One-Step Synthesis of Functional Sulfonated Polynaphthoylenebenzimidazoles for Biosensing Applications

Polynaphthoylenebenzimidazoles containing functional sulfo groups were synthesized by a one-step method in a sulfuric acid medium with oleum. A polymer-analogous transformation of these polymers with aqueous solutions of metal salts (K, Ca, and Cr) was carried out. Their chemical structure was characterized by FTIR, NMR, and elemental analysis. Polymer salt coatings were deposited on QCM sensor surfaces by electron beam-induced vacuum deposition. The morphology of the coatings was characterized by AFM. It was shown that the coatings formed from a series of polymer salts have different adsorption activity in acetaminophen–water solution compared to distilled water. The QCM results indicate that sensor signal correlates with polymer coating thickness, morphology, and its chemical composition

Star-Shaped Polydimethylsiloxanes with Organocyclotetrasilsesquioxane Branching-Out Centers: Synthesis and Properties

New non-crystallizable low-dispersity star-shaped polydimethylsiloxanes (PDMS) containing stereoregular cis-tetra(organo)(dimethylsiloxy)cyclotetrasiloxanes containing methyl-, tolyl- and phenyl-substituents at silicon atoms and the mixture of four stereoisomers of tetra[phenyl(dimethylsiloxy)]cyclotetrasiloxane as the cores were synthesized. Their thermal and viscous properties were studied. All synthesized compounds were characterized by a complex of physicochemical analysis methods: nuclear magnetic resonance (NMR), FT-IR spectroscopy, gel permeation chromatography (GPC), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), viscometry in solution, rheometry, and Langmuir trough study

A New Volume-Based Approach for Predicting Thermophysical Behavior of Ionic Liquids and Ionic Liquid Crystals

Volume-based prediction of melting points and other properties of ionic liquids (ILs) relies on empirical relations with volumes of ions in these low-melting organic salts. Here we report an accurate way to ionic volumes by Bader’s partitioning of electron densities from X-ray diffraction obtained via a simple database approach. For a series of 1-tetradecyl-3-methylimidazolium salts, the volumes of different anions are found to correlate linearly with melting points; larger anions giving lower-melting ILs. The volume-based concept is transferred to ionic liquid crystals (ILs that adopt liquid crystalline mesophases, ILCs) for predicting the domain of their existence from the knowledge of their constituents. For 1-alkyl-3-methylimidazolium ILCs, linear correlations of ionic volumes with the occurrence of LC mesophase and its stability are revealed, thus paving the way to rational design of ILCs by combining suitably sized ions

A New Volume-Based Approach for Predicting Thermophysical Behavior of Ionic Liquids and Ionic Liquid Crystals

Volume-based prediction of melting points and other properties of ionic liquids (ILs) relies on empirical relations with volumes of ions in these low-melting organic salts. Here we report an accurate way to ionic volumes by Bader’s partitioning of electron densities from X-ray diffraction obtained via a simple database approach. For a series of 1-tetradecyl-3-methylimidazolium salts, the volumes of different anions are found to correlate linearly with melting points; larger anions giving lower-melting ILs. The volume-based concept is transferred to ionic liquid crystals (ILs that adopt liquid crystalline mesophases, ILCs) for predicting the domain of their existence from the knowledge of their constituents. For 1-alkyl-3-methylimidazolium ILCs, linear correlations of ionic volumes with the occurrence of LC mesophase and its stability are revealed, thus paving the way to rational design of ILCs by combining suitably sized ions

Structural Properties and Phase Transition of Exfoliated-Restacked Molybdenum Disulfide

The product of exfoliation and restacking of MoS₂ in acidic conditions is studied in detail using X-ray powder diffraction, transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The temperature dependence of powder patterns reveals that the heating of exfoliated-restacked MoS₂ is a way to a new nanostructured MoS₂-based layered material that remains nanosized even upon heating to 850 °C. Previously this material has been described as 2H-MoS₂, but according to the X-ray diffraction (XRD) data, its structure cannot be correctly described by any of the “usual” MoS₂ polytypes. A model of the structure of the material describing its XRD patterns and thermal behavior is discussed in detail

Highly Flexible Molecule “Chameleon”: Reversible Thermochromism and Phase Transitions in Solid Copper(II) Diiminate Cu[CF₃C(NH)CFC(NH)CF₃]₂

Three thermochromic phases (α, green; β, red; γ, yellow) and six polymorphic modifications (α₁, monoclinic, <i>P</i>2₁/<i>n</i>, <i>Z</i> = 2; β₁, monoclinic, <i>P</i>2₁/<i>c</i>, <i>Z</i> = 4; β₂, triclinic, <i>P</i>1̅, <i>Z</i> = 4; β₃, monoclinic, <i>P</i>2₁/<i>n</i>, <i>Z</i> = 4; γ₁ and γ₂, tetragonal, <i>P</i>4₂/<i>n</i>, <i>Z</i> = 4) have been found and structurally characterized for copper­(II) diiminate Cu­[CF₃C­(NH)CFC­(NH)CF₃]₂ (<b>1</b>). The α phase is stable under normal conditions, whereas the high-temperature β and γ phases are metastable at room temperature and transform slowly into the more stable α phase over several days or even weeks. X-ray diffraction study revealed that the title molecules adopt different conformations in the α, β, and γ phases, namely, staircase-like, twisted, and planar, respectively. The investigation of the α, β, and γ phases by differential scanning calorimetry showed that the three endothermic peaks in the range 283, 360, and 438 K are present on their thermograms upon heating/cooling. The two peaks at 283 and 360 K correspond to the solid–solid phase transitions, and the high-temperature peak at 438 K belongs to the melting process of <b>1</b>. The temperature and thermal effect of all the observed transitions depend on the prehistory of the crystalline sample obtained. A reversible thermochromic single-crystal-to-single-crystal α₁⇌β₁ phase transition occurring within a temperature interval of 353–358 K can be directly observed using a CCD video camera of the X-ray diffractometer. A series of other solid–solid α₁→γ₁, β₂→γ₁, β₃→γ₁, and γ₁⇌γ₂ phase transitions can be triggered in <b>1</b> by temperature. It has been suggested that, under equilibrium conditions, the α₁→γ₁ and β₂→γ₁ phase transitions should proceed stepwise through the α₁→β₁→β₂→β₃→γ₁ and β₂→β₃→γ₁ stages, respectively. The mechanism of the phase transitions is discussed on the basis of experimental and theoretical data

Nanostructured Organosilicon Luminophores for Effective Light Conversion in Organic Light Emitting Diodes

Full characterization of nanostructured organosilicon luminophores NOL4 and NOL5 based on the donor 2,2’-bithiophene and acceptor 1,4-bis(2,2′- bithiophene-5-yl)benzene units in dilute solutions and thin films by UV-Vis spectroscopy, DSC, TGA and X-ray techniques was reported. It was found that usage of these molecules as dopants (10–20 wt%) to the electroactive polyfluorene host in organic light-emitting devices (OLEDs) leads to the efficient spectral long wavelength shifting of the electroluminescence and an increase of the OLED performance as compared to the devices based on pristine polyfluorene, NOL4 and NOL5

A Versatile Equilibrium Method for the Synthesis of High-Strength, Ladder-like Polyphenylsilsesquioxanes with Finely Tunable Molecular Parameters

A versatile equilibrium method for synthesizing ladder-like polyphenylsilsesquioxanes (L-PPSQs) with various molecular weights (from 4 to 500 kDa) in liquid ammonia was developed. The effect of diverse parameters, such as temperature, monomer concentration, reaction time, addition or removal of water from the reaction medium, on the polycondensation process was determined. The molecular weight characteristics and structure of the L-PPSQ elements obtained were determined by GPC, 1H, 29Si NMR, IR spectroscopy, viscometry, and PXRD methods. The physicochemical properties of L-PPSQs were determined by TGA and mechanical analyses

Stabilization of 1T-MoS₂ Sheets by Imidazolium Molecules in Self-Assembling Hetero-layered Nanocrystals

We report a facile, room-temperature assembly of MoS₂-based hetero-layered nanocrystals (NCs) containing embedded monolayers of imidazolium (Im), 1-butyl-3-methyl­imid­azolium (BuMeIm), 2-phenyl­imid­azolium, and 2-methyl­benz­imid­azolium molecules. The NCs are readily formed in water solutions by self-organization of the negatively charged, chemically exfoliated 0.6 nm thick MoS₂ sheets and corresponding cationic imidazole moieties. As evidenced by transmission electron microscopy, the obtained NCs are anisotropic in shape, with thickness varying in the range 5–20 nm and lateral dimensions of hundreds of nanometers. The NCs exhibit almost turbostratic stacking of the MoS₂ sheets, though the local order is preserved in the orientation of the imidazolium molecules with respect to the sulfide sheets. The atomic structure of NCs with BuMeIm molecules was solved from powder X-ray diffraction data assisted by density functional theory calculations. The performed studies evidenced that the MoS₂ sheets of the NCs are of the nonconventional 1T-MoS₂ (metallically conducting) structure. The sheets’ puckered outer surface is formed by the S atoms and the positioning of the BuMeIm molecules follows the sheet nanorelief. According to thermal analysis data, the presence of the BuMeIm cations significantly increases the stability of the 1T-MoS₂ modification and raises the temperature for its transition to the conventional 2H-MoS₂ (semiconductive) counterpart by ∼70 °C as compared to pure 1T-MoS₂ (∼100 °C). The stabilizing interaction energy between inorganic and organic layers was estimated as 21.7 kcal/mol from the calculated electron density distribution. The results suggest a potential for the design of few-layer electronic devices exploiting the charge transport properties of monolayer thin MoS₂

Multiarm Star-Shaped Polydimethylsiloxanes with a Dendritic Branching Center

New multiarm stars have been synthesized based on polylithium derivatives of high-generation carbosilane dendrimers. In the synthesis of multiarm stars based on the eighth-generation dendrimer, steric hindrances were observed even during the synthesis of a polylithium initiator. Subsequently, this led to chain transfer reactions between growing arms, as well as other side effects. As a result, dense nanogel formations with a higher tendency of ordering than in classical objects of this type were isolated from the reaction mixture. The study of the rheology of multiarm stars based on sixth-generation dendrimers made it possible to determine the activation energies of viscous flow in these objects, which makes it possible to consider them as objects with a macromolecular nature and a reptation flow mechanism