A facile and fast approach, based on microwave-enhanced Sonogashira coupling, has been employed to obtain in good yields both mono- and, for the first time, disubstituted push-pull Zn(II) porphyrinates bearing a variety of ethynylphenyl moieties at the β-pyrrolic position(s). Furthermore, a comparative experimental, electrochemical, and theoretical investigation has been carried out on these β-mono- or disubstituted Zn(II) porphyrinates and meso-disubstituted push-pull Zn(II) porphyrinates. We have obtained evidence that, although the HOMO-LUMO energy gap of the meso-substituted push-pull dyes is lower, so that charge transfer along the push-pull system therein is easier, the β-mono- or disubstituted push-pull porphyrinic dyes show comparable or better efficiencies when acting as sensitizers in DSSCs. This behavior is apparently not attributable to more intense B and Q bands, but rather to more facile charge injection. This is suggested by the DFT electron distribution in a model of a β-monosubstituted porphyrinic dye interacting with a TiO2 surface and by the positive effect of the β substitution on the incident photon-to-current conversion efficiency (IPCE) spectra, which show a significant intensity over a broad wavelength range (350-650 nm). In contrast, meso-substitution produces IPCE spectra with two less intense and well-separated peaks. The positive effect exerted by a cyanoacrylic acid group attached to the ethynylphenyl substituent has been analyzed by a photophysical and theoretical approach. This provided supporting evidence of a contribution from charge-transfer transitions to both the B and Q bands, thus producing, through conjugation, excited electrons close to the carboxylic anchoring group. Finally, the straightforward and effective synthetic procedures developed, as well as the efficiencies observed by photoelectrochemical measurements, make the described β-monosubstituted Zn(II) porphyrinates extremely promising sensitizers for use in DSSCs.

We investigated the impact of Singly Occupied Molecular Orbital (SOMO) energy on the n-doping efficiency of benzimidazole-derivatives. By designing and synthesizing a series of new air-stable benzimidazole-based dopants with different SOMO energy levels, we demonstrated that an increase of the dopant SOMO energy by only ~0.3 eV enhances the electrical conductivity of a benchmark electron-transporting naphthalenediimide-bithiophene polymer by more than one order of magnitude. By combining electrical, X-ray diffraction, and electron paramagnetic resonance measurements with density functional theory calculations and analytical transport simulations, we quantitatively characterized the conductivity, Seebeck coefficient, spin density, crystallinity of the doped polymer as a function of the dopant SOMO energy. Our findings strongly indicate that charge and energy transport are dominated by the (relative) position of the SOMO level, whereas morphological differences appear to play a lesser role. These results set molecular-design guidelines for next-generation ntype dopants.

In this work, we report on the improvement of microarray sensitivity provided by a crystalline silicon substrate coated with thermal silicon oxide functionalized by a polymeric coating. The improvement is intended for experimental procedures and instrumentations typically involved in microarray technology, such as fluorescence labeling and a confocal laser scanning apparatus. The optimized layer of thermally grown silicon oxide (SiO(2)) of a highly reproducible thickness, low roughness, and fluorescence background provides fluorescence intensification due to the constructive interference between the incident and reflected waves of the fluorescence radiation. The oxide surface is coated by a copolymer of N,N-dimethylacrylamide, N-acryloyloxysuccinimide, and 3-(trimethoxysilyl)propyl methacrylate, copoly(DMA-NAS-MAPS), which forms, by a simple and robust procedure, a functional nanometric film. The polymeric coating with a thickness that does not appreciably alter the optical properties of the silicon oxide confers to the slides optimal binding specificity leading to a high signal-to-noise ratio. The present work aims to demonstrate the great potential that exists by combining an optimized reflective substrate with a high performance surface chemistry. Moreover, the techniques chosen for both the substrate and surface chemistry are simple, inexpensive, and amenable to mass production. The present application highlights their potential use for diagnostic applications of real clinical relevance. The coated silicon slides, tested in protein and peptide microarrays for detection of specific antibodies, lead to a 5-10-fold enhancement of the fluorescence signals in comparison to glass slides.

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Two new metal‐free organic dyes, CR29 and CR52, with high extinction coefficients in the visible spectral region between 400–650 nm, have been synthesized. The donor–acceptor structure of the dyes feature benzodithiophene moieties BDT1 and BDT as rigid π‐conjugated spacers, which have so far been very little studied for dye‐sensitized solar cell (DSSC) applications. DFT/TDDFT calculations have been employed to guide the design of the chromophores as well as to shed light on their electronic and optical properties. Photophysical and electrochemical characterization studies have been carried out to gather information on the charge transfer processes occurring at the dye–semiconductor interfaces. Under standard AM 1.5 conditions, DSSC sensitized with CR29 showed good conversion efficiencies: 5.14 % in the liquid electrolyte cell setup and 2.47 % in the solid‐state DSSC.

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Three novel dyes based on ZnII porphyrinates combined, in β-pyrrolic position, with the π unit dithienylethylene (DTE) have been synthesized and investigated for application in DSSCs. The panchromatic effect due to elongation of the π-delocalized system through a bridge between the porphyrinic ring and the DTE unit such as the 4-ethynylstyryl (1), ethynyl (2), and ethenyl (3) bonds have been investigated by computational, electrochemical, and photoelectrochemical methods. For all three dyes the π conjugated substituents in the β position produced the expected panchromatic effect with broadened electronic absorption spectra over a wide range of wavelengths and IPCE spectra featuring a broad plateau in the region 430–650 nm. In addition both DFT computational and electrochemical data have shown a smaller HOMO–LUMO energy gap for dye 3, when compared to dye 2 suggesting a slightly more facile conjugation between the porphyrinic core and the DTE unit through the ethenylic bond. Conversely the photoelectrochemical investigation showed improved DSSC performances from 3 to 1. These results have been rationalized by an in-depth DFT computational study of dyes 2 and 3 interacting with a cluster of 82 TiO2 units. The small energetic overlap between the LUMO and the TiO2 conduction band characterizing the more structurally distorted dye 3 would suggest low quantum yield of electron injection, while dye 2 shows a greater interaction between the LUMO of the dye and the semiconductor. Consequently the increased linearity and planarity of the structure of dye 1 seems to be the origin of its best performance in DSSC. Therefore it appears that the nature of the bridge between the DTE unit and the porphyrinic ring is quite relevant for the efficiency of these dyes for DSSC, due to distortion from the planarity and linearity of the structure of the dye and the consequent changes on the dye π conjugation.

We compare and contrast the properties of hybrid organic−inorganic self-assembled nanodielectrics (SANDs) based on alternating layers of solution-processed ZrO x and either of two phosphonic acid-functionalized azastilbazolium π-units having opposite dipolar orientations. Conventional Zr-SAND and new inverted IZr-SAND are characterized by Kevin probe, optical spectroscopy, capacitance−voltage measurements, AFM, X-ray reflectivity, and electronic structure computation. The molecular dipolar orientation affects thin-film transistor (TFT) threshold and turn-on voltages for devices based on either p-channel pentacene or n-channel copper perfluorophthalocyanine. Specifically, Zr-SAND shifts threshold and turn-on voltages to more positive values, whereas IZr-SAND shifts them in the opposite direction. Capping these SANDs with −SiMe 3 groups enhances the effect, affording a 1.3 V difference in turn-on voltage for IZr-SAND vs Zr-SAND-gated organic TFTs. Such tunability should facilitate the engineering of more complex circuits. Previously, we reported families of robust, structurally welldefined self-assembled nanodielectrics (SANDs) offering high capacitance, facile fabrication, and broad applicability to diverse 50 semiconductors. 19,20 Our most advanced SANDs consist of 51 alternating high-k metal oxide (ZrO x or HfO x) and highly 52 f1 polarizable, high-k PAE dipolar nanolayers (Figure 1a), all 53 processed from solution under ambient. 21−23 To date, the 54 effects, if any, of PAE dipolar orientation on the dielectric 55 properties and OTFT response remain unknown. Here, we 56 address this issue using an "inverted" PAE unit, named IPAE, 57 to create a structurally inverted SAND (Figure 1b) and show 58 from Kevin probe measurements, molecular orbital computa-59 tions, and OTFT measurements that dipolar inversion occurs 60 and that it affects, in an informative and useful way, the 61 principal OTFT parameters relevant to circuit design and 62 fabrication. 24,25 63 ■ EXPERIMENTAL SECTION 64 IPAE Synthesis and Characterization. All reagents are 65 commercially available and were used without further purification 66 unless otherwise stated. Anhydrous dichloromethane was distilled