A series of thiazolo[5,4-d]thiazoles with bipolar character has been designed and synthesized. Compounds 4a-d and 5a,b consist of a central thiazolo[5,4-d]thiazole as the electron acceptor (A) and a terminal 9,9?-spirobifluorene fragment as the electron-donor (D). Both key structural features are connected through the thiophene ?-linker. The structure of all the compounds is fully ?-conjugated providing proximity of the frontier molecular orbitals (FMO). Accordingly, thiazolo[5,4-d]thiazole-based compounds 4a-d and 5a,b exhibit excellent electronic structures with energy gaps falling in the range of 2.5-3.0 eV. Appropriate thermal stability and valuable photophysical properties make these molecules valuable for applications in optoelectronic materials. Hence, electroluminescent devices with 4b and 5b as host materials showed yellowish-green and yellow-green emissions, which is quite unique for organic-small molecules demonstrating their potential in the development of novel, low-weight and fully organic dopants for electroluminescent (EL) devices.

Background: Cells exposed to stress factors experience time-dependent variations of metabolite concentration, acting as reliable sensors of the effective concentration of drugs in solution. NMR can detect and quantify changes in metabolite concentration, thus providing an indirect estimate of drug concentration. The quantification of bactericidal molecules released from antimicrobial-treated biomedical materials is crucial to determine their biocompatibility and the potential onset of drug resistance. Methods: Real-time NMR measurements of extracellular metabolites produced by bacteria grown in the presence of known concentrations of an antibacterial molecule (irgasan) are employed to quantify the bactericidal molecule released from antimicrobial-treated biomedical devices. Viability tests assess their activity against E. coli and S. aureus planktonic and sessile cells. AFM and contact angle measurements assisted in the determination of the mechanism of antibacterial action. Results: NMR-derived concentration kinetics of metabolites produced by bacteria grown in contact with functionalized materials allows for indirectly evaluating the effective concentration of toxic substances released from the device, lowering the detection limit to the nanomolar range. NMR, AFM and contact angle measurements support a surface-killing mechanism of action against bacteria. Conclusions: The NMR based approach provides a reliable tool to estimate bactericidal molecule release from antimicrobial materials. General significance: The novelty of the proposed NMR-based strategy is that it i) exploits bacteria as sensors of the presence of bactericidal molecules in solution; ii) is independent of the chemo-physical properties of the analyte; iii) establishes the detection limit to nanomolar concentrations.

Shaping two-dimensional (2D) materials in arbitrarily complex geometries is a key to designing their unique physical properties in a controlled fashion. This is an elegant solution, taking benefit from the extreme flexibility of the 2D layers but requiring the ability to force their spatial arrangement from flat to curved geometries in a delicate balance among free-energy contributions from strain, slip-and-shear mechanisms, and adhesion to the substrate. Here, we report on a chemical vapor deposition approach, which takes advantage of the surfactant effects of organic molecules, namely the tetrapotassium salt of perylene-3,4,9,10-tetracarboxylic acid (PTAS), to conformally grow atomically thin layers of molybdenum disulphide (MoS2) on arbitrarily nanopatterned substrates. Using atomically resolved transmission electron microscope images and density functional theory calculations, we show that the most energetically favorable condition for the MoS2 layers consists of its adaptation to the local curvature of the patterned substrate through a shear-and-slip mechanism rather than strain accumulation. This conclusion also reveals that the perylene-based molecules have a role in promoting the adhesion of the layers onto the substrate, no matter the local-scale geometry.

The selective detection of metal ions in water, using sustainable detection systems, is of crescent importance for monitoring water environments and drinking water safety. One of the key elements of future chemical sciences is the use of sustainable approaches in the design of new materials. In this study, we design and synthesize a low-cost, water-soluble potassium salt of 3,4,9,10-perylene tetracarboxylic acid (PTAS), which shows a selective optical response on the addition of Cu2+ and Pb2+ ions in aqueous solutions. By using a water-soluble chromophore, the interactions with the metal ions are definitely more intimate and efficient, with respect to standard methods employing cosolvents. The detection limits of PTAS for both Cu2+ and Pb2+ are found to be 2 mu M by using a simple absorbance mode, and even lower (1 mu M) with NMR experiments, indicating that this analyte-probe system is sensitive enough for the detection of copper ions in drinking water and lead ions in waste water. The complexation of PTAS with both ions is supported with NMR studies, which reveal the formation of new species between PTAS and analytes. By combining a low-cost water-soluble chromophore with efficient analyte-probe interactions due to the use of aqueous solutions, the results here obtained provide a basis for designing sustainable sensing systems.

Polydopamine is a bioinspired multifunctional material that is emerging in the last years for applications in the biomedical, energy, environmental and catalytic fields. Whereas the conformal coating of solid objects by polydopamine is a well assessed process, the development of polydopamine thin films is less explored and their potential advantages have still to be fully unveiled. Herein, we describe a green and straightforward fabrication of composite membranes based on polydopamine thin films self-assembled at the air/water interface, and two different biopolymers, bacterial cellulose and silk fibroin. Furthermore, the abundant phenolic hydroxyl groups enable the in situ Au nanoparticle decoration on the polydopamine side, providing the membrane surface with plasmonic features. The surface patterning of polydopamine layers using self-assembled templating structures is also demonstrated, opening up new perspectives for biocompatible functional membranes with tunable optical and spectroscopic properties. Lastly, we demonstrate that the obtained functional surfaces are promising tools for the fabrication of SERS substrates. By bridging dopamine chemistry with natural biopolymers and 2D photonic crystals, the results obtained within this paper establish an excellent platform for designing 2D nanoarchitectures with multiple functions.

Polymer solar cells based on fullerene acceptors have reached in recent years power conversion efficiencies (PCEs) approaching 13%. The advent of non-fullerene acceptors (NFAs) with the advantages of synthetic versatility, a strong absorption ability and high thermal stability has resulted in impressive PCEs of over 18% in single junction devices. The insertion of interlayers between the active components and electrodes plays a key role in charge collection, boosts the efficiency and improves the device stability. However, the mechanisms regulating the interaction between interlayer materials and active layers based on NFAs are not yet completely rationalized. This review article summarizes organic, inorganic and hybrid materials used as anode and cathode interlayers in conventional and inverted fullerene-free solar cells. Particular attention is paid to the distinctive features of the interlayers when used in non-fullerene solar cells. We will also comment on the fabrication processes with an emphasis on the transition from small area, lab devices to large area modules and on possible mechanisms which are behind.

Polymer solar cells (PSCs) based on non-fullerene acceptors have the advantages of synthetic versatility, strong absorption ability, and high thermal stability. These characteristics result in impressive power conversion efficiency values, but to further push both the performance and the stability of PSCs, the insertion of appropriate interlayers in the device structure remains mandatory. Herein, a naphthalene diimide-based cathode interlayer (NDI-OH) is synthesized with a facile three-step reaction and used as a cathode interlayer for fullerene and non-fullerene PSCs. This cationic polyelectrolyte exhibited good solubility in alcohol solvents, transparency in the visible range, self-doping behavior, and good film forming ability. All these characteristics allowed the increase in the devices' power conversion efficiencies (PCE) both for fullerene and non-fullerene-based PSCs. The successful results make NDI-OH a promising cathode interlayer to apply in PSCs.

Silk fibroin is a biocompatible, non-toxic, mechanically robust protein, and it is commonly used and studied as a material for biomedical applications. Silk fibroin also gained particular interest as a drug carrier vehicle, and numerous silk formats have been investigated for this purpose. Herein, we have prepared electrospun nanofibers from pure silk fibroin and blended silk fibroin/casein, followed by the incorporation of an anti-inflammatory drug, diclofenac. Casein serves as an excipient in pharmaceutical products and has a positive effect on the gradual release of drugs. The characteristics of the investigated composites were estimated by scanning electron microscope, transmission electron microscope, thermogravimetric analysis, and a lifetime of diclofenac by electron paramagnetic resonance analysis. The cumulative release in vitro of diclofenac sodium salt, together with the antiproliferative effect of diclofenac sodium salt-loaded silk nanofibers against the growth of two cancer cell lines, are presented and discussed.

Large area molybdenum disulfide (MoS2) monolayers are typically obtained by using perylene-3,4,9,10-tetracarboxylic acid tetrapotassium salt (PTAS) as organic seeding promoter in chemical vapor deposition (CVD). However, the influence of the seeding promoter and the involvement of the functional groups attached to the seed molecules on the physical properties of the MoS(2)monolayer are rarely taken into account. Here, it is shown that MoS(2)monolayers exhibit remarkable differences in terms of the electronic polarizability by using two representative cases of seeding promoter, namely, the commercial PTAS and a home-made perylene-based molecule,N,N-bis-(5-guanidil-1-pentanoic acid)-perylene-3,4,9,10-tetracarboxylic acid diimide (PTARG). By thermogravimetric analysis, it is verified that the thermal degradation of the promoters occurs differently at the CVD working condition: with a single detachment of the functional groups for PTAS and with multiple thermal events for PTARG. As a consequence, the promoter-dependent electronic polarizability, derived by free charges trapped in the monolayer, impacts on the photoluminescence emission, as well as on the electrical performances of the monolayer channel in back-gated field-effect transistors. These findings suggest that the modification of the electronic polarizability, by varying the molecular promoter in a pre-growth stage, is a path to engineer the MoS(2)opto-electronic properties.

In the 2D material framework, molybdenum disulfide (MoS2) was originally studied as an archetypical transition metal dichalcogenide (TMD) material. The controlled synthesis of large-area and high-crystalline MoS2 remains a challenge for distinct practical applications from electronics to electrocatalysis. Among the proposed methods, chemical vapor deposition (CVD) is a promising way for synthesizing high-quality MoS2 from isolated domains to a continuous film because of its high flexibility. Herein, we report on a systematic study of the effects of growth pressure, temperature, time, and vertical height between the molybdenum trioxide (MoO3) source and the substrate during the CVD process that influence the morphology, domain size, and uniformity of thickness with controlled parameters over a large scale. The substrate was pretreated with perylene-3,4,9,10-tetracarboxylic acid tetrapotassium salt (PTAS) seed molecule that promoted the layer growth of MoS2. Further, we characterized the as-grown MoS2 morphologies, layer quality, and physical properties by employing scanning electron microscopy (SEM), Raman spectroscopy, and photoluminescence (PL). Our experimental findings demonstrate the effectiveness and versatility of the CVD approach to synthesize MoS2 for various target applications.

A new amphiphilic perylene dye bearing two carboxylic and two amidic chains (PDA-CA) has been synthesized and the ability to form pi-pi driven aggregates or folded structures has been investigated in aqueous or organic solvents at different concentrations, by means of NMR spectroscopy, theoretical calculations and optical characterization. The H-1 NMR data showed the coexistence of supramolecular aggregates due to a synergetic effect of pi-pi stacking, hydrogen bonding and hydrophobic/hydrophilic interactions. The ratio between these species has been evaluated by concentration- and temperature-dependent H-1 NMR experiments and also by the effect of aqueous or organic solvents. UV-Vis measurements are in agreement with NMR data evidencing the presence of more organized structures in organic solvents and aggregated species in aqueous solution. The pi-stacking ability and the role intermolecular hydrogen bonds in the formation of different aggregated structures, was also estimated by density functional theory.

The crystallization of a model semicrystalline polymer, namely, poly-3-hexylthiophene (P3HT), was studied as a function of the curvature at the nanometric scale and substrate surface free energy (SFE). Nanostructured substrates with a controlled local curvature were prepared by deposition of a 235 nm SiO2 particle monolayer, and their SFE was modulated by functionalization with octadecyltrichlorosilane, followed by radiofrequency plasma oxidation. The crystallization of ultrathin P3HT thin films, on the curved portions of the substrate, was found to mostly depend on the substrate SFE, while spontaneous wetting occurred in all cases. The effect is analyzed in terms of the interplay of polymer wetting (affecting the interfacial free energy) and lamellar crystallization, implying the modulation of crystallization enthalpy, demonstrating that the balance between SFE minimization and crystallization enthalpy maximization governs the phenomenon. The results highlight the role played by the surface nanostructuring in driving soft matter organization.

N-substitution in perylene diimide (PDI) n-type semiconductors is critical for their performance in organic bulk heterojunction solar cells. In this work we synthesized and compared three perylene diimide-spirobifluorene derivatives, N-substituted with different alkyl side groups. These molecular systems are obtained by cost effective methods, using straightforward synthetic procedures and easy purification. These PDI derivatives were used as electron acceptor materials, in blend with a benchmark quinoxaline-benzodithiophene based donor polymer, in bulk heterojunction solar cells. All devices were processed by blade coating in air, also using non-chlorinated solvents. The three molecules presented identical HOMO/LUMO energy levels, very similar optical properties but different photovoltaic responses. These different performances were discussed through optical, electrical and morphological characterizations. The highest power conversion efficiency was achieved for the active layer based on the derivative with branched and longer alkyl groups in N-positions, which favored a morphology with reduced donor:acceptor phase segregation.

Perylene diimide derivatives containing pendant cysteine residues are subjected to a strong self-assembly onto [1 1 1] Au films due to the presence of thiol functionality. The preparation of two different Au surfaces easies the understanding of both surface packing and morphology of the aggregated ordered films, by means of the combination of X-ray photoelectron spectroscopy, atomic force microscopy, and grazing incident wide X-ray scattering - synchrotron radiation - techniques. A proper correlation of the resulting data, together with conformational calculations - using a detailed molecular modeling - allow supplying a coherent scenario. In particular, isolated ordered pillars upstanding to the substrate plane are detected on native gold surface, while a ?-stacked aggregation "unregistered" normally to the film plane is observed when perylene derivatives are grafted onto thermally annealed gold surface. Such a surface organization is expected to be favorable to the charge mobility, therefore its use in organic field effect transistor is envisioned

Core substituted perylene diimides (PDIs), obtained by introducing various functional groups into the perylenic bay positions, are well known as versatile materials for optoelectronic applications. The substitution of the perylene core affords mono-, di-and tri-substituted derivatives, governed by the regioisomeric mixture of the 1,6-and 1,7-disubstituted PDIs. Most often, the disubstituted isomers are used as a mixture because of the difficulty in separating them by conventional methods or time-consuming crystallization processes. In this work, from the regioisomeric mixture of bis[(9,9'-dioctylfluorenyl)]-N, N'-bis(10-nonadecyl)-perylene-3,4,9,10-bis(dicarboximide), the 1,6-(PDI-F1) and 1,7-(PDI-F2) isomers have been easily isolated and separated by column chromatography and were subsequently characterized. The spectral features, electronic density distribution, and ground and excited state dipole moments of PDI-F1 have been examined and compared with those of PDI-F2. Several differences have been observed in the properties of the two PDI isomers. The PDI-F1 absorption spectrum shows a unique broad band spanning from 450 nm to 640 nm, while PDI-F2 exhibits the lowest energy absorption at 570 nm and a strong band at 420 nm. The absorption and emission properties in different solvents have evidenced that although both regioisomers show dipole moment values of the excited states higher than those of the corresponding ground states, the dipole moment variation upon excitation is different for each isomer. Cyclic voltammetry measurements revealed that PDI-F2 has a stronger electron accepting ability, as evidenced by lower reduction potentials. Complementary density functional theory calculations are also reported in order to rationalize their electronic and optical properties.

Polymeric nanoparticles obtained by co-aggregation of a polybenzofulvene derivative with bulky substituted perylene diimide dyes in tetrahydrofuran/water mixtures display emission color tunable from blue to red, or deep-red, thanks to energy transfer processes from the polymer to the emissive dyes activated by nanoparticle shrinking. At high water concentrations the presence of well emissive perylene diimide dye micro-aggregates within the polymer nanoparticles limits the FRET efficiency leading to a combined emission from both the polymer (blue) and the dyes (red and deep-red). The optical properties of the NPs are retained also in the solid state where a weak blue contribution of the polymer emission is observed providing multicolor emission in the films obtained by NPs deposition.

We present the design and the synthesis of substituted 2,2?-bithiophene derivatives to be used as ?-conjugated bridges in donor-?-acceptor molecules for dye sensitized solar cells. Using a combined theoretical and experimental approach, the photophysical and electrochemical properties of these linkers are also presented. Finally, we show that the photophysical properties (absorption/emission) of these molecules are preserved when doped in host matrices.

The ability of a pi-stacked polybenzofulvene derivative to self-assemble with emissive dyes in supramolecular organizations that reduce unwanted microaggregation processes is demonstrated by a study of the photophysical properties of its blends with benzothiadiazole and two perylenediimide derivatives. Films displaying efficient emissions with quantum yields of 0.85 in the yellow, 0.54 in the red, and 0.39 in the deep-red regions are obtained thanks to combined homo-and heteroresonant energy transfer processes from the polymer excimer-like p-stacked chromophores to the emitting dyes.Published by AIP Publishing.

The development of new materials plays a key role for the exploitation of the new technologies. One important class of emerging semiconducting materials is represented by conjugated polyelectrolytes (CPEs) comprising an electronically delocalized ?-conjugated backbone with pendant groups bearing polar or ionic functionalities. CPEs bring together the typical properties of polymeric semiconductors, such as easy processability, chemical tunability, lightness and flexibility with the growing demand for environmentally friendly materials. In fact, the incorporation of polar/ionic side groups increases the solubility in water and alcohols, which can potentially provide increased biocompatibility for sensor applications and more environmentally friendly manufacturing options. Moreover, the possibility for orthogonal solvent processability opens the way to all-solution-processed organic multilayer devices. Interfacial engineering has been identified recently as an essential approach for maximizing efficiency and stability of electronic devices. In this contest, the intrinsic hybrid characteristics of CPEs make them promising candidates for tuning the interface properties of inorganic materials too. We have recently shown that the insertion of a thin CPE film between active layer and cathode in organic electronic devices results in the energy level tuning at the CPE/metal interface, which is crucial for achieving a high-performance device, due to the formation of permanent dipoles . In this view, we have designed, synthesized and tested CPEs featuring a fluorene-based backbone with pendant phosphonate and/or amine groups and we have tested them in different types of devices. In particular by comparing the effect of CPEs on OLEDs and OPVs behavior, we focus on the influence of the electrical conditioning of the CPE layer on the device performance. The same class of CPEs, thanks to their conjugated backbone and ionic functionality have shown to remarkably enhance the pseudocapacitance of MXene-based hybrid 2D materials .