With the aim of developing photostable near-infrared cell imaging probes, a convenient route to the synthesis of heteroleptic OsII complexes containing the Os(TAP)2 fragment is reported. This method was used to synthesize the dinuclear OsII complex, [{Os(TAP)2}2tpphz]4+ (where tpphz = tetrapyrido[3,2-a:2′,3′-c:3″,2′′-h:2‴,3′′′-j]phenazine and TAP = 1,4,5,8- tetraazaphenanthrene). Using a combination of resonance Raman and time-resolved absorption spectroscopy, as well as computational studies, the excited state dynamics of the new complex were dissected. These studies revealed that, although the complex has several close lying excited states, its near-infrared, NIR, emission (λmax = 780 nm) is due to a low-lying Os → TAP based 3MCLT state. Cell-based studies revealed that unlike its RuII analogue, the new complex is neither cytotoxic nor photocytotoxic. However, as it is highly photostable as well as live-cell permeant and displays NIR luminescence within the biological optical window, its properties make it an ideal probe for optical microscopy, demonstrated by its use as a super-resolution NIR STED probe for nuclear DNA.
The Black Thor intrusive complex (BTIC) contains a conduit-hosted, stratiform Cr-Ni-Cu-(PGE) deposit with a very large amount of chromite for an intrusion of its size. Most conduit-hosted stratiform deposits are Archean, formed from komatiitic magmas containing approximately 3000 ppm Cr2O3, and are typically saturated in chromite. The fundamental problem in understanding the genesis of the BTIC deposit and other deposits of this type is explaining how such large quantities of chromite crystalized from a magma that normally crystallizes only small amounts chromite and normally have a chromite:olivine abundance ratio of ~1:60. Current genetic models, such as in situ crystallization (by oxidation, pressure increase, magma mixing, and/or wholesale assimilation of felsic rocks or iron formation) or physical transportation of chromite slurries do not provide a wholly satisfactory explanation for the high abundance of chromite in this type of deposit. We are testing an alternative model: partial assimilation (as opposed to wholesale assimilation) of local oxide-silicate-facies iron formation by a Cr-rich magma. As low-Mg komatiite is saturated in chromite, the magma may dissolve the silicate component (quartz/chert and Fe-silicate minerals) of the iron formation, but would be unable to dissolve the oxide component (magnetite). Through interaction with the hightemperature (1400°C) Cr-rich magma, the fine-grained magnetite could be upgraded via diffusion to chromite during transportation within the conduit. This upgrading is similar to the upgrading of barren sulphide xenomelts that has been proposed for Ni-Cu-(PGE) deposits.
M(NN)(CO)3X (M = Re, Mn) complexes with a bulky diimine ligand catalyse electrochemical reduction of CO2 with high TON. A noble-metal free system of the Mn-complex photosensitised by a Zn-porphyrin photocatalytically reduces CO2 under visible light.
One of the dominant geological features in the arcuate, >175 km long, Mesoarchean to Neoarchean McFaulds Lake greenstone belt in northern Ontario is the semi-continuous trend of mafic to ultramafic intrusions belonging to the Ring of Fire intrusive suite, which hosts world-class Cr mineralization, major Ni-Cu-(PGE) mineralization, and potentially significant Fe-Ti-V-(P) mineralization. It appears to have been emplaced over a relatively short time interval of approximately 4 to 4.5 million years. The intrusive suite contains two subsuites: the less widely distributed Koper Lake subsuite, which consists of komatiitic ultramafic- dominated intrusions and typically hosts Cr and Ni-Cu-(PGE) mineralization (e.g. Esker intrusive complex), and the more widely distributed Ekwan River subsuite, which consists of tholeiitic high-Fe-Ti mafic-dominated intrusions and typically hosts Fe-Ti-V-(P) mineralization (e.g. Thunderbird intrusion). The Esker intrusive complex contains the majority of the known Cr and Ni-Cu-(PGE) mineralization in the Ring of Fire intrusive suite. It is a semi-continuous, structurally rotated, subvertical ultramafic-mafic sill-like body that is composed of multiple intrusions with morphologies that vary from bladed dyke morphologies (e.g. Eagle's Nest), transitional dyke/chonolith morphologies (e.g. Double Eagle, AT-3, and AT- 8), to some with transitional chonolith/sill morphologies (e.g. Black Thor). It extends over more than 16 km, youngs to the south-southeast, and is bordered to the north-northwest by several keel-like ultramafic intrusive bodies (e.g. AT-12, C-6, AT-5, AT-1). Clear connections between AT-12 and AT-1 and the overlying Black Thor and Double Eagle intrusions, respectively, and the continuous spectrum of intrusion morphologies suggest that the keels were originally subhorizontal blade-shaped dykes (e.g. Eagle's Nest), the upper parts of which expanded laterally to form transitional dykes/chonoliths (e.g. Double Eagle intrusion) and chonoliths/sills (e.g. Black Thor intrusion), which inflated laterally and coalesced over time to form the silllike Esker intrusive complex. Most of the Ni-Cu-(PGE) mineralization in the Esker intrusive complex appears to have formed by incorporation of sulphur from footwall oxide-silicate-sulphide iron formations, a process that is similar to most other komatiite-associated Ni-Cu-(PGE) deposits worldwide. A fundamental issue in the genesis of all stratiform chromite deposits is how to form thick layers of massive to semi-massive chromite, an issue exacerbated by the vast amounts of chromite in the Esker intrusive complex. A genetic model that resolves the mass balance problem involves partial melting of Fe+/-Ti oxide-rich rocks (oxide-facies iron formation or ferrogabbro) and conversion of fine-grained oxide xenocrysts to chromite by reaction with Cr-rich komatiitic magma in a dynamic magma conduit. This model has been recently challenged based on the capacity of komatiitic magma to dissolve large amounts of magnetite, which would prevent upgrading. However, alternative models cannot explain the presence of composite chromite-silicate-sulphide grains with textures like those in footwall magnetite-silicate-sulphide facies iron formations. More research is required to reconcile the discrepancies. Regardless of their origin, the wide diversity of mineral deposit types in the McFaulds Lake greenstone belt, including world-class Cr, significant Ni-Cu-(PGE), and potential Fe-Ti-V-(P) mineralization related to mafic and ultramafic rocks, make the Ring of Fire region an excellent exploration target to increase the world's supply of critical minerals.
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