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Lysinated molecular organic semiconductors are introduced as valuable multifunctional platforms for neural cells growth and interfacing. Cast films of quaterthiophene (T4) semiconductor covalently modified with lysine-end moieties (T4Lys) are fabricated and their stability, morphology, optical/electrical, and biocompatibility properties are characterized. T4Lys films exhibit fluorescence and electronic transport as generally observed for unsubstituted oligothiophenes combined to humidity-activated ionic conduction promoted by the charged lysine-end moieties. The Lys insertion in T4 enables adhesion of primary culture of rat dorsal root ganglion (DRG), which is not achievable by plating cells on T4. Notably, on T4Lys, the number on adhering neurons/area is higher and displays a twofold longer neurite length than neurons plated on glass coated with poly-l-lysine. Finally, by whole-cell patch-clamp, it is shown that the biofunctionality of neurons cultured on T4Lys is preserved. The present study introduces an innovative concept for organic material neural interface that combines optical and iono-electronic functionalities with improved biocompatibility and neuron affinity promoted by Lys linkage and the softness of organic semiconductors. Lysinated organic semiconductors could set the scene for the fabrication of simplified bioorganic devices geometry for cells bidirectional communication or optoelectronic control of neural cells biofunctionality., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

We report the expedient microwave-assisted synthesis of thiophene based 4-sulfo-2,3,5,6,-tetrafluorophenyl esters whose molecular structure was engineered to achieve blue to red bright fluorescence. The reactivity toward monoclonal antibodies of the newly synthesized fluorophores was analyzed in comparison with that of the corresponding N-succinimidyl esters. Single-fluorophore and multiple-fluorophore labeled antibodies were easily prepared with both types of esters. Multiple-fluorophore labeling with blue and orange emitting fluorophores resulted in white fluorescent antibodies. Thiophene based fluorophores displayed unprecedented fluorescence stability in immunostaining experiments. First-principles TD-DFT theoretical calculations helped us to interpret the behavior of fluorescence emission in different environments.

A soluble, low-weight fraction of poly(alpha-vinyl,omega-n-hexyl-quaterthiophene), PT4Hex, having n-hexylquaterthiophenes as side-chain groups, is prepared by free-radical polymerization of alpha-vinyl,omega-n-hexyl-quaterthiophene and the corresponding properties compared to those of free di-n-hexylquaterthiophene (T4Hex). Optical analysis (absorption and emission) and X-ray diffraction data indicate that in the polyvinyl-locked architecture the quaterthiophene pendants adopt a cofacial arrangement with a mutual distance close enough for pi-pi orbitals to overlap ( approximately 4 A). As a consequence of the close chain packing, a shift of the reduction potential of about 0.5 V toward less negative values with respect to free T4Hex, is found for PT4Hex films. Due to its enhanced electron affinity, PT4Hex displays an electron-acceptor behavior when blended with alkylated and silylated quaterthiophenes acting as donors.

Bovine serum albumin (BSA) was reacted with linear and newly synthesized branched oligothiophene N-hydroxysuccinimidyl ester fluorophores (TSEs) in moderately basic carbonate buffer solution. Optically stable BSA-TSE conjugates were obtained with a degree of labeling depending on experimental conditions. Conjugates with high fluorophore to BSA ratios (F/BSA = 8) displayed fluorescence quantum yields in the range of 10-30% in water at pH = 7.2, comparable to the quantum yield (25%) of the BSA-FITC conjugate prepared under the same conditions and with the same degree of labeling.

Oligomers of thiophene are widely studied compounds for their electronic and optoelectronic properties. Despite their strong fluorescence, their use as markers for biomolecules, especially for oligonucleotides (ONs), is still largely unexplored. Here, we describe the synthesis of a series of ON molecular beacons employing different oligothiophenes as fluorescent probes and discuss their fluorescence emissions in comparative experiments with and without dabcyl as a quencher, in their hairpin and linear conformations, and as duplexes after hybridization with a complementary target.

The synthesis of multicolor fluorescent oligothiophene N-succinimidyl esters (TSEs) is reported, and their optical properties are discussed with the aid of ab initio calculations. The esters were coupled to proteins and to 3'-amino-modified oligonucleotides in mild conditions and with similar modalities. A comparative study of the bioconjugate of IgG1 anti-CD3 antibody labeled with a blue fluorescent TSE and with fluorescein isothiocyanate (FITC) is reported, showing that the former achieves higher photoluminescence intensity and optical stability than the latter. Fluorescence resonance energy transfer experiments with TSE-labeled oligonucleotides and examples of cellular imaging via TSE-labeled proteins are reported.

In this paper we report the synthesis of a new class of fluorescent thiophene-based isothiocyanates containing a 3,5-disubstituted dithieno[3,2-b:2',3'-d]thiophene-4,4-dioxide moiety as the rigid core, using the palladium-catalyzed cross-coupling reaction of aryl stannanes with aryl bromides (Stille coupling). By changing the molecular structure through the progressive addition of thienylene or phenylene units, light emission from blue to orange was obtained. Photoluminescence quantum yields ranged from 0.65 to 0.90 for blue and green light emitters to 0.10-0.35 for yellow and orange ones. Optically and chemically stable fluorescent bioconjugates were prepared by spontaneous reaction of the isothiocyanates with monoclonal antibodies anti-CD3 and anti-CD8 in slightly basic solutions.

The regioselective synthesis of fluorescent oligothiophene isothiocyanates is described. The isothiocyanates were reacted with bovine serum albumin (BSA) following standard procedures and the optical properties of the oligothiophene-BSA conjugates were analyzed as a function of oligomer concentration, time, and irradiation power. The oligothiophene-BSA conjugates were chemically very stable and their photoluminescence characteristics persisted unaltered for several months. Photoluminescence data relative to the conjugate of an oligothiophene-S,S-dioxide isothiocyanate with monoclonal anti-CD8 antibody are reported. No fluorescence quenching was observed following the binding of the isothiocyanate to the antibody and the conjugate displayed high chemical stability and photostability.

The regioselective synthesis of three sexithiophenes characterized by the presence of one central 3,3′-dimethyl-2,2′-bithiophene subsystem is described. One of these compounds was obtained under mild conditions by microwave-mediated synthesis. All sexithiophenes were soluble in organic solvents and displayed 30–40% fluorescence quantum yields in solution. In thin films the fluorescence quantum yields dropped to 1–2%, indicating conformational changes and strong intermolecular interactions in the solid state. [Copyright &y& Elsevier]

Presents the x-ray structure of 3,3'-bis(2-hydroxyethyl)-2,2'-bithiophene which is the building block for the synthesis of head-to-head/tail-to-tail 2-hydroxyethyl-substituted oligothiophenes. Noncoplanar anti conformation and an inter-ring twist angle; Regioselective synthesis of the dimer and trimer; Force-field calculations.

We report an optical study of polymorphic single crystals of a polysubstituted α-conjugated quaterthiophene. The crystals exhibit two crystalline symmetries (monoclinic and triclinic) with different energy gaps and lifetimes of the elementary excitations. Their optical properties are correlated to the molecular structure, showing that the functionalization process determines an intrinsic tuning of the crystal properties. [ABSTRACT FROM AUTHOR]

The facile synthesis of poorly soluble unsubstituted and modified α-quinque- and sexithiophenes under microwave irradiation in the liquid phase is described. The use of microwave irradiation allowed these compounds to be prepared in a few minutes and at high yields by means of the Suzuki cross-coupling reaction. Unsubstituted sexithiophene was obtained in 10 min via the one-pot borylation/Suzuki reaction, purified according to a very simple procedure, and isolated in 84% yield. The efficient synthesis of two new methylated quinque- and sexithiophenes displaying liquid crystalline properties is reported. A new microwave-assisted methodology for the conversion of aldehyde-terminated quinque- and sexithiophenes into the corresponding cyano derivatives is also described. The use of microwaves was extended to the Sonogashira coupling reaction and found to be very effective in the preparation of a quinquethiophene containing acetylenic spacers. The electronic and optical characterization of this compound is reported and discussed in relation to that of unsubstituted quinquethiophene. [ABSTRACT FROM AUTHOR]

Highlights a study which used the reaction of the mono- and dibrominated thiophene S,S-dioxides to obtain the oligothiophene S,S-dioxides from dimers to pentamers. Oxidization of alkylated thiophenes; In-depth look at the rate of the reaction; Methodology used to conduct the study; Results of the study.