Olga Guselnikova

Preparation and X-ray Structural Study of Dibenziodolium Derivatives

New experimental procedures for the preparation of dibenziodolium salts by oxidative cyclization of 2-iodobiphenyl in the presence of appropriate strong acids are described. Particularly useful is a convenient one-pot synthesis of dibenziodolium hydrogen sulfate from 2-iodobiphenyl using Oxone as an inexpensive and environmentally safe oxidant. Dibenziodolium hydrogen sulfate, bis(triflyl)imidate, or triflate can be readily converted to various other dibenziodolium derivatives (chloride, bromide, thiocyanate, azide, cyanide, phenylsulfinate) by anion exchange. Structures of key products have been established by single-crystal X-ray diffraction analysis. Particularly interesting is the X-ray structure of dibenziodolium thiocyanate, which represents the first example of a structurally characterized hypervalent iodine compound with a relatively short iodine-sulfur secondary bond distance.

The convenient preparation of stable aryl-coated zerovalent iron nanoparticles.

Summary A novel approach for the in situ synthesis of zerovalent aryl-coated iron nanoparticles (NPs) based on diazonium salt chemistry is proposed. Surface-modified zerovalent iron NPs (ZVI NPs) were prepared by simple chemical reduction of iron(III) chloride aqueous solution followed by in situ modification using water soluble arenediazonium tosylate. The resulting NPs, with average iron core diameter of 21 nm, were coated with a 10 nm thick organic layer to provide long-term protection in air for the highly reactive zerovalent iron core up to 180 °C. The surface-modified iron NPs possess a high grafting density of the aryl group on the NPs surface of 1.23 mmol/g. FTIR spectroscopy, XRD, HRTEM, TGA/DTA, and elemental analysis were performed in order to characterize the resulting material.

Organic-inorganic hybrid nanoparticles controlled delivery system for anticancer drugs

The use of organic-inorganic hybrid nanocarriers for controlled release of anticancer drugs has been gained a great interest, in particular, to improve the selectivity and efficacy of the drugs. In this study, iron oxide nanoparticles were prepared then surface modified via diazonium chemistry and coated with chitosan, and its derivative chitosan-grafted polylactic acid. The purpose was to increase the stability of the nanoparticles in physiological solution, heighten drug-loading capacity, prolong the release, reduce the initial burst effect and improve in vitro cytotoxicity of the model drug doxorubicin. The materials were characterized by DLS, ζ-potential, SEM, TGA, magnetization curves and release kinetics studies. Results confirmed the spherical shape, the presence of the coat and the advantages of using chitosan, particularly its amphiphilic derivative, as a coating agent, thereby surpassing the qualities of simple iron oxide nanoparticles. The coated nanoparticles exhibited great stability and high encapsulation efficiency for doxorubicin, at over 500μg per mg of carrier. Moreover, the intensity of the initial burst was clearly diminished after coating, hence represents an advantage of using the hybrid system over simple iron oxide nanoparticles. Cytotoxicity studies demonstrate the increase in cytotoxicity of doxorubicin when loaded in nanoparticles, indirectly proving the role played by the carrier and its surface properties in cell uptake.

Synthesis, Characterization, and Antimicrobial Activity of Near-IR Photoactive Functionalized Gold Multibranched Nanoparticles

Abstract Surface‐modified gold multibranched nanoparticles (AuMs) were prepared by simple chemical reduction of gold chloride aqueous solution followed by in situ modification by using water‐soluble arenediazonium tosylates with different functional organic groups. Chemical and morphological structures of the prepared nanoparticles were examined by using transmission electron and scanning electron microscopies. The covalent grafting of organic compounds was confirmed by scanning electron microscopy with energy dispersive X‐ray spectroscopy (SEM‐EDX) and Raman spectroscopy techniques. Covalent functionalization of nanoparticles significantly expands the range of their potential uses under physiological conditions, compared with traditional non‐covalent or thiol‐based approaches. The antibacterial effect of the surface‐modified AuMs was evaluated by using Escherichia coli and Staphylococcus epidermidis bacteria under IR light illumination and without external triggering. Strong plasmon resonance on the AuMs cups leads to significant reduction of the light power needed kill bacteria under the mild conditions of continuous illumination. The effect of the surface‐modified AuMs on the light‐induced antibacterial activities was founded to be dependent on the grafted organic functional groups.

Reversible switching of PEDOT:PSS conductivity in the dielectric–conductive range through the redistribution of light-governing polymers

One of the biggest challenges in the field of organic electronics is the creation of flexible, stretchable, and biofavorable materials. Here the simple and repeatable method for reversible writing/erasing of arbitrary conductive pattern in conductive polymer thin film is proposed. The copolymer azo-modified poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) was synthesized to achieve reversible photo-induced local electrical switching in the insulator–semimetal range. The photoisomerization of the polymer was induced by grafting nitrobenzenediazonium tosylate to the PSS main chains. While the as-deposited PEDOT:PSS thin films showed good conductivity, the modification procedure generated polymer redistribution, resulting in an island-like PEDOT distribution and the loss of conductivity. Further local illumination (430 nm) led to the azo-isomerization redistribution of the polymer chains and the creation of a conductive pattern in the insulating polymer film. The created pattern could then be erased by illumination at a second wavelength (470 nm), which was attributed to induction of reverse azo-isomerization. In this way, the reversible writing/erasing of arbitrary conductive patterns in thin polymer films was realized.

Vapor Annealing and Colloid Lithography: An Effective Tool To Control Spatial Resolution of Surface Modification

Colloid lithography represents a simple and efficient method for creation of a large-scale template for subsequent surface patterning, deposition of regular metal nanostructures, or periodical surface structures. However, this method is significantly restricted by its ability to create only a limited number of structures with confined geometry and symmetry features. To overcome this limitation, different techniques, such as plasma treatment or tilting angle metal deposition, have been proposed. In this paper, an alternative method based on the vapor annealing of ordered single polystyrene (PS) microspheres layer, followed by the surface grafting with arenediazonium tosylates is proposed. Application of vapor treatment before surface grafting allows effective control of the area screened by PS microspheres. Pristine and vapor-annealed microsphere arrays on the gold substrate were electrochemically modified using ADTs. Subsequent removal of the PS microsphere mask enabled to prepare well-defined nanostructures with controllable surface features. In particular, prepared periodic arrangements were achieved by the grafting of OFGs to the empty interspaces between nanopore arrays. The process of sample preparation was controlled, and the properties of prepared structures were characterized by various techniques, including atomic force microscopy (AFM), conductive AFM, scanning electron microscopy energy-dispersive X-ray spectrometry, Raman spectroscopy, and voltammetry.

Smart, Piezo-Responsive Polyvinylidenefluoride/Polymethylmethacrylate Surface with Triggerable Water/Oil Wettability and Adhesion

The design of smart surfaces with externally triggerable water/oil wettability and adhesion represents one of the most up-to-date challenges in the field of material science. In this work, the intelligent surface with electrically triggerable wettability and water/oil adhesion is presented. As a basic material background exhibiting electric field (EF) sensitivity, the piezo-responsive polymethylmethacrylate/polyvinylidenefluoride polymer fibers were used. To expand the available range of water/oil contact angles (CAs) and adhesion, the fibers were grafted with hydrophilic or hydrophobic functional groups using diazonium chemistry. The fiber functionality was evaluated using the static CA and wettability hysteresis measurements (increasing/decreasing drop volume and tilting angles), drops adhesion/repellence and graphite self-cleaning test performed with and without the application of EF. It was found that the proposed method enables tuning the surface wettability in the superhydrophobic/superoleophobic-hydrophilic/oleophilic range and changing of surface properties from low adhesive to high adhesive for water and oil. More convincing results were achieved in the case of fiber surface modification by ADT-C8F17, which may result from a rearrangement of the grated -C6H4C8F17 functional group under the application of EF triggering. Moreover, the triggering which can be performed in the extremely fast way (the surface responds to the EF switching on/off in seconds) was found to be fully reversible. Finally, the additional tests indicate the satisfactory stability of created fiber-based coating against the mechanical treatment.