Abderrahim Yassar

Recent trends in crystal engineering of high-mobility materials for organic electronics

Acenes and heteroacenes are receiving great attention in fundamental and applied science due to their interesting optoelectronic and charge transport properties. Their easy synthesis and functionalization have enabled the rapid development of a large number of molecular materials with remarkable charge-transport properties. This perspective provides an overview of their fundamental properties, molecular packing/morphology and charge transport properties and summarizes the progress made in recent years in the development of new high-mobility small-molecule materials focusing in particular on crystalline materials that have been able to approach or surpass mobilities of amorphous silicon.

Amphiphilic conjugated block copolymers for efficient bulk heterojunction solar cells

The synthesis of random and diblock copolymers of poly(3-alkylthiophene)s bearing polar substituents was successfully developed by GRIM polymerization. 3-Hexyl-thiophene was successfully copolymerised with a new derivative, 3-functionalised-thiophene (propyl 5-(2-(thiophen-3-yl)ethoxy)pentanoate), bearing an ester function. Under optimized conditions, this ester proved to be fully compatible with the Grignard metathesis polymerization. Saponification of the copolymer esters provided the corresponding polyacids. Photovoltaic properties of copolymers were investigated in bulk heterojunction devices with PC61BM as acceptor. Among all the amphiphilic copolymers, P3HT-bb-P3AcidHT showed the best performance with a PCE of 4.2%, an open-circuit voltage (Voc) of 0.60 V, a short-circuit current density (Jsc) of 13.0 mA cm−2, and a fill factor (FF) of 0.60.

Structural and functional characteristics of chimeric avidins physically adsorbed onto functionalized polythiophene thin films.

Stabilized bioreceptor layers are of great importance in the design of novel biosensors. In earlier work, chimeric avidins enabled immobilization of biotinylated antibodies onto gold surfaces with greater stability compared to more conventional avidins (wild-type avidin and streptavidin). In the present study, the applicability of chimeric avidins as a general binding scaffold for biotinylated antibodies on spin-coated functionalized polythiophene thin films has been studied by surface plasmon resonance and atomic force microscopy. Novel chimeric avidins showed remarkably increased binding characteristics compared with other avidins, such as wild-type avidin, streptavidin, and bacterial avidin when merely physically adsorbed onto the polythiophene surface. They gave the highest binding capacities, the highest affinity constant, and the highest stability for biotinylated probe immobilization. Introduction of carboxylic acid groups to polythiophene layer further enhanced the binding level of the avidins. Polythiophene layers functionalized with chimeric avidins thus offered a promising generic platform for biosensor applications.

Molecular photo switch based on photochromic oligothiophenes

Here we describe a new chromene bearing at their 3 position terthiophene and quaterthiophene. When optically excited, these molecules undergo a structural change passing from a neutral state (closed form) to a strongly polarized one (open form). This photochromic process is also accompanied by a large increase in the electrical conductivity.

An experimental study of the electronic absorption and fluorescence spectral properties of new p-substituted-N-phenylpyrroles and their electrosynthesized polymers

Electronic absorption and fluorescence spectral properties of new p-substituted-N-phenylpyrroles (N-PhPys), including HOPhPy, MeOPhPy, ThPhPy, PhDPy, DPhDPy, PyPhThThPhPy, and their available, electrosynthesized polymers were investigated. Electronic absorption spectra, fluorescence excitation and emission spectra, fluorescence quantum yields (ΦF) and lifetimes (τF), and other photophysical parameters of these N-PhPy derivatives and their polymers were measured in DMF, DMSO diluted solutions and/or solid state at room temperature. The electronic absorption spectra of N-PhPy derivatives and their polymers included one to several bands, located in the 270-395 nm region, according to the p-phenyl substituent electron-donating effect and conjugated heteroaromatic system length. The fluorescence excitation spectra were characterized by one broad main peak, with, in most cases, one (or more) poorly resolved shoulder (s), appearing in the 270-405 nm region, and their emission spectra were generally constituted of several bands located in the 330-480 nm region. No significant shift of the absorption, fluorescence excitation and emission spectra wavelengths was found upon going from the monomers to the corresponding polymers. ΦF values were high, varying between 0.11 and 0.63, according to the nature of substituents(s) and to the conjugated system extension. Fluorescence decays were mono-exponential for the monomers and poly-exponential for PyPhThThPhPy and for polymers. τF values were relatively short (0.35-5.17 ns), and markedly decreased with the electron-donor character of the phenyl group p-substituent and the conjugated system extension.

Novel Fluorophores based on Regioselective Intramolecular Friedel‐Crafts Acylation of the Pyrene Ring Using Triflic Acid

The extension of the pyrene ring from dimethyl 2,2-(pyrene-1,6-diyl)dibenzoate derivatives by an intramolecular Friedel-Crafts acylation can be realized in an efficient and regioselective manner using triflic acid as proton source. Naphtho-tetracenone derivatives are obtained in high yields at room temperature while Bis-tetracene-diones are prepared upon heating. Both products display interesting fluorescence properties in the visible range with quantum yields varying from 50 to 60u2009%.