Highlights
bipyridine ligand specifically designed to change colour on contact with sarin. When the bipyridine ligand is coordinated to iron, electronic transitions give rise to a red colour. Reaction with organophosphorus compounds such as sarin alters the ligand’s structure, preventing it from being able to bind to iron. This prevents the electronic transitions so the colour vanishes. The team is now trying to adapt the
structure of the ligand to optimise its sensitivity towards sarin and develop chromogenic papers that are sensitive and selective to sarin vapour.
Visible-
light driven reduction of
CO2 Solar-driven reduction of carbon dioxide to value-added chemical fuels is a longstanding scientific challenge. Several key considerations must be balanced to develop
hydrogen generation from proton reduction; visible-light harvesting that matches the solar spectrum; and the use of cheap and earth-abundant catalytic components. Chemists from California report that the earth-abundant catalyst [Ni(Pr
effective CO2 fixation, including catalyst selectivity for promoting CO2
bimiq1)]2+ (where Pr bimiq1 = bis(3-
with high selectivity and activity and achieves turnover numbers and turnover frequencies reaching 98,000 and 3.9s-1
and an electron donor, acts as a visible- light photoredox system for the catalytic conversion of CO2
(imidazolyl)isoquinolinyl)propane) with Ir(ppy)3
to CO that proceeds ,
respectively (V. S. Thoi, N. Kornienko, C. G. Margarit, P. Yang, C. J. Chang; J. Am. Chem. Soc., 2013, 135, 14413) (Scheme 8). Although the overall efficiency of this
at the reduced nickel center and provide a starting point for improved photoredox
solar-to-fuel cycle may be limited by the formation of the active Ni catalyst and/ or the chemical reduction of CO2
to CO
expansion in a single phase as opposed to using a composite system. Linear thermal expansion coefficients, αl
,
ranging from −7.9(2) × 10-6 × 10-6
K–1 to +5.9(2) (12–500K) can be achieved
across the series; contraction and expansion limits are of the same order of magnitude as the expansion of typical ceramics.
56 Chemistry&Industry • November 2013 Scheme 9
This new material has potential to impact on technologies ranging from dental composites, microchips having improved efficiency and lifetimes, to high precision optical mirrors and any other devices where management of thermal stress due to mismatch in the thermal expansion properties of materials is required.
(where ppy = 2-phenylpyridine) reduction over competing
systems for sustainable carbon-neutral energy conversion.
Tunable thermal expansion Finally, Zr1-x
newly developed ceramic oxide with tunable thermal expansion; it can expand, contract or remain unchanged in response to heat depending upon the proportion of key components used to make it (S. E. Tallentire, F. Child, I. Fall, L. Vella-Zarb, I. R. Evans, M. G. Tucker, D. A. Keen, C. Wilson, J. S. O. Evans; J. Am. Chem. Soc., 2013, 135, 12849) (Scheme 9). These materials allow tunable
Snx Mo2 O8 (0 < x < 1) is a
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Scheme 7 Scheme 8
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