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Doping level of compact PEDT: PSS films can be adjusted by controlling the amount of charge infected during the electrochemical doping/redoping processes using tolusulfonic acid. By further investigation it was found that the OLEDs using electrochemically doped PEDT:PSS/ITO anodes show a significant reduction of operating voltage and improved device performance consistent with an increase of doping level of the polymer.

The in situ spectroelectrochemical and electron spin resonance (ESR) behavior of the recently prepared N,N,N',N'-tetrakis-(4-diphenylamino-phenyl)-thiophene-2,5-diamine 11 is presented. The results are compared to the ones of the parent 2,5-bis-diphenylamino-thiophene 41 as well as to the corresponding high-molar third dendrimer generation 8 containing the same thiophene-2,5-diamine core. The dendritic compound 11 can be reversibly oxidized in three separated steps to yield the corresponding stable monocation 11(•+), dication 11(2+), and tetracation 11(4+). A well resolved ESR spectrum of the corresponding cation radical 11(•+) with dominating splittings from two nitrogen atoms and two hydrogen atoms was observed at the first oxidation peak similar to 41(•+). The shape of the SOMOs orbitals very well correlates with the proposed distribution of the unpaired electron mainly on the thiophene center and neighboring nitrogen atoms. The spin delocalization on the central thiophene moiety in the monocations for all three model compounds 41(•+), 11(•+), and 8(•+) was confirmed. The computed single occupied molecular orbital (SOMO) for trication 11(•3+) is completely different compared to the SOMO of the corresponding monocation 11(•+), and it confirms a largely delocalized unpaired spin density. Dominating diamagnetic product was determined at the third oxidation peak, confirming the formation of a tetracation by a two electron oxidation of ESR silent dication. The positive charge is fully delocalized over the lateral parts of the molecule leading to the high stability of tetracation 11(4+). The estimated theoretical limit energy of the lowest optical transition S0 → S1 is 2.90 eV, and it can be achieved for the 3D dendrimer generation.

Reactions of 5-tert-butyl-2-hydroxy-3-methylsulfanylbenzaldehyde S-methylisothiosemicarbazone and 5-tert-butyl-2-hydroxy-3-phenylsulfanylbenzaldehyde S-methylisothiosemicarbazone with pentane-2,4-dione (Hacac) and triethyl orthoformate in the presence of M(acac)2 as template source at 107 °C afforded metal complexes of the type M(II)L(1) and M(II)L(2), where M = Ni and Cu, with a new Schiff base ligand with thiomethyl (H2L(1)) and/or thiophenyl (H2L(2)) group in the ortho position of the phenolic moiety. Demetalation of NiL(1) in CHCl3 with HCl(g) afforded H2L(1). The latter reacts with Zn(OAc)2·2H2O with formation of ZnL(1). The effect of -SR groups and metal ion identity on stabilization of phenoxyl radicals generated electrochemically was studied in detail. A marked stabilization of phenoxyl radical was observed in one-electron-oxidized complexes [ML(2)](+) (M = Ni, Cu) at room temperature, as demonstrated by cyclic voltammetry, EPR spectroscopy, and UV-vis-NIR measurements. In solution, the oxidized CuL(2) and NiL(2) display intense low-energy NIR transitions consistent with their classification as metal-delocalized phenoxyl radical species. While the CuL(2) complex shows reversible reduction, reduction of NiL(2), CuL(1), and NiL(1) is irreversible. EPR measurements in conjunction with density functional theory calculations provided insights into the extent of electron delocalization as well as spin density in different redox states. The experimental room temperature spectroelectrochemical data can be reliably interpreted with the (3)[CuL(2)](+) and (2)[NiL(2)](+) oxidation ground states. The catalytic activity of synthesized complexes in the selective oxidations of alcohols has been studied as well. The remarkable efficiency is evident from the high yields of carbonyl products when employing both the CuL(2)/air/TEMPO and the CuL(2)/TBHP/MW(microwave-assisted) oxidation systems.

The influence of the cage as well as of the cluster size has been studied in Gd-Sc nitride cluster fullerenes, which have been synthesized and isolated for these studies. A series of carbon cages ranging from C78 to C88 have been synthesized, isolated, and characterized in detail using absorption and vibrational spectroscopy as well as electrochemistry and density functional theory calculations. Gd-Sc mixed-metal cluster fullerenes in carbon cages different from C80 were described for the first time. A review of their structures, properties, and stability is given. The synthesis was performed with melamine as an effective solid source of nitrogen, providing high fullerene yield and suppressing empty fullerene formation. Substitution of gadolinium by scandium imposes a noticeable influence on the electronic structure of nitride cluster fullerenes as revealed by electrochemical, spectroscopic, and computational methods.

The 5,10,15,20-tetraphenyl-21-oxaporphyrin complexes of Mn(II), Co(II), and Zn(II) have been crystallized and studied by X-ray diffraction, NMR and UV/vis spectroscopy, and mass spectrometry as well as cyclic voltammetry. The X-ray structure of the earlier described Cu(II) complex is also reported. All complex structures possess a five-coordinate, approximately square-pyramidal geometry with a slight deviation of the heteroaromatic moieties from planarity. The packing structures are characterized by parallel strands of complex molecules interacting by weak hydrogen bonds. In the case of Zn(II) an octahedral complex has also been isolated using a side-chain hydroxy functionalized oxaporphyrin ligand; the structure was verified by NMR and EXAFS spectroscopy. Cyclic voltammetry studies reveal that the reduction of the complex bound Mn(II), Co(II), and Zn(II) ions is a ligand-centered process whereas the first oxidation step depends on the metal ion present.

The clusterfullerene Sc(4)O(2)@C(80) with a mixed redox state of scandium was found to be an exciting molecule for endohedral electrochemistry as demonstrated by means of an in situ electron spin resonance (ESR) spectroelectrochemical study of the spin density distribution in its electrochemically generated cation and anion radicals. The compound exhibits two reversible reduction and oxidation steps with a relatively small electrochemical gap of 1.10 V. The ESR spectra of the ion radicals have a rich hyperfine structure caused by two pairs of equivalent Sc atoms. The Sc-based hyperfine structure with large hyperfine coupling constants shows that both oxidation and reduction of Sc(4)O(2)@C(80) are in cavea redox processes, which is the subject of endohedral electrochemistry. The assignment of the experimentally determined a((45)Sc) values to the two types of Sc atoms in the Sc(4)O(2) cluster was accomplished by extended density functional theory and molecular dynamics simulations. Sc atoms adopting a divalent state in the neutral Sc(4)O(2)@C(80) exhibited an especially large coupling constant of 150.4 G in the cation radical, which is the record high a((45)Sc) value for Sc-based endohedral metallofullerenes. Such a high value is explained by the nature of the highest occupied molecular orbital (HOMO) localized on the six-atom Sc(4)O(2) cluster. This HOMO is a Sc-Sc bonding MO and hence has large contributions from the 4s atomic orbitals of Sc(II). We claim that ESR spectroelectrochemistry is an invaluable experimental tool in the studies of metal-metal bonding in endohedral metallofullerenes and in endohedral electrochemistry.

The magnetism of DySc(2)N@C(80) endofullerene was studied with X-ray magnetic circular dichroism (XMCD) and a magnetometer with a superconducting quantum interference device (SQUID) down to temperatures of 2 K and in fields up to 7 T. XMCD shows hysteresis of the 4f spin and orbital moment in Dy(III) ions. SQUID magnetometry indicates hysteresis below 6 K, while thermal and nonthermal relaxation is observed. Dilution of DySc(2)N@C(80) samples with C(60) increases the zero-field 4f electron relaxation time at 2 K to several hours.

The electrochemical doping of emeraldine salt and emeraldine bases with different weight average molecular weights was studied by in situ Fourier transform infrared (FTIR) spectroelectrochemistry using attenuated total reflection (ATR) technique. The formation and stabilization of charge carriers in polyaniline during p-doping was followed in dependence of the chain branching. The potential dependence of the IR bands during the oxidation of the polymer clearly demonstrates the formation of the different charged polymer structures (π-dimers, polarons, and bipolarons). It is shown that IR bands usually attributed to a semiquinoid polaron lattice correspond in fact to doubly charged species, π-dimers, which are face-to-face complexes of two polarons. Bands corresponding exclusively to polarons have been identified at 1266, 1033, and 1010 cm(-1), suggesting that polarons are predominantly stabilized on the linear segments near the polymer branches by phenazine.

Titanium/yttrium mixed metal nitride clusterfullerene (MMNCF) TiY(2)N@C(80) has been successfully synthesized, representing the first Ti-containing non-scandium MMNCF. TiY(2)N@C(80) has been isolated by multistep HPLC and characterized by various spectroscopies in combination with DFT computations. The electronic absorption property of TiY(2)N@C(80) was characterized by UV-vis-NIR spectroscopy, indicating the resemblance to that of TiSc(2)N@C(80) with broad shoulder absorptions. The optical band gap of TiY(2)N@C(80) (1.39 eV) is very close to that of TiSc(2)N@C(80) (1.43 eV) but much smaller than that of Y(3)N@C(80)(I(h), 1.58 eV). Such a resemblance of the overall absorption feature of TiY(2)N@C(80) to TiSc(2)N@C(80) suggests that TiY(2)N@C(80) has a similar electronic configuration to that of TiSc(2)N@C(80), that is, (TiY(2)N)(6+)@C(80)(6-). FTIR spectroscopic study and DFT calculations accomplish the assignment of the C(80):I(h) isomer to the cage structure of TiY(2)N@C(80), with the C(1) conformer being the lowest energy structure, which is different from the C(s) conformer assigned to TiSc(2)N@C(80). The electrochemical properties of TiY(2)N@C(80) were investigated by cyclic voltammetry, revealing the reversible first oxidation and first reduction step with E(1/2) at 0.00 and -1.13 V, respectively, both of which are more negative than those of TiSc(2)N@C(80), while the electrochemical energy gap of TiY(2)N@C(80) (1.11 V) is almost the same as that of TiSc(2)N@C(80) (1.10 V). Contrary to the reversible first reduction step, the second and third reduction steps of TiY(2)N@C(80) are irreversible, and this redox behavior is dramatically different from that of TiSc(2)N@C(80), which shows three reversible reduction steps, indicating the strong influence of the encaged group-III metal (Y or Sc) on the electronic properties of TiM(2)N@C(80) (M = Y, Sc).

Graphene|metal|ligand systems open a new realm in surface magnetochemistry. We show that by trapping metal atoms in the two-dimensional potential lattice of a graphene-ligand interface it is possible to build a chemical analogue of an optical lattice, a key setup in quantum information and strongly correlated systems. Employing sophisticated first-principles calculations, we studied electronic and dynamic properties of graphene|metal|ligand assemblies and showed that there is a general principle--spin-charge separation in π-d systems--that underlies the possibility of synthesizing and controlling such systems. We find that ligands can work as a local gate to control the properties of trapped metal atoms and can impose bosonic or fermionic character on such atomic nets, depending on the ligand's nature. Remarkably, the magnetization energy in such systems reaches record-high values of ca. 400 meV, which makes the respective magnetic phenomena utilizable at room temperature. Accompanied by spin polarization of the graphene π-conjugated system it leads to spin-valve materials and brings the realization of quantum computing one step closer.

By scanning tunneling microscopy imaging and electronic structure theory, we investigate a single-molecule switch based on tunneling electron-driven rotation of a triangular Sc3N cluster within an icosahedral C80 fullerene cage among three pairs of enantiomorphic configurations. Bias-dependent action spectra and modeling implicate the antisymmetric stretch vibration of Sc3N cluster as the gateway for energy transfer from the tunneling electrons into the cluster rotation. Hierarchical switching of conductivity among multiple stationary states while maintaining a constant molecular shape, offers an advantage for the integration of endohedral fullerene-based single-molecule switches into multiple logic state molecular devices.

The structure of emeraldine salt and emeraldine bases with different molar weight and their behavior in electrochemical doping was studied by different spectroscopic and spectroelectrochemical techniques. By Fourier transform infrared (FTIR) spectroscopy, the branching of the polymer chain at tri- and tetrasubstituted benzene rings as well as the presence of small amounts of phenazine units are shown. The branching of the polymer chains increases with the increasing of the molar weight of emeraldines. The optical transitions in protonated and unprotonated emeraldine were studied by ultraviolet-visible near-infrared (UV-vis NIR) spectroscopy. By comparison of the electron spin resonance (ESR) spectra of emeraldine in protic solvents and acidic solutions, the emeraldine bases are shown to be to some extent protonated. Applying in situ ESR-UV-vis NIR spectroelectrochemistry, the charged states in emeraldines upon p-doping were investigated considering the influence of the nonideal "linear" polymer structures. The initial stage of oxidation of the emeraldine base and salt consists of the different charged states. The phenazine units in the polymer chains stabilize the charged states in the emeraldines upon p-doping.

A novel cell for in situ Raman studies at hydrogen pressures up to 200 bar and at temperatures as high as 400 °C is presented. This device permits in situ monitoring of the formation and decomposition of chemical structures under high pressure via Raman scattering. The performance of the cell under extreme conditions is stable as the design of this device compensates much of the thermal expansion during heating which avoids defocusing of the laser beam. Several complex and metal hydrides were analyzed to demonstrate the advantageous use of this in situ cell. Temperature calibration was performed by monitoring the structural phase transformation and melting point of LiBH(4). The feasibility of the cell in hydrogen atmosphere was confirmed by in situ studies of the decomposition of NaAlH(4) with added TiCl(3) at different hydrogen pressures and the decomposition and rehydrogenation of MgH(2) and LiNH(2)., (© 2011 American Chemical Society)

The density functional theory calculations of molecular structure and spectroscopic and electronic properties of charged states in four triazine-heteroaryl star-shaped compounds are presented. The molecules end-capped with different heteroaryl groups, i.e., thiophene (TTT1), furan (TFT2), 3,4-ethylenedioxythienyl (TET3), and thiazole (TSNT4), were studied by electrochemical and in situ ESR/UV-vis-NIR spectroelectrochemical techniques in tetrahydrofuran/(TBA)BF(4). The charged states of monomers were created by cathodic reduction and the stability of generated anion radicals was characterized in detail both experimentally and theoretically. The TET3 molecule resulted in a star-shaped hyperbranched polymer formed anodically which in turn can be reversibly oxidized up to the tetracation. The nature and charge distribution of charge carriers at each redox state in the as-prepared polymer was clarified by calculations for the model (TET3)(3) trimer structure.

A family of highly stable (poly)perfluoroalkylated metallic nitride cluster fullerenes was prepared in high-temperature reactions and characterized by spectroscopic (MS, (19)F NMR, UV-vis/NIR, ESR), structural and electrochemical methods. For two new compounds, Sc(3)N@C(80)(CF(3))(10) and Sc(3)N@C(80)(CF(3))(12,) single crystal X-ray structures are determined. Addition pattern guidelines for endohedral fullerene derivatives with bulky functional groups are formulated as a result of experimental ((19)F NMR spectroscopy and single crystal X-ray diffraction) studies and exhaustive quantum chemical calculations of the structures of Sc(3)N@C(80)(CF(3))(n) (n = 2-16). Electrochemical studies revealed that Sc(3)N@C(80)(CF(3))(n) derivatives are easier to reduce than Sc(3)N@C(80), the shift of E(1/2) potentials ranging from +0.11 V (n = 2) to +0.42 V (n = 10). Stable radical anions of Sc(3)N@C(80)(CF(3))(n) were generated in solution and characterized by ESR spectroscopy, revealing their (45)Sc hyperfine structure. Facile further functionalizations via cycloadditions or radical additions were achieved for trifluoromethylated Sc(3)N@C(80) making them attractive versatile platforms for the design of molecular and supramolecular materials of fundamental and practical importance.

The influence of the molecular structure on the stabilization of charged states was studied in detail by in situ ESR UV-vis NIR spectroelectrochemistry at a novel α,ω-dicyano substituted β,β'-dibutylquaterthiophene (DCNDBQT) and the electrochemically generated cation and anion radicals have been proved for the first time. The voltammetry of DCNDBQT results in two separate oxidation steps with the reversible first one. The experimental absorption maxima at 646 and 1052 nm together with the calculated ones (by DFT method) as well as an ESR signal at the first anodic step prove the presence of a radical cation. Three additional optical bands (554, 906, and 1294 nm for CT-transition) can be attributed to the formation of cation radical dimer. The dicationic structure formed in the second oxidation step is not stable. The stabilization proceeds via a dimer formation in two chemical follow-up reactions. The existence of the dimeric structures was proved by ex situ MALDI TOF mass spectrometry. As the substitution by cyano groups opens the route to cathodic reductions, DCNDBQT shows a single quasi-reversible reduction step. Here, the in situ ESR UV-vis NIR spectroelectrochemical measurements and theoretical calculations let us confirm the electrochemical generation of an anion radical. As we found a low number of anion radicals by quantitative ESR spectroelectrochemistry and an appearance of additional bands in the UV-vis NIR absorption spectra, the formation of dimeric structures must be considered and was corroborated by mass spectrometry. The role of dimerization in the reaction mechanism of the DCNDBQT oxidation and reduction are discussed in general. The experimental results were interpreted using the quantum chemical calculations based on density functional theory.

The charged states of C(60)(CF(3))(2n) (2n = 2-10) derivatives have been studied by electron spin resonance (ESR) and vis-near-infrared (NIR) spectroelectrochemistry. The anion radicals and diamagnetic dianions were furthermore described by theoretical calculations. The ESR spectra of anion radicals exhibit complex patterns due to multiple CF(3) groups. Their interpretation is accomplished by DFT calculations with B3LYP functional. It is shown that calculations provide reliable results when the extended aug-cc-pCVTZ basis set is used for fluorine atoms; however, specially tailored basis sets such as EPR-III also give very similar results with only a fraction of the computational cost. Absorption spectra of the anions exhibit NIR absorption bands, whose assignment is provided by time-dependent DFT calculations.

The recently isolated TiSc(2)N@C(80) was used to study the spin state of a Ti(3+) ion in a mixed metal nitride cluster in a fullerene cage. The electronic state of the new clusterfullerene is characterized starting with the redox behavior of this structure. It differs markedly from that of homometallic nitride clusterfullerenes in giving reversible one-electron transfers even on the cathodic scale. Both oxidation and reduction of TiSc(2)N@C(80) occur at the endohedral cluster changing the valence state of Ti from Ti(II) in anion to Ti(IV) in cation. The unpaired electron in TiSc(2)N@C(80) is largely fixed at the Ti ion as shown by low temperature ESR measurements. Isotropic g-factor 1.9454 points to the significant spin-orbit coupling with an unquenched orbital momentum of the 3d electron localized on Ti. Measurements with the frozen solution also point to the strong anisotropy of the g-tensor. DFT computations show that the cluster can adopt several nearly isoenergetic configurations. DFT-based Born-Oppenheimer molecular dynamics (BOMD) simulations reveal that, unlike in Sc(3)N@C(80), the cluster dynamics in TiSc(2)N@C(80) cannot be described as a 3D rotation. The cluster rotates around the Ti-N axis, while the Ti atom oscillates in one position around the pentagon/hexagon edge. Evolution of the spin populations along the BOMD trajectory has shown that the spin distribution in the cluster is very flexible, and both an intracluster and cluster-cage spin flows take place. Fourier transformation of the time dependencies of the spin populations results in the spin-flow vibrational spectra, which reveal the major spin-flow channels. It is shown that the cluster-cage spin flow is selectively coupled to one vibrational mode, thus, pointing to the utility of the clusterfullerene for the molecular spin transport. Spin-flow vibrational spectroscopy is thus shown to be a useful method for characterization of the spin dynamics in radicals with flexible spin density distribution.

A detailed study on the relaxation mechanisms of higher cage fullerene sizes is done as a prerequisite for studies of the influence of the endohedral structures on fullerene cage carbon relaxation. Recent studies of the dynamic behavior of C(60) and C(70) in aromatic solvents and CS(2) solution show the influence of the shape and the symmetry of the cage to be highly important as well as the influence of the solvent to be negligible. As higher fullerene cages have more than one stable isomer, the isolation of isomeric pure structures is of high importance for a detailed study of the dynamic behavior of such fullerenes. Here we investigated the three higher fullerene cage isomers D(2)-C(76), C(2v)(3)-C(78), and D(2)-C(80) with respect to the relaxation rate of the carbons measured in their temperature dependence. Thus, we study the influence on the relaxation of the carbons and the dynamic behavior of these fullerenes in solution. Besides the diffusion dependence on the shape of the carbon cage, the relaxation behavior at lower temperatures is found to be dependent on the difference in chemical shift anisotropy within the carbon cage. This difference is originated from the changes of symmetry and results in polarization of electron density. Furthermore, the mobility of the carbons is influenced by their pyramidalization.

The row of endohedral fullerenes is extended by a new type of sulfur-containing clusterfullerenes: the metal sulfide (M(2)S) has been stabilized within a fullerene cage for the first time. The new sulfur-containing clusterfullerenes M(2)S@C(82)-C(3v)(8) have been isolated for a variety of metals (M = Sc, Y, Dy, and Lu). The UV-vis-NIR, electrochemical, and FTIR spectroscopic characterization and extended DFT calculations point to a close similarity of the M(2)S@C(82) cage isomeric and electronic structure to that of the carbide clusterfullerenes M(2)C(2)@C(2n). The bonding in M(2)S@C(82) is studied in detail by molecular orbital analysis as well as with the use of quantum theory of atom-in-molecules (QTAIM) and electron localization function (ELF) approaches. The metal sulfide cluster formally transfers four electrons to the carbon cage, and metal-sulfur and metal-carbon cage bonds with a high degree of covalency are formed. Molecular dynamics simulations show that Sc(2)S cluster exhibits an almost free rotation around the C(3) axis of the carbon cage, resulting thus in a single line (45)Sc NMR spectrum.

The redox behavior of N,N,N',N'-tetrakis(4-aminophenyl)benzidine (A) and its N,N,N',N'-tetrakis(4-methoxyphenyl)-substituted analogue (B) was studied in detail by a new designed in situ thin layer electron spin resonance (ESR)/UV-vis-NIR spectroelectrohemical cell. The spectroelectrochemical studies of cation radicals, dications, and tetracations indicate a strong difference in stability of higher ions of two model compounds with different phenyl substitution. In cyclovoltammetry the small peak separation of the first two oxidation peaks for both compounds points to a small energetic difference in the first two electron transfers, while the peak separation of the second and third peak is quite large. A well resolved ESR spectrum of the B(*+) cation radical with dominating splittings from two nitrogen atoms is observed and an ESR silent product was determined at the third oxidation peak for both compounds, confirming the formation of a tetracation by a two electron transfer at the third voltammetric peak. In contrast to structure A a more complex redox behavior was found for B under voltammetric cycling. The reaction mechanism indicates the transformation of B in a new product P with a carbazole moiety. This compound can form a highly stabilized cation radical P(*+). A theoretical study based on density functional theory calculations has clarified the role of charging in changes to the structures of both triarylamine derivatives A and B.

Y(3)C(80) obtained in the synthesis of nitride clusterfullerenes Y(3)N@C(2n) (2n = 80-88) by the reactive atmosphere method is found to be a genuine trimetallofullerene, Y(3)@C(80), with low ionization potential and divalent state of yttrium atoms. DFT studies of the electronic structure of Y(3)@C(80) show that this molecule mimics Y(3)N@C(80) with the pseudoatom (PA) instead of the nitrogen atom. Topology analysis of the electron density and electron localization function show that yttrium atoms form Y-PA bonds rather than direct Y-Y bonds. Molecular dynamics simulations show that the Y(3)PA cluster is as rigid as Y(3)N and rotates inside the fullerene cage as a single entity.

The role of the phenazine structure in the stabilization of charged states in polyaniline was studied by in situ electron spin resonance (ESR)-UV/vis-near-infrared (NIR) spectroelectrochemistry of polyaniline and the copolymers of aniline and a phenazine derivative (3,7-diamino-5-phenylphenazinium chloride, phenosafranine). It is shown that the copolymer can be prepared by electropolymerization, and its structure was confirmed by mass spectrometry and IR spectroscopy. The electrochemistry of polyaniline and its copolymer pointed to preferred stabilization of a polaron pair in the charged states at the initial charge transfer reaction instead of polarons that are formed by equilibrium reaction at higher electrode potentials. A second polaron pair is detected for higher doped states of the polymer films. A mechanism of the formation of charged states in polyaniline and their equilibrium is given. It is shown that in situ ESR-UV/vis-NIR spectroelectrochemistry is the method of choice to differentiate between polarons and polaron pairs in their potential-dependent formation. Thus, by this in situ spectroelectrochemical method the influence of phenazine structure on the formation of polarons in aniline polymers and copolymers can be followed.

The combination of NMR spectroscopy and electrochemistry provides an in situ method to measure structural changes of the redox components in an electrochemical reaction by proton NMR experiments. As the use of metal thin film radio frequency (RF) transparent electrodes in NMR spectroelectrochemical studies is limited by layer thickness and electrodes size, we present a new spectroelectrochemical NMR cell design consisting of nearly metal free symmetrically arranged large scale carbon fiber electrodes. Due to the advantages of modern NMR spectroscopy, a cell rotation is not necessary for high resolution measurements. This makes the presented cell for in situ spectroelectrochemical NMR measurements easy to prepare. The cell design is universal for a large variety of NMR spectrometers and frequencies used for detection of different nuclei. The feasibility of this new in situ NMR spectroelectrochemical cell is demonstrated in a detailed study of the electrochemical behavior of p-benzoquinone in different aqueous solutions.

Raman spectroscopy and in situ Raman spectroelectrochemistry were applied to study the selective etching of thin tubes by lithium vapor in doped single-walled carbon nanotubes (SWCNTs). A strong doping of SWCNTs after the reaction with Li vapor was confirmed by the vanishing of the radial breathing mode (RBM) and by a strong attenuation of the tangential displacement (TG) band in the Raman spectra. The Raman spectra of the Li-vapor-treated SWCNTs after subsequent reaction with water showed changes in the diameter distribution compared with that of a pristine sample (nanotubes with diameters of <1 nm disappeared from the Raman spectra). The samples were tested by the Raman pattern with five different laser lines, and a removal of narrower tubes was confirmed. The remaining wider tubes were not significantly damaged by the treatment with Li, as indicated by the D line in the Raman spectra. Furthermore, the small-diameter tubes are converted not into amorphous carbon but into lithium carbide, which could easily be removed by hydrolysis. The treated samples were further charged electrochemically. It was shown by spectroelectrochemistry that anodic charging may lead to removal of the residual chemical doping from the thicker nanotubes in the sample, but the thin nanotubes did not appear in the spectra. This is a further confirmation of the removal of the small-diameter tubes.

A recently developed rotating spectroelectrochemical cell for in situ Raman spectroscopic studies of photoreactive compounds without marked decomposition of the sample is presented. Photochemically and thermally sensitive redox systems are difficult to be studied under stationary conditions by in situ spectroelectrochemistry using laser excitation as in Raman spectroscopy. A rotating spectroelectrochemical cell can circumvent these difficulties. It can be used for any type of a planar electrode and for all electrode materials in contact with aqueous or nonaqueous solutions as well as with ionic liquids. The innovative technical solution consists of the precession movement of the spectroelectrochemical cell using an eccentric drive. This precession movement allows a fixed electrical connection to be applied for interfacing the electrochemical cell to a potentiostat. Hence, any electrical imperfections and noise, which would be produced by sliding contacts, are removed. A further advantage of the rotating cell is a dramatic decrease of the thermal load of the electrochemical system. The size of the spectroelectrochemical cell is variable and dependent on the thickness of the cuvettes used ranging up to approximately 10 mm. The larger measuring area causes a higher sensitivity in the spectroscopic studies. The as constructed spectroelectrochemical cell is easy to handle. The performance of the cell is demonstrated for ordered fullerene C(60) layers and the spectroelectrochemical behavior of nanostructured fullerenes. Here the charge transfer at highly ordered fullerene C(60) films was studied by in situ Raman spectroelectrochemistry under appropriate laser power and accumulation time without marked photodecomposition of the sample.

A combined spectroelectrochemical study by ESR/UV-vis-NIR as well as FTIR spectroscopy on the influence of the copolymer composition on the stabilization of charges upon electrochemical p-doping is presented. As compared to the parent homopolymers 3-hexylthiophene (3-HeTh) and 3-methylthiophene (3-MeTh) which seems to be irregular, FTIR studies of the copolymer of both monomers (copMeHeTh) point to a regioregular structure. The in situ ESR and UV-vis-NIR spectroelectrochemistry at higher doping levels of the polymeric materials proves bipolarons and polaron pairs as stable charged states in poly(3-hexylthiophene) as well as the copolymer copMeHeTh. During the p-doping of poly(3-methylthiophene) bipolarons are the dominating species at higher doping levels. It is demonstrated that only the simultaneous use of both the ESR and the UV-vis-NIR spectroscopy enables the differentiation of polarons (paramagnetic) and polaron pairs (diamagnetic) in a conducting polymer.

The first spectroscopic characterization of the dimeric dicationic fullerene complex [(C(70))(2)](2+)(Ti(3)Cl(13))(-)(2) is reported and supported by DFT calculations. The IR spectrum of the dimer is interpreted in terms of the normal modes of the pristine C(70), and the effects of charging C(70) and the intercage bond formation between C(70) units on the IR spectrum are discussed. Analysis of the vibrational spectrum of the anion, Ti(3)Cl(13)(-), is also provided. NIR absorption and fluorescence spectra of the complex are studied, and the dimer is shown to have a small HOMO-LUMO gap of 0.8 eV. The electronic structure of [(C(70))(2)](2+) is studied with the use of DFT and compared to that of the other single-bonded fullerene dimers, including [(C(70))(2)](2-), (C(69)N)(2), and [(C(60))(2)](2-). Characteristic features in the vibrational spectra and electronic structure of all single-bonded fullerene dimers are revealed.

DFT calculations of Sc(3)N@C(80) in the neutral and anionic states are performed which revealed that in the neutral state of the nitride clusterfullerene the lowest energy structure has C(3) symmetry, while in the anionic and dianionic states the C(3v) conformer has the lowest energy. Barriers to the cluster rotation inside the cage are also found to increase in the charge states. The (45)Sc hyperfine slitting constant, a(Sc), in Sc(3)N@C(80) anion radical is calculated by different theoretical approaches and in different conformations of Sc(3)N cluster. It is found that a(Sc) is strongly dependent on the cluster orientation with respect to the cage, covering a range form -10 to +25 Gauss at the B3LYP/6-311G*//PBE/TZ2P level of theory. A thorough analysis of the computed values as well as comparison of unrestricted and orbital-restricted calculations revealed that the polarization contribution to a(Sc) is about -10 Gauss and does not depend on the cluster orientation. Dependence of the predicted a(Sc) values on the density functional form (LSDA, BP, PBE, BLYP, OLYP, TPSS, B3LYP, and TPSSh), the basis set, as well as on the scalar-relativistic and spin-orbit corrections were investigated. The analysis of the charge distribution in the Sc(3)N@C(80)(-) anion radical revealed an interesting peculiarity of its electronic structure: while the spin density mostly resides on the cluster, only a slight decrease of its charge is found using both Bader and Mulliken definitions of atomic charges. A set of other endohedral metallofullerenes, including nitride clusterfullerenes Sc(3)N@C(2n) (2n = 68, 70, 78) and Y(3)N@C(2n) (2n = 78-88), carbide clusterfullerenes Sc(2)C(2)@C(68), Sc(2)C(2)@C(82), Sc(3)C(2)@C(80), Ti(2)C(2)@C(78), Y(2)C(2)@C(82), and dimetallofullerenes Sc(2)@C(76), Y(2)@C(82), La(2)@C(2n) (2n = 72, 78, 80), was also studied in the neutral and anionic state, and a spatial charge-spin separation is found to be a general rule for all endohedral fullerenes with high contribution of metal atoms to the LUMO.

In situ spectroelectrochemistry is of high importance for the characterization of doping reactions in pi-conjugated polymers. In this paper we present the results of simultaneous ESR and UV-vis-NIR measurements performed in situ during electrochemical p- and n-doping of polyazulene (PAz). In previous studies on p-doping of PAz the assignment of the optical absorption bands to specific charge carriers have been somewhat controversial, therefore the aim of this study is to clarify the nature of the doping-induced charge carriers and their corresponding optical absorption bands by in situ ESR-UV-vis-NIR spectroelectrochemistry. PAz was polymerized in two different potential ranges in order to obtain films with different structures and morphologies. On the basis of our spectroelectrochemical results we propose that polarons and polaron pairs are formed during p-doping in the two different types of PAz films electrodeposited on ITO. For studying n-doping of PAz, a Pt electrode was used. The ESR signal first decreased in intensity at low doping levels and then increased in intensity at higher doping levels pointing to the formation of new paramagnetic species. At high negative potentials there occurred an additional line broadening of the ESR signal indicating the existence of rather localized negative charge carriers.

The redox behavior of Sc 3N@C 68 is studied systematically by means of electrochemistry, in situ ESR/Vis-NIR spectroelectrochemistry, and detailed theoretical treatment. Formation of the negatively and positively charged paramagnetic species for the same trimetallic nitride endohedral fullerene is demonstrated for the first time. The electrochemical study of Sc 3N@C 68 exhibits two electrochemically irreversible but chemically reversible reduction steps and two reversible oxidation steps. A double-square reaction scheme is proposed to explain the observed redox reaction at cathodic potentials involving the reversible dimerisation of the Sc 3N@C 68 monoanion. The spin state of the radical cation and the radical anion is probed by ESR spectroscopy, indicating that in both states, the large part of the unpaired spin is delocalized on the fullerene cage. The charged states of the non-isolated pentagon rule fullerene are characterized furthermore by in situ absorption spectroscopy. The interpretation of experimental data is supported by the density functional theory (DFT) calculations of the spin distribution in the anion and cation radicals of Sc 3N@C 68 and time-dependent DFT calculations of the absorption spectra of the charged species.

The detailed analysis of the in situ Raman spectroelectrochemical behavior of single walled carbon nanotube (SWCNT) bundles is presented. The Raman modes of metallic SWCNTs exhibit striking changes even before the potential of the first van Hove singularity is achieved. Special attention has been paid to the development of the tangential (TG) mode broadening, which subsequently vanishes if the potential is shifted away from V = 0. The tangential mode band has been fitted by four components. During the electrochemical doping, three components of the tangential mode follow the predictions of a theoretical model for the LO modes of metallic tubes based on the Kohn anomaly. On the other hand, the behavior of the fourth component is consistent with a model based on electron-plasmon coupling. The TO mode of metallic tubes has been identified only at a doping level corresponding to 1.0 V or above. Our results also indicate an asymmetry in the behavior of the TG mode for positive electrode potentials relative to negative ones.

The first non-IPR C(76) cage based on a mixed metal nitride cluster, DySc(2)N@C(76), was successfully synthesized and isolated. DySc(2)N@C(76) is a stable fullerene with a small band gap of 0.96 eV. According to the FTIR spectroscopic study in combination with extensive DFT calculations, the cage structure of DySc(2)N@C(76) has been assigned to the non-IPR C(s): 17490-I isomer having two pairs of the adjacent pentagons. DySc(2)N@C(76)provides the first example of stabilization of the non-IPR C(76) cage by encapsulation of an asymmetric DySc(2)N mixed cluster, revealing the role of the cluster structure on the stability of the fullerene cage. As the asymmetric DySc(2)N cluster has a more suitable geometry for the inner space of the C(76) cage compared to that of the homogeneous clusters like Sc(3)N or Dy(3)N, the highest yield for C(76)-based cluster fullerenes with the Dy(x)Sc(3)-(x)N mixed nitride cluster is achieved for the DySc(2)N@C(76)

In situ Raman spectroelectrochemistry has been used to distinguish between thin single-wall carbon nanotubes (SWCNT) and the inner tubes of double-wall carbon nanotubes (DWCNT). The spectroelectrochemical method is based on the different change of the electronic structure of the inner tube in DWCNT and that of SWCNT during electrochemical charging, which is reflected in the Raman spectra. During electrochemical charging the inner tubes of DWCNT exhibit a delayed attenuation of the intensities of their Raman modes as referred to the behavior of SWCNT of similar diameter. The changes are pronounced for the radial breathing mode (RBM), and thus, these modes are diagnostic for the distinction of inner tubes of DWCNT from the thin SWCNT. The different sensitivities of inner and outer tubes to the applied electrochemical charging is a simple analytical tool for differentiation of SWCNT and DWCNT in a mixture. The significance of the proposed method is demonstrated on a commercial DWCNT sample.

It is shown for the first time that the most important intermediate formed during aniline polymerization, the p-aminodiphenylamine, forms a pi-dimer under oxidation at room temperature in acidified organic solvents that are used in electropolymerization. N-Phenylquinonediimine, which is generally assumed to be formed under oxidation, is only formed in basic solutions and in ionic liquids. Most of the mechanistic studies reported so far take the formation of N-phenylquinonediimine under consideration, although it is not consistent with the UV-vis spectra measured during oxidation of p-aminodiphenylamine. The formation of a pi-dimer is very well consistent with the electronic spectra of the oxidation product. In this way the pi-dimer is very important for the interpretation of the UV-vis spectra of higher oligomers and polyaniline as well. Furthermore, it offers a new interpretation of the redox behavior of p-aminodiphenylamine as found by cyclic voltammetry and has to be considered in the mechanism of the electrochemical polyaniline formation.

Extensive semiempirical calculations of the hexaanions of IPR (isolated pentagon rule) and non-IPR isomers of C(68)-C(88) and IPR isomers of C(90)-C(98) followed by DFT calculations of the lowest energy structures were performed to find the carbon cages that can provide the most stable isomers of M(3)N@C(2n) clusterfullerenes (M = Sc, Y) with Y as a model for rare earth ions. DFT calculations of isomers of M(3)N@C(2n) (M = Sc, Y; 2n = 68-98) based on the most stable C(2n)(6-) cages were also performed. The lowest energy isomers found by this methodology for Sc(3)N@C(68), Sc(3)N@C(78), Sc(3)N@C(80), Y(3)N@C(78), Y(3)N@C(80), Y(3)N@C(84), Y(3)N@C(86), and Y(3)N@C(88) are those that have been shown to exist by single-crystal X-ray studies as Sc(3)N@C(2n) (2n = 68, 78, 80), Dy(3)N@C(80), and Tb(3)N@C(2n) (2n = 80, 84, 86, 88) clusterfullerenes. Reassignment of the carbon cage of Sc(2)@C(76) to the non-IPR Cs: 17490 isomer is also proposed. The stability of nitride clusterfullerenes was found to correlate well with the stability of the empty 6-fold charged cages. However, the dimensions of the cage in terms of its ability to encapsulate M(3)N clusters were also found to be an important factor, especially for the medium size cages and the large Y(3)N cluster. In some cases the most stable structures are based on the different cage isomers for Sc(3)N and Y(3)N clusters. Up to the cage size of C(84), non-IPR isomers of C(2n)(6-) and M(3)N@C(2n) were found to compete with or to be even more stable than IPR isomers. However, the number of adjacent pentagon pairs in the most stable non-IPR isomers decreases as cage size increases: the most stable M(3)N@C(2n) isomers have three such pairs for 2n = 68-72, two pairs for n = 74-80, and only one pair for n = 82, 84. For C(86) and C(88) the lowest energy IPR isomers are much more stable than any non-IPR isomer. The trends in the stability of the fullerene isomers and the cluster-cage binding energies are discussed, and general rules for stability of clusterfullerenes are established. Finally, the high yield of M(3)N@C(80) (Ih) clusterfullerenes for any metal is explained by the exceptional stability of the C(80)(6-) (Ih: 31924) cage, rationalized by the optimum distribution of the pentagons leading to the minimization of the steric strain, and structural similarities of C(80) (Ih: 31924) with the lowest energy non-IPR isomers of C(760(6-), C(78)(6-), C(82)(6-), and C(84)(6-) pointed out.

The frontier orbitals of 22 isolated and characterized C(60)(CF(3))(n) derivatives, including seven reported here for the first time, have been investigated by electronic spectroscopy (n = 2 [1], 4 [1], 6 [2], 8 [5], 10 [6], 12 [3]; the number of isomers for each composition is shown in square brackets) fluorescence spectroscopy (n = 10 [4]), cyclic voltammetry under air-free conditions (all compounds with n

Molecular structures of Dy(3)N@C(78) and Tm(3)N@C(78) clusterfullerenes are addressed by the IR and Raman vibrational spectroscopic studies and density functional theory (DFT) computations. First, extensive semiempirical calculations of 2927 isomers of C(78) hexaanions followed by DFT optimization were applied to establish their relative stability. Then, DFT calculations of a series of M(3)N@C(78) (M = Sc, Y, Lu, La) isomers were performed which have shown that the stability order of the isomers depends on the cluster size. While the Sc(3)N cluster is planar in the earlier reported Sc(3)N@C(78) (D(3)h: 24,109) clusterfullerenes, relatively large Y(3)N and Lu(3)N clusters would be forced to be pyramidal inside this cage, which would result in their destabilization. Instead, these clusters remain planar in the nonisolated pentagon rule (non-IPR) C(2): 22,010 isomer making Y(3)N@C(78) and Lu(3)N@C(78) clusterfullerenes with this cage structure the most stable ones. Finally, on the basis of a detailed analysis of their IR and Raman spectra supplemented with DFT vibrational calculations, the recently isolated Tm(3)N@C(78) and the major isomer of Dy(3)N@C(78) are assigned to the non-IPR C(2): 22,010 cage structure. A detailed assignment of their experimental and computed IR and Raman spectra is provided to support this conclusion and to exclude other cage isomers.

The high-yield synthesis of Dy3N@C80 (I) opens the possibility of characterizing its molecular and vibrational structures. We report on the structure determination of Dy3N@C80 (I) by X-ray crystallographic study of single crystal of Dy3N@C80.Ni(OEP).2C6H6, revealing a nearly planar Dy3N cluster encapsulated in an Ih-C80 cage. The vibrational structure of Dy3N@C80 (I) is studied by Fourier transform infrared (FTIR) and Raman spectroscopy in combination with force-field calculations. A correlation was found between the antisymmetric metal-nitrogen stretching vibration and the structure of the M3N cluster of M3N@C80 (I) (M = Y, Gd, Tb, Dy, Ho, Er, Tm). Moreover, a stronger interaction between the encaged nitride cluster and the C80 carbon cage was found in the class II M3N@C80 (I) (M = Y, Gd, Tb, Dy, Ho, Er, Tm) than in Sc3N@C80 (I). This study demonstrates that the cluster size plays the dominating role in the structure of the M3N cluster in M3N@C80 (I).

Unconventional fullerenes are those smaller than C(60) or those intermediate between C(60) and C(70), which are not stable in structure as none of the unconventional fullerene isomers satisfying the "isolated-pentagon-rule" (IPR). Below we report the synthesis of a stable unconventional fullerene derivative C(64)H(4) by introducing methane in the fullerene productions with the normal Krätschmer-Huffman method. We also applied various spectroscopic measurements such as mass spectrometry, (13)C NMR, IR, UV-vis absorption spectrometry, etc. to characterize the structural and electronic properties of this molecule, revealing an unprecedented fullerene cage with a triplet of directly fused pentagons in the framework of C(64)H(4). Four hydrogen atoms are added to the carbons at vertexes of fused pentagons to allow the bond angles at these sites close to the sp(3) tetrahedral angle, which essentially release the sp(2) bond strains on the abutting-pentagon sites of C(64). Ab initio calculations were performed to explore the electronic property and simulate the (13)C NMR and IR spectra of this fulleride, which reproduced well the experimental results and confirmed the structural assignment of the C(64)H(4).

A new homologous series of alpha,alpha'-bis(diphenylamino)-capped oligothiophenes, prepared by a palladium-catalyzed coupling reaction of stannylated 2-diphenylaminothiophenes with 2-mono- or 2,5-dibromothiophenes and their homologues, was studied by in situ ESR/UV-vis/NIR spectroelectrochemistry. In general, the oxidation potentials of these oligothiophenes were found to be proportional to the inverse number of thiophene units. However, the potential slope of the first oxidation is completely different from that of higher oxidation steps. Trication radicals were identified by electron spin resonance (ESR) for higher thiophene homologues in addition to monocation radicals (polarons). According to the ESR hyperfine structures, the unpaired electron is delocalized in the conjugated system. In contrast to the parent alpha,alpha'-bis(diphenylamino)-capped oligothiophenes, the UV-vis/NIR absorption maxima of the oxidized species strongly depend on the number of thiophene units. Spin-restricted and spin-unrestricted Kohn-Sham density functional calculations were used to explain and to understand these properties. Absorption wavelength and intensities were calculated by the time-dependent density functional response theory. Unrestricted density functional calculations of oligothiophene dications (bipolarons) with five or more thiophene rings result in spin-broken structures which may be considered as two-polaron biradicals (polaron pairs).

Poly(3,4-ethylenedithiathiophene) (PEDTT) is a polythiophene-like conjugated polymer in which each thiophene ring is functionalized with an ethylenedithia bridge. As such, PEDTT is the sulfur analogue of the well-known poly(3,4-ethylenedioxythiophene) (PEDOT). Substituent effects, namely the presence of sulfur atoms in PEDTT replacing the oxygen atoms of PEDOT, do not provide a simple explanation for the different electronic properties of the two polymers in the neutral state. This paper reports the spectroscopic properties of PEDTT, studied by in situ techniques such as IR-, Vis-, and electron spin resonance (ESR) spectroelectrochemistry. The differences observed upon electrochemical oxidation of PEDTT and PEDOT (e.g., the different infrared active vibrational band patterns in IR spectroelectrochemistry as well as the different nature of the charged states) are even more marked than those observed in the neutral state. These results, with AM1 calculations, indicate conformational effects as a possible explanation for the different electronic and spectroscopic properties of PEDTT and PEDOT.

Raman spectra of electrochemically charged single-wall carbon nanotubes (HiPco) were studied by five different laser photon energies between 1.56 and 1.92 eV. The bands of radial breathing modes (RBM) were assigned to defined chiralities by using the experimental Kataura plot. The particular (n,m) tubes exhibit different sensitivity to electrochemical doping, monitored as the attenuation of the RBM intensities. Tubes which are in good resonance with the exciting laser exhibit strong doping-induced drop of the RBM intensity. On the other hand, tubes whose optical transition energy is larger than the energy of an exciting photon show only small changes of their RBM intensities upon doping. This rule presents a tool for analysis of mixtures of single-walled carbon tubes of unknown chiralities. It also asks for a re-interpretation of some earlier results which were reported on the diameter-selectivity of doping. The radial breathing mode in strongly n- or p-doped nanotubes exhibited a blue-shift. A suggested interpretation follows from the charging-induced structural changes of SWCNTs bundles, which also includes a partial de-bundling of tube ropes.

The electronic and vibrational structure of the nitride clusterfullerene Tm3N@C80 (I) was investigated by cyclic voltammetry, FTIR, Raman, and X-ray photoemission spectroscopy. The electrochemical energy gap of Tm3N@C80 (I) is 1.99 V, which is 0.13 V larger than that of Sc3N@C80 (I). FTIR spectroscopy showed that the C80:7 (I(h)) cages in Tm3N@C80 (I), Er3N@C80 (I), Ho3N@C80 (I), Tb3N@C80 (I), Gd3N@C80 (I), and Y3N@C80 (I) have the same bond order. The analysis of low-energy Raman spectra points to two uniform force constants which can be used to describe the interaction between the encaged nitride cluster and the C80:7 (I(h)) cage in M3N@C80 (I) (M = Tm, Er, Ho, Tb, Gd, and Y). Because the M3N-C80 bond strength is strongly dependent on the charge of the metal ions, this is a direct hint for a 3+ formal valence state of the metal ions in these nitride clusterfullerene series, including Tm3N@C80 (I). Photoemission spectra of the Tm 4d core level and the Tm 4f valence electrons provided a direct proof for a (4f)12 electronic configuration of the encapsulated thulium. In conclusion, thulium in Tm3N@C80 (I) has a formal electronic ground state of +3, in contrast to the +2 state found in Tm@C82. It is demonstrated that the valence state of metal atoms encaged in fullerenes can be controlled by the chemical composition of the endohedral fullerene.

In this letter, we show for the first time the use of metal oxides as catalysts in the synthesis of single-walled carbon nanotubes (SWCNTs) using laser ablation. Further, SWCNTs have been synthesized at low temperature (down to room temperature), where their nucleation cannot be explained via fullerene nucleation. The data point to a nucleation mechanism previously not identified, that places a stable oxidized ring as the root cause for the growth of SWCNTs.

Dysprosium-based trimetallic nitride endohedral fullerenes (clusterfullerenes)-the Dy(3)N@C(2)(n) (38

In situ ESR, UV-visible, and FT-IR-ATR spectroelectrochemistry were used to study the charge transfer for electrochemically synthesized poly(N,N'-ethylenebis(salicylideneiminato)Cu(II)), which represents a macromolecular metal chelate with ESR-active central metal ions. Structural evidence for different charged states in electroactive poly(Cu(II)-salen) was obtained from ESR, UV-visible, and FT-IR spectra under reversible redox cycling. The changes in a characteristic broad ESR line without hyperfine splitting originating from Cu(II) as well as in the corresponding UV-visible and infrared spectra are discussed in order to describe an electron transfer to the redox-active sites within the polymer chains in detail.