Joachim Bargon

Bio: Joachim Bargon is an academic researcher from University of Bonn. The author has contributed to research in topics: Catalysis & CIDNP. The author has an hindex of 34, co-authored 173 publications receiving 4625 citations. Previous affiliations of Joachim Bargon include IBM.

Electrochemical studies of some conducting polythiophene films

Abstract: Polythiophene and ..beta..-substituted polythiophenes are prepared by electrochemical oxidation and polymerization of their respective monomers. A property-structure correlation between monomers and their corresponding polymers is obtained by systematic variation of the chemical structure of the monomers. Film growth and conductivities are dependent on ..beta..-substituents, with conductivity of the order of 1 ohm/sup -1/ cm/sup -1/ obtained for poly(..beta..-methylthiophene).

Para hydrogen induced polarization in hydrogenation reactions

Abstract: Hydrogenation de composes acetyleniques ou ethyleniques en presence de complexes de rhodium carbonyle ou de palladium

Substituent effects in the electropolymerization of aromatic heterocyclic compounds

Abstract: Oxydation electrochimique de l'indole, d'indoles substitues et de thianaphtene donnant des polymeres semiconducteurs avec des conductivites de 10 −2 ohm −1 cm −1 . Les effets electroniques induits par les substituants sont etudies par calculs d'orbitale moleculaire INDO

Efficient NMR Pulse Sequences to Transfer the Parahydrogen-Induced Polarization to Hetero Nuclei

Abstract: The PASADENA or PHIP effect originates from the breakdown of the parahydrogen symmetry when the two protons are found in magnetically inequivalent positions after hydrogenation. As a result, a signal enhancement of up to 104 in the proton NMR spectra can be observed. We introduce three polarization transfer techniques, namely PH-INEPT, PH-INEPT+, and INEPT(+π/4), that are highly effective to record in situ hetero NMR spectra of parahydrogen-labeled compounds. A complete product operator treatment as well as experimental results for 13C and 29Si have been given. With these sequences we obtained a signal enhancement of 500 which allows in situ NMR investigations of hetero nuclear systems at natural abundance.

The Development of L2X2RuCHR Olefin Metathesis Catalysts: An Organometallic Success Story

Abstract: In recent years, the olefin metathesis reaction has attracted widespread attention as a versatile carbon−carbon bond-forming method. Many new applications have become possible because of major advances in catalyst design. State-of-the-art ruthenium catalysts are not only highly active but also compatible with most functional groups and easy to use. This Account traces the ideas and discoveries that were instrumental in the development of these catalysts, with particular emphasis on (PCy3)2Cl2RuCHPh and its derivatives. The discussion includes an analysis of trends in catalyst activity, a description of catalysts coordinated with N-heterocyclic carbene ligands, and an overview of ongoing work to improve the activity, stability, and selectivity of this family of L2X2RuCHR complexes.

Electrochemically Active Polymers for Rechargeable Batteries.

Abstract: Electrochemical energy storage systems (batteries) have a tremendous role in technical applications In this review the authors examine the prospects of electroactive polymers in view of the properties required for such batteries Conducting organic polymers are considered here in the light of their rugged chemical environment: organic solvents, acids, and alkalis The goal of the present article is to provide, first of all in tabular form, a survey of electroactive polymers in view of potential applications in rechargeable batteries It reviews the preparative methods and the electrochemical performance of polymers as rechargeable battery electrodes The theoretical values of specific charge of the polymers are comparable to those of metal oxide electrodes, but are not as high as those of most of the metal electrodes normally used in batteries Therefore, it is an advantage in conventional battery designs to use the conducting polymer as a positive electrode material in combination with a negative electrode such as Li, Na, Mg, Zn, MeH{sub x}, etc 504 refs

Platinum Group Organometallics Based on “Pincer” Complexes: Sensors, Switches, and Catalysts

Abstract: Since the first reports in the late 1970s on transition metal complexes contain- ing pincer-type ligands—named after the particular coordination mode of these ligands—these systems have at- tracted increasing interest owing to the unusual properties of the metal centers imparted by the pincer ligand. Typical- ly, such a ligand comprises an anionic aryl ring which is ortho,ortho-disubsti- tuted with heteroatom substituents, for example, CH2NR2 ,C H 2PR2 or CH2SR, which generally coordinate to the met- al center, and therefore support the MC s bond. This commonly results in a terdentate and meridional coordina- tion mode consisting of two metalla- cycles which share the MC bond. Detailed studies of the formation and the properties of a large variety of pincers containing platinum group metal complexes have provided direct access to both a fundamental under- standing of a variety of reactions in organometallic chemistry and to a range of new applications of these complexes. The discovery of alkane dehydrogenation catalysts, the mecha- nistic elucidation of fundamental transformations (for example, CC bond activation), the construction of the first metallodendrimers for sustain- able homogeneous catalysis, and the engineering of crystalline switches for materials processing represent only a few of the many highlights which have emanated from these numerous inves- tigations. This review discusses the synthetic methodologies that are cur- rently available for the preparation of platinum group metal complexes con- taining pincer ligands and especially emphasizes different applications that have been realized in materials science such as the development and engineer- ing of sensors, switches, and catalysts.

Metal and Metal Oxide Nanoparticles in Chemiresistors: Does the Nanoscale Matter?

Abstract: Sensor technology is one of the most important key technologies of the future with a constantly increasing number of applications, both in the industrial and in the private sectors. More and more gas sensors are used for the control of technical processes, in environment monitoring, healthcare, and automobiles. Consequently, the development of fast and sensitive gas sensors with small cross sensitivity is the subject of intense research, propelled by strategies based on nanoscience and -technology. Established systems can be improved and novel sensor concepts based on bottom-up approaches show that the sensor properties can be controlled by molecular design. This Review highlights the recent developments and reflects the impact of nanoscience on sensor technology.