An iodine-BODIPY-carbazole multidye was found to be effective against human breast cancer cells (cell viability of 85%) at low doses when irradiated with green light from an LED in a photodynamic therapy process.

CdS QDs were synthesized by using (3-mercaptopropyl)trimethoxysilane (MPS) as ligand to form CdS(MPS) and mixed with an amphiphilic p(phenyleneethynylene) copolymer, coPE, which presents alternating p(phenyl-eneethynylene) moieties bearing dodecanoxy and 1-OH undecanoate lateral chains, at different pHs. SS NMR and XPS spectroscopy confirmed the functionalization of CdS(MPS) with coPE at pH 5.5 to yield an inorga-nic-organic hybrid, CdS(MPS)-coPE but they also revealed hydrolysis and successive polymerization of the silane group of MPS, which leads to spherical superstructures, as found by STEM. STEM tomography confirms the 3D nature of the superstructures and demonstrates that they are stable under high vacuum conditions. AFM revealed that they are preserved even in spun films, which tunes the fluorescence from yellow (copolymer) to green (hybrid). This peculiar supramolecular behavior could be profited for host-guest white light emission or biosensing.

Functionalization of nanoparticles with specific ligands is helpful to control specific diagnostic and therapeutic responses such as protein adsorption, cell targeting, and circulation. Precision delivery critically depends on a fundamental understanding of the interplay between surface chemistry, ligand dynamics, and interaction with the biochemical environment. Due to limited atomic-scale insights into the structure and dynamics of nanoparticle-bound ligands from experiments, relationships of grafting density and ligand chemistry to observable properties such as hydrophilicity and protein interactions remain largely unknown. In this work, we uncover how self-assembled monolayers (SAMs) composed of multisegment ligands such as thioalkyl-PEG-(N-alkyl)amides on gold nanoparticles can mimic mixed hydrophobic and hydrophilic ligand coatings, including control of patterns, hydrophilicity, and specific recognition properties. Our results are derived from molecular dynamics simulations with the INTERFACE-CHARMM36 force field at picometer resolution and comparisons to experiments. Small changes in ligand hydrophobicity, via adjusting the length of the N-terminal alkyl groups, tune water penetration by multiples and control superficial ordering of alkyl chains from 0 to 70% regularity. Further parameters include the grafting density of the ligands, curvature of the nanoparticle surfaces, type of solvent, and overall ligand length, which were examined in detail. We explain the thermodynamic origin of the formation of heterogeneous patterns of multisegment ligand SAMs and illustrate how different degrees of ligand order on the nanoparticle surface affect interactions with bovine serum albumin. The resulting design principles can be applied to a variety of ligand chemistries to customize the behavior of functionalized nanoparticles in biological media and enhance therapeutic efficiency.

CdS QDs were synthesized by using (3-mercaptopropyl)trimethoxysilane (MPS) as ligand to form CdS(MPS) and mixed with an amphiphilic p(phenyleneethynylene) copolymer, co PE , which presents alternating p(phenyleneethynylene) moieties bearing dodecanoxy and 1-OH undecanoate lateral chains, at different pHs. SSNMR and XPS spectroscopy confirmed the functionalization of CdS(MPS) with co PE at pH 5.5 to yield an inorganic-organic hybrid, CdS(MPS)- co PE but they also revealed hydrolysis and successive polymerization of the silane group of MPS, which leads to spherical superstructures, as found by STEM. STEM tomography confirms the 3D nature of the superstructures and demonstrates that they are stable under high vacuum conditions, AFM revealed that they are preserved even in spun films, which tunes the fluorescence from yellow (copolymer) to green (hybrid). This peculiar supramolecular behavior could be profited for host-guest white light emission or biosensing.

We report on the optoelectronic properties of a series of unsymmetrical π-conjugated phenyleneethynylene macromolecules bearing ferrocene (Fc) as the electron-donor group (D), (benzyl) benzoate (Bz) or benzoic acid (Ac) as the electron attractor group (A) and connected through 2,5-di(alcoxy) phenyleneethynylene(s) (nPE) with n = 1, 2, 3 as π-conjugated bridges. In the series, by increasing the distance between the electron-attracting and electron-donor groups, the push-pull effect decreases. The intramolecular charge transfer (D → π → A) was evaluated by static and dynamic spectroscopy, electrochemistry, and density functional theory (DFT) theoretical calculations. The longest oligomer Fc3PEBz formed the best optical quality films. A study at the atomic level by scanning tunneling microscopy (STM) revealed that the molecules self-assemble on highly ordered pyrolytic graphite (HOPG) in domains with a short-range order. Films are mesoporous and the molecules arrange in a lamellar-like pattern, with an edge-on conformation with respect to HOPG, where the conjugated backbones lie parallel to the surface. Two different assemblies were identified in the monoatomic film, which depends on the ferrocene-ferrocene or benzyl-benzyl interactions.

Supported Lipid Bilayers (SLBs) on Polyelectrolyte Multilayers (PEMs) have large potential as models for developing sensor devices. SLBs can be designed with receptors and channels, which benefit from the biological environment of the lipid layers, to create a sensing interface for ions and biomarkers. PEMs assembled by the Layer-by-Layer (LBL) technique and used as supports for a lipid bilayer enable an easy integration of the bilayer on almost any surface and device. For electrochemical sensors, LBL assembly enables nanoscale tunable separation of the lipid bilayer from the electrode surface, avoiding undesired effects of the electrode surface on the lipid bilayers. We study the fabrication of valinomycin-doped SLBs on PEMs as a model system for biophysical studies and for selective ion sensing. SLBs are fabricated from dioleoylphosphatidylcholine (DOPC) and dioleoylphosphatidylserine (DOPS) 50:50 vesicles doped with valinomycin, as a K+-selective carrier. SLBs were deposited on electrodes coated with poly(allyl amine hydrochloride) (PAH) and poly(styrene sodium sulfonate) (PSS) multilayers. Lipid bilayer formation was monitored by using Quartz Crystal Microbalance with Dissipation (QCMD) technique and Atomic Force Microscopy (AFM). Electrochemical impedance spectroscopy (EIS) and potentiometric measurements were performed to assess K+ selectivity over other ions and the potential of valinomycin-doped SLBs for K+-sensing.

Thin films of a series of symmetrical 2,5-bis(dodecanoxy)phenyleneethynylenes, bearing a butadiyne central group and 4, 6 and 8 phenyleneethynylene moieties, were prepared by spin coating. In general, narrower and red shifted peaks are observed in both absorption and emission spectra with respect to the solutions previously reported, however, the fluorescence quantum yield was quenched. All of these features are explained with the planarization of the conjugated chain, and intra/intermolecular interactions, as supported by spectroscopic aggregation studies and by atomic STM and microscopic AFM characterization. By cathodoluminescence spectroscopy, hot charged states are found that may also affect the fluorescence and electroluminescence properties. From the series, the latter were studied for the hexamer 6DAc for which an oLED with configuration ITO/ PEDOT:PSS/6DAc/Al was constructed in ambient conditions, giving a threshold voltage of 11 V and quantum yield of 0.031 ph/e%, of the same order of other phenyleneethynylenes or phenylenebutadyines devices.

We report on the scanning tunneling microscopy and small-wide angle X-ray scattering and diffraction of four linear and rigid pi-conjugated p-phenyleneethynylene (PPE) oligomers. The four compounds possess two dode-canoxy side chains on the central PPE moiety, differ in conjugated length (3 and 5 phenyleneethynylene moieties) and are benzyl, Bz3PEBz, Bz5PEBz, or carboxylic acid, Ac3PEAc, Ac5PEAc, end-capped. We found that in the benzylbenzoate terminated oligomers, a staggered arrangement of molecules is obtained endorsed by the pi-pi interaction between the benzyls. In contrast, for the carboxylic acid terminated oligomers, a rather linear type arrangement is promoted by the hydrogen bond created between the carboxylic acid groups. In general, all of the molecules form a lamellar like pattern adopting face-on arrangements, where the conjugated backbones are flat-lying on the HOPG surface. The lamella length corresponds to the oligomer conjugation length, while within the lamellae, the calculated distances correspond to the spacing between conjugated backbones with an average value of 2.06 nm, consistent with that found by XRD, SAXS and DFT/def-SVP for the oligomers that self-assemble with the lateral alkyl chains interdigitated. The lack of more dodecanoxy side chains on the rest of the phe-neyleneethynylene moieties gives rise to mesoporous type self-assembled monolayers on HOPG.

The fabrication, molecular structure, and spectroscopy of a stable cholesteric liquid crystal platinum acetylide glass obtained from trans-Pt(PEt3)2(C≡C-C6H5-C≡N)(C≡C-C6H5-COO-Cholesterol), are described and designated as PE1-CN-Chol. Polarized optical microscopy, differential scanning calorimetry, and wide-angle X-ray scattering experiments show room temperature glassy/crystalline texture with crystal formation upon heating to 165 °C. Further heating results in conversion to cholesteric phase. Cooling to room temperature leads to the formation of a cholesteric liquid crystal glass. Scanning tunneling microscopy of a PE1-CN-Chol monolayer reveals self-assembly at the solid-liquid interface with an array of two molecules arranged in pairs, oriented head-to-head through the CN groups, giving rise to a lamella arrangement. The lamella structure obtained from molecular dynamics calculations shows a clear phase separation between the conjugated platinum acetylide and the hydrophobic cholesterol moiety with the lamellae separation distance being 4.0 nm. Ultrafast transient absorption and flash photolysis spectra of the glass show intersystem crossing to the triplet state occurring within 100 ps following excitation. The triplet decay time of the film compared to aerated and deoxygenated solutions is consistent with oxygen quenching at the film surface but not within the film. The high chromophore concentration, high glass thermal stability, and long triplet lifetime in air show that these materials have potential as nonlinear absorbing materials.

Two series of 2,5-di(butoxy)phenyleneethynylenes, one halogenated (nPEC4-X; n=2, 3, or 4) and the other boron-dipyrromethene (BODIPY) terminated (nPEC4-By; n=3, 4, or 5; By=BODIPY), were synthesized monodirectionally by the step-by-step approach and the molecular structure was corroborated by NMR spectroscopy (H-1, C-13-DEPTQ-135, COSY, HSQC, HMBC, B-11, F-19) and MALDI-TOF mass spectrometry. The multiplicity and J-coupling constants of H-1, B-11, and F-19/B-11 NMR signals revealed, in the nPEC4-By series, that the phenyl in the meso position of BODIPY becomes electronically part of the conjugation of the phenyleneethynylene chain, whereas BODIPY is electronically isolated. The photophysical, electrochemical, and theoretical studies confirm this finding because the properties of nPEC4-By are comparable to those of the nPEC4-X oligomers and BODIPY, indicating negligible electron communication between BODIPY and the nPEC4 moieties. Nevertheless, energy transfer (ET) from nPEC4 to BODIPY was rationalized by spectroscopy and theoretical calculations. Its yield decreases with the nPEC4 conjugation length, according to the increase in distance between the two chromophores, resulting in dual emission for the longest oligomer in which ET is quenched.

The staining of agrobacteria was successfully demonstrated through a benzoateethynylene by fluorescence spectroscopy, laser confocal microscopy and microRaman.

Covalent grafting of nylon-6 (Ny-6) and pristine multi-walled carbon nanotubes (MWCNT-P) was performed in-situ via microwave assist polymerization (MAP) of epsilon-caprolactam and 6-aminocaproic acid at different power and time conditions. The results showed that the microwave dielectric heating of the MWCNT-P activates the nanotube vacancies to react with the amine group of 6-aminocaproic acid at 175 degrees C. When the reaction temperature reaches 230 degrees C, Ny-6 polymerization ensues, simultaneously, with insertion of Ny-6 chains on the amine-activated MWCNT to obtain a nanohybrid, MWCNT-Ny, with a grafted Ny-6 coating of 14 nm. The hybridization reaction therein affects the entire polymerization process and the molecular weight and yield of both the hybrid and Ny-6. Raman, XPS and electrical conductivity data for the MWCNT-Ny films show that the nanotube structure remains intact in the films which display an electrical surface conductivity range of 0.47-0.06 S/m. The compatibility and dispersion of the MWCNT-Ny nanohybrid in Ny-6, as observed by crystallization and fusion of the so-formed hybrid polymer nanocomposite, HPNC, exceed those obtained by conventional methods of preparation using ultrasound and functionalized nanotubes.

Few if any reports exist that elucidate the phenomena that take place in the microwave-assist polymerization (MAP) of heterogeneous multi-component systems to form polymer nanohybrid composites. We elucidate the four distinct steps that take place during the in-situ MAP of Nylon-6 from epsilon-caprolactam and 6-aminocaproic in the presence of graphite oxide (GrO), which results in the formation of a reduced graphene oxide Nylon-6 nanohybrid in a one-step synthesis; exfoliation, reduction take place in <60 s; polymerization occurs after 60 s; hybridization during both periods. An increase in molecular weight and conversion of non-grafted Nylon-6 during hybridization takes place unlike in conventional in-situ polymerizations of Nylon-6/GrO where reduction of the MW is observed. It is also shown for the first time that the crystallization of grafted Nylon-6 in the hybrid exists in both a and y phases. The grafted molecules represent 50 wt % of the hybrid. (C) 2018 Elsevier Ltd. All rights reserved.

Change of the permanent molecular electric dipole moment, Δμ, in a series of nominally centrosymmetric and noncentrosymmteric ferrocene-phenyleneethynylene oligomers was estimated by measuring the two-photon absorption cross-section spectra of the lower energy metal-to-ligand charge-transfer transitions using femtosecond nonlinear transmission method and was found to vary in the range up to 12 D, with the highest value corresponding to the most nonsymmetric system. Calculations of the Δμ performed by the TD-DFT method show quantitative agreement with the experimental values and reveal that facile rotation of the ferrocene moieties relative to the organic ligand breaks the ground-state inversion symmetry in the nominally symmetric structures.

A series of fulleropyrrolidines-conjugatedbridge- ferrocene or triazene oligomers were selectively synthesized by the Sonogashira reaction by applying the step-by-step approach. The bridge is constituted by 1, 2 and 3 benzoateethynylene units ( BzE) and bears triazene ( Et2N3) or ferrocene as terminal groups affording the C60-2PEN(3) and C60-3PEN(3) dyads and C60-1PEFe, C60-2PEFe and C60-3PEFe triads. DQF-COSY, HETCOR, H-1 and C-13 NMR and the MALDI-TOF characterization clearly confirmed the expected molecular structure. The absorption spectra of the fulleropyrrolidine oligomers do not match the sum of the individual spectra: N-methylfulleropyrrolidine (NMF) and BzEs, suggesting electronic interaction between the two moieties in the ground state. The fluorescence of the BzE is strongly quenched after functionalization with NMF, which could be indicative of energy or electron transfer from the triazene or ferrocene as electron donor to the fulleropyrrolidine electron acceptor through the p-bridge. The latter process was confirmed by cyclic voltammetry. The strength of the electron-accepting group gets to increase anodically the oxidation potential, or decrease cathodically the reduction potential in the order C60-pyrrolidine > benzoate. The character of the HOMO in the series is defined by the electron-donating ferrocene or triazene moiety, whereas the character of the LUMO is mainly determined by the electron-accepting group and is further supported by theoretical calculations. Photovoltaic devices presented low efficiencies, due to the absorption range of the oligomers being out of the maximum solar irradiance and the inhomogeneous organization in the films. (C) 2018 Elsevier B.V. All rights reserved.

Use of multi-wall carbon nanotubes (MWCNTs) in external layers (A-layers) of ABA-trilayer polypropylene films was investigated, with the purpose of determining intrinsic and extrinsic factors that could lead to antistatic behavior of transparent films. The incorporation of 0.01, 0.1, and 1 wt % of MWCTNs in the A-layers was done by dilution through the masterbatch method. Masterbatches were fabricated using isotactic polypropylene (iPP) with different melt flow indexes 2.5, 34, and 1200 g/10 min, and using different ultrasound assist methods. It was found that films containing MWCNTs show surface electrical resistivity of 1012 and 1016 Ω/sq, regardless of the iPP melt flow index (MFI) and masterbatch fabrication method. However, electrostatic charge was found to depend upon the iPP MFI, the ultrasound assist method and MWCNT concentration. A percolation electron transport mechanism was determined most likely responsible for this behavior. Optical properties for films containing MWCNTs do not show significant differences compared to the reference film at MWCNT concentrations below 0.1 wt %. However, an enhancement in brightness was observed, and it was attributed to ordered iPP molecules wrapping the MWCNTs. Bright transparent films with low electrostatic charge were obtained even for MWCNTs concentrations as low as 0.01 wt %.

Ronald F. Ziolo, Webster, N.Y. Xerox Corporation, Stamford, Conn. Inventor: Assignee: Appl. No.: 536,806 Filed: Sep. 28, 1983 Int. Cl........................... G03G 9/14; G03G 9/08 U.S. Cl. ................................. 430/106.6; 430/137; 430/903; 430/126; 252/62.54; 252/62.56 Field of Search ..................... 430/106.6, 109, 110, 430/903, 137; 252/62.54, 62.56 References Cited U.S. PATENT DOCUMENTS

Resistant and efficient electrocatalysts for hydrogen evolution reaction (HER) are desired to replace scarce and commercially expensive platinum electrodes. Thin-film electrodes of metal carbides are a promising alternative due to their reduced price and similar catalytic properties. However, most of the studied structures neglect long-lasting chemical and structural stability, focusing only on electrochemical efficiency. Herein we report on a new approach to easily deposit and control the micro/nanostructure of thin-film electrodes based on niobium carbide (NbC) and their electrocatalytic response. We will show that, by improving the mechanical properties of the NbC electrodes, microstructure and mechanical resilience can be obtained while maintaining high electrocatalytic response. We also address the influence of other parameters such as conductivity and chemical composition on the overall performance of the thin-film electrodes. Finally, we show that nanocomposite NbC electrodes are promising candidates toward HER and, furthermore, that the methodology presented here is suitable to produce other transition-metal carbides with improved catalytic and mechanical properties.

The impact of polyanions on the formation of lipid bilayers on top of polyelectrolyte multilayers (PEMs) with poly(allylamine hydrochloride) (PAH) as the top layer is studied for the deposition of vesicles of mixed lipid composition, 50:50 molar ratio of zwitterionic 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) and negatively charged 1,2-dioleoyl-sn-glycero-3-phospho-l-serine (DOPS). PEMs are assembled with polystyrene sulfonate (PSS), poly(acrylic acid) (PAA), and alginic acid sodium salt (Alg) as polyanions. The assembly of the vesicles on the PEMs is followed by means of the quartz crystal microbalance with dissipation. Fluorescence recovery after photobleaching measurements are applied to evaluate bilayer formation. Whereas a bilayer is formed on top of PAH/PSS multilayers, the vesicles are adsorbed on top of PAH/Alg and PAH/PAA multilayers, remaining unruptured or only partially fused. The influence of the surface composition of the PEM and of the bulk properties of the film are analyzed. The phosphate ions present in phosphate-buffered saline (PBS) play a fundamental role in bilayer formation on top of PAH/PSS as they complex with PAH and render the surface potential close to zero. For PAH/PAA and PAH/Alg, PBS renders the surface negative. X-ray photoelectron spectroscopy shows that the dibasic phosphate ions from PBS complex preferentially with PAH in PAH/PAA and PAH/Alg multilayers, whereas monobasic phosphates complex with PAH in PAH/PSS. An explanation for the absence of bilayer formation on PAH/PAA and PAH/Alg is given on the basis of the different affinities of phosphate ions for PAH in combination with the different polyanions.