Andrzej Łapiński

Novel supramolecular organogels based on a hydrazide derivative: non-polar solvent-assisted self-assembly, selective gelation properties, nanostructure, solvent dynamics

In this work, we report the complementary studies of supramolecular organogels composed of a newly synthesized low molecular mass gelator 4-(4-morpholinyl)-3-nitro-benzoylhydrazide (1) with benzene, toluene, and p-xylene. Intermolecular hydrogen bonding and π–π stacking interactions are the main driving forces promoting gelation of the system and the self-assembly of the new gelator molecules. The former interactions were revealed by the FT-IR and Raman studies, whereas the latter ones were postulated on the basis of the molecular structure of the gelator, UV-Vis spectra and comparison with the previously published data for other hydrazide derivatives. The strengths of the hydrogen bonding interactions are comparable as indicated by the FT-IR spectra analysis. Therefore, we correlated the differences in the calculated enthalpies of the gelator aggregates of 1 in the gels studied with the differences in the strengths of the π–π stacking interactions. The gel of 1 with benzene is characterized by the highest value of enthalpy. The images taken by the SEM and POM methods reveal differences in the architecture of gelator 1 aggregates, which are lamellar-like in toluene and fibrillar in benzene and p-xylene. The dispersion of spin–lattice relaxation times of solvents in the gel phase, observed by the NMR relaxometry method at low frequencies, is an indicator of the solvent–gelator interactions. As a result of this interaction, a significant slowing down of the motion (5 orders of magnitude as compared to bulk solvents) of the fraction of solvent molecules at the pore surface in the gel phase takes place. The diffusion of solvents in gels is restricted as shown by PGSE NMR. The apparent diffusion coefficient measured as a function of diffusion time can be used to estimate the pore size of the gel matrix, which for the gel of 1 with toluene is about 22 μm.

SILENT AND HIGHER-ORDER VIBRATIONS OF C60 AND ITS COMPOUNDS

Abstract We present rich IR spectra of solid samples of C 60 and its derivatives. Most of the IR lines are identified as the activated silent modes of the C 60 or second-order combination modes. The method of preparation of a complex of C 60 and chloro(triphenyl-phosphine) gold grown from toluene solution is described. Basic physical properties, in particular IR transmission of the single crystals of the complex, are studied as a function of temperature. Anomalies in the temperature dependences of the linewidths, their frequencies and intensities are observed and discussed.

Vibrational and Electronic Properties of Perylenediimide Linked to Fullerene and Tetrathiafulvalene

Solid-state electronic (UV-Vis) and vibrational (IR) spectra of the tetrathiafulvalene-perylenediimide (PDI-TTF) 1 and perylenediimide-fullerene (PDI-C60) 2 dyads as well as PDI 3 , TTF 8 and fullerene 9 derivatives used as references molecules were investigated in the frequency range between 400 and 45,500 cm−1. Electronic and vibrational features of the dyads were compared and analysed. Molecular geometry of the compounds and their IR and Raman theoretical spectra were calculated. It was stated, that small redistribution of the charges occurs in both moieties of these dyads. This effect is observed as shifts of both electronic and vibrational bands of the dyads in comparison with the respective bands of free components.

Structural Distortions upon Oxidation in Heteroleptic [Cp2W(dmit)] Tungsten Dithiolene Complex: Combined Structural, Spectroscopic, and Magnetic Studies

Four different cation radical salts are obtained upon electrocrystallization of [Cp(2)W(dmit)] (dmit = 1,3-dithiole-2-thione-4,5-dithiolato) in the presence of the BF(4)(-), PF(6)(-), Br(-), and [Au(CN)(2)](-) anions. In these formally d(1) cations, the WS(2)C(2) metallacycle is folded along the S···S hinge to different extents in the four salts, an illustration of the noninnocent character of the dithiolate ligand. Structural characteristics and the charge distribution on atoms, for neutral and ionized complexes with various folding angles, were calculated using DFT methods, together with the normal vibrational modes and theoretical Raman spectra. Raman spectra of neutral complex [Cp(2)W(dmit)] and its salts formed with BF(4)(-), AsF(6)(-), PF(6)(-), Br(-), and [Au(CN)(2)](-) anions were measured using the red excitation (λ = 632.8 nm). A correlation between the folding angle of the metallacycle and the Raman spectroscopic properties is analyzed. The bands attributed to the C═C and C-S stretching modes shift toward higher and lower frequencies by about 0.3-0.4 cm(-1) deg(-1), respectively. The solid state structural and magnetic properties of the three salts are analyzed and compared with those of the corresponding molybdenum complexes. Temperature dependence of the magnetic susceptibility shows the presence of one-dimensional antiferromagnetic interactions in the BF(4)(-), PF(6)(-), and [Au(CN)(2)](-) salts, while an antiferromagnetic ground state is identified in the Br(-) salt below T(Néel) = 7 K. Interactions are systematically weaker in the tungsten salts than in the isostructural molybdenum analogs, a consequence of the decreased spin density on the dithiolene ligand in the tungsten complexes.

Charge Transfer Salt with Substituted Lindquist Polyoxometalate: Synthesis, Crystal Structure, and Physical Properties of α-(BEDT-TTF)6(VW5O19)⋅DMF⋅2H2O

A new charge transfer salt based on bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF) and the vanadium substituted Lindquist anion [VW5O19]3− was synthesized and characterized by X-ray and spectroscopic analysis. Monoclinic, C2, Fw=3789.2, a=41.5019(5), b=11.2600(2), c=12.7514(2) Å, β=101.877(5)°, Z=2, R=0.060, based on 12095 reflections with I>2σ(I). The structure consists of alternating organic and inorganic layers. The inorganic layer is generated by [VW5O19]3− anions, dimethylformamide (DMF) and water molecules. The organic layer, which is generated by three different BEDT-TTF units, belongs to the α-type of packing and consists of trimerized chains parallel to the c direction. The compound is a semi-conductor with σ300 K=1.1 S⋅cm−1 and Ea=0.1 eV. Polarized reflectance spectra of single crystals were measured over the spectral range from 650 to 25000 cm−1. FT-NIR Raman spectra of powdered crystals dispersed in KBr pellets were also recorded. Vibrational and electronic features are discussed.

Molecular interactions in high conductive gel electrolytes based on low molecular weight gelator.

Organic ionic gel (OIG) electrolytes, also known as gel electrolytes or ionogels are one example of modern functional materials with the potential to use in wide range of electrochemical applications. The functionality of OIGs arises from the thermally reversible solidification of electrolytes or ionic liquids and their superior ionic conductivity. To understand and to predict the properties of these systems it is important to get the knowledge about the interactions on molecular level between the solid gelator matrix and the electrolyte solution. This paper reports the spectroscopic studies (FT-IR, UV-Vis and Raman) of the gel electrolyte based on low molecular weight gelator methyl-4,6-O-(p-nitrobenzylidene)-α-d-glucopyranoside and solution of quaternary ammonium salt, tetramethylammonium bromide. The solidification process was based on sol-gel technique. Below characteristic temperature, defined as gel to sol phase transition temperature, Tgs, the samples were solid-like and showed high conductivity values of the same order as observed for pure liquid electrolytes. The investigations were performed for a OIGs in a wide range of molar concentrations of the electrolyte solution.

Infrared spectra of the new molecular complex C60 ·2[(C6H5)3P]AuCl·0.1 C6H5CH3

We report on the wealth of IR spectra of single crystals of the C60 complex with chloro(triphenylphosphine)gold grown from toluene solution. The spectra are strongly temperature-dependent at about 200 K. The dependence of the spectral parameters is attributed to variations in the molecular dynamics of the C60 molecules and changes in the interactions between the fullerene and donor/solvent molecules. Some general considerations on the origin of the IR spectral variation vs. temperature are also presented.

Proton conducting system (ImH2)2SeO4·2H2O investigated with vibrational spectroscopy

Imidazolium selenate dihydrate (ImH2)2SeO4·2H2O crystals have been investigated using Raman and IR spectroscopy. Experimental data were supported by the quantum-chemical calculations (DFT), Hirshfield surfaces and fingerprint plots analysis, and Bader theory calculations. The imidazolium selenate dihydrate crystal exhibits high proton conductivity of the order of ~10-1S/m at T=333K. The spectra of this compound are dominated by bands related to the lattice modes, the internal vibrations of the protonated imidazole cation, selenate anion, water molecules, and hydrogen bonds network. For the imidazolium selenate dihydrate crystal, the formal classification of the fundamental modes has been carried out.

Supramolecular Structure and Spectral Properties of Selected Fullerene–Organic Chromophore Systems

The goal of the article is to collect and discuss spectral data for the dyads and reference molecules in the large spectral range, using various methods of investigations. We present information on change of configurations, electronic and vibrational properties of both parts of the dyads after their formation, and their possible relationship with electron transfer mechanism. From the conformational and spectral investigations, a strong correlation between the molecular structure of investigated species and their electronic as well as vibrational spectra arises. It testifies a significant redistribution of the charges upon the covalent linkage of a dyad.

Spectroscopic and quantum chemical studies of interaction between the alginic acid and Fe3O4 nanoparticles

In this work, we present the spectral investigation of the interactions between the coverage with alginic acid (AA) and nanoparticles for three different composites containing 74, 80, and 88wt% of magnetite. These results show that the Fe3O4 nanoparticles are coated with the AA and indicate that there is an interaction between them. Moreover, we have investigated the thermal and magnetic properties of all investigated compounds. We show that bonding of alginic acid to the surface of magnetite results in better thermal stability of the polymer and in higher temperature of AA chains degradation. We find that for dense assembly of magnetite nanoparticles, at low temperatures, the intergranular coupling becomes much stronger than between nanoparticles dispersed in composites.