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Charge transfer processes and space charge accumulation phenomena are fundamental topics concerning the technological applications of organic heterointerfaces. The possibility to achieve localized regions with enhanced charge density is, indeed, a powerful strategy to improve the performances of a vast plethora of electronic devices such as light emitting diodes, photodetectors and field-effect transistors. However, because of the complex structures of many organic compounds and the diversity of electronic interactions ruled by specific morphological features, the interfacial energy landscape of any combination of materials is needed to be carefully investigated. In this work, we provide a detailed analysis of the surface potential landscape of P3HT/PDIF-CN2 donor/acceptor organic heterointerfaces. The electrical characterization, relying on the field-effect transistor configuration, outlined that the presence of a PDIF-CN2 overlayer induces a semiconductor-to-conductor transition into spin-coated P3HT OFETs. The mutual doping of the two organic materials was analyzed by Scanning Kelvin Probe Force Microscopy (SKPFM) as a function of the PDIF-CN2 coverage and nominal thickness, with the results clearly pointing at the occurrence of charge transfer phenomena between the two materials. The related band bending at the interface brings to the formation of a hole rich area within the P3HT layer and an electron rich area within the PDIF-CN2 layer. The related thickness and charge density have been estimated in 15 nm and ≈1018cm-3, respectively. Significantly, by tuning the PDIF-CN2 overlayer coverage, the P3HT work function can be tuned within 1 eV, opening an interesting perspective for the achievement of organic optoelectronic devices with improved functionalities.

Three novel diketopyrrolopyrrole (DPP) based small molecules have been synthesized and characterized in terms of their chemical-physical, electrochemical and electrical properties. All the molecules consist of a central DPP electron acceptor core symmetrically functionalized with donor bi-thienyl moieties and flanked in the terminal positions by three different auxiliary electron-acceptor groups. This kind of molecular structure, characterized by an alternation of electron acceptor and donor groups, was purposely designed to provide a significant absorption at the longer wavelengths of the visible spectrum: when analysed as thin films, in fact, the dyes absorb well over 800 nm and exhibit a narrow optical bandgap down to 1.28 eV. A detailed DFT analysis provides useful information on the electronic structure of the dyes and on the features of the main optical transitions. Organic field-effect transistors (OFETs) have been fabricated by depositing the DPP dyes as active layers from solution: the different end-functionalization of the dyes had an effect on the charge transport properties with two of the dyes acting as n-type semiconductors (electron mobility up to 4.4∙10 -2 cm 2 /V∙s) and the third one as a p-type semiconductor (hole mobility up to 2.3∙10 -3 cm 2 /V∙s). Interestingly, well-balanced ambipolar transistors were achieved by blending the most performant n-type and p-type dyes with hole and electron mobility in the order of 10 -3 cm 2 /V∙s.

Eight novel isoindigo (iI) based small molecules have been successfully synthesized. Their molecular structure consists of an electron acceptor iI core symmetrically linked to two furan (F-series) or thiophene (T-series) rings and end-functionalized with four auxiliary electron withdrawing groups (EWGs) of different strength. The optical properties of the dyes in chloroform solution are uniformly modulated by the terminal EWGs so that absorption maxima wavelengths move to higher values as the EWG's strength increases. A computational (DFT level) analysis provides useful information on the electronic structure of the dyes: upon photoexcitation, the electron density moves away from iI core or towards it according to the different EWG considered. Optical analysis is performed on dyes' thin films as well and a general broadening and red shift of the absorption is observed as compared to the behaviour in solution; all the dye's thin films are characterized by narrow bandgaps (

The effect of chalcogen bonding interaction led to the interesting crystal packing and coordination geometry of copper(ii) in novel organic-inorganic hybrids. The reactions of organic bridging ligands 1,2,5-benzothiadiazole (btd) and 1,2,5-benzoselenazadiazole (bsed) with CuCl2 and CuBr2 by slow diffusion of two miscible solvents afforded three isomorphic 2D-network polymers, [CuCl2(btd)]n (1), [CuBr2(btd)]n (2), and [CuCl2(bsed)]n (3), and one molecular hybrid, CuBr2(bsed)2 (4). The crystal structures of these novel hybrids were determined by single X-ray crystallography. The three isomorphic hybrids consist of 2-D sheets in which [Cu(μ-X)2]n infinite linear chains running along the a axis are linked through N-coordinated molecules of btd and bsed along the b axis. On the other hand, the crystal packing of 4 is strongly influenced by the presence of the [Se⋯N]2 supramolecular synthon and Se⋯Br short interactions, all based on chalcogen bonding, that link the dimeric complex molecules into two-dimensional arrays parallel to the ac plane.

Four 4-nitrophenyl-functionalized benzofuran (BF1, BF2) and benzodifuran (BDF1, BDF2) compounds were synthesized by a convenient route based on the Craven reaction. All the compounds underwent a detailed chemical physical characterization to evaluate their structural, thermal and optical properties. An investigation on the therapeutic potential of the reported compounds was performed by analyzing their antiproliferative activity on prostatic tumour cells (PC-3). In both classes of compounds, anticancer potential is in direct correlation with the lipophilicity. From our study it emerged that antiproliferative activity was higher for benzofuran derivatives as compared to benzodifuran systems. Moreover, we report a mechanistic study relative to the most promising molecule, i.e. the apolar benzofuran BF1, that relates the antiproliferative properties found in our investigation to its ability to bind telomeric DNA (proven by CD and fluorescence techniques on tel(22) G4 DNA), and highlights its unexpected impact on cell cycle progression. (C) 2018 Elsevier B.V. All rights reserved.

Background Giant cell tumor of bone (GCTB) is a progressive osteolytic tumor with proven response to denosumab when unresectable or at high surgical risk. We report on incidence of suspected (sONJ) and adjucated (aONJ) osteonecrosis of the jaw cases, from a single institution series of patients treated with denosumab within a phase 2 study Methods Patients were enrolled with unresectable GCTB (Cohort 1), resectable GCTB with planned high morbidity surgery (Cohort 2). Denosumab was given 120 mg SC every 4 weeks with loading doses on days 8 and 15. The primary endpoint was safety: aONJ and s ONJ rate; efficacy endpoints included proportion of Cohort 2 patients without surgery, and progression-free survival for all patients Results Baseline characteristics and ONJ results for 52 patients are shown in the Table 1. Median follow-up was 103 months (95%CI 55-126) in Cohort 1 and 105 months (95%CI 94-116) in Cohort 2. Overall response rate was 20% in all sample. Of 9 Cohort 1 patients, 1 ended denosumab for GCTB progression after 70 months of follow-up. Overall Kaplan Meier (KM) estimates (95% CI) for GCTB progression-free in these patients were 88% (39-98%). 23 Cohort 2 pts (53%) ended denosumab without GCTB progression, and 20 (47%) recurred with a KM estimate of 67% (51-79) at 24 months, and 52% (36-66%) at 60 months. Median time of denosumab therapy was 80 months in Cohort 1 and 14 months in Cohort 2. Within Cohort 2 patients with planned surgery, 88% underwent surgery and 12% continued with denosumab only. Following surgery, recurrence occurs higher after curettage than resection (47% vs 5%). ONJ rate is reported in Table 1. Conclusions Denosumab was generally well tolerated with excellent long-term disease control in unresectable patients. A 47% recurrence rate following surgery was seen in this high-risk, selected, resectable population. Denosumab has major, long-lasting antitumor activity in unresectable or metastatic GCTB, with an aONJ and sONJ rate of 4% and 8%, respectively, in this series.

Four novel diketopyrrolopyrrole (DPP) derivatives have been synthesized and characterized: the dyes are based on a DPP electron acceptor core symmetrically functionalized with donor bi-furyl moieties and end capped with four different auxiliary electron-acceptor groups. Because of the alternation along the molecular backbone of electron acceptor and donor groups, all the dyes are characterized by optical absorption maxima approaching or exceeding 700 nm. In the solid state, this optical behavior determines for all the dyes a very low optical bandgap ranging from 1.57 eV to 1.29 eV, while electrochemical characterization shows a clear dependence of the LUMO energies on the strength of the auxiliary electron-acceptor groups. All the dyes are characterized by stable LUMO energies suitable for their application as n-type semiconductors. Organic field-effect transistors based on the reported compounds display actually n-type behavior and, in three cases, a very interesting and balanced ambipolar charge transport behavior was moreover observed.

Here we report the solid-state experimental and computational analysis of naphtho[2,3-c][1,2,5]thiadiazole (1) and naphtho[2,3- c][1,2,5]selenadiazole (2) showing that the three different crystal phases of polymorphic 1 and the sole crystal phase of nonpolymorphic 2 are characterized by predominance of some intermolecular motifs over the others. In particular, the intermolecular interactions present in the compounds, π···π, C−H···π, C−H···N, S···N, and Se···N, are hierarchically ranked, in such a way that in 1 polymorphism is observed, with the three different phases showing different combinations of the intermolecular interactions, while in 2 only the packing that maximizes the strongest intermolecular interaction by far, i.e., chalcogen bond, is observed. Moreover we also show that different packings produce different responses in the solid-state topochemical reactivity of the crystalline compounds, spanning from nonreactive packings to packings producing butterfly dimers. In order to rationalize the different responses, the relevance of the transverse parallel shift of molecules is suggested, as an important factor, in addition to the known Schmidt’s rules for solid-state topochemical reactions.

We report here on the synthesis of four novel pyran-based DSSC photosensitizers. The dyes are constituted of a pyran core functionalized with different electron acceptor groups and with peripheral cyano-acrylic groups. The molecules were carefully characterized for what concerns optical and electrochemical properties and a clear dependence from the strength of the electron-acceptor group functionalizing the pyran core was observed. A detailed DFT analysis on the dyes gave a better insight of the electronic properties and showed a good accord with the experimental properties. The dyes were used as photosensitizers both in n-type and p-type DSSCs. In the first case, the stabilization of the LUMO achieved partially prevented a fast kinetics of the electron injection. To overcome this, we used an I-based electrolyte containing an excess of LiI: the photoconversion efficiency significantly increases for all the dye-sensitized devices, up to a maximum of 2.1%. The dyes were successfully employed the as photosensitizers in p-type DSSC, obtaining PCEs approaching 0.1%, a promising result in the field on NiO-based devices. More remarkably, as far as we are aware, this is the first paper in which a single series of dyes is effectively employed as sensitizers in both n and p-type DSSCs.

Molecules of the title compound, C24H8F4N2O8, have C i point-group symmetry in the crystal, as they lie on crystallographic inversion centres (Z′ = 1/2). The difluorophenyl ring is disordered over two orientations; the final refined occupancy factors of the two components of disorder are 0.947 (4) and 0.053 (4). In the crystal, some Car—H...F interactions are present, which involve the most acidic H atom of the molecule.

Reversible martensitic transitions in molecular crystals are an unusual phenomenon, and most of the cases reported in the literature occur at relatively low temperatures. The title compound, 2-(5-(benzo[d]thiazol-2-yl)-1,3,4-oxadiazol-2-yl)-5-(diethylamino)phenol (DBOX), reveals an interesting and rich polymorphism, characterized by a reversible single-crystal-to-single-crystal transition occurring at 185 degrees C. The transition can be repeated several times on a single crystal without degradation and/or damage. The crystal structure of this high-temperature phase (II) and two low-temperature polymorphs (I and III) are solved by single-crystal X-ray analysis to fully elucidate the mechanism of the reversible I -> II transition. Changes in the molecular packing are preceded by anomalous thermal expansion and evolve as slipping/rotation motions of molecular dimers, activated by steric disengagement along the anomalous expansion direction and resulting in the reversible contraction of the long crystal axis and lateral expansion. Uncommon panchromatic- and white-emitting fluorescence properties of the reported compound are also described.

Data‐driven materials discovery has become increasingly important in identifying materials that exhibit specific, desirable properties from a vast chemical search space. Synergic prediction and experimental validation are needed to accelerate scientific advances related to critical societal applications. A design‐to‐device study that uses high‐throughput screens with algorithmic encodings of structure–property relationships is reported to identify new materials with panchromatic optical absorption, whose photovoltaic device applications are then experimentally verified. The data‐mining methods source 9431 dye candidates, which are auto‐generated from the literature using a custom text‐mining tool. These candidates are sifted via a data‐mining workflow that is tailored to identify optimal combinations of organic dyes that have complementary optical absorption properties such that they can harvest all available sunlight when acting as co‐sensitizers for dye‐sensitized solar cells (DSSCs). Six promising dye combinations are shortlisted for device testing, whereupon one dye combination yields co‐sensitized DSSCs with power conversion efficiencies comparable to those of the high‐performance, organometallic dye, N719. These results demonstrate how data‐driven molecular engineering can accelerate materials discovery for panchromatic photovoltaic or other applications., C.B.C. and J.A.V. gratefully acknowledge funding from the Winston Churchill Foundation of the United States. S.F. acknowledges financial support from MINECO (CTQ2014‐52331‐R) and the Gobierno de Aragón‐FEDER‐Fondo Social Europeo 2014‐2020 (E14_17R). X.Z. acknowledges support from the Hong Kong Research Grants Council (HKBU22304115‐ECS and C5015‐15GF), Areas of Excellence Scheme ([AoE/P‐03/08]), and the Hong Kong Baptist University (RC‐ICRS/15‐16/02E, RC‐ICRS/1617/02C‐CHE, and RC‐IRMS/16/17/02CHEM). J.M.C. thanks the 1851 Royal Commission of the Great Exhibition for the 2014 Fellowship in Design, hosted by Argonne National Laboratory where work was done supported by DOE Office of Science, Office of Basic Energy Sciences, and research resources from the Center of Nanoscale Materials and the Argonne Leadership Computing Facility, which are DOE Office of Science Facilities, all under contract no. DE‐AC02‐06CH11357.

A new nonlinear-optical (NLO) chromophore containing L-Shape 2-benzofuranyldiazene in π-electron bridge has been synthetized and its chemical and thermal properties examined. Evaluation of the second order NLO properties was performed by EFISH measurements of μβ on chloroform solution and by SHG measurements on amorphous spin-coated thin films obtained from a blend of polymer and chromophores crosslinked “in situ”. The value of 830∙10−48 esu for μβ measured on the dye and of 10 pm/V for the d33 for the poled network are in medium range for similar systems, confirming the proper employ of the molecule to build NLO active networks. The crystal structures dye and its precursor examined by single-crystal analysis show a planar geometry and bond lengths pattern confirm the push pull L-shape nature of the D-π-A systems.

e23506 Background: Metastatic osteosarcoma (MOS) with synchronous metastases accounts for 20-25% of all new cases of osteosarcoma. Lungs are the most common site of metastases at presentation (80%) followed by Bone (10%). 5- years Overall Survival (OS) of MOS ranges from 11 to 40%. In a previous study from our institution (Bacci G 2006) on 57 pts < 40 years old (1995-2000) the 2- and 5-year OS were 55% and 18%. Methods: Data of patients with pathologic and radiologic confirmed MOS with adequate follow up were reviewed (EC Approval N 916/2020/Oss/IOR). Time-to-event outcomes were estimate with Kaplan-Meier method and compared between groups with log-rank test and Cox model. Results: From August 2000 to October 2018, 92 patients had a diagnosis of MOS: median age 16.5 yrs (6-73, twelve pts > 40 ), gender rate was M 51/F 41, axial primary tumor in 15 cases, extremity in 77. Lung only metastases were described in 66 (71.7%). In 75/90 cases primary tumor was surgically removed, 43 (46%) cases had at least one surgical metastasectomy. All patients received chemotherapy: preoperative only in 6 cases, postoperative in 6, and pre and postoperative in 66 patients. The 1st line chemotherapy was a combination of drugs: Adriamycin in 91/92 pts, Cisplatin in 89/92, Ifosfamide in 88/92, Methotrexate in 83/92; 59 patients received a 2nd line chemotherapy, 34 pts received a 3rd line; most employed regimen were Gemcitabine-Docetaxel, Ifosfamide 15 gr/m2, Cyclophosphamyde-Etoposide, TKI (Pazopanib, Sorafenib), and a few received experimental drugs. Complete remission (CR) was obtained in 26/92 (28%), in 19 cases after surgical metastasectomy.In 30 pts the information of PGP (P- glycoprotein) was available; patients with positive PGP (19/30) had a worst overall survival as compared to those PGP negative (P = 0.038). Of those in Complete Remission 14/26 relapsed. At December 2020 with a median follow-up of 95 ms (IQR 34-159): 65/92 (70%) died , 12 are alive and free from disease , 6 are alive with disease, 9 were lost . The 2-yrs OS for all 92 pts from diagnosis was 66% (95%CI 55-75) and 5-yrs OS was 26% (95% CI 16-37). From the end of treatment, for those who reached a CR the 5-year OS was 57% vs 9% for those who did not (P < 0.001). At univariate analysis, primary tumor site (2-y OS 48% axial vs 72% extremity, P < 0.001), site of metastases (2-y OS 74% only lung vs 48% other, P = 0.004) and number of lung nodules (P = 0.007), were significantly associated to OS. At multivariate analysis, only site of metastases (other vs. only lung HR = 2.26, 95%CI: 1.21-4.22) and number of lung nodules (≥10 nodules vs ≤3 HR = 2.44, 95%CI: 1.24-4.81) were confirmed as significant for OS. Conclusions: Compared to our previous report from 20 yrs ago, 2-years and 5 yrs OS of MOS has improved but it remain unsatisfactory (66% vs 55% and 26% vs 18%).

e22010 Background: Osteosarcoma is a malignant primitive bone tumor whose prognosis is not changed since 4 decades, after the introduction of neoadjuvant chemotherapy with Methotrexate, Cisplatin, Doxorubicine and Ifosfamide. Histologic response to preoperative chemotherapy is a significant prognostic factor. Huvos I (necrosis ≤ 50%) has worst prognosis . Previous studies reported a 3 years EFS of this Huvos I patients around 25% (Tsuda Y,2020). In order to evaluate if survival has changed in recent years in this unfavourable prognostic group we evaluated the outcome of osteosarcoma patients with Huvos I. Methods: from our Pathology archieves we retrieved all cases of localized osteosarcoma treated at Rizzoli with neoadjuvant chemotherapy who reported an histologic necrosis below or equal to 50% (Huvos I grade) after preoperative chemotherapy MAP (Ethical C. Approval 917/2020/Oss/IOR). Results: from 2003 to 2019 we had 70 cases of localized osteosarcoma with Huvos I necrosis after neoadjuvant chemotherapy ( MAP in 66 and MAPI in 4) evaluable. Median age 21,5 (3-70); M:F = 44:26. 10/70 had axial localization vs extremity(60), subhistotype distribution:46 osteoblastic,11 chondroblastic, 7 fibroblastic, 5 teleangectatic, one not classified. In 24 cases PgP was available(14 PgP positive). With a median follow up of 86.7 ms (IQR 41-136) 43/70 had already relapsed. The median EFS was 25 ms (95% CI 15-42) and the 3 yrs EFS was 40.6% (95% CI 29-52). The 3 yrs overall survival was 80% (95%CI 68-88) and median OS was not reached. Axial tumor site was associated with significant inferior EFS (P = .004). Conclusions: these data confirm the poor prognosis of patients with necrosis ≤50% and the need of new drugs to improve their survival in this sub-group.

Correction for ‘Space-charge accumulation and band bending at conductive P3HT/PDIF-CN2 interfaces investigated by scanning-Kelvin probe microscopy’ by Federico Chianese et al., J. Mater. Chem. C, 2021, DOI: 10.1039/d1tc04840f.

Four nobel metal free dyes for application as photosensitizers in DSSC have been synthesized and their chemical–physical properties characterized by UV–vis absorption spectroscopy, cyclic voltammetry and DFT theoretical computations. The dyes are based on a pyran core, functionalized with different electron acceptor groups, symmetrically linked to carbazole electron donor mojeties. The four dyes have different optical absorption properties, affording a range of colors ranging from orange to blue, covering most of the visible spectral region. All the dyes feature high molar extinction coefficient, up to a value of 1.0 × 10 5 L mol −1 cm −1 . The dyes were used as photosensitizers in DSSC and the photovoltaic characterization of these devices was performed under simulated solar radiation. The cell performance is higher for chromophores featuring higher LUMO energies as a consequence of a better electron injection in TiO 2 oxide. A maximum power conversion efficiency of 1.9% has been achieved.

Dye sensitized solar cells (DSSC) are considered one of the most promising photovoltaics technologies alternative to the traditional silicon based solar cells because of their compatibility with low cost manufacture methodologies, their peculiar optical and mechanical properties and their high indoor efficiency. Photosensitizers represent one of the most important part in a DSSC device and probably the most thoroughly investigated in the last twenty years, with thousands of dyes that have been proposed and tested for this kind of application. In this review we aimed to give an overview of the three main classes of DSSC photosensitizers, namely ruthenium (II) polypyridyl complexes, Zn-porphyrin derivatives and metal free organic dyes. After a brief introduction on the architecture and operational principles of a DSSC and on the state of the art of the other main components of this kind of device, we focused our discussion on photosensitizers. We defined the several requirements DSSC photosensitizers should fulfil and provided an excursus about their historical development along the years; by examining specific dyes reported in the literatures, we attempted to highlight the molecular design strategies that have been established for the optimization of their performance in actual devices both for what concerns efficiency (that recently reaches an outstanding 14.3 %) and operational stability. We finally discussed, in the last section, about the possible future developments of this intriguing technology.

The title compound crystallizes with half a mol­ecule in the asymmetric unit and shows Car—H⋯F inter­actions in the crystal packing., Mol­ecules of the title compound, C24H8F4N2O8, have C i point-group symmetry in the crystal, as they lie on crystallographic inversion centres (Z′ = 1/2). The di­fluoro­phenyl ring is disordered over two orientations; the final refined occupancy factors of the two components of disorder are 0.947 (4) and 0.053 (4). In the crystal, some Car—H⋯F inter­actions are present, which involve the most acidic H atom of the mol­ecule.

We have prepared new hydroxyphenyl derivatives of [1,2,4]triazolo[3,2-c][1,2,4]triazole and investigated their tautomeric behavior, for the neutral and the monoprotonated forms, either computationally and experimentally in solution and the solid state. The results of our analysis indicate that the tautomeric behavior, in particular for the monoprotonated forms, is strongly dependent on the position of the OH group in the phenyl ring. The different position of the group (ortho, meta, para) has an effect on the relative energy of the various tautomeric forms of the cations but also on their ability to get an optimum packing, which is driven by directional hydrogen bonds. In particular, with the OH in para position, the two tautomers 1H-3H and 2H-3H of the singly protonated form have a similar energy and can be selectively isolated in the solid state with different counterions; with OH in the meta position, though the energy difference between the tautomers is even smaller, only the 2H-3H is present in the solid state, because of optimum packing interactions (hydrogen-bonding pairing); finally, with ortho OH, only the 1H-3H is isolated in the solid state because it has energy significantly lower than 2H-3H.

The application of four pyran based dyes as sensitizers for p-type dye-sensitized solar cells (p-DSCs) is here proposed. The dyes differ for the nature of the electron acceptor group which functionalizes the pyran core. Such a structural variation significantly influences the optical properties of the dyes so that the new pyrans overall cover most of the visible spectrum. In some cases, the p-DSCs employing these pyran-based dyes display power conversion efficiency significantly higher than the device sensitized with sensitizer benchmark P1. The relevant photo-electrochemical activity of one of the reported dyes combined with its ability to absorb the visible radiation in the lower energy portion (λ > 500 nm) makes it a promising candidate to be used in a tandem DSC (t-DSC) with the photoanode sensitized by a dye typically absorbing the higher energy zone of the visible spectrum (λ

This work reports the synthesis and characterization of three novel carbazole-based push-pull dyes that have been purposely designed to be applied in p-type dye-sensitized solar cells (DSSCs). By using the same electron-donor moiety (the carbazole group) and three different electron acceptor groups, we explore how these new substituents affect the optical and electrochemical properties of the dye. State-of-the-art theoretical characterization at the DFT and TD-DFT levels of theory provides the means to understand and elucidate the connection between the chemical composition, the structure and the electronic features of these dyes. The interface between the dyes and the prototypical p-DSSC electrode (i.e. NiO) is also investigated by first-principles calculations, highlighting the importance of taking into account the dye/electrode mutual polarization for a correct alignment of the relevant electronic states (e.g., dye HOMO and NiO valence band edge). Following these characterizations, preliminary studies on the photoelectrochemical performances of the new dyes in p-DSSCs provide promising results and motivate future investigations on these new systems.

In this paper, Scanning Kelvin Probe Microscopy (SKPM) was applied in combination with standard current-voltage measurements to assess the contact resistance (RC) effects and to estimate the contact-free charge carrier mobility in n-type transistors based on evaporated films of PDIF-CN2. This analysis was carried out in particular as a function of the applied polarization voltages. The separate contributions to the RC phenomenon coming from the injecting (source) and extracting (drain) electrodes were investigated with the possibility to separately analyze the specific electrical behaviour of these two regions. In agreement with previous results, the experimental data here discussed show that the devices under analysis are not simply injected limited. Voltage drops at both the injecting and extracting contacts must be taken into consideration. However, it is worth to mention that for the bottom-contact devices here investigated, a minimum RC of 5.5 kΩ cm was found in linear regime. These values are significantly lower (i.e. by a factor 5×) than those previously reported for other perylene dimiide thin-film devices with bottom-contact configuration.

The acid-base properties of selected derivatives of the [1,2,4]triazolo[3,2-c][1,2,4]triazole fused aromatic system have been investigated by UV–vis spectroscopy. Neutral heterobicycles (HL) exhibit amphoteric behavior (they can deliver the N–H proton forming the conjugated base L− and can accept up to two protons, forming the species H2L+ and H3L++) and show an unprecedented tautomeric switching upon protonation, as revealed by single crystal X-ray analysis and confirmed by theoretical calculations. By varying the groups attached at the heterocycle, a remarkable shift of pKai values, up to 5–6 units, is observed. In particular, with strong electron attractor groups at position 7 (e.g. p-nitrophenyl or pentafluorophenyl) the neutral compounds are stronger acids than phenol or p-nitrophenol.

The title compound, bis(4-butyloxyacetophenon)azine, exhibits a rich phase behavior. It has two different crystal phases and one liquid crystal phase before transition to the isotropic liquid phase. The liquid crystalline phase is nematic. All the phase transitions of the compound are reversible. In particular, the solid–solid transition at 83 °C is single-crystal-to-single-crystal as proven by optical and electron microscopy and X-ray diffraction analysis and it shows a remarkable degree of reversibility; single crystals can undergo several cycles of transition between the two phases without any damage. The crystal phase stable at lower temperature has been fully characterized by single crystal X-ray analysis. It shows an arrangement of the molecules in layers in the plane (a, b), with the layers piled up along c without interdigitation of the alkyl tails of molecules belonging to consecutive layers. The crystal phase stable at higher temperature is disordered.

Fine control of the tautomeric forms of [1,2,4]triazolo[3,2-c][1,2,4]-triazole derivatives in acidic conditions has been achieved by acting on the electronic character of the substituent at position 7 of the heterobicycle and on the counterion. Strong electron releasing or electron withdrawing substituents lead almost exclusively to a single tautomeric form, the 1H-3H or the 2H-3H, respectively. In the case of the phenol substituent, both tautomeric forms are present in comparable amount in solution; the two tautomers can also be selectively precipitated in different crystalline salts using suitable counterions.

Three different pyran based dyes were synthesized and tested for the first time as photosensitizers of NiO based p-type dye-sensitized solar cells (p-DSSC). The molecules feature a similar molecular structure and are based on a pyran core that is functionalized with electron acceptor groups of different strength and is symmetrically coupled to phenothiazine donor branches. Optical properties of the dyes are deeply influenced by the nature of the electron-acceptor group, so that the overall absorption of the three dyes covers the most of the visible spectrum. The properties of devices based on the NiO electrodes sensitized with the investigated dyes were evaluated under simulated solar radiation: the larger short circuit current density exceeded 1 mA/cm2 and power conversion efficiency as high as 0.04% could be recorded. The performances of the fabricated p-DSSC have been compared to a reference cell sensitized with P1, a high level benchmark, which afforded a photoelectrochemical activity similar to the best example of our pyran sensitized devices (Jsc = 1.19 mA* cm−2 and η = 0.049%).

The synthesis by direct heteroarylation of three novel low bandgap donor-acceptor-donor molecules is reported herein. The molecules are based on three different diketopyrrolo-pyrrole (DPP) electron deficient cores, functionalized with different electron rich heteroarenes, (thiophene, thiazole and thienothiophene) and symmetrically linked to two terminal donor phenothiazine rings. The optical properties of the synthesized dyes have been measured both in solution and as thin film and a focus has been given on the study of optoelectronic properties as a function of the different heteroarenes (thiophene, thiazole or thienothiophene) functionalizing the DPP core. Bandgap values as small as 1.55 eV have been observed. The energy of the Frontier orbitals has been estimated by means of electrochemical characterization. The electronic properties of the reported molecules have been investigated more in details by computational analysis performed at the DFT level. The new dyes were used as donor materials in BHJ solar cells and the photovoltaic characterization of these devices led to a maximum power conversion efficiency of 0.7%.

Reaction of N-rich conjugated bis(3,4-diamino-1,2,4-triazole)s with dilute hydrochloric acid affords bis(3,4-diamino-1,2,4-triazol-2-ium)chlorides. These compounds form layered structures in which planar layers of molecules are parallelly stacked. The π-stacking distance of the layers is relatively short, as compared with all-carbon-containing aromatic compounds, ranging between 3.00 and 3.22 Å at 173 K, and several contacts shorter than the sum of van der Waals radii are observed in the crystal structures. The features of the crystal structures are discussed in terms of the high nitrogen content of the compounds and of the H-bonding patterns. Periodic ab initio theoretical calculations of the crystal structures have allowed decomposing the lattice energy into various contributions in order to put up the relevance of van der Waals interactions for the π-stacking. In particular, it is found that van der Waals interactions account for about 10% of the total lattice energy and about 50% of the stacking energy (interlayer energy).

The increasing acceptance of Network Function Virtualization (NFV) and Software Defined Networks (SDN) paradigms is enabling the creation of cloud technologies combining Real-Time multimedia Communications (RTC) and multimedia processing for big data. Although many vendors already provide solutions in these areas, none of them comprises a single platform for end-to-end service provisioning and deployment addressing all the complexities of combining RTC and media processing. As a result, developing such types of applications is still extremely complex. Following this, we present NUBOMEDIA, an open-source platform enabling developers to create and deploy RTC applications with advanced media processing capabilities. For this, NUBOMEDIA introduces the concept of Media Pipeline: chains of interconnected media processing elements. At deployment time, NUBOMEDIA follows a Platform as a Service (PaaS) scheme, which abstracts for developers most of the complex infrastructure-related tasks such as: provisioning, scaling or QoS and network management. In this paper we present the NUBOMEDIA architecture, which bases on ETSI NFV recommendations, and introduce the main interfaces and capabilities it exposes to developers. To conclude, we present some early experiments demonstrating, through benchmarks, the suitability of the platform to combine RTC and advanced media processing algorithms maintaining the stringent QoS requirements of RTC.

A class of novel pyran based chromophores has been synthesized and characterized for what concerns their optical and electrochemical properties. The electronic structures were investigated in details by means of DFT theoretical computations. The molecular structures of the chromophores are based on a pyran core, functionalized with different electron acceptor groups, symmetrically linked to phenothiazine electron donor moieties. The dyes have different optical absorption properties, affording a set of colors ranging from orange to blue, covering most of the visible spectral region and they are characterized by high molar extinction coefficient, up to a value of 6.4·10 4 cm −1 M −1 . The dyes were used as photosensitizers in DSSC and the photovoltaic characterization of these devices was performed under simulated solar radiation. A maximum efficiency of 2.82% has been achieved. The most promising device underwent an accelerated ageing test, performed at 85 °C for 50 days: no variation of the main electrical parameters of the DSSC was observed during the test, indicating an excellent stability for devices based on this class of photosensitizers.

Layer-by-layer of polyelectrolytes has emerged as one of the easiest and most controlled techniques to deposit ultrathin polymer layers mainly driven by electrostatic interactions. However, this kind of interaction results to be weak and easily breakable in physiological environment. Here we report on the preparation of nanocapsules completely made of natural biomaterials: a lipophilic core (soybean oil and egg lecithin as surfactant) as nanometric template and a polysaccharide-based multilayer shell (glycol chitosan and heparin) covalently cross-linked. We first modified glycol chitosan with a thiol moiety and heparin with an alkene moiety, respectively, and then we built a polymer multilayer film with a covalent cross-linkage among layers, exploiting the light initiated thiol-ene reaction, known as click chemistry. We showed the possibility to perform the covalent cross-linkage without any photoinitiator or metal catalyst, thus avoiding cytotoxic effects and further purification steps. The so realized nanocapsules resulted to be stable and completely biocompatible and, therefore, of interest for the biotechnology fields, mainly for drug delivery.

In this paper, the metal-semiconductor contacts in n-type bottom-contact bottom-gate Organic Field-Effect Transistors (OFET), based on evaporated films of a perylene diimide derivative (PDI8-CN2), have been investigated by Scanning Kelvin Probe Microscopy (SKPM). OFET were characterized for different thicknesses of the PDI8-CN2 film and in the light of the gold electrode functionalization with an aromatic thiol self-assembled monolayer. SKPM experiments reveal that aromatic thiol functionalization produces a 30% reduction in the contact resistance (Rc), while lowering the organic film thickness, the contact resistance (Rc) phenomenon tends to be magnified. The experimental observation that the voltage drops occurring close the drain electrode are even larger than those taking place at the source contact suggests that it is not possible, for these devices, to explain the overall Rc effects by simply referring to the presence of a reverse-biased Schottky junction limiting the electron injection process into the active channel.

A new push–pull molecule, containing an (alkylamino)thiophene as electron donor and 1,3-bis(dicyanomethylidene)-2- indenylindene as electron acceptor, has been synthesized and characterized in the solid state by X-ray crystallography, in solution by UV/Vis and NMR spectroscopy and by theoretical calculations. The quinoidal zwitterionic form of this compound was underscored both in the solid state and in moderately polar solvents. Experimental and theoretical analyses were also performed on two similar push–pull molecules, selectively chosen to vary basic chemical features such as the esonance energy of the aromatic group and the steric hindrance of the attractor. Comparative analysis of the three compounds has shown that steric hindrance, resonance en- ergy and the polarity of the environment play a significant role in stabilizing one limiting resonance form over the other. By varying these chemical variables, fine tuning of the electronic ground state of a push–pull molecule, from the neutral aromatic form to the charge-separated zwitterion, passing through a form in which the two limiting forms contribute almost equally (the cyanine limit), can be achieved.

Three new azo-polyurethanes containing the s-triazolo[3,4-b]thiadiazole heterocycle have been prepared and characterized. The polymers showed glass transition temperatures between 183 °C and 232 °C and a moderate to good thermal stability in air. The thermal cis–trans isomerization around the azo group was analyzed in solution and the kinetic constant of this process was calculated. One of the synthesized polymers was processed in form of thin films (thickness was 1.2 μm) and some experiments of optical laser writing were performed on it: three different surface relief gratings (SRGs) structures were realized at micrometer scale (a square, a concentric square pattern and a grating) indicating this polymer as an interesting candidate for the azo-lithography.