Electrochromic and electrofluorochromic properties of a new boron dipyrromethene–ferrocene conjugate

A new boron dipyrromethene–ferrocene (BODIPY–Fc) conjugate with pentafluorophenyl as the meso substituent and two Fc termini was synthesized and its spectroscopic and electrochemical features were analyzed. An intramolecular charge transfer from the donor Fc to the acceptor BODIPY has been predicted by theory and confirmed experimentally, leading to efficient fluorescence quenching when the dyad is in the neutral state. Fluorescence can be triggered by oxidizing both ferrocenyl units either chemically or electrochemically. Eventually, a fully reversible fluorescence switch is evidenced by coupling TIRF microscopy with electrolysis in an electrochemical cell

An insight into polarization states of solid-state organic lasers

The polarization states of lasers are crucial issues both for practical applications and fundamental research. In general, they depend in a combined manner on the properties of the gain material and on the structure of the electromagnetic modes. In this paper, we address this issue in the case of solid-state organic lasers, a technology which enables to vary independently gain and mode properties. Different kinds of resonators are investigated: in-plane micro-resonators with Fabry-Perot, square, pentagon, stadium, disk, and kite shapes, and external vertical resonators. The degree of polarization P is measured in each case. It is shown that although TE modes prevail generally (P>0), kite-shaped micro-laser generates negative values for P, i.e. a flip of the dominant polarization which becomes mostly TM polarized. We at last investigated two degrees of freedom that are available to tailor the polarization of organic lasers, in addition to the pump polarization and the resonator geometry: upon using resonant energy transfer (RET) or upon pumping the laser dye to an higher excited state. We then demonstrate that significantly lower P factors can be obtained.Comment: 12 pages, 12 figure

Incorporation Of Water-Soluble Porphyrins In Sol-Gel Matrices And Application To pH Sensing

The incorporation of H₂TPPS⁴- into sol-gel materials has been used to determine the pH inside a sol-gel matrix

Designing dye–nanochannel antenna hybrid materials for light harvesting, transport and trapping

We discuss artificial photonic antenna systems that are built by incorporating chromophores into one-dimensional nanochannel materials and by organizing the latter in specific ways. Zeolite L (ZL) is an excellent host for the supramolecular organization of different kinds of molecules and complexes. The range of possibilities for filling its one-dimensional channels with suitable guests has been shown to be much larger than one might expect. Geometrical constraints imposed by the host structure lead to supramolecular organization of the guests in the channels. The arrangement of dyes inside the ZL channels is what we call the first stage of organization. It allows light harvesting within the volume of a dye-loaded ZL crystal and also the radiationless transport of energy to either the channel ends or center. One-dimensional FRET transport can be realized in these guest–host materials. The second stage of organization is realized by coupling either an external acceptor or donor stopcock fluorophore at the ends of the ZL channels, which can then trap or inject electronic excitation energy. The third stage of organization is obtained by interfacing the material to an external device via a stopcock intermediate. A possibility to achieve higher levels of organization is by controlled assembly of the host into ordered structures and preparation of monodirectional materials. The usually strong light scattering of ZL can be suppressed by refractive-index matching and avoidance of microphase separation in hybrid polymer/dye–ZL materials. The concepts are illustrated and discussed in detail on a bidirectional dye antenna system. Experimental results of two materials with a donor-to-acceptor ratio of 33:1 and 52:1, respectively, and a three-dye system illustrate the validity and challenges of this approach for synthesizing dye–nanochannel hybrid materials for light harvesting, transport, and trapping

Single living cell processing in water medium using focused femtosecond laser-induced shockwave and cavitation bubble

edition: 3status: publishe

Superhydrophobic polypyrene films to prevent Staphylococcus aureus and Pseudomonas aeruginosa biofilm adhesion on surfaces: high efficiency deciphered by fluorescence microscopy

International audienc

Mutual influence of gold and silver nanoparticles on Tris-(2,2′bipyridine)-Ru(II) core complexes: Post-functionalization processes, optical and electrochemical investigations

International audienc

Ultrafast time-resolved spectroscopy elucidating photo-driven electron and energy transfer processes in a broadband light-absorbing BODIPY-C

Photoinduced electron and energy transfer pathways are elucidated in a panchromatic light-absorbing, covalently linked triad (BODIPY-C60-distyryl BODIPY, noted as BDP-C60-DSBDP) along with the two reference dyads: BODIPY-C60 (BDP-C60) and distyryl-BODIPY-C60 (DSBDP-C60). The flexible linker between the BODIPY and C60 units leads to different possible conformations with varying donor–acceptor distances. Ultrafast transient absorption along with the time-resolved emission spectroscopies revealed the occurrence of different photoinduced electron/energy transfer processes in these conformers. Photoexcitation of the BODIPY units in the two reference dyads leads to one electron and two energy transfer steps from BODIPY to C60. However, in the BDP-C60-DSBDP triad, additional energy transfer processes from BDP to DSBDP were evidenced upon photoexcitation of the BDP unit. The singlet excited state of DSBDP in the triad then follows the same relaxation route as that of the DSBDP-C60 dyad. The intricate photophysics, particularly the formation of radical ion pairs in these flexible covalently linked donor–acceptor systems contribute to our fundamental understanding of electron and energy transfer mechanisms, which is important to build donor–acceptor assemblies for energy applications