Versatile electrochemiluminescent organic emitters

Organic luminophores for electrochemiluminescence (ECL), namely polycyclic aromatic hydrocarbons, have been the first molecules investigated since the beginning of ECL studies. Moving from organic solvents to water-based solutions in view of analytical applications, the attention on ECL emitters shifted to soluble inorganic complexes, which prevailed in both fundamental and applied research. However, the investigation of organic molecules has recently revived owing to new synthetic procedures and concepts. Polymeric nanoparticles, surface functionalisation, aggregation-induced emission (AIE), and thermally activated delayed fluorescence (TADF) sparked the research with renovated interest for organic molecules. Here, we introduce and summarise these new concepts behind organic emitters for ECL.     

Extraction of fullerene mixture from fullerene soot with organic solvents

Investigation of extraction of fullerene mixture from the fullerene soot obtained by plasma erosion of graphite rod in helium atmosphere with different solvents such as α-chloronaphthalene, o-dichlorobenzene, o-xylene, toluene, benzene, carbon tetrachloride, and n-hexane at 25°C was carried out. Completeness and effectiveness of extraction as well as relative content of light (C₆₀, C₇₀) and heavy (C₇₆, C₇₈, C₈₄) fullerenes in the extract were evaluated.     

Versatile new uranyl(VI) dihalide complexes supported by tunable organic amide ligands

A series of uranyl(VI) dihalide complexes UO2X2L2 (X = Cl, Br) supported by organic amide ligands (L = R'C(O)NR2; R' = i-Pr; R = i-Pr, i-Bu, s-Bu) offers the versatile combination of facile synthesis using benchtop methods, air-stable crystalline solids obtained in high yield, high solubility in common organic solvents and tunable steric/electronic properties.     

Versatile scheme for the step-by-step assembly of nanoparticle multilayers

A versatile scheme for the preparation of nanoparticle (NP) multilayers is presented. The method is based on the step-by-step assembly of NPs and bishydroxamate disulfide ligand molecules by means of metal-organic coordination using easily synthesized tetraoctylammonium bromide (TOAB)-stabilized gold NPs. The assembly of NP multilayers was carried out via a Zr(IV)-coordinated sandwich arrangement of the hydroxamate ligands on Au and glass surfaces. The latter were precoated with electrolessly deposited Au clusters to enable binding of the first NP layer. The new method avoids the need to perform elaborate colloid reactions to prepare the NP building blocks. Au NP monolayer and multilayer films prepared in this manner were characterized by UV-vis spectroscopy, atomic force microscopy (AFM), and cross-sectional transmission electron microscopy (TEM), showing a regular growth of NP layers. The use of coordination chemistry as the binding motif between repeat layers allows for the convenient assembly of hybrid nanostructures comprising molecular and NP components. This was demonstrated by the construction of Au NP multilayers with controlled spacing from the surface or between two NP layers. Drying the samples during or after the construction process induces NP aggregation and changes in the film morphology and optical properties.     

Effective dispersion of fullerene with methacrylate copolymer in organic solvent and poly(methyl methacrylate)

Dispersion of fullerene, C₆₀, by addition of polymethacrylate dispersant in methyl methacrylate (MMA) and incorporation of C₆₀ into poly(methyl methacrylate) (PMMA) were investigated. Copolymers synthesized by radical copolymerization of MMA and 2-naphthyl methacrylate (NMA), poly(MMA-co-NMA), effectively dispersed C₆₀ in MMA to form clusters of 20?nm. In these cases, addition of minimal 110 naphthyl groups per unit C₆₀ molecule afforded to give clusters with minimum of 20?nm sizes. Furthermore, block copolymers, poly(MMA-b-NMA) with MMA/NMA mole ratio from 12:1 to 20:1, also efficiently dispersed C₆₀ to give formation of clusters of 20?nm size by addition of minimal 40 naphthyl groups per unit C₆₀ molecule, which was corresponding to approximate nine layers of naphthyl group in block copolymer adsorbed on the surface of the cluster. Hybrid films of C₆₀/PMMA, prepared by casting of C₆₀-dispersed solution containing PMMA, exhibited absorbance at 400?nm linearly increased with C₆₀ content.     

Binary nanoparticle superlattices in the semiconductor-semiconductor system: CdTe and CdSe

We report binary nanoparticle superlattices obtained by self-assembly of two different semiconductor quantum dots. Such a system is a means to include two discretized, quantum-confined, and complimentary semiconductor units in close proximity, for purposes of band gap matching and/or energy transfer. From a range of possible structures predicted, we observe an exclusive preference for the formation of Cuboctahedral AB13 and AB5 (isostructural with CaCu5) obtained in the system of 8.1 nm CdTe and 4.4 nm CdSe nanoparticles. For this system, a possible ionic origin for the formation of structures with lower packing densities was ruled out on the basis of electrophoretic mobility measurements. To understand further the principles of superlattice formation, we constructed space-filling curves for binary component hard spheres over the full range of radius ratio. In addition, the pair interaction energies due to core-core and ligand-ligand van der Waals (VDW) forces are estimated. The real structures are believed to form under a combined influence of entropic driving forces (following hard-sphere space filling principles) and the surface (due to ligand-ligand VDW).     

QSPR modeling for solubility of fullerene (C(60)) in organic solvents

Solubility of fullerene C(60) in 75 organic solvents was examined to develop quantitative structure-solubility relationships. Topological indices and polarizability parameter computed from refractive index were used to form the regression models. The models suggested for individual data sets such as alkanes, alkyl halides, alcohols, cycloalkanes, alkylbenzenes, and aryl halides have good predictive ability and are better than the models for the combined groups. Inclusion of an indicator parameter which is a combination of atom contributions and contributions of substituents' position in benzenes improved the predictive ability significantly.     

Crystallographic characterization and structural analysis of the first organic functionalization product of the endohedral fullerene Sc(3)N@C(80)

The structure of Sc3N@C80-C10H12O2, a Diels-Alder cycloadduct of Sc3N@C80, has been determined. The crystallographic data shows that cycloaddition occurs at a C-C bond of 6:5 ring junction, and that the fullerene C1-C2 bond is elongated and pulled out from the fullerene. The Sc3N unit is well-ordered within the C80 cage and positioned away from the site of addition. The proximity of the Sc atoms to the cage carbon atoms causes those carbon atoms to protrude slightly from the surface of the fullerene cage.     

Absolute configuration of D(2)-symmetric fullerene C(84)

The D(2)-symmetric isomer of fullerene C(84) predominantly found in soots is inherently chiral. We determine its absolute configuration by comparison of the experimental electronic circular dichroism (CD) spectrum with time-dependent density functional calculations.     

A chiral dumbbell shaped bis(fullerene) oligoelectrolyte

The first icosacationic bis(fullerene) whose water solubility is provided by twenty peripheral ammonium groups has a rigid, almost cylindrical shape and was synthesized by connecting two fullerene cores with a chiral cyclo-bis(malonate), followed by the regioselective addition of ten amino-terminated malonates into the octahedral positions of the fullerene moieties and subsequent cleavage of the Boc-protecting groups.     

Interaction of fullerene C60 with iodine in organic solvents

The interaction of fullerene C₆₀ with molecular iodine in organic solvents was studied. The stoichiometry of the complex formed, C₆₀I₂=13, was determined spectrophotometrically and by the interphase distribution technique. The constant of the formation of the adduct in toluene was calculated to be logK=8.9±0.3.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 481–483, March, 1995.     

Fluorescence study of fullerene in organic solvents at room temperature

At room temperature, fluorescence spectra for C60 in organic solvents of four typical kinds have been reported, which indicate that intensity of fluorescence and fine structure of fluorescence peaks are dependent on the interaction between C60 and solvent. It is shown that the solvents of effective electron donors could make a comparatively strong interaction with fullerenes due to formation of the charge transfer adduct, which could greatly distort the molecular symmetry, leading to the strong and well-resolved fluorescence. The strong fluorescence spectra for C70 in room temperature solutions are also observed.     

Colloidal dispersion of fullerene C60 free of organic solvents

A new procedure for preparing aqueous colloidal dispersion of C₆₀ in water was developed.     

Versatile and convenient routes to functionalized poly(ferrocenylsilanes)

Functionalized organometallic polymers are reported. Direct substitution reactions on poly(ferrocenylsilanes) using nucleophiles with protected amines led to amine‐functionalized polymers. The use of protecting group and monomer substitution strategies were found to be compatible with ring‐opening polymerization protocols allowing the synthesis of high polymers with amino, bromo, ester, or quarternary ammonium functionalities.     

Electrochemistry and [60]fullerene displacement reactions of (dihapto-[60]fullerene) pentacarbonyl metal(0) (M = Cr, Mo, W)

Cyclic voltammetry (CV) measurements on (eta(2)-C(60))M(CO)(5) complexes (M = Cr, Mo, W) in dichloromethane show three [60]fullerene-centered and reversible reduction/oxidation waves. The E(1/2) values of these waves are shifted to positive values relative to the corresponding values of the uncoordinated [60]fullerene in the same solvent. A Jahn-Teller type distortion of the spherical surface of [60]fullerene promoted by [60]fullerene-metal pi-backbonding may explain the observed positive shifts. Lewis bases (L = piperidine and triphenyl phosphine) displace [60]fullerene from (eta(2)-C(60))M(CO)(5) complexes. Analysis of the activation parameters for the metal-[60]fullerene dissociation, the metal-[60]fullerene bond enthalpies (from DFT computations), and metal-solvent (benzene) bond enthalpies (from DFT computations) suggests appreciable solvent contribution to the transition state leading to formation of the intermediate species solvent-M(CO)(5). Appreciable transition state stabilization due to solvation of the intermediate species is inferred for M = Mo and W. For M = Cr, stabilization of the intermediate species due to solvation is not accompanied by the corresponding transition state stabilization.     

Using organic nanoparticle fluorescence to determine nitrite in water

Organic fluorescence nanoparticles (1-aminopyrene nanoparticles) were prepared under ultrasonic radiation and used to determine nitrite. Such nanoparticles have a broad, continuous excitation spectrum, but they are also photochemically stable and water-soluble. Nitrite determination was based upon nitrite quenching the fluorescence of the nanoparticles due to a simple diazotization reaction; a simple and specific method. Under optimal conditions, the linear range of the calibration curve was 20–1400 ng ml^–1, with a correlation coefficient of 0.9987 for nitrite. The detection limit was 3 ng ml^–1. The method was applied to various water samples from several sources. Quantitative nitrite recoveries and satisfactory results were achieved.     

Magnetic properties of the fullerene organic compounds in strong magnetic fields

Magnetisation study of the C₆₀·TMTSF·2CS₂ molecular complex in magnetic field up to 47 T for the temperature range 1.8–300 K and ESR spectroscopy of the molecular complex (ET)₂C₆₀ at T=1.8 K for the frequency range 60–90 GHz in magnetic field up to 32 T provide the experimental evidence that a paramagnetic centers with the reduced g-factor values g<1 control magnetic properties of these solids. Anomalous g-factor values may be caused by dynamic Jan-Teller effect on the negative C₆₀ ions, which appear as defects in crystalline structure with a weak charge transfer.