Synthesis, characterization and photoconductive properties of optically active methacrylic polymers bearing side-chain 9-phenylcarbazole moieties

The synthesis of two novel optically active monomers containing 9-phenylcarbazole moieties, such as (S)-(+)-2-methacryloyloxy-N-[4-(9-carbazolyl)phenyl]succinimide [(S)-(+)-MCPS] and (S)-(+)-3-methacryloyloxy-N-[4-(9-carbazolyl)phenyl]pyrrolidine [(S)-(+)-MCPP], is described. Each monomer has been radically homopolymerized to afford the corresponding optically active polymeric derivatives, which have been fully characterized. Their spectroscopic, thermal and photoconductive properties were compared to those of the new achiral homopolymer poly[N-(2-methacryloyloxyethyl)-N-[4-(9-carbazolyl)phenyl]ethylamine] {poly[MCPE]}, devised as an optically inactive macromolecular model compound, as well as to analogue polymeric derivatives containing side-chain optically active carbazolyl moieties. The chiroptical properties of the chiral polymers are quantitatively higher than in the corresponding monomers. Owing to the substantially stereoirregular structure of the main chain, this suggests that the overall optical activity is mainly due to conformational dissymmetry of the macromolecules. Spectroscopic evidence suggests the presence in all polymeric derivatives of dipole-dipole interactions between the 9-phenylcarbazolyl chromophores, occurring as a consequence of their anchorage to the polymer backbone, which favours their aggregation and justifies their high decomposition temperatures.     

Novel aminated benzimidazo[1,2-a]quinolines as potential fluorescent probes for DNA detection: Microwave-assisted synthesis, spectroscopic characterization and crystal structure determination

A synthesis of novel benzimidazo[1,2-a]quinolines, substituted with piperidine, pyrrolidine and piperazine nuclei has been accomplished using an uncatalyzed amination protocol under microwave heating. All compounds were characterized by means of ¹H, ¹³C NMR, IR, UV/Vis and fluorescence spectroscopy. Crystal and molecular structures of 2-chloro- and 2-piperidinyl-benzimidazo[1,2-a]quinoline-6-carbonitrile were determined by X-ray diffractometry. These molecules are essentially planar. Their molecular assembly is characterized by the existence of weak intermolecular hydrogen bonds of C-H⋅⋅⋅N type and π-π aromatic interactions. The π-π aromatic stacking observed in the solid state structures of the 2-chloro- and 2-piperidinyl- derivatives are not analogous. The spectroscopic properties of these amino substituted benzimidazo[1,2-a]quinolines as their hydrochloride salts in the presence of ct-DNA were studied by means of fluorescence spectroscopy. Comparison of binding properties of amino substituted benzimidazo[1,2-a]quinoline hydrochloride salts to ct-DNA revealed significantly enhanced fluorescence emission intensity and thus offer the potential applications as a DNA-specific fluorescent probes.     

Synthesis,crystal structure and DNA-binding studies of a Ru(II) complex containing two main ligands

A new Ru(II)-polypyridyl complex, [Ru(L)(dppz)₂](PF₆)₄ (L = 5,5′-di(1-(trimethylammonio)methyl)-2,2′-dipyridyl cation; dppz = dipyrido[3,2-a:2′,3′-c]phenazine]), has been synthesized and structurally characterized. The binding of this complex with calf thymus DNA (CT-DNA) has been investigated by spectroscopic and viscosity measurement. Results indicate that the complex binds to CT-DNA via an intercalative mode. Moreover, the complex reveals a highly efficient DNA cleavage activity upon irradiation at 365 nm, during which supercoiled pBR322 DNA was converted to nicked DNA.     

Novel magnesium and zinc porphyrazines containing galactose moieties: Synthesis via click reaction and characterization

In this study, galactose conjugated new magnesium and zinc porphyrazines were synthesized by the cyclotetramerization reaction of 2,3-bis[1-(2,2,7,7-tetramethyltetra-hydro-bis[1,3]dioxolo[4,5-b;4′,5′-d]pyran-5,methyl)-1H-[1,2,3]triazol-4-yl methylsulfanyl]-but 2-enedinitrile. This substituted dicyano compound was prepared via two different routes. One started from cis-1,2-dicyano-1,2-ethylenedithiolate disodium, [1-(2, 2, 7,7-tetramethyltetrahydrobis[1,3]dioxolo[4,5-b;4′,5′-d]pyran-5-yl-methyl)-1H-[1,2,3]triazo-l-4-yl]methanol and ended in a multi-step reaction sequence via Click procedures. The other reaction was between 5-azidomethyl-2,2,7,7-tetramethyltetrahydro-bis[1,3]dioxolo[4,5-b;4′,5′-d]pyran and (2Z)-2,3-bis(prop-2-yl-1-yl-thio)but-2-enedinitrile. A very soluble galactose linked magnesium porphyrazine derivative in common polar solvents and water was achieved by the deprotected isopropylidene groups in TFA and water media. It is first time, zinc porphyrazine complex has been achieved at one-step reaction by using Zn(BuO)₂ as template agent. The new compounds have been characterized by a combination of elemental analysis, ¹H, ¹³C NMR, IR, UV–vis and MS spectral data.     

Synthesis and characterization of [Ga(TPP)H] (TPP=tetraphenylporphyrinato)

The synthesis, spectroscopic and structural characterization of the stable gallium hydride compound [Ga(TPP)H] (TPP=5,10,15,20-tetraphenylporphyrinato) have been reported. The hydride compound was synthesized in high yield (85%) by reducing [Ga(TPP)Cl] with sodium borohydride in N,N-dimethylformamide. The title compound was fully characterized by spectroscopic methods (IR, UV–Vis, and ¹H NMR spectroscopy) and its molecular structure was established by X-ray crystallography. The Ga–H IR stretch occurs at 1864 cm⁻¹, and the hydride ¹H NMR resonance locates at −6.47 ppm. The gallium–hydrogen distance is 1.48(4) Å, whereas the gallium atom lies 0.46(1) Å from the perfect porphyrin plane.     

Orientational order and thermodynamic properties of mainchain trimer liquid crystals: a combined use of H NMR, PVT and high-pressure differential thermal analysis

The trimer compounds (4,4′-bis[ω-(4-cyanobiphenyl-4′-yloxy)alkoxy]biphenyls) (CBA-Tn, n=9, 10) with n indicating the number of carbon atoms in the spacer exhibit a nematic order on cooling from the melt. The orientational characteristics of the central and terminal mesogenic cores were separately investigated in the liquid-crystalline (LC) state for CBA-T10 by the ²H NMR method. The ratio of the quadrupolar splittings was found to remain nearly constant over the entire range of the nematic state, suggesting that the conformation of the intervening spacer is also stable. The pressure-dependence of the phase boundary curves has been studied for transitions such as crystal↔nematic LC↔isotropic melt by the high-pressure differential thermal analysis. The transition entropies have been obtained according to the Clapeyron relation. A combined use of the PVT data led to an estimate of the constant-volume transition entropies, which is in reasonable agreement with the conformational transition entropies estimated previously by the rotational isomeric state analysis of the spectroscopic data.     

The synthesis and photophysical properties of halide sensitive acridizinium dyes

A series of acridizinium (benzo[b]quinolizinium) salts containing methoxy, fluoro and chloro substituents were synthesized and their spectroscopic properties and sensitivity towards halide quenching in water were determined. The salts have substantially improved properties over the commonly employed quinolinium and acridinium fluorophores for the sensing of bromide and iodide ions. Of the substituted acridiziniums investigated, 8,10-difluoro-acridizinium bromide has the best combination of properties as a bromide or iodide sensor.     

Synthesis,structure, and catalytic activity of a new chiral NHC–iridium(III) complex

The new chiral NHC–iridium complex 3 has been prepared in CH₃CN from the reaction between [Ir(COD)Cl]₂, NaOAc, KI, and dibenzimidazolium salt 2 which is derived from (S)-2,2′-diamino-6,6′-dimethyl-1,1′-biphenyl. Complex 3 has been characterized by various spectroscopic techniques, elemental analyses, and X-ray diffraction analysis. It has a distorted-octahedral IrC₂N₂IH core structure, and shows good catalytic activity for the asymmetric hydrosilylation of arylmethyl ketones, leading to 1-arylethanol with moderate ee values.     

Electrochemistry and spectroelectrochemistry of a novel selenophene-based monomer

A stereocontrolled synthesis of a novel selenophene-based monomer namely (E,E)-1,4-dimethoxy-2,5-bis[2-(selenophen-2-yl)ethenyl]benzene has been successfully performed starting from 1,4-dimethoxybenzene. Its spectra, electrochemistry and polymerization have been studied.     

Synthesis of a gold(I) complex with a (thio)phosphine-modified β-cyclodextrin

A gold(I) complex with the bidentate ligand 6^A-S-[2-(diphenylphosphino)-ethyl]thio-β-cyclodextrin has been prepared. The complex has been studied by mass spectrometry as well as IR and NMR spectroscopy. The influence of the ligand:metal ratio on the coordination mode has also been examined.     

Facile synthesis of diamine-functionalized hollow mesoporous silica sphere with self-templating method

A new N-[3-(trimethoxysilyl)propyl]ethylenediamine-functionalized hollow mesoporous silica sphere (DA-HMSS) was synthesized by a two-step self-templating method, including hydrolysis and co-condensation of tetraethyl orthosilicate and N-[3-(trimethoxysilyl)propyl]ethylenediamine in the presence of ammonia solution and hexadecyltrimethylammonium bromide, following with hydrothermal incubation in pure water after the removal of hexadecyltrimethylammonium bromide. The successful formation of silica framework and incorporation of organic component in DA-HMSS were confirmed by Fourier transform infrared and solid-state ²⁹Si cross-polarization/magic-angle-spinning nuclear magnetic resonance spectroscopic measurements as well as CHN elemental analysis. The hollow morphology of DA-HMSS was revealed by transmission electron microscopy, whereas its porosity was disclosed by nitrogen adsorption–desorption isotherm measurement. Furthermore, its carbon dioxide adsorption capability was also investigated.     

Ru(III)/Os(VIII) Catalysed Oxidation of Gabapentin (Neurotin) Drug by Diperiodatoargentate(III) in Aqueous Alkaline Medium (Stopped Flow Technique): A Comparative Study

The kinetics of ruthenium(III) (Ru(III)) and osmium(VIII) (Os(VIII)) catalysed oxidation of neuroleptic drug, gabapentin (GBP) by diperiodatoargentate(III) (DPA) in alkaline medium at 27 °C and a constant ionic strength of 0.60 mol dm^?3 was studied spectrophotometrically. The oxidation products in both the cases are 1-(hydroxymethyl) cyclohexane acetic acid and Ag(I). The stoichiometry is the same in both the catalysed reactions i.e. [gabapentin]:[DPA] = 1:1. The reaction is of first order in Os(VIII)/Ru(III) and [DPA] and has less than unit order in both [GBP] and [alkali]. The oxidation reaction in alkaline medium has been shown to proceed via a Os(VIII)/Ru(III)-gabapentin complex, which further reacts with one mole of monoperiodatoargentate(III) (MPA) species in a rate determining step followed by other fast steps to give the products. The main products were identified by spot test and spectroscopic studies. The reaction constants involved in the different steps of the mechanism are calculated. The catalytic constant (K _c) was also calculated for both catalysed reactions at different temperatures. From the plots of log K _c versus 1/T, values of activation parameters with respect to the catalyst have been evaluated. The activation parameters with respect to slow step of the mechanism are computed and discussed and thermodynamic quantities are also determined. It has been observed that the catalytic efficiency for the present reaction is in the order of Os(VIII)>Ru(III). The probable active species of catalyst and oxidant have been identified.     

Synthesis and binding properties of polymeric calix[4]arene nitriles

Two new polymers containing pendant calix[4]arene units with nitrile functionalities at their lower rim have been synthesized via radical initiated reactions involving a vinylic monomer 6 {5,11,17,23-tetra-tert-butyl-25,26,27-tris(cyanomethoxy)-28-(2-acryloyloxy) ethoxycalix[4]arene} and with styrene. A five atom spacer group was incorporated between the bulky calixarene core and the acrylate moiety in order to minimize steric interactions which proved to impede the polymerization. The complexation studies were made by using liquid–liquid extraction procedures. It has been deduced from the observations that both polymers show a good selectivity towards Hg²⁺ like their precursor 5,11,17,23-tetra-tert-butyl-25,26,27-tricyanomethoxy-28-(2-hydroxy)ethoxycalix[4]arene 5, which supports their utility as adsorbents or potential candidate materials for fabricating membranes and sensors, which can separate or detect Hg²⁺ metal ions in a high selectivity.     

CFD simulation of bubble columns incorporating population balance modeling

A computational fluid dynamics (CFD)-code has been developed using finite volume method in Eulerian framework for the simulation of axisymmetric steady state flows in bubble columns. The population balance equation for bubble number density has been included in the CFD code. The fixed pivot method of Kumar and Ramkrishna [1996. On the solution of population balance equations by discretization—I. A fixed pivot technique. Chemical Engineering Science 51, 1311-1332] has been used to discretize the population balance equation. The turbulence in the liquid phase has been modeled by a k-ε model. The novel feature of the framework is that it includes the size-specific bubble velocities obtained by assuming mechanical equilibrium for each bubble and hence it is a generalized multi-fluid model. With appropriate closures for the drag and lift forces, it allows for different velocities for bubbles of different sizes and hence the proper spatial distributions of bubbles are predicted. Accordingly the proper distributions of gas hold-up, liquid circulation velocities and turbulence intensities in the column are predicted. A survey of the literature shows that the algebraic manipulations of either bubble coalescence or break-up rate were mainly guided by the need to obtain the equilibrium bubble size distributions in the column. The model of Prince and Blanch [1990. Bubble coalescence and break-up in air-sparged bubble columns. A.I.Ch.E. Journal 36, 1485-1499] is known to overpredict the bubble collision frequencies in bubble columns. It has been modified to incorporate the effect of gas phase dispersion number. The predictions of the model are in good agreement with the experimental data of Bhole et al. [2006. Laser Doppler anemometer measurements in bubble column: effect of sparger. Industrial & Engineering Chemistry Research 45, 9201-9207] obtained using Laser Doppler anemometry. Comparison of simulation results with the experimental measurements of Sanyal et al. [1999. Numerical simulation of gas-liquid dynamics in cylindrical bubble column reactors. Chemical Engineering Science 54, 5071-5083] and Olmos et al. [2001. Numerical simulation of multiphase flow in bubble column reactors: influence of bubble coalescence and breakup. Chemical Engineering Science 56, 6359-6365] also show a good agreement for liquid velocity and gas hold-up profiles.     

Synthesis,characterization and evaluation of antioxidant and anticancer activities of novel benzisoxazole-substituted-allyl derivatives

A novel series of various 2-allylbenzo[d]isoxazol-3(2H)-ones were synthesized using benzo[d]isoxazol-3(2H)-one treated with different allyl bromides/chlorides in the presence of water-mediated cesium carbonate as a new catalyst 3(a-h). The structures of the newly synthesized Benzisoxazole-substituted-allyl derivatives were characterized by spectroscopic methods and mass spectrometry. These synthesized compounds were evaluated for their in vitro antioxidant and anticancer activity. Compounds 3b, d, f, h were identified as the best hit against HT-29 Human colon cancer cells. Similarly, compounds like 3b, d, f, h showed significant antioxidant activity compared to the standard drug butylated hydroxy toluene (BHT).      

The Mechanisms of Making Molecules to Order

The mechanisms of formation of a [2]catenane and one of its molecular components have been investigated. While the synthesis of the tetracationic cyclophane, [BBIPYBIXYCY] ⁴⁺ from bipyridine (BP) and 1,4-bis(bromomethyl)benzene (BBB) , directed by the template, 1,5–bis[2(2–hydroxyethoxy)ethoxy]naphthalene (1/5BHEEN) becomes less efficient (23 to 5%) under ultra-high pressure reaction conditions (12 kbars), the self-assembly of {[2]-[BPP34C10]-[BBIPYBIXYCY] catenane}⁴⁺ from BP and BBB in the presence of BPP34C10 can be achieved with increased efficiency (18 to 42%) at 12 kbars. This difference in the trends of the yields can be ascribed to the enhanced templating action of BPP34C10 relative to that of 1/5BHEEN when two moles of BP and two moles of BBB are being employed to construct the tetracationic cyclophane. The self-assembly of the [2]catenane from BP, BBB , and BPP34C10 has been followed by ¹H NMR spectroscopy in D₇-DMF solution. On the basis of this spectroscopic evidence and supporting chemical data, the formation of {[2]-[BPP34C10]-[BBIPYBIXYCY] catenane} ⁴⁺ from two moles of BP , two moles of BBB , and one mole of BPP34C10 is believed to proceed via the monoquatemary intermediate, [MBXYBIPY] ⁺, which has not been isolated, and the dicationic species, [BBIPYXY] ²⁺, which has been isolated and shown to be an intermediate in the self-assembly process leading to the [2]catenane, presumably via the [BXYBBIPYXY] ³⁺ trication — the final intermediate which again has not been isolated.     

Blue organic light-emitting diodes using novel spiro[fluorene-benzofluorene]-type host materials

Deep blue colored, fluorescent, spiro-type host materials, 5-[4-(1-naphthyl)phenyl]-spiro[fluorene-7,9′-benzofluorene] and 5,9-bis[4-(1-naphthyl)phenyl]-spiro[fluorene-7,9′-benzofluorene] were designed and successfully prepared by the Suzuki reaction. The electroluminescence characteristics of the two compounds as blue host materials doped with blue dopant materials, diphenyl[4-(2-[1,1;4,1]terphenyl-4-yl-vinyl)phenyl]amine and 1,6-bis[(p-trimethylsilylphenyl)amino]pyrene (SPP) were evaluated. The device used comprised ITO/N,N′-bis-[4-(di-m-tolylamino)phenyl]-N,N′-diphenylbiphenyl-4,4′-diamine)/bis[N-(1-naphthyl)-N-phenyl]benzidine/Host:5% dopant/tris(8-hydroxyquinolinato)aluminium/Al–LiF. The device obtained from 5-[4-(1-naphthyl)phenyl]-spiro[fluorene-7,9′-benzofluorene] doped with 1,6-bis[(p-trimethylsilylphenyl)amino]pyrene displayed high color purity (0.138, 0.138) and high efficiency (3.70 cd/A at 7 V).     

Modified cross-linked polyacrylamide supported palladium salts as a new heterogeneous catalyst for Heck reaction

A novel palladium catalyst supported on poly[N-(2-aminoethyl)acrylamido]-imino-3-pyridine carbaldehyde, has been prepared and exhibits excellent activity and stability in the Heck reaction.     

The synthesis and complexation study of some novel 3-methoxyphenyl chromenone crown ethers using conductometry

7,8-Dihydroxy-3-(3,4-dimethoxyphenyl)-2H-chromenones, 7,8-dihydroxy-3-(3,5-dimethoxyphenyl)-2H-chromenones and 7,8-dihydroxy-3-(3,4,5-trimethoxyphenyl)-2H-chromenones, o-dihydroxy-3-methoxyphenylcoumarins, were prepared from 2,3,4-trihydroxybenzaldehyde and corresponding methoxyphenylacetic acid in NaOAc/Ac₂O, respectively. 3-Methoxyphenyl-7,8-dihydroxy-2H-chromenone reacted with the polyethylene glycol ditosylate or dichloride in CH₃CN/alkali carbonate to afford [12]crown-4, [15]crown-5 and [18]crown-6-chromonones.The chromatographically purified novel chromenone crown ethers were identified with IR, ¹H NMR, ¹³C NMR and low and high resolution mass spectroscopy and elemental analysis.Stability constants for the 1:1 complexes of Na⁺ and K⁺ with different substituted methoxyphenyl derivatives of coumarino[12]crown-4, coumarino[15]crown-5 and coumarino[18]crown-6 (5a–5i) have been determined by conductometry at 25 °C in a binary solvent, dioxane/water. For all the coumarino crown ether derivatives, the stability constant decreases for K⁺ ion compared to Na⁺ ion.The selectivity sequence of these crown ethers in dioxane/water has showed an irregular order with respect to their cavity size.     

Solid phase peptide synthesis on an acrylate copolymer attached to porous silica beads

Porous silica beads have been internally coated with a new copolymer prepared from N-[2-(4-acetoxyphenyl)ethyl]acrylamide and N-[3-(triethoxysilyl)propyl]acrylamide. The derivatized silica beads have been used as a solid phase support for the synthesis of the opoid heptapeptide H-Try-Gly-Gly-Gly-Lys-Met-Gly-OH.