Near-infrared unsymmetrical squaraine core-based sensitizers for co-sensitized high-photocurrent dye-sensitized solar cells

Increased conversion of near-infrared (NIR) photons to electricity is needed to improve dye-sensitized solar cells (DSCs). Here, we report two squaraine dyes (RR13 and RR14) with unsymmetrical cores as NIR dyes in DSCs. Both dyes feature a conjugated indolizine donor with an indoline donor on the opposite side of the squaraine core. The dyes are studied via absorption spectroscopy, computational interrogation, and electrochemical analysis. The use of the strongly donating indolizine donor results in NIR photon-to-current conversion extending beyond 800 nm on TiO2 in DSC devices. The DSC devices were characterized by current-voltage curves, incident photon-to-current conversion efficiency measurements, and electrical impedance spectroscopy. After co-sensitized DSC device optimizations, the NIR-absorbing squaraine dyes complemented with commercial organic dyes (D35 and Y123) gave a high photocurrent output of ∼21 mA/cm2 with a PCE of 9.4%

Innovating standards through informal consortia: The case of wireless telecommunications

International audienceWe empirically examine the effects of industry consortia on the coordination of innovation strategies of the members. Our analyses utilize membership data from 32 consortia in wireless telecommunication technology subfields from 2000 to 2005 and prior art citations in standard-essential patents. We find that connections among firms in informal and technically-oriented consortia significantly increase the likelihood that firms cite each other's patents in subsequent patents essential for the UMTS wireless telecommunication standard. Inventions that are likely to become part of the UMTS system tend to build on inventions by firm peers who were members of the same consortia, controlling for patent or firm fixed effects, technology class, and other characteristics. Consortia may enhance productivity of invention and increase the incentives to invest in R&D by internalizing potential externalities. They may also enhance efficiency of standardization by facilitating the interaction of committee and market processes. Consortia thus structure and constrain the process of innovating standardized technologies. This is problematic if consortia are not truly accessible for all the relevant parties. Policymakers thus need to balance these effects. For managers, the results show that participation in a variety of technical consortia enables influencing peers' innovation strategies related to compatibility standards

Pyridyl CO\u3csub\u3e2\u3c/sub\u3eFixation Enabled by a Secondary Hydrogen Bonding Coordination Sphere

Copyright © 2020 American Chemical Society. Reversible CO2 binders under ambient conditions are of significant interest for multiple applications in sensing and capture technologies. In this paper, a general systematic way to evaluate CO2 receptors with π-systems is put forward. A series of receptors (five pyridine-based and one triazine-based) are evaluated as CO2 binders in terms of number of hydrogen bonding sites, strength of hydrogen bond donors, and number of nucleophilic sites. The binding of CO2 to the receptors was probed by computational models, absorption spectroscopy, fluorescence spectroscopy, cyclic voltammetry, and 1H NMR studies. Multiple solvents with varying ionic strength additives are probed to analyze the effects on CO2-bound intermediates. The receptors were screened progressively down-selecting through the different analytical techniques arriving at a promising pyridine receptor, which shows evidence of CO2 binding with each of the analytical techniques. The diaminopyridine motif demonstrates reversible CO2 binding and has convenient substitution sites for derivatization to incorporate into functional sensor systems

SWIR Emissive RosIndolizine Dyes With Nanoencapsulation In Water Soluble Dendrimers

Shortwave infrared (SWIR) emission has great potential for deep-tissue in vivo biological imaging with high resolution. In this article, the synthesis and characterization of two new xanthene-based RosIndolizine dyes coded PhRosIndz and tolRosIndz is presented. The dyes are characterized via femtosecond transient absorption spectroscopy as well as steady-state absorption and emission spectroscopies. The emission of these dyes is shown in the SWIR region with peak emission at 1097 nm. TolRosIndz was encapsulated with an amphiphilic linear dendritic block co-polymer (LDBC) coded 10-PhPCL-G3 with high uptake yield. Further, cellular toxicity was examined in vitro using HEK (human embryonic kidney) cells where a \u3e90% cell viability was observed at practical concentrations of the encapsulated dye which indicates low toxicity and reasonable biocompatibility

Acyloxylation of Cyclic Enones: Synthesis of Densely Oxygenated Guaianolides

The α′-acyloxylation of cyclic enones with linear carboxylic acids is described. The reaction is promoted by KMnO4 in the presence of a carboxylic acid and its corresponding carboxylic anhydride. The optimization of the reaction has been carried out using the statistical methodology known as design of experiments. The optimized reaction conditions have been evaluated in terms of substrate scope and compatibility with different functional groups. The methodology has been applied to the synthesis of densely oxygenated guaianes and guaianolides

Allylic Oxidation of Alkenes Catalyzed by a Copper−Aluminum Mixed Oxide

A strategy for the allylic oxidation of cyclic alkenes with a copper−aluminum mixed oxide as catalyst is presented. The reaction involves the treatment of an alkene with a carboxylic acid employing tert-butyl hydroperoxide as the oxidant. In all cases, the corresponding allylic esters are obtained. When L-proline is employed, the allylic alcohol or ketone is obtained. The oxidation of cyclohexene and valencene has been optimized by design of experiments (DoE) statistical methodology

Geotourism, iconic landforms and island-style speciation patterns in National Parks of East Africa:

Many of the national parks in East Africa are equally as famous for their iconic landforms as they are for their diversity and concentrations of fauna and flora. The newly formed Ngorongoro-Lengai Geopark in northern Tanzania is the first geopark to be established in the region, but there is remarkable potential for geotourism in the majority of the national parks. The most spectacular landforms have been shaped by the East African Rift System. Formation of the two major rifts in the region, the Albertine Rift (or western branch) and the Gregory Rift (or eastern branch), was accompanied, or in some cases preceded, by extensive alkaline volcanism. The rifting and volcanism are primarily Late Cenozoic phenomenon that dissected and overprinted the older regional plateaus. Rifting impacted the regional drainage and captured major rivers, including the Victoria Nile