Optical control of NMDA-receptors with a diffusible photoswitch

N-methyl-D-aspartate receptors (NMDARs) play a central role in synaptic plasticity, learning and memory, and are implicated in various neuronal disorders. We synthesized a diffusible photochromic glutamate analogue, azobenzene-triazole-glutamate (ATG), which is specific for NMDARs and functions as a photoswitchable agonist. ATG is inactive in its dark-adapted trans-isoform, but can be converted into its active cis-isoform using one-photon (near UV) or two-photon (740 nm) excitation. Irradiation with violet light photo-inactivates ATG within milliseconds, allowing agonist removal on the timescale of NMDAR deactivation. ATG is compatible with Ca2+ imaging and can be used to optically mimic synaptic coincidence detection protocols. Thus, ATG can be used like traditional caged glutamate compounds, but with the added advantages of NMDAR specificity, low antagonism of GABAR-mediated currents, and precise temporal control of agonist delivery

High photovoltage in perovskite solar cells: New physical insights from the ultrafast transient absorption spectroscopy

To understand the cause of the high open circuit photovoltage (VOC) achieved by todays' state of the art perovskite solar cells (PSCs), we examine formamidinium lead bromide CH(NH2)(2)PbBr3 films by ultrafast transient absorption spectroscopy (TAS). By using TiO2 and spiro-OMeTAD as charge extraction layers, the devices based on the CH(NH2)(2)PbBr3 films yield VOC as high as 1.5 V ascertaining their high quality. TAS establish that the presence of charge extraction layers has very little influences on the nature of a negative band at 535 nm corresponding to the bleaching of the absorption band edge and two positive bands in the CH(NH2)(2)PbBr3 films. Therefore, we contend that the V-OC in PSC is predominantly determined by the quasi Fermi level splitting within the perovskite layer. (C) 2017 Published by Elsevier B. V

Roadmap on organic inorganic hybrid perovskite semiconductors and devices

Metal halide perovskites are the first solution processed semiconductors that can compete in their functionality with conventional semiconductors, such as silicon. Over the past several years, perovskite semiconductors have reported breakthroughs in various optoelectronic devices, such as solar cells, photodetectors, light emitting and memory devices, and so on. Until now, perovskite semiconductors face challenges regarding their stability, reproducibility, and toxicity. In this Roadmap, we combine the expertise of chemistry, physics, and device engineering from leading experts in the perovskite research community to focus on the fundamental material properties, the fabrication methods, characterization and photophysical properties, perovskite devices, and current challenges in this field. We develop a comprehensive overview of the current state of the art and offer readers an informed perspective of where this field is heading and what challenges we have to overcome to get to successful commercializatio

Data for: Effect of S/Se ratios on the photovoltaic performance of spray pyrolysis processed CZTS solar cells based on superstrate architecture

Experimental dat

Data for: Effect of S/Se ratios on the photovoltaic performance of spray pyrolysis processed CZTS solar cells based on superstrate architecture

Experimental dataTHIS DATASET IS ARCHIVED AT DANS/EASY, BUT NOT ACCESSIBLE HERE. TO VIEW A LIST OF FILES AND ACCESS THE FILES IN THIS DATASET CLICK ON THE DOI-LINK ABOV

Data for: Impact of CdS layer thickness on the composition, structure and photovoltaic performance of superstrate CZTSSe solar cells

Research data of the kesterite solar cellsTHIS DATASET IS ARCHIVED AT DANS/EASY, BUT NOT ACCESSIBLE HERE. TO VIEW A LIST OF FILES AND ACCESS THE FILES IN THIS DATASET CLICK ON THE DOI-LINK ABOV

Excited state dynamics of PPI dendrimers functionalized with 4-(4′-ethoxybenzoyloxy)salicylaldehyde chromophores

Femtosecond transient absorption spectroscopy has been applied for the investigation of the excited state dynamics of poly(propyleneimine) dendrimers functionalized with 4-(40-ethoxybenzoyl-oxy)salicylaldehyde (SA) promesogenic units. Different transient absorption dynamics of three different tautomeric forms of SA chromophore groups have been distinguished. Cis-keto and enol-closed tautomeric forms experience opening of pseudo-aromatic ring and fast relaxation to the conformationally distorted ground state of trans-keto tautomeric form. No tautomeric changes take place under direct excitation of the trans-keto tautomers.M.F. acknowledges EU Structural Funds project “Postdoctoral Fellowship Implementation in Lithuania” for funding his postdoctoral fellowship. This research was also funded by the European Social Fund under the Global Grant measure.Peer Reviewe

Excited-state relaxation of dendrimers functionalized with cyanoazobenzene-type terminal groups

Excited-state relaxation of dendrimers functionalized with terminal cyanoazobenzene-type groups was studied by means of fluorescence and femtosecond transient absorption spectroscopy. We compare the relaxation dynamics with that of azobenzene molecules in solutions and conclude that the excited-state relaxation is determined by the excited state twisting of terminal groups, which takes place on a time scale of several picoseconds. The twisting dynamics only slightly differs in solutions and in solid film, which indicates that conformational motions during the twisting reaction are only weakly coupled to the environment. © 2009 Elsevier B.V. All rights reserved.This work has been supported by projects: COST TD0802 and CTQ2006-15611-CO2-01 (Ministerio de Ciencia e Innovación, Spain) and Gobierno de Aragón.Peer Reviewe

PPI-SA and PAMAM-SA dendrimers assisted synthesis of silver nanoparticles: structure, optical properties and stability

et al.>Poly(propylene-imine) (PPI) and poly(amidoamine) (PAMAM) dendrimers of different generations functionalized with 4-(4′-pentoxybenzoyloxy) salicylaldehyde (SA) promesogenic units were applied for the synthesis of silver (Ag) nanoparticles in tetrahydrofuran-water mixture solution. Influence of the dendrimer type and their generations on formation and stability of nanoparticles were studied. Structural and optical properties of Ag nanoparticles, and their modifications with aging were characterized by means of transmission electron microscopy, UV-vis absorption and Fourier transform infrared spectroscopy. Experimental investigations showed that immediately after the synthesis the particles were of spherical shapes with slightly different sizes depending on the used dendrimer type, but independent of their generation. The dendrimer type strongly influenced particle modifications during the aging: particles protected with PPI-SA dendrimers undergone significant alterations in time both in their sizes and shapes, while the particles remained almost unchanged when PAMAM-SA dendrimers were used for their protection. We, therefore, presume that morphological differences of aged nanoparticles are mainly determined by different chemical structures of dendrimer cores rather than by their terminal groups; additional carbonyl groups in PAMAM-SA dendrimer core units play an important role in stabilizing Ag nanoparticles. © Springer Science+Business Media 2014.M. Franckevičius acknowledges EU Structural Funds Project ‘‘Postdoctoral Fellowship Implementation in Lithuania’’ for funding his postdoctoral fellowship. M. Marcos and J. L. Serrano acknowledge support by Spanish Ministerio de Economía y Competitividad (MINECO), under Project CTQ2012-35692 and Fondo Europeo de Desarrollo Regional (FEDER) funding, EU, and by the Gobierno de Aragón (Research Group E04).Peer Reviewe

Practical synthesis of (S)-pyrrolidin-2-yl-1H-tetrazole, incorporating efficient protecting group removal by flow-reactor hydrogenolysis

A practical, safe, high-yielding and efficient synthesis of (S)-pyrrolidin-2-yl-1H-tetrazole has been developed, which avoids the generation of ammonium azide in the cyclisation step and the use of a 9:1 acetic acid-water mixture as the solvent in the hydrogenation. The previously extended hydrogenolysis reaction time (three days) is now reduced to hours through the use of an H-Cube (TM) (a continuous-flow reactor employing a mixed hydrogen-liquid flow stream)