Aromatic Bis[aminomethylidenebis(phosphonic)] Acids Prevent Ovariectomy-Induced Bone Loss and Suppress Osteoclastogenesis in Mice

Osteoporosis is a skeletal disease associated with excessive bone turnover. Among the compounds with antiresorptive activity, nitrogen-containing bisphosphonates play the most important role in antiosteoporotic treatment. In previous studies, we obtained two aminomethylidenebisphosphonates—benzene-1,4-bis[aminomethylidene(bisphosphonic)] (WG12399C) acid and naphthalene-1,5-bis[aminomethylidene(bisphosphonic)] (WG12592A) acid—which showed a significant antiproliferative activity toward J774E macrophages, a model of osteoclast precursors. The aim of these studies was to evaluate the antiresorptive activity of these aminobisphosphonates in ovariectomized (OVX) Balb/c mice. The influence of WG12399C and WG12592A administration on bone microstructure and bone strength was studied. Intravenous injections of WG12399C and WG12592A bisphosphonates remarkably prevented OVX-induced bone loss; for example, they sustained bone mineral density at control levels and restored other bone parameters such as trabecular separation. This was accompanied by a remarkable reduction in the number of TRAP-positive cells in bone tissue. However, a significant improvement in the quality of bone structure did not correlate with a parallel increase in bone strength. In ex vivo studies, WG12399C and WG12592A remarkably bisphosphonates reduced osteoclastogenesis and partially inhibited the resorptive activity of mature osteoclasts. Our results show interesting biological activity of two aminobisphosphonates, which may be of interest in the context of antiresorptive therapy

Electron-to Hole Transport Change Induced by Solvent Vapor Annealing of Naphthalene Diimide Doped with Poly(3-Hexylthiophene)

Herein we report on fabrication and properties of organic field-effect transistors (OFETs) based on the spray-coated films of N,N′-dioctyl naphthalene diimide (NDIC8) doped with 2.4 wt% of poly (3-hexylthiophene) (P3HT). OFETs with the untreated NDIC8:P3HT films revealed electron conductivity [μe* = 5 × 10–4 cm2×(Vs)−1]. After the annealing in chloroform vapor the NDIC8:P3HT films revealed the hole transport only [μh* = 0.9 × 10–4 cm2×(Vs)−1]. Due to the chemical nature and energy levels, the hole transport was not expected for NDIC8-based system. Polarized optical- and scanning electron microscopies indicated that the solvent vapor annealing of the NDIC8:P3HT films caused a transition of their fine-grained morphology to the network of branched, dendritic crystallites. Grazing incidence wide-angle X-ray scattering studies indicated that the above transition was accompanied by a change in the crystal structure of NDIC8. The isotropic crystal structure of NDIC8 in the untreated film was identical to the known crystal structure of the bulk NDIC8. After the solvent annealing the crystal structure of NDIC8 changed to a not-yet-reported polymorph, that, unlike in the untreated film, was partially oriented with respect to the OFET substrate

Composition-Temperature Phase Diagrams and Crystal Growt in Solution-Crystallized Poly(3-hexylthiophene):N,N'-Alkylated Naphthtalene Diimide Blends

Architecture of alkyl substituents and π-π interactions between aromatic parts are the key factors governing self-assembly and crystallization of alkyl-bearing aromatic molecules or macromolecules [1,2]. It was demonstrated that interactions between alkyl chains of N-substituted aromatic diimide derivatives (ADI) and poly(3-hexylthiophene) (P3HT) may drive formation of different crystal structures in P3HT:ADI blends [3,4]. In this work we discuss in detail the influence of composition of P3HT:ADI blends and temperature on phase behavior and crystal growth in the blends.We focused here on the blends of P3HT with N,N’-alkylated naphthalene diimides (NDI). Crystal structure and morphology of the blends were studied by X-ray diffraction (XRD). In order to gain insight into phase transitions we used differential scanning calorimetry (DSC). These studies were supplemented with scanning electron microscopic (SEM) imaging to provide information about morphology of the blends. Results of our experiments indicated that packing of molecules in crystalline phases as well as phase transition temperatures were related to molecular architecture of NDI and compositions of the blends. Based on DSC and XRD data we have plotted the phase diagrams for the blends of P3HT with NDI. In all the P3HT:NDI blends melting (isotropisation) points forming the liquidus line depend on their composition. The liquidus lines in different blends reveal characteristic minima located at different P3HT-to-NDI ratios. These characteristic minima are referred to as pseudoeutectic points. Our study revealed that extending the alkyl chains of the NDI molecules caused a shift of the pseudoeutectic points towards the NDI component in the phase diagram (i.e. towards the NDI weght fraction = 1). At the pseudoeutectic composition of the P3HT:NDInC8 blend, we have observed additional transition occurring neither in pure P3HT nor pure NDI. Based on our diffraction data we attributed this point to the formation of new crystalline phase resulting probably from co-crystallization of P3HT and NDI molecules. References[1] J. P. Sun et al., Org. Electron., 2016, 35, 151.[2] S. Y. Son et al., J. Am. Chem. Soc., 2016, 138, 8096.[3] D. Chlebosz et al., Dyes and Pigments, 2017, 140, 491.[4] L. Bu et al., ACS Nano, 2015, 9, 1878.AcknowledgementThe work was supported by National Science Centre, Poland through the grant DEC-2016/22/E/ST5/00472. Variable-temperature and grazing-incidence XRD measurements were partly performed using the 10 keV beam at the BL9 beamline at DELTA synchrotron facility in Dortmund (Germany). The Authors thank Dr. Christian Sternemann for support during the experiments

Properties of Heterogeneous Materials for Organic Electronics: Crystal Structure and Phase Behavior of Thiophene-based Polymers-Aromatic Diimides Blends

Organic electronics has been attracting attention both from academic institutions and industry for more than two decades. That interest is due to the unique combination of inherent flexibility of some organic materials and their electronic properties. Such properties enable potential novel applications including e.g. wearable, deformable photovoltaic cells, diode-based lighting, epidermal human-health monitoring systems or artificial skin for robots to name just few.[1] Reaching these challenging horizons requires, however, solving fundamental problems in the field of materials science. Significant number of issues the field of organic electronics is related to the synthesis and processing of materials into the form that is useful in unit electronic devices. In the case of organic semiconductors, it is often a problem of fabrication of thin films. Therefore, conjugated polymers with their good film-forming properties, flexibility, mechanical stability and unique ability to transfer charge carriers, play an important role here.[2] The charge transport characteristics of conjugated polymers can be tuned by blending them with polyaromatic small molecules.[3,4] The conjugated polymer-small molecule binary blends may reveal improved apparent charge carrier mobility (in comparison to the corresponding pure polymers) or ambipolar charge carrier transport in thin-film based transistors.[4,5] Binary blends show also increased power conversion efficiency in photovoltaic cells.[6] There are three major sources that altered/enhanced electronic properties stem from. First: at the molecular level, it is the right match between the electronic band structure of the blend components. Second reason for the enhanced electronic properties of the blends is formation of the heterojunctions (interfaces between the components with unequal band gaps). And the third thing is the formation of percolation networks enabling effective transport of charge carriers through the volume of the film. Significant part of the binary organic semiconductors is based on conjugated polymers and crystalline small-molecular additives. Hence formation of the heterojunction and percolation network can be considered a problem of crystallization-driven phase separation in the blends. Since conjugated polymer-based films are typically fabricated by solution based techniques (like spin- or spray-coating, printing etc.) their formation can be considered a special case of solution crystallization. The time necessary for evaporation of solvent used for fabrication of the film is typically significantly shorter than the time necessary to form stable crystal structure of the components. Therefore the films are often subjected to additional solvent treatment (solvent-vapor annealing) and/or heat treatment in order to have them kinetically equilibrated. The processing procedures applied during and after fabrication of films cause changes in their crystal structure.[7] The altered crystal structure is the reason for changed electronic properties of the post-processed films. Despite, however, that correlation is rather intuitive, researchers pay little or no attention when choosing the parameters of the post-processing procedure – they are often arbitrary selection-based or random. Capturing generalized patterns of crystallization and crystal growth in the binary films should therefore facilitate engineering of properties of the binary blends used in organic electronics. Finding the patterns of properties requires, however, systematic studies on the binary blends.Based on the motivation above, we have performed a systematic study on the blends of poly(3-hexylthiophene) (P3HT) and variable ratios of either of five different polyaromatic diimides: N,N’-n-hexylated pyromellitic diimide (PIRnC6), N,N’-n-butyl-, N,N’-n-hexyl-, and N,N’-n-octyl naphthalene diimide (NDInC4, NDInC6, NDInC8 respectively) and N,N’-n-hexylated perylenediimide (PDInC6). Such blends were already reported for their unique electronic properties in thin-film field effect transistors and photovoltaic cells.[4,8] In our experimental approach we have analyzed bulk crystal structure of the blends and thin films deposited on silicon/silicon dioxide substrates – as in model electronic devices. The crystal structure of the blends was determined by X-ray diffraction (XRD). The XRD was also used to determine thermally-induced growth of crystal domains in the blends and also solvent-vapor-induced structure changes of the films. The latter was additionally studied by scanning electron microscopy. Combination of XRD and differential scanning calorimetry (DSC) enabled determination of the phase transition landscapes in the blends. Analysis of experimental results collected for over 30 different blends enabled correlating the crystal structure and the phase behavior of the blends with molecular structure of the blend components. These results were further compared with charge carrier mobility in the field-effect thin-film transistors based on the above blends. Generally, it was found that the phase transition points of the blends depend on their composition. The phase diagrams of all the blends featured the characteristic lowest melting (isotropisation) points resembling the eutectic point observed in some conventional binary alloys. Because of that similarity we called that point “pseudoeutectic”. The position of the pseudoeutectic points depended on the length of the alkyl chains of the blend and the size of the aromatic cores of the small molecular compound. Based on the analysis of the NDI series it was found that longer alkyl chains caused a shift of the pseudoeutectic points towards lower P3HT content in the blends. Comparison of the datasets for PIR, NDI and PDI-based compounds indicated that increasing the size of the aromatic core caused pseudoeutectic point to move towards the higher P3HT content. Morphological studies on the blends revealed that the pseudoeutectic behavior were related to physical sizes of the crystal domains formed directly after crystallization as well as to their Scherrer’s coherence lengths. Peak charge carrier mobilities were found following the trends for pseudoeutectic points – the mobilities were always the highest around the blend compositions for which pseudoeutectic points were found. Solvent-vapor annealing of the blend-based films caused changes in structure and morphology: a growth of the crystal domains, and also altered also their orientation. Such changes in structure caused non-trivial alterations in charge carrier mobility in the studied blends. In general, in this study we demonstrate how does molecular structure of the components affect crystal morphology and charge transport in homological series of blends based on P3HT and polyaromatic small molecules. Hence, from this perspective, this study can be considered a basis for designing properties of such blends. Acknowledgement This work was supported by the National Science Centre, Poland through the grant UMO-2016/22/E/ST5/00472. Variable-temperature- and grazing-incidence XRD measurements were partly performed using the 10 keV beam at the BL9 beamline at DELTA synchrotron facility in Dortmund (Germany). The Authors thank Dr. Christian Sternemann for support during the experiments at BL9. References[1] Xi, Z., et al., Organic Electronics for a Better Tomorrow:Innovation, Accessibility, Sustainability. A White Paper from the Chemical Sciences and Society Summit (CS3), 2012, 1, 1.[2] Guo, X. Müllen, K., Prog. Polym. Sci., 2013, 38, 1832.[3] Orgiu, E., et al., Chem. Comm., 2012, 48, 1562.[4] Puniredd, S.R., et al., J. Mater. Chem. C, 2013, 1, 2433.[5] Janasz, L., et al., J. Mater. Chem. C, 2018, 6, 7830.[6] Su, G.M., et al., J. Mater. Chem. A, 2014, 2, 1781.[7] Chlebosz, D., et al., Dyes Pigment., 2017, 140, 491.[8] He, Q., et al. Dyes Pigment. 2016, 128, 226

Monosubstituted Acetophenone Thiosemicarbazones as Potent Inhibitors of Tyrosinase: Synthesis, Inhibitory Studies, and Molecular Docking

A set of 12 monosubstituted acetophenone thiosemicarbazone derivatives (TSCs) were synthesized and their inhibitory properties toward tyrosinase activity were tested. Moreover, their ability to inhibit melanogenesis in the B16F10 murine melanoma cell line was studied. In order to investigate the nature of interactions between the enzyme and the inhibitors, molecular docking to the active site was performed. TSCs 5, 6, 8, and 9 revealed a half maximal inhibitory concentration (IC50) below 1 µM. Compound 6 turned out to be the most potent tyrosinase inhibitor. All investigated compounds showed reversible inhibition of competitive or mixed type. The para-substituted TSCs had higher affinity for the enzyme as compared to their ortho- and meta-analogues. All investigated compounds inhibited melanin production in B16F10 cells at the micromolar level. Molecular docking showed that the sulfur atom of the thiourea moiety penetrates the active site and interacts with copper ions. The above outcomes might be helpful in the design of new tyrosinase inhibitors in the food and cosmetic industries

Synthesis, Solution, and Solid State Properties of Homological Dialkylated Naphthalene Diimides—A Systematic Review of Molecules for Next-Generation Organic Electronics

This systematic study aimed at finding a correlation between molecular structure, solubility, self-assembly, and electronic properties of a homological series of N-alkylated naphthalene diimides (NDIs). NDIs are known for their n-type carrier mobility and, therefore, have potential in the field of organic electronics, photovoltaics, and sensors. For the purpose of this study, nine symmetrical N,N′-dialkylated naphthalene diimides (NDIC3-NDIC11) were synthesized in the reaction of 1,4,5,8-naphthalenetetracarboxylic dianhydride with alkylamines ranging from propyl- to undecyl-. The NDIs were characterized by spectroscopic (NMR, UV-Vis, FTIR), microscopic, and thermal methods (TGA and DSC), and X-ray diffraction (XRD). Our experimental study, extensively referring to findings reported in the literature, indicated that the NDIs revealed specific trends in spectroscopic and thermal properties as well as solubility and crystal morphology. The solubility in good solvents (chloroform, toluene, dichlorobenzene) was found to be the highest for the NDIs substituted with the medium-length alkyl chains (NDIC5–NDIC8). Systematic FTIR and XRD studies unraveled a distinct parity effect related to the packing of NDI molecules with odd or even numbers of methylene groups in the alkyl substituents. The NDIs with an even number of methylene groups in the alkyl substituents revealed low-symmetry (P1−) triclinic packing, whereas those with an odd number of carbon atoms were generally monoclinic with P21/c symmetry. The odd–even parity effect also manifested itself in the overlapping of the NDIs’ aromatic cores and, hence, the π-π stacking distance (dπ-π). The odd-numbered NDIs generally revealed slightly smaller dπ-π values then the even-numbered ones. Testing the NDIs using standardized field-effect transistors and unified procedures revealed that the n-type mobility in NDIC6, NDIC7, and NDIC8 was 10- to 30-fold higher than for the NDIs with shorter or longer alkyl substituents. Our experimental results indicate that N,N′-alkylated NDIs reveal an optimum range of alkyl chain length in terms of solution processability and charge transport properties

Monosubstituted Acetophenone Thiosemicarbazones as Potent Inhibitors of Tyrosinase: Synthesis, Inhibitory Studies, and Molecular Docking

A set of 12 monosubstituted acetophenone thiosemicarbazone derivatives (TSCs) were synthesized and their inhibitory properties toward tyrosinase activity were tested. Moreover, their ability to inhibit melanogenesis in the B16F10 murine melanoma cell line was studied. In order to investigate the nature of interactions between the enzyme and the inhibitors, molecular docking to the active site was performed. TSCs 5, 6, 8, and 9 revealed a half maximal inhibitory concentration (IC50) below 1 µM. Compound 6 turned out to be the most potent tyrosinase inhibitor. All investigated compounds showed reversible inhibition of competitive or mixed type. The para-substituted TSCs had higher affinity for the enzyme as compared to their ortho- and meta-analogues. All investigated compounds inhibited melanin production in B16F10 cells at the micromolar level. Molecular docking showed that the sulfur atom of the thiourea moiety penetrates the active site and interacts with copper ions. The above outcomes might be helpful in the design of new tyrosinase inhibitors in the food and cosmetic industries

Phase Diagrams of poly(3-hexylthiophene):N,N’-alkyl Substituted Naphthalene Diimides Blends

Fabrication of electronic devices based on organic semiconductors at the fundamental level can be considered a problem of engineering of polycrystalline materials. Tuning the charge transport properties in such materials requires controlling of size, perfection, distribution, and orientation of crystalline domains in the semiconducting films1. Those parameters can be controlled through film formation and post-processing conditions, such as thermal annealing. While the casting parameters (solvent, temperature etc.) exert an influence on the primary crystallization and formation of polycrystalline system, the annealing induces the further growth of crystalline domains, increases perfection of crystal packing but may also trigger phase transitions of the ordered phases crystallized from solution2. Insufficient insight into the processes occurring upon the annealing may lead to erroneous conclusions related to properties - especially when samples reveal a complex phase behavior like the one observed in the case of aromatic, conjugated molecules or polymers. These materials may show multiple packings in crystalline phases as well as multiple thermally-induced transitions between crystalline and liquid crystalline phases before reaching the isotropic state3. Different packing of molecules and hence different geometrical overlap of aromatic moieties may affect charge transport properties4. Thus in our research we concentrated on relationships between packing of molecules in the ordered domains and electronic properties of materials.The study was focused on the blends of poly(3-hexylthiophene) (P3HT) with butyl- or hexyl- or octyl-substituted naphthalene diimides (NDI). In our experimental approach we have applied differential scanning calorimetry (DSC) to determine phase transition points and X-ray diffraction (XRD) to gain insights into the structure of molecular assemblies in the system. These studies were supplemented with images from scanning electron microscopy (SEM) providing information about the morphology of the blends. In order to correlate the structure and morphology with charge transport properties, the blends were tested in organic field effect transistors (OFETs).Results of our experiments indicated that packing of molecules in crystalline phases and mesophases as well as phase transition temperatures were related to molecular architecture of NDI and compositions of the blends. XRD and DSC data were used to determine phase diagrams for the blends of P3HT with NDI. It was found that decreasing content of NDI in the blends caused a notable decrease of the isotropization temperature of the NDI component. The melting point of P3HT also significantly drops as its content in the blend decreases. The profile of the isotropization points of the P3HT:NDI blends plotted as a function of composition reveals a clear minimum resembling the eutectic point. In some of the blends, we observed additional transitions that may suggest formation of new crystalline phases occurring neither in pure P3HT nor pure NDI. The studies of the blends by means of scanning electron microscopy indicated that compositions of the blends also exerted an influence on the crystalline morphology. The studies electronic properties in the model field-effect transistors (OFETs) revealed that the blends with the uniform, fine-grained polycrystalline morphologies enable balanced ambipolar charge carrier transport. This, once again, indicates that the fine tuning of the blends composition is crucial for engineering of organic electronic devices.References[1] Brady M. A. et al., Soft Matter, 7, 11065 (2011)[2] Chlebosz D. et al., Dyes and Pigments, 140, 491 (2017)[3] Yuan Y. et al., Polymer, 105, 88 (2016)[4] Kakinuma T. el al., Journal of Materials Chemistry C, 1, 5395 (2013