Selective deprotection of trityl group on carbohydrate by microflow reaction inhibiting migration of acetyl group

The trityl group is an important and useful protecting group for primary hydroxy groups on carbohydrates. However, during deprotection, neighboring acetyl groups can easily migrate to the deprotected hydroxy groups. Hence, deprotection of trityl groups was optimized using a microreactor with regard to flow rate, reagent concentration, reaction time, and substrate concentration. The optimized microflow reaction conditions inhibited migration and could be applied to large-scale reactions and other substrates.     

Self-modeling curve resolution (SMCR) analysis of near-infrared (NIR) imaging data of pharmaceutical tablets

The idea of quality by design (QbD) has been proposed in pharmaceutical field. QbD is a systematic approach to control the product performance based on the scientific understanding of the product quality and its manufacturing process. In the present study, near-infrared (NIR) imaging is utilized as a tool to achieve this concept. A practical use of a chemometrics technique called self-modeling curve resolution (SMCR) is demonstrated with NIR imaging analysis of pharmaceutical tablets containing two ingredients, a soluble active ingredient, pentoxifylline (PTX), and an insoluble excipient, palmitic acid. Concentration profiles obtained by SMCR reveal that the homogenous distribution of chemical ingredients strongly depends on the grinding time and that its process plays a central role in quantitative control, say sustained-release of PTX. In addition, pure component spectra by SMCR indicate a sequential change of specific NIR peak intensities following the increase of the grinding time. The spectra change shows a molecular structure change related to its crystallinity during grinding process. Accordingly, this study clearly demonstrates that NIR imaging combined with SMCR can be a powerful tool to reveal chemical or physical mechanism induced by the manufacturing process of pharmaceutical products and that it may be a solid solution for QbD of pharmaceutical products.     

Efficient formation of giant liposomes through the gentle hydration of phosphatidylcholine films doped with sugar

Giant liposomes, or giant vesicles, are cell-size (approximately 5-100 microm) compartments enclosed with phospholipid bilayers, and have often been used in biological research. They are usually generated using hydration methods, "electroformation" and "gentle hydration (or natural swelling)", in which dry lamellar films of phospholipids are hydrated with aqueous solutions. In gentle hydration, however, giant liposomes are difficult to prepare from an electrostatically neutral phospholipid because lipid lamellae cannot repel each other. In this study, we demonstrate the efficient formation of giant liposomes using the gentle hydration of neutral phospholipid (dioleoyl phosphatidylcholine, DOPC) dry films doped with nonelectrolytic monosaccharides (glucose, mannose, and fructose). A mixture of DOPC and such a sugar in an organic solvent (chloroform/methanol) was evaporated to form the films, which were then hydrated with distilled water or Tris buffers containing sodium chloride. Under these conditions, giant liposomes spontaneously formed rapidly and assumed a swollen cell-sized spherical shape with low lamellarity, whereas giant liposomes from pure DOPC films had multilamellar lipid layers, miscellaneous shapes and smaller sizes. This observation indicates that giant unilamellar vesicles (GUVs) of DOPC can be obtained efficiently through the gentle hydration of sugar-containing lipid dry films because repulsion between lipid lamellae is enhanced by the osmosis induced by dissolved sugar.     

Dehydration performance of a hydrophobic DD3R zeolite membrane

The all silica DDR membrane turns out to be well suited to separate water from organic solvents under pervaporation conditions, despite its hydrophobic character. All-silica zeolites are chemically and hydrothermally more stable than aluminum containing ones and are therefore preferred for membrane applications, including for dehydration, even though these type of membranes are hydrophobic. Permeation of water, ethanol and methanol through an all-silica DDR membrane has been measured at temperatures ranging from 344 to 398 K. The hydrophobic membrane shows high water fluxes (up to 20 kg m⁻² h⁻¹). The pure water permeance is insensitive to temperature and is well described assuming weak adsorption. Excellent performance in dewatering ethanol (N=2$N=2$ kg m⁻² h⁻¹and _αw=1500${\alpha }_{\text{w}}=1500$ at 373 K and _xw=0.18$x_{\text{w}}=0.18$) is observed and the membrane is also able to selectively remove water from methanol (N=5$N=5$ kg m⁻² h⁻¹ and _αw=9${\alpha }_{\text{w}}=9$). Water could also be removed from methanol/ethanol/water (_αwater_/EtOH=1500${\alpha }_{\text{water}/\text{EtOH}}=1500$, _αMeOH_/EtOH=70${\alpha }_{\text{MeOH}/\text{EtOH}}=70$ at 373 K) mixtures, even at water feed concentrations below 1.5 mol%.     

Selective Preparation of Phosphorus Mononitride (P≡N) from Phosphinoazide and Reversible Oxidation to Phosphinonitrene

The interstellar candidate phosphorus mononitride PN, a metastable species, was generated through high-vacuum flash pyrolysis of (o-phenyldioxyl)phosphinoazide in cryogenic matrices. Although the PN stretching band was not directly detected because of its low infrared intensity and possible overlaps with other strong bands, o-benzoquinone, carbon monoxide, and cyclopentadienone as additional fragmentation products were clearly identified. Moreover, an elusive o-benzoquinone-PN complex formed when (o-phenyldioxyl)phosphinoazide was exposed to UV irradiation at λ=254 nm. Its recombination to (o-phenyldioxyl)-λ⁵-phosphinonitrile was observed upon irradiation with the light at λ=523 nm, which demonstrates for the first time the reactivity of PN towards an organic molecule. Energy profile computations at the B3LYP/def2-TZVP density functional theory level reveal a concerted mechanism. To provide further evidence, UV/Vis spectra of the precursor and the irradiation products were recorded and agree well with time-dependent DFT computations.     

Chemical Characterization and Bioactivity of Commercial Essential Oils and Hydrolates Obtained from Portuguese Forest Logging and Thinning

Essential oils (EOs) and hydrolates (Hds) are natural sources of biologically active ingredients with broad applications in the cosmetic industry. In this study, nationally produced (mainland Portugal and Azores archipelago) EOs (11) and Hds (7) obtained from forest logging and thinning of Eucalyptus globulus, Pinus pinaster, Pinus pinea and Cryptomeria japonica, were chemically evaluated, and their bioactivity and sensorial properties were assessed. EOs and Hd volatiles (HdVs) were analyzed by GC-FID and GC-MS. 1,8-Cineole was dominant in E. globulus EOs and HdVs, and α- and β-pinene in P. pinaster EOs. Limonene and α-pinene led in P. pinea and C. japonica EOs, respectively. P. pinaster and C. japonica HVs were dominated by α-terpineol and terpinen-4-ol, respectively. The antioxidant activity was determined by DPPH, ORAC and ROS. C. japonica EO showed the highest antioxidant activity, whereas one of the E. globulus EOs showed the lowest. Antimicrobial activity results revealed different levels of efficacy for Eucalyptus and Pinus EOs while C. japonica EO showed no antimicrobial activity against the selected strains. The perception and applicability of emulsions with 0.5% of EOs were evaluated through an in vivo sensory study. C. japonica emulsion, which has a fresh and earthy odour, was chosen as the most pleasant fragrance (60%), followed by P. pinea emulsion (53%). In summary, some of the studied EOs and Hds showed antioxidant and antimicrobial activities and they are possible candidates to address the consumers demand for more sustainable and responsibly sourced ingredients.     

The microenvironment in polymer solids with added plasticizers. An attempt to measure the size and distribution of free volume in poly(methyl methacrylate) solids

Various amounts of n-alkylbenzenes (C_n: C₆H₅-C_nH_2n+1 (n = 3-16)) were doped into poly(methyl methacrylate) (PMMA) films, and the emission and thermal properties of each film were measured in detail together with their solid-state ¹³C NMR spectra. The aim of the present work was to estimate the size distribution of free volume in amorphous regions of polymer solids heavily doped with plasticizers by using C_n as models of a plasticizer. The excimer fluorescence yields of C_n in PMMA were found to depend on both the amount of C_n and the length of the alkyl chains of C_n, although the fluorescence spectra of all of the C_ns in dilute fluid solution were almost the same. The quantitative analysis showed: (1) C_n with n ? 12 induces a phase separation in PMMA, in which almost all of the C_n molecules are in a separated phase, and thus they cannot penetrate regions in which PMMA chains are aggregated. This means that C_n with n ? 12 cannot enlarge the space between PMMA chains. (2) Smaller C_n (n < 11) can enter free volumes between PMMA chains that correspond to their molecular size, but they can enlarge them only to a limited extent. Thus, the amount by which plasticization can increase the free volume of PMMA is limited by the size of the dopant and the inherent free volume of the polymer matrix. (3) The efficiency of excimer formation was found to reveal the maximum amount of C_n that could fit in the free volume of PMMA. Thus our fluorescence measurements showed that PMMA solids that were plasticized to their limit had a free volume that was larger than the volume occupied by all the conformers of C₅ and smaller than the volume occupied by almost all the conformers of C₁₂. In conclusion, we were able to obtain information on plasticization and to demonstrate a method of monitoring microenvironments in polymer solids after they have been doped with plasticizers.     

One-electron reduction of superoxide radical-anions by 3-alkylpolyhydroxyflavones in micelles. Effect of antioxidant alkyl chain length on micellar structure and reactivity

In micellar solutions, one-electron reduction of (*)O 2 (-) radical-anions by 3-alkylpolyhydroxyflavones (FnH) with alkyl chains of n = 1, 4, 6, 10 carbons produces phenoxyl radicals ( (*)Fn) identical to those obtained by one-electron oxidation by (*)Br 2 (-) radical-anions or by repair of tryptophan radicals. In cetyltrimethylammonium bromide (CTAB), F1H localizes in the Stern layer, and alkyl chains of other FnH solubilize in the hydrophobic interior, interacting with cetyl tails. This interaction produces more compact micelles with lower intramicellar fluidity, as suggested by the increase in the pseudo-first-order rate constant of (*)Fn formation ( k 1) from approximately 390 s (-1) for n = 1 to 610 s (-1) for n = 10, leading to an intramicellar bimolecular rate constant of 1 x 10 (5) M (-1) s (-1). Additionally, (*)F1 and (*)F4 decay by intermicellar bimolecular reaction (2 k = 20 and 2 x 10 (5) M (-1) s (-1), respectively) whereas other (*)Fn radicals are stable over seconds due to increased localization with regards to the Stern layer. In contrast, the thick uncharged hydrophilic palisade layer and the compact hydrophobic core of Triton X100 micelles are responsible for a much higher microviscosity resulting in a decrease in k 1 from approximately 15.6 s (-1) for n = 1 to 9.6 s (-1) for n = 10.