Benzannelated analogs of phenanthro[1,2-b]- and [2,1-b]thiophene: Synthesis and structural characterization by two-dimensional NMR and X-ray techniques

Syntheses of benzo[3,4]phenanthro[1,2-b]thiophene, benzo[3,4]phenanthro[2,1-b]thiophene and their 1-methyl analogs are reported as potential constituents of solvent refined coal liquids and for mutagenicity testing. The attempted synthesis of the 13-methyl analogs which gave the 11-methyl isomers is also described. Total assignments of the ¹H- and ¹³C-nmr spectra based on long range optimized heteronuclear protoncarbon two-dimensional chemical shift correlation are reported. Carbon assignments obtained for benzo[3,4]-phenanthro[1,2-b]thiophene using this approach were confirmed with a 125 MHz ¹³C–¹³C INADEQUATE spectrum. X-Ray crystal structures were determined for benzo[3,4]phenanthro[1,2-b]thiophene and 1-methyl-benzo[3,4]phenanthro[2,1-b]thiophene. Both molecules were helically distorted from planarity. Close intramolecular contacts between the bay region H1–H13 and ClMe-H13 of 2.03 and 2.28 Å, respectively, were responsible for the distortions. There were no close intermolecular contacts of <3.5Å. both molecules refined to an R value of <0.05.     

Angular polycyclic thiophenes containing two thiophene rings. I

We describe the synthesis of thieno[2,3-c]dibenzothiophene ( 6 ), thieno[3,2-c]dibenzothiophene ( 10 ), thieno-[3,2-a]dibenzothiophene ( 14 ), thieno[2,3-a]dibenzothiophene ( 16 ), benzo[1,2-b:4,3-b]bisbenzo[b]thiophene ( 18 ), benzo[1,2--6:3,4-b]bisbenzo[b]thiophene ( 20 ), benzo[2,1--6:3,4-b]bisbenzo[b]thiophene ( 22 ), benzo[1,2-b:3,4-g]bisbenzo[b]thiophene ( 27 ), benzo[1,2-b:4,3-e]bisbenzo[b]thiophene ( 29 ), benzo[2,1--6:3,4-g]bisbenzo[b]thiophene ( 36 ), benzo[2,1--6:4,3-e]bisbenzo[b]thiophene ( 38 ), benzo[1,2--6:4,3-g]bisbenzo[b]thiophene ( 41 ), benzo[1,2-b:4,5-g]bisbenzo[b]thiophene ( 42 ), benzo[1,2-b:3,4-e]bisbenzo[b]thiophene ( 44 ) and benzo-[1,2-b:5,4-e]bisbenzo[b]thiophene ( 45 ).     

The synthesis of phenanthrodibenzothiophenes

The synthesis of phenanthro[1,2-c]dibenzothiophene (6) , phenanthro[4,3-c]dibenzothiophene (10) , phenanthro[2,1-a]dibenzothiophene (14) , phenanthro[3,4-a]dibenzothiophene (16) , phenanthro[1,2-a]dibenzothiophene (19) , phenanthro[2,1-b]dibenzothiophene (20) , 8-methylphenanthro[3,2-a]dibenzothiophene (24) , 7-methylphenanthro[1,2-a]dibenzothiophene (25) , phenanthro[3,4-a]dibenzothiophene (27) , phenanthro[4,3-a]-dibenzothiophene (28) , 6-methylphenanthro[2,3-a]dibenzothiophene (31) , and 5-methylphenanthro[4,3-a]dibenzothiophene (32) is described.     

Heterogeneous catalysts for cyclic carbonate synthesis from carbon dioxide and epoxides

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Preparation of polymeric monoliths by copolymerization of acrylate monomers with amine functionalities for anion-exchange capillary liquid chromatography of proteins

Two novel polymeric monoliths for anion-exchange capillary liquid chromatography of proteins were prepared in a single step by a simple photoinitiated copolymerization of 2-(diethylamino)ethyl methacrylate and polyethylene glycol diacrylate (PEGDA), or copolymerization of 2-(acryloyloxy)ethyl trimethylammonium chloride and PEGDA, in the presence of selected porogens. The resulting monoliths contained functionalities of diethylaminoethyl (DEAE) as a weak anion-exchanger and quaternary amine as a strong anion-exchanger, respectively. An alternative weak anion-exchange monolith with DEAE functionalities was also synthesized by chemical modification after photoinitiated copolymerization of glycidyl methacrylate (GMA) and PEGDA. Important physical and chromatographic properties of the synthesized monoliths were characterized. The dynamic binding capacities of the three monoliths (24 mg/mL, 56 mg/mL and 32 mg/mL of column volume, respectively) were comparable or superior to values that have been reported for various other monoliths. Chromatographic performance was also similar to that provided by a modified poly(GMA-ethylene glycol dimethacrylate) monolith. Separation of standard proteins was achieved under gradient elution conditions using these monolithic columns. Peak capacities of 34, 58 and 36 proteins were obtained with analysis times of 20–30 min. This work represents a successful attempt to prepare functionalized monoliths via direct copolymerization of monomers with desired functionalities. Compared to earlier publications, additional surface modifications were avoided and the PEGDA crosslinker helped to improve the biocompatibility of the monolithic backbone.     

Bilinear electric field gradient focusing

Electric field gradient focusing (EFGF) uses an electric field gradient and a hydrodynamic counter flow to simultaneously separate and focus charged analytes in a channel. Previously, most EFGF devices were designed to form a linear field gradient in the channel. However, the peak capacity obtained using a linear gradient is not much better than what can be obtained using conventional CE. Dynamic improvement of peak capacity in EFGF can be achieved by using a nonlinear gradient. Numerical simulation results indicate that the peak capacity in a 4-cm long channel can be increased from 20 to 150 when changing from a linear to convex bilinear gradient. To demonstrate the increased capacity experimentally, an EFGF device with convex bilinear gradient was fabricated from poly(ethylene glycol) (PEG)-functionalized acrylic copolymers. The desired gradient profile was confirmed by measuring the focusing positions of a standard protein for different counter flow rates at constant voltage. Dynamically controlled elution of analytes was demonstrated using a monolith-filled bilinear EFGF channel. By increasing the flow rate, stacked proteins that were ordered but not resolved after focusing in the steep gradient segment were moved into the shallow gradient segment, where the analyte peak resolution increased significantly. In this way, the nonlinear field gradient was used to realize a dynamic increase in the peak capacity of the EFGF method.     

Monolithic bed structure for capillary liquid chromatography

Monolithic stationary phases show promise for LC as a result of their good permeability, ease of preparation and broad selectivity. Inorganic silica monoliths have been extensively studied and applied for separation of small molecules. The presence of a large number of through pores and small skeletal structure allows the chromatographic efficiencies of silica monoliths to be comparable to columns packed with 5 μm silica particles, at much lower back pressure. In comparison, organic polymeric monoliths have been mostly used for separation of bio-molecules; however, recently, applications are expanding to small molecules as well. Organic monoliths with high surface areas and fused morphology rather than conventional globular morphology have shown good performance for small molecule separations. Factors such as domain size, through-pore size and mesopore size of the monolithic structures have been found to govern the efficiency of monolithic columns. The structure and performance of monolithic columns are reviewed in comparison to particle packed columns. Studying and characterizing the bed structures of organic monolithic columns can provide great insights into their performance, and aid in structure-directed synthesis of new and improved monoliths.