SYNTHESIS AND CHARACTEAIZATION OF POLY(PYRROLY METHINE)

A novel small band-gap conjugated polymer - poly [(3-acetylpyrrole-2,5-diyl)(4-dimethylaminobenzyliene)(3-acetylpyrrolequinodimethane-2,5-diyl)] (PAPDMABE) - and its precursor were synthesized by a simple method and characterized by H-1-NMR, FT-IR, TGA and UV-VIS. The polymer can be dissolved in strong polar solvents such as DMSO, DMF or NMP. The band-gap energy of PAPDMABE, was found to be 0.95 eV. The conductivity of doped products with iodine falls in the range of a semiconductor.

Synthesis and Characterization of Small Band-gap Conjugated Polymers - Poly(pyrrolyl methines)

A kind of small band-gap conjugated polymers-poly (pyrrolyl methines) and their precursors-(poly pyrrolyl methanes) have been synthesized by a simple method and characterized by 1HNMR, FT-IR, TGA and UV-Vis. These polymers can be dissolved in high polar solvents such as DMSO, DMF or NMP. The results reveals that the band-gap of the synthesized conjugated polymers are in the range of 0.96~1.14 eV and they all belong to the small band-gap polymers. The conductivity of doped products with iodine is in the range of semiconductor.

Synthesis and Photophysical Properties of Novel Highly Stable Zero/Bis-Zero Methine Cyanine Dyes Based on N-Bridgehead Heterocycles

Cyanine dyes of zero/bis-zero methine incorporating imid-azo(1,2-a)Pyridine (quinoline) or pyrazino(1,2-a)pyridine (quinoline) with stable C-N bond were synthesized using keto-oxime methylene C-link heterocyclic quaternary salts [1-phenyl-3-methyl-pyrazolino-4-keto-oxime-α-methylene-bis-pyridin-(quinoin)-1(4)-di-ium-iodide(ethiodide) salts and 1-phenyl-3-methyl-pyrazolino- 4-ketooxime-α-methylene-N-2-methyl-bis pyridin (quinoin)-1(4)-di-ium-iodide(ethiodide) salts]. Such heterocyclic precursors and related dyes were identified by elemental and spectral analyses. The absorption spectra properties of such dyes were investigated in 95% Ethanol to attempt and throw some light on the influence of such new heterocyclic nuclei and to compare or evaluate spectral behaviors. The absorption spectra of dyes in different pure solvents were examined in the visible region showing solvatochromism and the colour changes of dyes with solvents having different polarities. This permits a selection of the optimal solvent (fractional solvent) when such dyes are applied as photosensitizers. The spectral behavior of some selected newly synthesized cyanine dyes is observed in mixed solvents of different polarities and progressively increasing quantities of one solvent over the other were studied and showed an increase in the absorbance of CT band with increasing proportion of that solvent. Evidence for hydrogen bond formation between the solute molecules and solvent molecules allows measurement of certain energies such as hydrogen bonding, orientation, and free energies.

Aniline as a TICT rotor to derive methine fluorogens for biomolecules:A curcuminoid-BF2 compound for lighting up HSA/BSA

The unique structure of fluorescent proteins in which the fluorophore is encapsulated by the protein shell to restrict rotation and emit light inspired the screening of chromophores that selectively bind to biomolecules to generate fluorescence. In this paper, we report a curcuminoid-BF2-like fluorescent dye NBF2containing 4-dimethylaniline as an electron-donating group. When this dye is combined with HSA or BSA, the fluorescence is enhanced 90/112-fold, and the fluorescence quantum yield increases from <0.001to 0.16/0.19. Such a large change in fluorescence enhancement is due to the encapsulation of N-BF2in the protein cavity by HSA/BSA, which inhibits the intramolecular rotation of the aniline moiety caused by charge transfer after the fluorophore is excited by light. N-BF2has fast and strong binding to HSA or BSA and was found to be reversible in solution and intracellularly. Since N-BF2also has the ability to target lipid droplets, the complex of N-BF2/HSA realizes the regulation of reversible lipid droplet staining in cells.

Synthesis and optical properties of soluble low bandgap poly （pyrrole methine） with alkoxyl substituent

A soluble low bandgap poly （pyrrole methine） with alkoxyl substituent, poly {（3-hexanoyl）pyrrole-[2,5- diyl（p-tetradecyloxybenzylidene）]} （PHPDTBE）, was synthesized and characterized by 1H nuclear magnetic resonance （1H-NMR）, Fourier transform-infrared （FT-IR）, elemental analysis （EA） and gel permeation chromatography （GPC）. PHPDTBE was readily soluble in weak polar organic solvents. The absorption peaks of PHPDTBE solution and film were located at around 458 and 484 nm, respectively. The optical bandgaps of PHPDTBE film for indirect allowed and direct allowed transitions were measured to be 1.66 and 2.35 eV, respectively. PHPDTBE film had few defects in the energy band and the Urbach energy of PHPDTBE film was calculated to be about 0.19 eV. The resonant third-order nonlinear optical susceptibilities of PHPDTBE solution and film measured by degenerate four-wave mixing （DFWM） technique at 532nm were all in the order of 10 8 esu, which was about 1-3 orders of magnitude larger than that of the other ordinary n-conjugation polymers.