The covalent functionalization of photosynthetic proteins with properly tailored organic molecular antennas represents a powerful approach to build a new generation of hybrid systems capable of exploiting solar energy. In this paper the strategy for the synthesis of the tailored aryleneethynylene organic fluorophore (AE) properly designed to act as light harvesting antenna is presented along with its successful bioconjugation to the photosynthetic reaction center RC from the bacterium Rhodobacter sphaeroides .

The aggregation behavior of two D-glucose-substituted phenyleneethynylenes, an alternate copolymer (AP) and a homooligomer (HO), has been investigated by means of UV−vis absorption, circular dichroism (CD) and fluorescence spectroscopy. CD reveals superior capability to detect the early stages of aggregation and to provide information about aggregate geometries. The multiband CD spectrum of the AP and of analogous chiral PPEs is rationalized on the basis of the exciton coupling between vibronic transitions localized on proximate portions of the chromophoric chains.

Ternary blends comprising an ‘energy-cascade former’ in addition to the donor and the acceptor materials increasingly attract attention in the organic solar cell area as they seem to provide a tool to positively manipulate the open-circuit voltage of bulk-heterojunction devices. By comparing two additives that have similar HOMO/LUMO levels and that can be expected to lead to an energy cascade in ternaries with the prototypical P3HT:PC60BM system, we demonstrate here that the compatibility of the additive with, in this specific case, the fullerene, that can be tailored by peripheral chemical functionalization, plays a critical role in energy cascade formation. A compromise needs to be found between good mixing (favoring energy cascade formation) and phase separation (supporting charge extraction) that affect the open-circuit voltage in an as important fashion as their electronic features, providing critical insights for future materials design activities.

Light machine: The simplest photosynthetic protein able to convert sunlight in other energy forms is covalently functionalized with a tailored organic dye to obtain a fully functional hybrid complex that outperforms the natural system in light harvesting and conversion ability.

The interaction of hydrogen with gold nanoparticles (Au NPs) and gold thin films also functionalized with thiols is investigated. Au NPs deposited on silicon substrates by radio frequency sputtering of a gold target and gold thin films have been exposed to a remote H(2) plasma and subsequently functionalized by the aromatic (4-methoxyterphenyl-3 '',S ''-dimethanethiol) and aliphatic (dodecanethiol) thiols. The impact of hydrogenation on changes of the charge on gold surfaces and nanoparticles, on the kinetics of the thiol self-assembled monolayer (SAM) formation, and on the density of the resulting SAMs has been investigated combining spectroscopic ellipsometry (SE), Raman spectroscopy, and surface potential Kelvin probe microscopy (SP-KPM) in conjunction with noncontact atomic force microscopy (AFM). We found that remote H(2) plasma pretreatments of gold surfaces are effective in improving thiolate adsorption, making SAMs more uniform and densely packed. We also demonstrate that hydrogenation of nanoparticles improves stability of thiol functionalized Au NPs, avoiding their aggregation. Additionally, we demonstrate that a remote H(2) plasma processing is also effective in the selective removal of the carbon chain and of sulfur atoms from gold surfaces, therefore allowing tailoring of their optical and chemical properties.

We describe the synthesis of two novel poly(1,4-arylene-2,5-thienylene)s P1 and P2 containing benzo[c][2,1,3]thiadiazole monomeric units via Suzuki–Miyaura polymerization of a thiophene diboronic ester with aryl diiodides. The use of a catalyst complex consisting of Pd(OAc)2 in combination with the electron-rich biaryl phosphine S-Phos resulted in efficient polymerization reactions. The polymers synthesized, P1 and P2, were characterized by UV–vis spectroscopy and cyclic voltammetry. Theoretical calculations and electrochemical measurements on P1 suggested a favorable position of the molecular orbitals for employment in polymer solar cells in combination with PCBM. Devices containing P1:PCBM 1:2 in the active layer showed an efficiency of 1.2% by simple spin casting from chloroform.

Organic field-effect transistors (OFETs) are key devices in organic electronics, and their performances largely depend on molecular structure and solid-state organization of the π-conjugated compounds used as semiconductors. This microreview reports several examples of materials for OFET devices and sensors, which have been selected to highlight the basic criteria of molecular design together with the synthetic logic driving the development of organic semiconductors. Versatile synthetic methodologies enable to optimize properties by tailoring molecular structures and functionalization, thus playing a key role in the progress of OFET technology, and more in general of organic electronics, which is emphasized in the discussion.

A new set of linear oligoarylene thiol molecules, namely (4'-(Thiophen-2-yl) Biphenyl-3,5-diyl) Dimethanethiol (TBD), (4'-(Thiophen-2-yl) Biphenyl-4-yl) Methanethiol (TBM) and ([ 1,1'; 4',1''] Terphenyl-3,5-diyl) Dimethanethiol (TD), were synthesized and used for functionalizing the polycrystalline gold electrodes. Such molecules differ for the number of anchoring groups (TBM vs. TBD) and the terminal rings (TD vs. TBD). As shown by electrochemical measurements, they form homogeneous and pinholes-free self-assembly monolayers (SAMs) when deposited on the gold electrode. Moreover, the wettability of the functionalized surface and the morphological changes of pentacene films grown on SAMs were investigated by contact angle and atomic force microscopy, respectively. OTFT has been used as organic gauge for investigating the metal-SAM-organic semiconductor structure. Charge carriers mobility, threshold voltage, contact resistance were measured in both air and vacuum to assess the influence of the anchoring groups and the terminal rings to the transistor performance. Although these SAMs do not show an improvement of mobility due to an increase of contact resistance, they allow a better modulation of the current flowing across the electrode-organic semiconductor (OS) interface, pointing out the structural differences between the three SAMs in terms of resistance drop combined with the critical voltage.

Several organometallic methods are used to synthesize pi-conjugated molecules and polymers with alternating thiophene-dialkoxyphenylene units in the conjugated backbone. Here we describe our approaches to the synthesis of materials based on the dialkoxyphenylenethienylene structural motif via palladium catalyzed cross-coupling reactions of organomagnesium or organoboron reagents with aryl halides. The properties of the resulting compounds and their applications in (opto)electronic devices (organic field effect transistors, resistive gas sensors, field effect chiral sensors, photoelectrochemical cells and bulk-heterojunction solar cells) are also discussed, highlighting the role of the synthetic logic in the design of multifunctional organic materials.

Four thiolated oligoarylene molecules (i) 4- methoxy-terphenyl-4″-methanethiol (MTM), (ii) 4-methoxyterphenyl- 3″,5″-dimethanethiol (MTD), (iii) 4-nitro-terphenyl- 4″-methanethiol (NTM), and (iv) 4-nitro-terphenyl-3″,5″- dimethanethiol (NTD) were synthesized and self-assembled as monolayers (SAMs) on polycrystalline Au electrodes of organic field-effect transistors (OFETs). SAMs were characterized by contact angle and AC/DC electrochemical measurements, whereas atomic force microscopy was used for imaging the pentacene films grown on the coated electrodes. The electrical properties of functionalized OFETs, the electrochemical SAMs features and the morphology of pentacene films were correlated to the molecular organization of the thiolated oligoarylenes on Au, as calculated by means of the density functional theory. This multi-methodological approach allows us to associate the systematic replacement of the SAM anchoring head group (viz. methanethiol and dimethanethiol) and/or terminal tail group (viz. nitro-, −NO2, and methoxy, −OCH3) with the change of the electrical features. The dimethanethiol head group endows SAMs with higher resistive features along with higher surface tensions compared with methanethiol. Furthermore, the different number of thiolated heads affects the kinetics of Au passivation as well as the pentacene morphology. On the other hand, the nitro group confers further distinctive properties, such as the positive shift of both threshold and critical voltages of OFETs with respect to the methoxy one. The latter experimental evidence arise from its electron-withdrawing capability, which has been verified by both DFT calculations and DC electrochemical measurements.

Phenylene-thiophene oligomers bearing peracetylated beta-D-glucose or N-BOC-L-phenylalanine as chiral substituents were synthesized in good yields by a versatile protocol based on the Suzuki-Miyaura cross-coupling reaction. Aryl iodides bearing the chiral biomolecules as substituents efficiently reacted with pinacol boronates of bi- or terthiophenes leading to the bio-functionalized oligomers in good yields.

This chapter discusses the most important synthetic routes to the main classes of electroluminescent -conjugated polymers, highlighting advantages and limitations of the different methods in terms of versatility, stereo- and regioselectivity, efficiency. The discussion covers not only the synthesis of basic classes of polymers such as polyarylenes, poly(arylenevinylene)s, poly(aryleneethynylene)s, but describes routes to systems with more complex structures, including multifunctional copolymers and coordination polymers.

In this article we discuss synthetic routes to organic conjugated oligomers and polymers bearing triple C-C bonds that have been recently developed in our laboratories, based on Pd-catalyzed Csp-Csp2 coupling reactions. Experimental protocols have been tuned to face synthetic challenges such as the presence in the main conjugated backbone of multifunctional substituents or

A novel class of tetrathiolated aryleneethynylene oligomers was obtained by the Cassar–Heck–Sonogashira coupling between S,S'-(5-ethynyl-1,3-phenylene)bis(methylene)diethanethioate (1) and aryl diiodides or dibromides. Although standard coupling conditions are effective in the case of iodo derivatives, the addition of free triphenylphosphane to the reaction mixture was required to overcome the slower reaction rate of dibromoarenes. Oligomers with an extended conjugated system could be obtained starting from a higher homologue of 1 by applying the same synthetic approach. These oligomers represent interesting molecular wires, potentially able to self-assemble on various substrates, including gold and other noble metals in the form of thin films or nanoparticles. The chelating arrangement of the thiol functionalities should ensure stable anchoring and would also represent an interesting novel feature in the study of single molecule conduction with respect to traditional monodentate systems.

Self-assembled monolayers (SAMs) derived of 4-methoxy-terphenyl-300,500-dimethanethiol (TPDMT) and 4-methoxyterphenyl- 400-methanethiol (TPMT) have been prepared by chemisorption from solution onto gold thin films and nanoparticles. The SAMs have been characterized by spectroscopic ellipsometry, Raman spectroscopy and atomic force microscopy to determine their optical properties, namely the refractive index and extinction coefficient, in an extended spectral range of 0.75-6.5 eV. From the analysis of the optical data, information on SAMs structural organization has been inferred. Comparison of SAMs generated from the above aromatic thiols to well-known SAMs generated from the alkanethiol dodecanethiol revealed that the former aromatic SAMs are densely packed and highly vertically oriented, with a slightly higher packing density and a absence of molecular inclination in TPMT/Au. The thermal behavior of SAMs has also been monitored using ellipsometry in the temperature range 25-500 C. Gold nanoparticles functionalized by the same aromatic thiols have also been discussed for surface enhanced Raman spectroscopy applications. This study represents a step forward tailoring the optical and thermal behavior of surfaces as well as nanoparticles.

Cellulose nanopaper (CNP) features appealing properties, including transparency, flatness, a low thermal expansion coefficient and thermal stability, often outperforming conventional paper. However, free-standing crystalline cellulose films usually swell in water or upon moisture sorption, compromising part of their outstanding properties. This remains a major problem whenever working in a water environment is required. Freestanding cellulose nanopaper is prepared by solution casting water suspensions of cellulose nanocrystals with an average width of 10 nm and an average aspect ratio of 28, isolated from Avicel by acid hydrolysis and extensively characterized by AFM and FE-SEM measurements and GPC detection of their degree of polymerization. We demonstrate by elemental analyses, FT-IR, Raman spectroscopy, XRD measurements and water contact angle detection that wet treatment with lauroyl chloride results in surface hydrophobization of nanopaper. The hydrophobized nanopaper, C12-CNP, shows a more compact surface morphology than the starting CNP, due to the effect of chemical functionalization, and presents enhanced resistance to water, as assessed by electrochemical permeation experiments. The new hydrophobized nanopaper is a promising substrate for thin film devices designed to work in a humid environment.

Alkyl thiols are processing additives for bulk heterojunction (BHJ) solar cells useful for substituting post-production treatment with low energy consuming processes (1). They modify the solubility of donor:acceptor couple in the host solvent, impacting solid state nanoscale phase separation. After deposition, thiol solvent presumably evaporates from the blend. Conjugated structures with pending alkylthiol groups could be interesting for ternary blend (2) polymer solar cells. Such materials could not only optimize the active layer morphology, but contribute by means of their conjugated structure to light harvesting and charge generation processes operating in the solar cell. Building on our experience in the synthesis of thiolated materials (3), we recently synthesized a family of organic semiconductors with low bandgap and pending alkylthiol groups. Their study in all organic or hybrid nanostructures represents an unexplored dimension in new generation photovoltaics. We present their synthesis and demonstrate the photovoltaic response of one of these compounds employed as additive in P3HT:PCBM solar cells. (1) Solar Energy 2011, 85,1226; (2) Adv. Mater. 2013, 25, 4245; (3) J. Org. Chem. 2007,72, 10272; Eur. J. Org. Chem. 2011, 529; Curr. Org. Synth., 2012, 9, 764.