The Sensitized Quantum Yield at Photodehydrogenation Reaction of Abietic Acid

The re-cycled irradiation of abietic acid above 300 nm with benzophenone and copper(ii) pivalate in toluene solution has resulted in conversion to dehydroabietic acid with a quantum yield ranging from 9.6 to 5.5. The high quantum yield may be attributed to the re-generation of benzophenone by means of the electron transfer reaction of benzophenone radical and to some additional reactions on formation of dehydroabietic acid.     

Synthesis and properties of a new photostable polymer: Perylene-3,4,9,10-tetracarboxylic acid-bis-(N,N′-dodecylpolyimide)

The synthesis of perylene-3,4,9,10-tetracarboxylic acid-bis(N,N′-dodecyl-polyimide) (poly PTDI) and polyamic acid has been achieved from perylene dianhydride and dodecylamine. It was found that this new polyimide has very high thermal photostability. Poly PTDI decomposes at 475°C and shows weak fluorescence compared with the monomer PTDI possibly due to aggregration in the polymer. Its solubility in some of the common organic solvents, acetonitrile, dimethyl formamide, etc., makes spectroscopic and photochemical studies and applications possible in the liquid phase. The emission characteristics are similar to mono PTDI. Poly PTDI, a luminescent electron acceptor polymer, is a new reliable probe for a photosensitizer at energy transfer and election transfer photochemical reactions. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 2137–2142, 1997     

Electrochemical and optical properties of novel donor‐acceptor thiophene‐perylene‐thiophene polymers

In this study, donor‐acceptor type thiophene‐perylene‐thiophene monomers were synthesized and polymerized by both oxidative polymerization using FeCl₃ as catalyst and the electrochemical process. UV–vis, FTIR, ¹H NMR, and elemental analysis techniques were used for structural characterization. Thermal behaviors of these compounds were determined by using TGA system. The highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) energy levels and electrochemical and optical band gap values were calculated by using the results of cyclic voltammetry and UV–vis measurements, respectively. The number–average molecular weight (M_n), weight–average molecular weight (M_w), and polydispersity index (PDI) values of synthesized polymers were determined by size exclusion chromatography. Conductivity measurements of these polymers were carried out by electrometer by using a four‐point probe technique. The conductivity was observed to be increased by iodine doping. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1974–1989, 2008     

Structure and Luminescent Properties of the 4-Arylidene-2-Aryl-5-Oxazolones(Azlactones)In Solution and Crystalline State

Experimental and theoretical evaluations have proven that very low fluorescence quantum yields of azlactones in solution are not caused by an efficient inter system crossing from S₁*(ππ) to T*(nπ) states, but rather from solvation and steric effects, that result in non-planarity of the molecular system. High fluorescence quantum yields in the solid state are attributed to the planarity of the azlactone molecule upon packing into the crystal lattice. Supporting evidence was found upon observation of the excited state proton transfer (ESIPT) bands of fluorescence emissions of o-hydroxyarylidene derivatives. The photoinstability of azlactones in liquid states are attributed to photochemical E-Z isomerization and cleavage of the hetero ring α to the carbonyl group.     

A new donor–acceptor double‐cable carbazole polymer with perylene bisimide pendant group: Synthesis,electrochemical, and photovoltaic properties

We report here electrochemical synthesis of novel soluble donor–acceptor (D–A) polymer with suitably functionalized perylenetetracarboxylic diimide dye derivative covalently linked to carbazole moiety (Cbz‐PDI). The band gap, E_g was measured using UV–Vis spectroscopy and compared with that obtained by cyclic voltammetry (CV). Efficient intramolecular electron transfer from carbazole‐donor to perynediimide‐acceptor leads to remarkable fluorescence quenching of the perylene core. Furthermore, spectroelectrochemical property and surface morphology of the polymer film were investigated. Characteristic monoanion and dianion radical bands on the UV–Vis absorption spectra attributed to the electrochemical reduction of the neutral polymer were observed. During the reduction process, red color of the film turned into blue and violet, respectively. Finally, the photovoltaic performance of the D–A double‐cable polymer was checked and nearly 0.1% electrical conversion efficiency is obtained under simulated AM 1.5 solar light with 100 mW/cm² radiation power. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 6280–6291, 2009     

A panchromatic boradiazaindacene (BODIPY) sensitizer for dye-sensitized solar cells

A novel distyryl-substituted boradiazaindacene (BODIPY) dye displays interesting properties as a sensitizer in DSSC systems, opening the way to further exploration of structure-efficiency correlation within this class of dyes.     

A Thermal and Photostable Reference Probe for Qf Measurements: Chloroform Soluble Perylene 3,4,9,10-Tetracarboxylic Acid-bis-N,N-Dodecyl Diimide

The synthesis of a chloroform soluble perylene 3, 4, 9, 10-tetracarboxylic acid-bis-N, N′-dodecyl diimide via condensation of perylene 3, 4, 9, 10-tetracarboxylic dianhydnde and 1, 12-diamino dodecane is described. The thermal analysis is shown thermal stabilities above 400°C. Thermal and photostable dye is measured to have a fluorescence quantum yield of unity, Q_f = 1.00, in chloroform solutions. Perylene bis-dodecyl diimide is an ideal reference probe for fluorescence quantum yield measurements in 500–650 nm region and a reliable soluble photosensitizer for solar photochemical applications.     

Epithelial-to-Mesenchymal Transition Is Not a Major Modulating Factor in the Cytotoxic Response to Natural Products in Cancer Cell Lines

Numerous natural products exhibit antiproliferative activity against cancer cells by modulating various biological pathways. In this study, we investigated the potential use of eight natural compounds (apigenin, curcumin, epigallocatechin gallate, fisetin, forskolin, procyanidin B2, resveratrol, urolithin A) and two repurposed agents (fulvestrant and metformin) as chemotherapy enhancers and mesenchymal-to-epithelial (MET) inducers of cancer cells. Screening of these compounds in various colon, breast, and pancreatic cancer cell lines revealed anti-cancer activity for all compounds, with curcumin being the most effective among these in all cell lines. Although some of the natural products were able to induce MET in some cancer cell lines, the MET induction was not related to increased synergy with either 5-FU, irinotecan, gemcitabine, or gefitinib. When synergy was observed, for example with curcumin and irinotecan, this was unrelated to MET induction, as assessed by changes in E-cadherin and vimentin expression. Our results show that MET induction is compound and cell line specific, and that MET is not necessarily related to enhanced chemosensitivity.     

Multicomponent Assembly of Macrocycles and Polymers by Coordination of Pyridyl Ligands to 1,4‐Bis(benzodioxaborole)benzene

Multicomponent reactions between 1,4‐benzenediboronic acid, catechol, and different pyridyl ligands are reported. The condensation of 1,4‐benzenediboronic acid with catechol gives 1,4‐bis(benzodioxaborole)benzene. Upon crystallization, the ester aggregates with the N‐donor ligands through dative B? N bonds. Depending on the nature of the pyridyl ligand, molecularly defined macrocycles or polymeric structures are obtained. 1D polymers are formed with 4,4‐bipyridine and 1,2‐di(4‐pyridyl)ethylene, whereas a 2D network is obtained with the tetradentate ligand tetra(4‐pyridylphenyl)ethylene. These results highlight the utility of dative B? N bonds in structural supramolecular chemistry and crystal engineering.