A fluorescence and fluorescence probe study of benzonaphthyridines.

A series of benzo[b][1,8]naphthyridines has been synthesized by Friedländer condensation of 2-aminoquinoline-3-carbaldehyde 1 (o-aminoaldehyde) with alicyclic ketones in basic medium. Benzonaphthyridines branched with various side-chains and substituents are prepared with the aim of being investigated as a good fluorescent material. Electronic absorption and fluorescence properties of some representative benzonaphthyridines in organic solvents, water-dioxane, and SDS, CTAB and Triton-X-100 micelles have been examined. The linear correlation between solvent polarity and fluorescence properties is observed. This study may provide new directions for the development of fluorescence probes as reporters of microenvironments of organized assemblies.

Effects of homogeneous media, binary mixtures and microheterogeneous media on the fluorescence and fluorescence probe properties of some benzo[b][1,8]naphthyridiens with HSA and BSA.

A rapid and efficient method for the synthesis of various poly-substituted benzo[b][1,8]naphthyridines in high yield has been developed via the Friedländer condensation of 2-aminoquinoline-3-carbaldehyde 1 with various alicyclic ketones in a base catalyst (aq. potassium hydroxide). A series of benzo[b][1,8]naphthyridines branched with various side-chains and substituents were prepared with the aim of being investigated as a fluorescent agents. Electronic absorption and fluorescence properties of some representative benzonaphthyridines (3d, 5b and 21f) in homogeneous organic solvents, dioxane-water binary mixtures and in the microheterogeneous media (sodium dodecyl sulphate (SDS), cetyl trimethyl ammonium bromide (CTAB) and Triton-X100 micelles) have been examined. A linear correlation between solvent polarity and fluorescence properties was observed. Further, the interaction of these benzonaphthyridines (3d, 5b and 21f) with human serum albumin (HSA) and bovine serum albumin (BSA) in phosphate buffer have been examined by UV-vis absorption and fluorescence spectroscopy. The fluorescence intensity of 3d, 5b and 21f increases with the increasing HSA and BSA concentration. These benzonaphthyridines also quench the 345 nm fluorescence of BSA in phosphate buffer (λ(ex) 280 nm). These compounds have potential for use as neutral and hydrophobic fluorescence probes for examining the microenvironments in proteins, polymers, micelles, etc.

A fluorescence study of new angular polycyclic blue light-emitting pyrazolo[3,4-h][1,6]naphthyridine and their interaction with bovine serum albumin (BSA).

The blue light-emitting pyrazolo[3,4-h][1,6]naphthyridines has been synthesized by Friedländer condensation of 4-amino-3-(4-phenyl)-1-phenyl-1H-pyrazolo[3,4-b]pyridine-5-carbaldehyde (o-aminoaldehyde) 1 with different cyclic ketones and 1,3-diketones. The synthesized angular polycyclic naphthyridine derivatives were studied for Semi-empirical, thermal, UV-vis and fluorescence spectroscopic properties on binding with bovin serum albumin (BSA). These fluorescence properties together with the neutral, hydrophobic nature of these compounds make these fluorophores good fluorescence probe for studying the micropolarity of proteins like BSA and in general the ligand-protein interactions. All of them displays bright absorption at 394 nm & emission in visible region (491 nm). Quantum yields of all synthesized compounds were calculated.

Effect of specific solute-solvent interaction and electron donor-acceptor substituents of novel pyrazolo naphthyridines on fluorescence.

Heterocyclic orthoaminoaldehyde such as 4-amino-3-(4-phenyl)-1-phenyl-1H-Pyrazolo[3,4-b]pyridine-5-carbaldehyde was synthesized by multistep reactions involving reduction of azido derivative 2 with LAH to yield aminoalcohol 3 and oxidation of it with MnO(2) to aminoaldehyde 4.The pyridine ring annulated on to 4 by Friedländer condensation using acetophenones in presence of base to obtained pyrazolo[3,4-h][1,6]naphthyridine 5 in excellent yield. Study of photophysical properties of 5 revealed that the absorption and emission of them depends up on the substituents present on benzene ring in newly annulated pyridine ring.

Effect of donor-acceptor chromophores on photophysical properties of newly synthesized pyrazolo-pyrrolo-pyrimidines (PPP).

Novel pyrazolo-pyrrolo-pyrimidine (PPP) derivatives having remarkable photophysical properties are designed with the help of theoretical semiempirical calculations. These compounds then synthesized successfully and studied effect of substituents on its photophysical properties.

Synthesis and fluorescence investigation of differently substituted benzo[b][1,8]naphthyridines: interaction with different solvents and bovine serum albumin (BSA).

A series of benzo[b][1, 8]naphthyridines has been synthesized by Friedländer condensation of 2-aminoquinoline-3-carbaldehyde 1 (o-aminoaldehyde) with active methylenes in basic medium. The fluorescence spectroscopic properties of some representative compounds has been studied in different organic solvents; moreover interaction with bovine serum albumin (BSA) in phosphate buffer was examined by UV-vis and fluorescence spectroscopy. The effect of electron donor-acceptor substituents on fluorescence properties of benzo[b][1, 8]naphthyridines 13(a-n) has been investigated along with their fluorescent quantum yields.

Binary mixtures of (ß-C12G2) with cationic and non-ionic surfactants: micelle and surface compositions.

Surfactants used for practical applications are usually surfactant mixtures because they often exhibit a performance that is superior to the individual surfactants. In the present study binary mixtures of the sugar based surfactant n-dodecyl-ß-D-maltoside (ß-C12G2) with the cationic surfactant dodecyl trimethylammonium bromide (C12TAB) and the non-ionic hexaethylene-glycol dodecyl ether (C12E6), respectively, were investigated at different bulk mole fractions. Surface tension measurements were used to determine the critical micelle concentration and the surfactant composition at the surface. In addition, the regular solution theory was used to calculate interaction parameters as well as the mole fractions of the individual surfactants in the mixed air-water monolayer and in the mixed micelles, respectively. It was found that n-dodecyl-ß-D-maltoside interacts weakly with the cationic surfactant (C12TAB) and that it dominates in both the mixed monolayer and the mixed micelles. On the other hand, ß-C12G2 and C12E6 mix ideally in solution. For both surfactant mixtures the surfactant composition at the surface determined by surface tension measurements and by the regular solution theory, respectively, were compared and discussed in detail.

Study of beta-cyclodextrin/fluorinated trimethyl ammonium bromide surfactant inclusion complex by fluorinated surfactant ion selective electrode.

The construction and performance of a liquid membrane electrode responsive to N-(1,1,2,2-tetrahydroperfluorooctyl)-N,N,N-trimethylammonium bromide (FTABr) and its use for the study of beta-cyclodextrin/fluorinated surfactant inclusion complex is described. The electrode is based on the use of tetrahydroperfluorooctyltrimethylammonium-tetraphenylborate ion pair as electro active material in polyvinyl chloride (PVC) matrix plasticized using 2-Nitrophenyl octyl ether (NPOE). The electrode exhibits a fast, stable, reproducible and "Nernstian" response (59+/-2 mV) for FTABr over the concentration range of 10(-5) to 2 x 10(-3) mol L(-1) at 298 K. The lowest detection limit is 2 x 10(-6) mol L(-1) and the response time is around 20-30s. The validity of the electrode, for detection of fluorinated surfactant ions and hence to carry out electrochemical measurements to study micellization of fluorinated surfactant, is verified by comparing the critical micelle concentration (cmc) value of FTABr obtained by using the electrode, with that obtained by surface tension measurements. Association constant K for beta-cyclodextrin/FTABr complex is evaluated from the potentiometric measurements carried out using this electrode and is observed to be approximately 1.26 x 10(5). The results suggest that beta-cyclodextrin forms an equimolar association complex with the FTA+ surfactant ion.

Traumatic extrusion and replacement of autoclaved diaphyseal segment of radius: a case report.

A 17-year-old patient had a traumatic extrusion of 10 cm distal radial segment. The segment of bone was replaced after cleaning and autoclaving. At four years follow-up, there was complete incorporation with almost full functional recovery. We report this case for its rarity and successful result.