Microporous structure and drug release kinetics of polymeric nanoparticles

The aim of the present study was to characterize pegylated nanoparticles (NPs) for their microporosity and study the effect of microporosity on drug release kinetics. Blank and drug-loaded NPs were prepared from three different pegylated polymers, namely, poly(ethylene glycol)1%-graft-poly(D,L)-lactide, poly(ethylene glycol)5%-graft-poly(D,L)-lactide, and the multiblock copolymer (poly(D,L)-lactide-block-poly(ethylene glycol)-block-poly(D,L)-lactide)n. These NPs were characterized for their microporosity using nitrogen adsorption isotherms. NPs of the multiblock copolymer showed the least microporosity and Brunauer-Emmett-Teller (BET) surface area, and that of PEG1%-g-PLA showed the maximum. Based on these results, the structural organization of poly(D,L)-lactide (PLA) and poly(ethylene glycol) (PEG) chains inside the NPs was proposed and was validated with differential scanning calorimetry (DSC) and X-ray photoelectron spectroscopy (XPS) surface analysis. An in vitro drug release study revealed that PEG1%-g-PLA NPs exhibited slower release despite their higher surface area and microporosity. This was attributed to the presence of increased microporosity forming tortuous internal structures, thereby hindering drug diffusion from the matrix. Thus, it was concluded that the microporous structure of NPs, which is affected by the molecular architecture of polymers, determines the release rate of the encapsulated drug.     

Cationic Gold(II) Complexes: Experimental and Theoretical Study**

Gold(II) complexes are rare, and their application to the catalysis of chemical transformations is underexplored. The reason is their easy oxidation or reduction to more stable gold(III) or gold(I) complexes, respectively. We explored the thermodynamics of the formation of [Au^II(L)(X)]⁺ complexes (L=ligand, X=halogen) from the corresponding gold(III) precursors and investigated their stability and spectral properties in the IR and visible range in the gas phase. The results show that the best ancillary ligands L for stabilizing gaseous [Au^II(L)(X)]⁺ complexes are bidentate and tridentate ligands with nitrogen donor atoms. The electronic structure and spectral properties of the investigated gold(II) complexes were correlated with quantum chemical calculations. The results show that the molecular and electronic structure of the gold(II) complexes as well as their spectroscopic properties are very similar to those of analogous stable copper(II) complexes.     

Octahedral ruthenium(II) alkenyl complexes containing {\text{N}}{\text{S}} coordinated heterocyclic ligands

Summary Hexacoordinated ruthenium(II) alkenyl complexes of the type Ru(CO)(CR=CHPh)( )(PPh₃)₂ have been prepared from coordinately unsaturated -vinyl complexes [Ru(CO)Cl(CR=CHPh)(PPh₃)₂] (R = H or Ph) and the sodio-derivative of the containing heterocyclic ligands [ = 3,4-substituted 1,2,4-triazole-5-thione and 5-alkylthio-1,3,4-thiadiazole-2-thione] in a CH₂Cl₂/MeOH mixture at ambient temperature. The complexes were characterized by their elemental analysis, i.r., ¹H and ³¹P n.m.r. spectra. An octahedral structure with transphosphorus ligands has been assigned on the basis of the spectral data.     

Sonochemical asymmetric hydrogenation of isophorone on proline modified Pd/Al2O3 catalysts

The sonochemical asymmetric hydrogenation of isophorone (3,3,5-trimethyl-2-cyclohexenone) by proline-modified Pd/Al2O3 catalysts is described; presonication of a commercial Pd/Al2O3-proline catalytic system resulted in highly enhanced enantioselectivities (up to 85% ee).     

Validated scale-up procedure to predict blockage condition for fluidized dense-phase pneumatic conveying systems

This paper presents results of an ongoing investigation into modelling fluidized dense-phase pneumatic conveying of powders. For the reliable design of dense-phase pneumatic conveying systems, an accurate estimation of the blockage boundary condition or the minimum transport velocity requirement is of sig- nificant importance. The existing empirical models for fine powder conveying in fluidized dense-phase mode are either based on only a particular pipeline and product or have not been tested for their accuracy under a wide range of scale-up conditions. In this paper, a validated test design procedure has been devel- oped to accurately scale-up the blockage boundary with the help of a modelling format that employs solids loading ratio and Froude number at pipe inlet conditions using conveying data of two different samples of fly ash, electro-static precipitation （ESP） dust and cement （particle densities： 2197-3637 kgJm3; loose poured bulk densities： 634-1070kg/m3; median size： 7-30 l~m）. The developed models （in power func- tion format） have been used to predict the blockage boundary for larger diameter and longer pipelines （e.g. models based on 69 mm I.D. ~ 168 m long pipe have been scaled up to 105 mm I.D. and 554 m length）. The predicted blockage boundaries for the scale-up conditions were found to provide better accuracy compared to the existing models.     

Structural and elastic properties of KBr at high pressure and high temperature

To study phase transition and elastic properties at high pressures and high temperatures, we have developed a realistic interaction potential model (RIPZ_pe) including temperature effects. This model is completely suitable for explaining the inter-atomic interaction involved at high temperature and high pressure as it includes the three-body interaction (TBI) and zero point energy effects. The phase transition of KBr crystal at high pressure and high temperatures including the TBI is done for the first time. We have estimated the phase transition pressures, volume collapses and elastic behaviour at various high pressure and high temperatures by RIPZ_pe approach and the results found are well suited with available experimental data.     

A novel C3v-symmetric molecular clip with tris(diamide) recognition sites on trindane platform for H2PO4− recognition

To avoid the deprotonation events occurred in the receptor upon recognition of basic anions, a novel C_3v-symmetric anion receptor 2 with two amide groups appended in each arm was designed and synthesized by using the trindane tricarboxylic acid as tripodal molecular framework. The anion recognition ability by 2 was examined by ¹H NMR titration study in DMSO-d₆, which revealed that the addition of H₂PO₄^? guests caused substantial downfield shifts of the amide-NH protons peaks due to the formation of a host-guest complex in 1:1 binding stoichiometry with the estimated binding constant (K_a) of 244?M^?1. No noticeable binding of 2 was observed with other tested anions such as F^?, Cl^?, Br^?, I^?, NO₃^? and HSO₄^? under similar conditions.     

Detection of enantiomers of chiral primary amines by 1H NMR analysis via enamine formation with an enantiopure γ-position aldol product of a β-keto ester

A ¹H NMR analysis method that detects enantiomers of molecules bearing a primary amino group has been developed. The method uses a β-keto ester-derived probe that forms enamines with the amines and is able to discriminate enantiomers of functionalized amines and amines that have chiral centers at positions remote from the amine group.     

Synthesis and antibacterial activity of some novel triazolothienopyrimidines

A novel series of some novel 5-substituted-1,2,4-triazolo[4,3-c]8,9,10-trihydrocyclopenta/8,9,10,11,12-pentahydrocyclohepta[b]thieno[3,2-e]pyrimidin-3-thiones has been synthesized. The intermediates 4-chloro-2-substituted-5,6,7-trihydrocyclopenta/5,6,7,8,9-pentahydrocyclohepta[b]thieno[2,3-d]pyrimidines were prepared by warming 2-substituted-5,6,7-trihydrocyclopenta/5,6,7,8,9-pentahydrocyclohepta[b]thieno[2,3-d]pyrimidin-4[3H]-ones with oxalyl chloride. Thieno[2,3-d]pyrimidin-4[3H]-ones were prepared by a novel, microwave assisted, solvent free, synthetic route under basic conditions hitherto unreported in the literature from ortho amino ester of thiophene. The chloro derivatives, without further purification, were hydrazinated to yield 2-substituted-4-hydrazino-5,6,7-trihydrocyclopenta/5,6,7,8,9-pentahydrocyclohepta[b]thieno[2,3-d]pyrimidines. These compounds were cyclized with carbon disulphide to give the title compounds in quantitative yields. The final compounds were screened for antibacterial activity by Kirby Bauer's method using ampicillin as the standard against various gram positive and gram negative bacteria. All the compounds showed antibacterial activity comparable with the standard.