Development of Dendrimers: Macromolecules for Use in Organic Light-Emitting Diodes and Solar Cells
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ABSTRACT: The interaction of poly(amidoamine)-G3 (PAMAM-G3) dendrimer with nicotinic acid (NA) was investigated by using molecular dynamics (MD) simulations. First, sample free energy profiles of NA crossing PAMAM-G3 at pH 6 and 3 were computed using the adaptive biasing force (ABF) method. We found that PAMAM-G3 provides a more appropriate environment for NA inclusion when internal tertiary amine groups are unprotonated (at pH 6). However, when internal tertiary amine groups are protonated (at pH 3), the PAMAM cavities are less hydrophobic; therefore the drug-dendrimer interactions become similar to drug-solvent interactions. Traditional MD simulations were also performed to investigate the structural stability of the PAMAM-NA complexes near the free energy minima at pH 6. We found that association of NA and PAMAM adopts a preferred binding mode around the surface of PAMAM, where hydrogen bond (HB) interactions with the amino and amide NH groups of the nearby monomers are established. These interactions are very stable whether additional van der Waals interactions between pyridine ring of NA and methylene groups of the more external monomers of PAMAM are established.Journal of molecular graphics & modelling 11/2012; 39C:71-78. DOI:10.1016/j.jmgm.2012.11.003 · 2.02 Impact Factor
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ABSTRACT: a b s t r a c t A new thieno[3,2-b]thiophenediketopyrrolopyrrole-benzo[1,2-b:4,5-b 0 ]dithiophene based narrow optical gap co-polymer (PTTDPP-BDT) has been synthesized and characterized for field-effect transistors and solar cells. In field-effect transistors the polymer exhibited ambipolar charge transport behaviour with maximum hole and electron mobilities of 10 À3 cm 2 V À1 s À1 and 10 À5 cm 2 V À1 s À1 , respectively. The respectable charge transporting properties of the polymer were consistent with X-ray diffraction measurements that showed close molecular packing in the solid state. The difference in hole and electron mobilities was explained by density functional theory calculations, which showed that the highest occupied molecular orbital was delocalized along the polymer backbone with the lowest unoccupied molecular orbital localized on the bis(thieno[3,2-b]thiophene)dike-topyrrolopyrrole units. Bulk heterojunction photovoltaic devices with the fullerene accep-tor PC 70 BM were fabricated and delivered a maximum conversion efficiency of 3.3% under AM1.5G illumination.Organic Electronics 07/2012; 13(10). DOI:10.1016/j.orgel.2012.05.046 · 3.68 Impact Factor
- Stoichiometry and Research - The Importance of Quantity in Biomedicine, 03/2012; , ISBN: 978-953-51-0198-7