Metal-organic conjugated microporous polymer containing a carbon dioxide reduction electrocatalyst

A metal-organic conjugated micorporous polymer (CMP) containing a manganese carbonyl electrocatalyst for CO2 reduction has been synthesised and electrochemically characterised. Incorporation in a rigid framework changes the behavior of the catalyst, preventing reductive dimerization. These initial studies demonstrate the feasibility of CMP electrodes that can provide both high local CO2 concentrations and well defined electrocatalytic sites

Aromatic polymers made by reductive polydehalogenation of oligocyclic monomers as conjugated polymers of intrinsic microporosity (C-PIMs)

Reductive dehalogenation polycondensation of a series of penta-or hexacyclic, bisgeminal tetrachlorides with dicobalt octacarbonyl leads to the formation of homopolymers and copolymers with very different optical spectra. While the formation of tetrabenzoheptafulvalene connectors introduces efficient conjugation barriers due to their strongly folded structure, linking of 5-membered ring-based pentacyclic building blocks via bifluorenylidene connectors allows for an extended π-conjugation along the main chain. A comparison of homopolymer P57 and copolymer P55/77 indicates a quite different reactivity for dichloromethylene functions if incorporated into 5-or 7-membered rings. Interestingly, all investigated (co)polymers show an intrinsic microporosity in the solid-state (forming so-called Conjugated Polymers of Intrinsic Microporosity C-PIMs) and have SBET values of up to 760 m2 g-1 for homopolymer P77. This value is one of the highest reported values to date for C-PIMs

Sulfone-containing covalent organic frameworks for photocatalytic hydrogen evolution from water

Nature uses organic molecules for light harvesting and photosynthesis, but most man-made water splitting catalysts are inorganic semiconductors. Organic photocatalysts, while attractive because of their synthetic tunability, tend to have low quantum efficiencies for water splitting. Here we present a crystalline covalent organic framework (COF) based on a benzo-bis(benzothiophene sulfone) moiety that shows a much higher activity for photochemical hydrogen evolution than its amorphous or semicrystalline counterparts. The COF is stable under long-term visible irradiation and shows steady photochemical hydrogen evolution with a sacrificial electron donor for at least 50 hours. We attribute the high quantum efficiency of fused-sulfone-COF to its crystallinity, its strong visible light absorption, and its wettable, hydrophilic 3.2 nm mesopores. These pores allow the framework to be dye-sensitized, leading to a further 61% enhancement in the hydrogen evolution rate up to 16.3 mmol g −1 h −1 . The COF also retained its photocatalytic activity when cast as a thin film onto a support

Nitrogen Containing Linear Poly(phenylene) Derivatives for Photo-catalytic Hydrogen Evolution from Water

Here we study how the introduction of nitrogen into poly(p-phenylene) type materials affects their ability to act as hydrogen evolution photocatalysts. Direct photocatalytic water splitting is an attractive strategy for clean energy production, but understanding which material properties are important, how they interplay, and how they can be influenced through doping remains a significant challenge, especially for polymers. Using a combined experimental and computational approach, we demonstrate that introducing nitrogen in conjugated polymers results in either materials that absorb significantly more visible light but worse predicted driving force for water/sacrificial electron donor oxidation, or materials with an improved driving force that absorb relatively less visible light. The latter materials are found to be much more active and the former much less. The trade-off between properties highlights that the optimization of a single property in isolation is a poor strategy for improving the overall activity of materials

Photocatalytic proton reduction by a computationally identified, molecular hydrogen-bonded framework

We show that a hydrogen-bonded framework, TBAP-α, with extended π-stacked pyrene columns has a sacrificial photocatalytic hydrogen production rate of up to 3108 μmol g-1 h-1. This is the highest activity reported for a molecular organic crystal. By comparison, a chemically-identical but amorphous sample of TBAP was 20-200 times less active, depending on the reaction conditions, showing unambiguously that crystal packing in molecular crystals can dictate photocatalytic activity. Crystal structure prediction (CSP) was used to predict the solid-state structure of TBAP and other functionalised, conformationally-flexible pyrene derivatives. Specifically, we show that energy-structure-function (ESF) maps can be used to identify molecules such as TBAP that are likely to form extended π-stacked columns in the solid state. This opens up a methodology for the a priori computational design of molecular organic photocatalysts and other energy-relevant materials, such as organic electronics

Six propositions on the sonics of pornography

Pornography (and all its contentious pleasures, contested politics and attendant problematics) is enjoying a fresh wave of academic attention. The overwhelming majority of these studies, however, focus on the visual discourses of sexually explicit material. This risks the sonic dimensions of pornography being overlooked entirely. Yet porn is anything but silent. This speculative article maps out some of the ways in which the sounds of pornography (and the pornography of sound) might be approached in the analytical context of gay male culture. Not only do the texts of porn contain assorted sounds (dialogue, soundtracks, non-verbal noises of participation, background and accidental audio), they also seek to prompt sounds (not least the non-verbal noises pornography seeks to elicit during the moments of its consumption) and sometimes depend on sound alone (telephone lines that allow access to recorded narratives or ‘live’ chat). Pornography speaks in particular accents, it mobilizes particular music, it dances to particular tunes and it relies on the pants we hear as much as the pants we see. If queer cultures have their own distinctive worlds of sound, then the sonic armouries of porn play a prominent role within them

Integrated Covalent Organic Framework/Carbon Nanotube Composite as Li-Ion Positive Electrode with Ultra-High Rate Performance

Covalent organic frameworks (COFs) are promising electrode materials for Li-ion batteries. However, the utilization of redox-active sites embedded within COFs is often limited by the low intrinsic conductivities of bulk-grown material, resulting in poor electrochemical performance. Here, a general strategy is developed to improve the energy storage capability of COF-based electrodes by integrating COFs with carbon nanotubes (CNT). These COF composites feature an abundance of redox-active 2,7-diamino-9,10-phenanthrenequinone (DAPQ) based motifs, robust β‑ketoenamine linkages, and well-defined mesopores. The composite materials (DAPQ-COFX—where X = wt% of CNT) are prepared by in situ polycondensation and have tube-type core-shell structures with intimately grown COF layers on the CNT surface. This synergistic structural design enables superior electrochemical performance: DAPQ-COF50 shows 95% utilization of redox-active sites, long cycling stability (76% retention after 3000 cycles at 2000 mA g−1), and ultra-high rate capability, with 58% capacity retention at 50 A g−1. This rate translates to charging times of ≈11 s (320 C), implying that DAPQ-COF50 holds excellent promise for high-power cells. Furthermore, the rate capability outperformed all previous reports for carbonyl-containing organic electrodes by an order of magnitude; indeed, this power density and the rapid (dis)charge time are competitive with electrochemical capacitors

Gene-Environment Interactions Relevant to Estrogen and Risk of Breast Cancer: Can Gene-Environment Interactions Be Detected Only among Candidate SNPs from Genome-Wide Association Studies?

In this study we aim to examine gene–environment interactions (GxEs) between genes involved with estrogen metabolism and environmental factors related to estrogen exposure. GxE analyses were conducted with 1970 Korean breast cancer cases and 2052 controls in the case-control study, the Seoul Breast Cancer Study (SEBCS). A total of 11,555 SNPs from the 137 candidate genes were included in the GxE analyses with eight established environmental factors. A replication test was conducted by using an independent population from the Breast Cancer Association Consortium (BCAC), with 62,485 Europeans and 9047 Asians. The GxE tests were performed by using two-step methods in GxEScan software. Two interactions were found in the SEBCS. The first interaction was shown between rs13035764 of NCOA1 and age at menarche in the GE|2df model (p-2df = 1.2 × 10−3). The age at menarche before 14 years old was associated with the high risk of breast cancer, and the risk was higher when subjects had homozygous minor allele G. The second GxE was shown between rs851998 near ESR1 and height in the GE|2df model (p-2df = 1.1 × 10−4). Height taller than 160 cm was associated with a high risk of breast cancer, and the risk increased when the minor allele was added. The findings were not replicated in the BCAC. These results would suggest specificity in Koreans for breast cancer risk

Determinants of penetrance and variable expressivity in monogenic metabolic conditions across 77,184 exomes

Penetrance of variants in monogenic disease and clinical utility of common polygenic variation has not been well explored on a large-scale. Here, the authors use exome sequencing data from 77,184 individuals to generate penetrance estimates and assess the utility of polygenic variation in risk prediction of monogenic variants