and benzene in high-temperature high-pressure conditions studied by NMR and dynamic solvation-shell model

The self-diffusion coefficients of water and organic solvents in the high-temperature high-pressure conditions are studied by using high-temperature NMR and MD simulation methods. The experimental results are analyzed using a scheme based on the solvation shell relaxation time obtained by MD simulation. The dynamic effect of hydrogen bonding is discussed through the comparison between water and a nonpolar organic solvent, benzene, over a wide range of density and temperature. The hydrogen-bonding effects are as follows: (1) the self-diffusion coefficient of water depends on density more weakly than that of benzene, (2) the self-diffusion coefficient of water at the ambient density depends on temperature more strongly than that of benzene at the density, (3) the turnover from the mobile-shell type to the in-shell type with increasing density does not occur in supercritical water up to the ambient density, whereas such turnover is observed in benzene. These contrasts are reflecting the dynamic effect of the anisotropic attractive interactions.

Facile synthesis of monodisperse, size-tunable SnS nanoparticles potentially for solar cellenergy conversion

A simple strategy to synthesize monodisperse, single-crystalline and size-tunable SnSnanoparticles was reported. An active sulfur precursor bis(trimethylsilyl)sulfide was appliedto enable fast nucleation of tin species in oleylamine. As-synthesized nanoparticles wereeasily dispersed in a non-polar organic solvent and formed a uniform solutionwhich showed complete absorption of visible light. The smooth, dense-packedand crack-free SnS film was achieved by spin-coating that showed an enhancedphotoresponse via methanol treatment. Owing to their noble merits, as-synthesizedSnS nanoparticles could be a potential nanomaterial for solar cell application.

Non-covalent functionalization, solubilization of graphene and single-walled carbon nanotubes with aromatic donor and acceptor molecules

Non-covalent functionalization, solubilization of graphene and single-walled carbon nanotubes (SWNTs) has been explored in non-polar organic solvents with various electron-donor and -acceptor molecules. Large aromatic surfaces of electron-donor and -acceptor molecules direct them onto the surface of the graphene/SWNTs through π–π stacking interactions whereas the alkyl chains as well as the glycol chains on the aromatic molecules promote the solubility, thereby giving stable dispersions of SWNT/graphene composites in non-polar solvents. Composites of graphene and SWNTs with electron-donor and -acceptor showed significant changes in the electronic and Raman spectra which were found to be characteristic of molecular charge-transfer interactions.

β-Carotene to bacteriochlorophyll c energy transfer in self-assembled aggregates mimicking chlorosomes

Carotenoids are together with bacteriochlorophylls important constituents of chlorosomes, the light-harvesting antennae of green photosynthetic bacteria. Majority of bacteriochlorophyll molecules form self-assembling aggregates inside the chlorosomes. Aggregates of bacteriochlorophylls with optical properties similar to those of chlorosomes can also be prepared in non-polar organic solvents or in aqueous environments when a suitable non-polar molecule is added. In this work, the ability of β-carotene to induce aggregation of bacteriochlorophyll c in aqueous buffer was studied. Excitation relaxation and energy transfer in the carotenoid-bacteriochlorophyll assemblies were measured using femtosecond and nanosecond transient absorption spectroscopy. A fast, ∼100-fs energy transfer from the S 2 state of β-carotene to bacteriochlorophyll c was revealed, while no evidence for significant energy transfer from the S 1 state was found. Picosecond formation of the carotenoid triplet state (T 1) was observed, which was likely generated by singlet homo-fission from the S 1 state of β-carotene.

Sub-10 nm strontium titanate nanocubes highly dispersed in non-polar organic solvents

Strontium titanate (SrTiO(3)) nanoparticles with well defined cubic shape and sub-10 nm size that are highly dispersible in non-polar organic solvents were successfully synthesized by hydrothermal (HT) processing. Water-soluble titanium complexes and strontium hydroxide were employed as precursors. When the HT process was carried out without oleic acid, the SrTiO(3) particles obtained were relatively large and aggregated. However, SrTiO(3) nanocubes that are highly dispersible in hexane were obtained via the HT process using oleic acid and hydrazine.

Versatile chiroptics of peptide-induced assemblies of metalloporphyrins

Zinc porphyrin functionalized with double long-chain alkylated L-glutamide (GTPP-Zn) was synthesized for the first time, and its self-assembling behaviour was investigated in nonpolar organic solvents. The uniqueness of this functionalized porphyrin is characterized by its drastic colour change from dark green to purple via the formation of chirally stacked structures through selective axial coordination on zinc with pyridine derivatives. In this paper, we report the versatility of the GTPP-Zn assembly process as a stimuli-responsive chiroptical switching system and describe the remarkable ligand-specific induction of secondary chirality accompanied by aggregation morphological change.

Interfacial Cu/ZnO contact by selective photodeposition of copper onto the surface of small ZnO nanoparticles in non-aqueous colloidal solution

Nanoscale copper was selectively photodeposited onto the surface of hexadecylamine (HDA) stabilized (monodispersed not agglomerated) ZnO nanoparticles (NPs) of a diameter of 2-5 nm, which leads to HDA-stabilized Cu/ZnO NPs of varied Cu loading. The particles are soluble in non-polar organic solvents. The line broadening and the red shift of the surface plasmon band of Cu/ZnO NPs relative to HDA-stabilized Cu NPs, the profound decrease of the Cu/ZnO NPs visible photoluminescence at 525 nm, the increase of the UV emission intensity at 365 nm and the enhancement of the Raman scattering (RS) intensity in comparison to the parent ZnO NPs confirmed the interfacial contact between the Cu and ZnO phase.

A simple method to synthesize multifunctional silica nanocomposites, NPs@SiO2, using polyvinylpyrrolidone (PVP) as a mediator

The well-investigated method to prepare various nanoparticles is a thermolysis method in hot organic solutions. These nanoparticles are usually dispersible in nonpolar organic solvents, which sometimes causes problem to overcoat them with silica due to the polar alcoholic solvent in the silica forming process. We have developed a general procedure to incorporate high quality nanoparticles into silica beads. Organic-dispersible nanoparticles do not form precipitates in alcoholic solution in the presence of hydrophilic polyvinylpyrrolidone (PVP), and successive addition of TEOS with a basic catalyst can generate silica coating on nanocrystals. The PVP stabilized nanoparticles can also be easily adsorbed on the amino-functionalized silica bead surface to form interesting core-shell type structures. Many different nanoparticles from the thermolysis can be used in our preparation method, and these multifunctional silica nanocomposites are expected to be utilized in many applied fields where wettability, biocompatibility and ease of surface modification are very critical.

Hydrogen bonding properties of non-polar solvents

A combination of high-throughput NMR titration experiments, UV-Vis absorption titrations and data collected from the literature on 1:1 H-bonded complexes has been used to characterise the H-bond properties of non-polar organic solvents: alkanes, perfluorocarbons, aromatic and halogenated organic solvents. The results are analysed in the context of the electrostatic solvent competition model, which assumes that solvent effects on intermolecular interactions can be interpreted based on the exchange of specific functional group contacts, with minimal involvement of the bulk solvent. For solvents where the H-bond parameters have been measured as solutes in carbon tetrachloride solution, the H-bond parameters measured here for the same compounds as solvents are practically identical, i.e. solute and solvent H-bond parameters are directly interchangable. For the very non-polar solvents, alkanes and perfluorocarbons, the experimental H-bond parameters are significantly larger than expected based on calculated molecular electrostatic potential surfaces. This suggests an increase in the relative importance of van der Waals interactions when electrostatic effects are weak, but there is no detectable difference between the solvation properties of cyclic and linear alkanes, which have different van der Waals interaction properties.

Ion-pair induced self-assembly in aqueous solvents

The intriguing advantages of supramolecular chemistry and particularly the application of self-assembly for the construction of defined nanostructures from small, preferably synthetically easily accessible molecules has become a promising area of modern chemistry in the last years. However, the main focus of early work was based on H-bond induced self-assembly which is limited to nonpolar organic solvents. In the past years the field started to shift more and more towards obtaining self-assembling architectures in polar solvents and even water. This tutorial review will discuss some representative examples for self-assembling systems in polar solvents in order to illustrate the different concepts and strategies that can be used. We will also briefly discuss the special properties of water as the ultimate protic solvent from the perspective of a supramolecular chemist to elucidate the challenges that this solvent still poses even today to obtain specific self-assembled nanostructures.

Physically and chemically mixed TiO 2-supported Pd and Au catalysts: unexpected synergistic effects on selective hydrogenation of citral in supercritical CO 2

The selective hydrogenation of citral was studied with various TiO 2-supported monometallic and bimetallic Pd and Au catalysts and their physical mixtures in supercritical CO 2 (scCO 2). Significant synergistic effects appeared when active Pd species was chemically or physically mixed with less active Au species. The total rate of conversion was greatly enhanced and the selectivity to citronellal (CAL) was improved. The physical properties of those catalysts were characterized by TEM, HRTEM-EDS, XPS, and UV/Vis and their features of H 2 desorption were examined by TPD. The physical and chemical characterization results were used to discuss the reasons for the unexpected synergistic effects observed. The same selective hydrogenation was also conducted in a conventional non-polar organic solvent of n-hexane to examine the roles of scCO 2. The use of scCO 2 was effective for accelerating the hydrogenation of citral and improving the selectivity to CAL.

Linear Organo-Soluble Poly(p-benzamide)

Organo-soluble, shape-persistent oligo- and poly(p-benzamide)s were synthesized and characterized. A triethylene glycol (TEG) substituent was introduced to the p-aminobenzoic acid monomer structure as a solubilizing side chain giving 4-amino-2-triethylene glycol benzoic acid. This new monomer was polymerized by the facile polycondensation of the corresponding acid halide derivative of the amine hydrochloric salt. Additionally, a well-defined heptamer was prepared from this monomer on a peptide synthesizer as a model compound. The TEG-substituted oligomers and polymers exhibited good solubility yet high aggregation tendency in common polar and nonpolar organic solvents. The solution self-organization of the poly(2-TEG-p-benzamide) was examined by GPC, NMR, and UV/vis spectroscopy. Transmission electron microscopy (TEM) allowed the visualization of the supramolecular assemblies, showing the formation of micrometer-sized rigid superstructures.

Conjugated Polymers Combined with a Molecular Beacon for Label‐Free and Self‐Signal‐Amplifying DNA Microarrays

AbstractA conjugated polymer (CP) and molecular‐beacon‐based solid‐state DNA sensing system is developed to achieve sensitive, label‐free detection. A novel conjugated poly(oxadiazole) derivative exhibiting amine and thiol functional groups (POX‐SH) is developed for unique chemical and photochemical stability and convenient solid‐state on‐chip DNA synthesis. POX‐SH is soluble in most nonpolar organic solvents and exhibits intense blue fluorescence. POX‐SH is covalently immobilized onto a maleimido‐functionalized glass slide by means of its thiol group. Molecular beacons having a fluorescent dye or quencher molecule as the fluorescence resonance energy transfer (FRET) acceptor are synthesized on the immobilized POX‐SH layer through direct on‐chip oligonucleotide synthesis using the amine side chain of POX‐SH. Selective hybridization of the molecular beacon probes with the target DNA sequence opens up the molecular beacon probes and affects the FRET between POX‐SH and the dye or quencher, producing a sensitive and label‐free fluorescence sensory signal. Various molecular design parameters, such as the size of the stem and loop of the molecular beacon, the choice of dye, and the number of quencher molecules are systematically controlled, and their effects on the sensitivity and selectivity are investigated.

Development of biosensor for phenol detection using agarose–guar gum based laccases extracted from Pleurotus ostreatus

AbstractLaccases from Pleurotus ostreatus was extracted from the Shaken flask cultures of Pleurotus ostreatus grown at 25°C with continuous agitation (110 rpm.) in baffled 1000 mL Erlenmeyer flasks containing 200 mL medium. The basal GYP medium used for cultures contained 20 g glucose l−1, 5 g yeast extract l−1, 5 g peptone from casein l−1, and 1 g MgSO4.7H2O l−1. The pH was adjusted to 5.0 with H3PO4 before sterilization. The kinetics of oxidation reactions catalyzed by laccases was studied using 2,2′‐azino‐bis (3‐ethylbenzthiazoline‐6‐sulphonic acid). The laccases showed lower specific activity and higher activity in nonpolar organic solvents. A biosensor using laccases was constructed for the determination of phenol. The enzyme was extracted from Pleurotus ostreatus and entrapped in agarose–guar gum composite biopolymer matrix. Phenol was determined by direct reduction of biocatalytically liberated quinone species at −0.1 V versus Ag/AgCl (3M KCl). The response was found to be linear and concentration dependent.It has a shelf life of more than 2 months when stored at 4°C. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

New Lecithin Organogels with Sugars of RNA and DNA

Abstract We report a new method for forming lecithin organogels that consist of reverse worm-like micelles. This method utilizes trace amounts of d-ribose or 2-deoxy-d-ribose in combination with lecithin and a nonpolar organic solvent.