Search results for "Donor"

Strong donor–acceptor couplings in a special pair-antenna model

2010

A special pair model composed of two cofacial zinc porphyrins (acceptor) linked to a free base (donor) acts as an energy transfer dyad. Despite the absence of conjugation, ππ*/charge transfer excited states and ultrafast energy transfer (∼5 ps) are noted.

Large Quadratic Hyperpolarizabilities with Donor–Acceptor Polyenes Exhibiting Optimum Bond Length Alternation: Correlation Between Structure and Hype…

1997

Donor-acceptor polyenes of various lengths, and that combine aro- matic electron-donating moieties with powerful heterocyclic electron-withdraw- ing terminal groups, have been synthe- sized and characterized as efficient non- linear optical (NLO) chromophores. Their linear and nonlinear optical proper- ties have been investigated, and variations in these properties have been related to ground-state polarization (dipole p) and structure. In particular, unprecedented quadratic hyperpolarizabilities (p) have been achieved (up to p(0) =I500 x 10-30esu) by reduction of the bond- length alternation (BLA) in the polyenic chain. In each series of homologous com-

Extension of Conjugation Leading to Bathochromic or Hypsochromic Effects in OPV Series

2004

Four OPV series 1-4 (a-d) with a terminal dialkylamino group as electron donor were prepared by Wittig-Horner reactions. To study the influence of the push-pull effect on the long-wavelength absorption, three of the four series contained terminal acceptor groups (CN, CHO, NO(2)). The length of the chromophores strongly affects the intramolecular charge transfer (ICT)-an effect which superimposes upon the extension of the conjugation. Increasing numbers n of repeat units cause an overall bathochromic shift for the purely donor-substituted series 1 a-4 a and the series 1 b-4 b with CN as weak acceptor. The two effects annihilate each other in the series 1 c-4 c with terminal CHO groups, so th…

Tantalocenehydridephosphorus chemistry.

2002

Abstract The aim of this paper is to look for a better knowledge of the behaviour of bent tantalocenes that bear hydrides, phosphorus PR2X (R=Me, Ph; X=H, lone pair) and cyclopentadienyl (Cp=C5H5, Cp′=C5H2tBu(Me)2, Cp*=C5Me5) ligands. An orbital control of regioselectivity of insertion of the PR2 phosphide fragment of chlorophosphines PR2Cl into the central TaH bond of trihydrides Cp2TaH3 leading to the formation of metallophosphonium cations is discussed. Neutralisation of cationic complexes with strong bases leads either to the Ta(V)–phosphide or to the Ta(III)–phosphine species depending on the nature of the cyclopentadienyl ligand; good electron donor Cp′ and Cp* rings favour the forma…

Oligo(phenylenvinylene) mit terminaler Donor-Acceptor-Substitution

2002

ProC Global: the first functional screening assay for the complete protein C pathway.

1997

Abstract In clinical practice, venous thromboembolic complications are much more frequent than bleeding disorders. In fact, disturbances within the protein C pathway due to coagulation factor V (FV) Leiden mutation and deficiency of protein C or protein S are the most frequent abnormalities in hereditary thrombophilia. Furthermore, acquired dysfunctions of the protein C system may predispose the single individual to an increased thrombotic risk. A routine-suited screening assay that would allow the monitoring of the proper interplay of factors in the protein C pathway could add an important factor to the basic coagulation profile. This consists of the prothrombin time and of the activated p…

Extended pancreas donor program – the EXPAND study rationale and study protocol

2013

Background Simultaneous pancreas kidney transplantation (SPK), pancreas transplantation alone (PTA) or pancreas transplantation after kidney (PAK) are the only curative treatment options for patients with type 1 (juvenile) diabetes mellitus with or without impaired renal function. Unfortunately, transplant waiting lists for this indication are increasing because the current organ acceptability criteria are restrictive; morbidity and mortality significantly increase with time on the waitlist. Currently, only pancreas organs from donors younger than 50 years of age and with a body mass index (BMI) less than 30 are allocated for transplantation in the Eurotransplant (ET) area. To address this …

Tuning of the photoinduced charge transfer process in donor-acceptor "double cable" copolymers

2003

The covalent linking of acceptor molecules to electron donating conjugated polymer is an approach for the development of new photoactive materials for the fabrication of organic photoelectric conversion devices. With this strategy we have designed a polyalkylthiophene copolymer series containing in the side chain anthraquinone molecules as electron acceptor. The peculiar features of the copolymers are the good processability and the ease in tailoring the content of acceptor moieties. Their potential use as photoactive materials is investigated in terms of the photoinduced charge transfer properties, studied by FTIR photoinduced absorption and Light Induced Electron Spin Resonance spectrosco…

¿Conjugated? Copolymers from a Pechmann Dye Derivative

2016

A Straightforward Electroactive π-Extended Tetrathiafulvalene (exTTF) Building Block

2012

The synthesis and X-ray structure of a new and readily available exTTF derivative (6) bearing a methyltriphenylphosphonium bromide moiety as a new building block for the construction of electroactive molecules is reported. The phosphonium salt 6, which was prepared in one step from 2-hydroxymethyl-exTTF as a stable yellow solid in 84 % yield, efficiently undergoes Wittig olefination reactions with a variety of aldehydes to predominantly form the E isomer. Electronic spectra and cyclic voltammetry of the novel compounds reveal the electronic communication between the electroactive units.