Extrem aufgeweitete Tetrathiafulvalene mit Polyen-Spacern. Carotinoide Tetrathiafulvalene. Polymethin-tetracyanotetrathiafulvalen-Radikalkationen,eine neue Klasse von Violenen

Extremely Expanded Tetrathiafulvalenes with Polyene Spacers. Carotinoid Tetrathiafulvalenes. Polymethin-Tetracyanotetrathiafulvalene Radical Cations, a New Class of Violenes The synthesis of extended tetrathiafulvalenes 11 with di-, tetra-, hexa-, octa-, deca- and dodecamethine spacers is described by a PPh₃-induced Wittig-reaction-like condensation of the corresponding polyenedials 10 with 2-thio-1,3-dithiole-4,5-dicarbonitrile ( 9 ). By the same procedure, the dimethyloctamethine- and the tetramethyl-hexadecamethine-tetrathiafulvalenes 14 and 15 , respectively, were obtained. The extended tetrathiafulvalenes represent multistep vinylogous redox systems of the ‘violene type’. They can be oxidized to give the cyanine-like radical cations, e.g. 11 _sem, 14 _sem, and 15 _sem, and the dications, e.g. 11 _ox, 14 _ox, and 15 _ox; their UV/VIS/NIR spectra are reported. The crystal and molecular structure of (all-E)-2,2′-(octa-2,4,6-trien-1,8-diylidene)bis[1,3-dithiole-4,5-dicarbonitrile] ( 11e ) was determined: it is a rod-like, planar molecule; in the crystal, it forms staples along the longest molecule axis. The CV measurements confirm that the redox potentials of 11, 14 , and 15 decrease asymptotically with the increasing length of the spacer. Because of the close relationship of the extended tetrathiafulvalenes (ETTF's) to the carotinoids, they are named ‘caroviologenes’; they formally belong to the class of molecular wires.     

Due-window assignment with identical jobs on parallel uniform machines

A scheduling problem with a common due-window, earliness and tardiness costs, and identical processing time jobs is studied. We focus on the setting of both (i) job-dependent earliness/tardiness job weights and (ii) parallel uniform machines. The objective is to find the job allocation to the machines and the job schedule, such that the total weighted earliness and tardiness cost is minimized. We study both cases of a non-restrictive (i.e. sufficiently late), and a restrictive due-window. For a given number of machines, the solutions of the problems studied here are obtained in polynomial time in the number of jobs.     

Electrocatalytic Carbon Dioxide Reduction by Using Cationic Pentamethylcyclopentadienyl–Iridium Complexes with Unsymmetrically Substituted Bipyridine Ligands

Eight [Ir(bpy)Cp*Cl]⁺‐type complexes (bpy= bipyridine, Cp*=1,2,3,4,5‐pentamethylcyclopentadienyl) containing differently substituted bipyridine ligands were synthesized and characterized. Cyclic voltammetry (CV) of the complexes in Ar‐saturated acetonitrile solutions showed that the redox behavior of the complexes could be fine tuned by the electronic properties of the substituted bipyridine ligands. Further CV in CO₂‐saturated MeCN/H₂O (9:1, v/v) solutions showed catalytic currents for CO₂ reduction. In controlled potential electrolysis experiments (MeCN/MeOH (1:1, v/v), E_app=?1.80 V vs Ag/AgCl), all of the complexes showed moderate activity in the electrocatalytic reduction of CO₂ with good stability over at least 15 hours. This electrocatalytic process was selective toward formic acid, with only traces of dihydrogen or carbon monoxide and occasionally formaldehyde as byproducts. However, the turnover frequencies and current efficiencies were quite low. No direct correlation between the redox potentials of the complexes and their catalytic activity was observed.     

Scheduling with a due-window for acceptable lead-times

Due-dates are often determined during sales negotiations in two stages: (i) in the pre-sale stage, the customer provides a time interval (due-window) of his acceptable due-dates, (ii) in the second stage, the parties agree on the delivery penalties. Thus, the contract reflects penalties of both parts of the sales negotiations: earliness/tardiness penalties of the due-dates (as a function of the deviation from the agreed upon due-window), and earliness/tardiness penalties of the actual delivery times (as a function of the deviation from the due-dates). We model this setting of a two-stage negotiation on a single machine, and reduce the problem to a well-known setting of minimizing the weighted earliness/tardiness with a given (fixed) due-window. We adopt (and correct) a pseudo-polynomial dynamic programming algorithm for this NP-hard problem. The algorithm is extended to a setting of parallel identical machines, verifying that this case remains NP-hard in the ordinary sense. Moreover, an efficient greedy heuristic and a tight lower bound are introduced and tested. Extremely small optimality gaps are obtained in our numerical tests.     

Catalytic asymmetric epoxidation of cyclic enones

A highly enantioselective epoxidation of cyclic enones with hydrogen peroxide has been developed that is catalyzed by chiral primary amine salts.     

DNA--metal base pairs

Recent developments show encouraging results for the use of DNA as a construction material for nanometer-sized objects. Today, however, DNA-based molecular nanoarchitectures are constructed with mainly unmodified or at best end-modified oligonucleotides, thus shifting the development of functionalized DNA structures into the limelight. One of most recent developments in this direction is the substitution of the canonical Watson-Crick base pairs by metal complexes. In this way "metal-base pairs" are created, which could potentially impart magnetic or conductive properties to DNA-based nanostructures. This review summarizes research which started almost 45 years ago with the investigation of how metal ions interact with unmodified DNA and which recently culminated in the development of artificial ligand-like nucleobases so far able to coordinate up to ten metal ions inside a single DNA duplex in a programmable fashion.     

Novel palladium complexes employing mixed phosphine phosphonates and phosphine phosphinates as anionic chelating [P,O] ligands

A route to various substituted phosphine phosphonic acid compounds of the general form Ar(2)PC(6)H(4)PO(OH)(2) (Ar = Ph, o-MeC(6)H(4), o-MeOC(6)H(4)) has been investigated. These compounds were employed as bidentate anionic [P,O] ligands in neutral palladium complexes. The [P,O] chelating coordination was determined by X-ray crystallography of a representative palladium complex. Furthermore, the bifunctional ligand Ph(2)PC(6)H(4)PO(OH)Ph represents the first example of a chelating anionic [P,O] ligand resulting from the combination of a phosphine and a phosphinate moiety.