Search results for "donor"

Probing molecular wire: synthesis of donor-acceptor ensembles exhibiting long range electron transfer

2005

A series of donor–acceptor arrays (C60–oligo-PPV–exTTF; 16–20) incorporating p-conjugated oligo(phenylenevinylene) wires (oligo-PPV) of different length between p-extended tetrathiafulvalene (exTTF) as electron donor and C60 as electron acceptor has been prepared by multistep convergent synthetic approaches. The electronic interactions between the three electroactive species present in 16–20 were investigated by UV-visible spectroscopy and cyclic voltammetry (CV). Our studies clearly show that, although the C60 units are connected to the exTTF donors through a p-conjugated oligo- PPV framework, no significant electronic interactions are observed in the ground state. Interestingly, photoindu…

Molecular wires - long range electron tunneling and hopping in novel donor-acceptor ensembles

2004

Enhanced electron-transfer properties of cofacial porphyrin dimers through pi-pi interactions

2009

pi-pi assisted: Photoinduced electron transfer from cofacial porphyrin dimers to electron acceptors is prominently accelerated, whereas the back electron transfer is decelerated, relative to the corresponding porphyrin monomer (see figure).The radical cation of zinc tetrapentylporphyrin is dimerized with an excess of the neutral counterpart to form the dimer radical cation in which the unpaired electron is delocalized over both porphyrin rings. The dimeric radical cation exhibits an NIR absorption spectrum characteristic of weak pi-bond formation between the porphyrin rings. When cofacial porphyrin dimers, linked by different spacers, are oxidized such pi-bond formation between the porphyri…

Electrochemical study of intramolecular charge transfer complexes derived from 1,4-naphthoquinone Part 1. Electroreduction

1995

Abstract Electrochemical investigations (polarography, cyclic voltammetry, rotating ring-disk electrode voltammetry) of intramolecular charge transfer complexes (AC) derived from 1,4-naphthoquinone were performed in acetonitrile. It is concluded that in the first one-electron stage of its electrochemical reduction the AC is in a complexed form. At the same time the amino moiety, which shows a marked inductive (−I) effect, acts as an electron donor in the donor-acceptor (D-A) interaction. Facilitation of the reduction of the quinone part by the aryl amine residue is compensated by the D-A interaction, which makes the electroreduction more difficult. By using ultramicroelectrodes it was shown…

Analysis of mebendazole binding to its target biomolecule by laser flash photolysis

2016

[EN] Mebendazole (MBZ) and related anticancer benzimidazoles act binding the beta-subunit of Tubulin (TU) before dimerization with alpha-TU with subsequent blocking microtubule formation. Laser flash photolysis (LFP) is a new tool to investigate drug-albumin interactions and to determine binding parameters such as affinity constant or population of binding sites. The aim of this study was to evaluate the interactions between the nonfluorescent mebendazole (MBZ) and its target biomolecule TU using this technique. Before analyzing the MBZ@TU complex it was needed to determine the photophysical properties of MBZ triplet excited state ((3)MBZ*) in different media. Hence, 3MBZ* showed a transien…

Retrograde in situ versus antegrade pulmonary preservation in clinical lung transplantation: a single-centre experience.

2014

OBJECTIVE Experimental and clinical studies have indicated a beneficial effect of retrograde lung preservation on post-transplant results. Accordingly, we conducted a non-randomized trial. METHODS A total of 209 consecutive recipients transplanted with low-potassium dextrane (LPD)-preserved lungs were eligible for analysis. Antegrade lung preservation (AP) was performed in 173 patients and retrograde in situ perfusion (RP) in 36 patients using low-potassium dextrane solution in all cases. The prostacycline was added to preservation solution. RESULTS The main donor, graft and recipient characteristics did not differ significantly between groups. There was a beneficial trend toward improved o…

Ab Initio Modeling of Donor–Acceptor Interactions and Charge-Transfer Excitations in Molecular Complexes: The Case of Terthiophene–Tetracyanoquinodim…

2015

This work presents a thorough quantum chemical study of the terthiophene-tetracyanoquinodimethane complex as a model for π-π donor-acceptor systems. Dispersion-corrected hybrid (B3LYP-D) and double hybrid (B2PLYP-D), hybrid meta (M06-2X and M06-HF), and recently proposed long-range corrected (LC-wPBE, CAM-B3LYP, and wB97X-D) functionals have been chosen to deal with π-π intermolecular interactions and charge-transfer excitations in a balanced way. These properties are exhaustively compared to those computed with high-level ab initio SCS-MP2 and CASPT2 methods. The wB97X-D functional exhibits the best performance. It provides reliable intermolecular distances and interaction energies and pre…

Cost-Effectiveness Analysis of Different Testing Strategies that Use Antibody Levels to Detect Chronic Hepatitis C in Blood Donors.

2016

Aim. We conducted a cost-effectiveness analysis of seven hepatitis C virus (HCV) testing strategies in blood donors. Methods. Three of the seven strategies were based on HCV diagnosis and reporting guidelines in Mexico and four were from previous and current recommendations outlined by the CDC. The strategies that were evaluated determine antibody levels according to the signal-to-cut-off (S/CO) ratio and use reflex Immunoblot (IMB) or HCV RNA tests to confirm true positive (TP) cases of chronic HCV infection. Costs were calculated from the perspective of the Mexican Institute of Social Security (IMSS). A decision tree model was developed to estimate the expected number of true positive cas…

N-Glycosyl Amides as Glycosyl Donors in Stereoselective Glycosylation Reactions

2004

Due to their high stability, N-glycosyl amides have so far not been considered as glycosyl donors for glycosylation reactions. Two new procedures for the cleavage of the anomeric amide functionality under mild reaction conditions and further stereoselective in situ conversions of the activated glycosyl donors with alcohols and amines to give β-configured O- and N-glycosides are described in this article.

Sin registro de donantes de gametos: cerca de treinta años esperando su creación

2015

En este estudio planteamos la necesidad de un registro de donantes de gametos y presentamos las claves de por qué no existe aún en España un registro de estas características. Frente a las consecuencias negativas que se pueden derivar de la inexistencia de este tipo de registro, reflexionamos sobre la conveniencia y oportunidad de crear una red de registros de donantes para la medicina del siglo XXI In this study it is stated the idea that a register for gametes donors is necessary and we identify the key points explaining why such a register does not exist in Spain. Facing the negative consequences derived from the nonexistence of register for gametes donors, we make a mental construction …