22009-40-1Relevant articles and documents
Large Converse Piezoelectric Effect Measured on a Single Molecule on a Metallic Surface
Stetsovych, Oleksandr,Mutombo, Pingo,?vec, Martin,?ámal, Michal,Nejedly, Jind?ich,Císa?ová, Ivana,Vázquez, Héctor,Moro-Lagares, María,Berger, Jan,Vacek, Jaroslav,Stará, Irena G.,Stary, Ivo,Jelínek, Pavel
, p. 940 - 946 (2018)
The converse piezoelectric effect is a phenomenon in which mechanical strain is generated in a material due to an applied electrical field. In this work, we demonstrate the converse piezoelectric effect in single heptahelicene-derived molecules on the Ag(111) surface using atomic force microscopy (AFM) and total energy density functional theory (DFT) calculations. The force-distance spectroscopy acquired over a wide range of bias voltages reveals a linear shift of the tip-sample distance at which the contact between the molecule and tip apex is established. We demonstrate that this effect is caused by the bias-induced deformation of the spring-like scaffold of the helical polyaromatic molecules. We attribute this effect to coupling of a soft vibrational mode of the molecular helix with a vertical electric dipole induced by molecule-substrate charge transfer. In addition, we also performed the same spectroscopic measurements on a more rigid o-carborane dithiol molecule on the Ag(111) surface. In this case, we identify a weaker linear electromechanical response, which underpins the importance of the helical scaffold on the observed piezoelectric response.
Spirobifluorene-based Porous Organic Polymers as Efficient Porous Supports for Pd and Pt for Selective Hydrogenation
Trandafir, Mihaela Mirela,Pop, Lidia,H?dade, Niculina D.,Hristea, Ioana,Teodorescu, Cristian Mihail,Krumeich, Frank,van Bokhoven, Jeroen A.,Grosu, Ion,Parvulescu, Vasile I.
, p. 538 - 549 (2018/10/09)
Spirobifluorene-based porous organic polymers (POP) were synthesized following two different protocols; the acetylenic coupling reaction conditions and the Sonogashira cross-coupling reaction. These were utilized as support for the hydrogenation of a series of species containing unsaturated C=C and C=O bonds (4-nitrostyrene, 4-bromobenzophenone, acetophenone, 7-nitro-1-tetralone and 1,2-naphtoquinone confirmed their efficiency). POP1 prepared via a copper-catalysis protocol was completely inactive, while POP2-4 containing residual Pd exhibited different activities in accordance to the accessibility of the substrates to the metal. Further deposition of 0.5 wt% Pd led to active and stable catalysts. They were easily separated by filtration, and after re-dispersion, afforded the same performances for ten successive cycles. This study also evidenced the specific role of the support in these reactions by comparing the behavior of Pd/POP with that of a Pd/C catalyst with the same loading of palladium. The deposition of Pt on these supports led to sub-nanometric particles and, in accordance, to a different catalytic behavior reflected merely by differences in the selectivity.
Development of sulfonamide compounds as potent methionine aminopeptidase type II inhibitors with antiproliferative properties
Kawai, Megumi,BaMaung, Nwe Y.,Fidanze, Steve D.,Erickson, Scott A.,Tedrow, Jason S.,Sanders, William J.,Vasudevan, Anil,Park, Chang,Hutchins, Charles,Comess, Kenneth M.,Kalvin, Douglas,Wang, Jieyi,Zhang, Qian,Lou, Pingping,Tucker-Garcia, Lora,Bouska, Jennifer,Bell, Randy L.,Lesniewski, Richard,Henkin, Jack,Sheppard, George S.
, p. 3574 - 3577 (2007/10/03)
We have screened molecules for inhibition of MetAP2 as a novel approach toward antiangiogenesis and anticancer therapy using affinity selection/mass spectrometry (ASMS) employing MetAP2 loaded with Mn2+ as the active site metal. After a series
