Metal cations are potent environmental pollutants that negatively impact human health and the environment. Despite advancements in sensor design, the simultaneous detection and discrimination of multiple heavy metals at sub‐nanomolar concentrations in complex analytical matrices remain a major technological challenge. Here, the design, synthesis, and analytical performance of three highly emissive conjugated polyelectrolytes (CPEs) functionalized with strong iminodiacetate and iminodipropionate metal chelates that operate in challenging environmental samples such as seawater are demonstrated. When coupled with array‐based sensing methods, these polymeric sensors discriminate among nine divalent metal cations (CuII, CoII, NiII, MnII, FeII, ZnII, CdII, HgII, and PbII). The unusually high and robust luminescence of these CPEs enables unprecedented sensitivity at picomolar concentrations in water. Unlike previous array‐based sensors for heavy metals using CPEs, the incorporation of distinct π‐spacer units within the polymer backbone affords more pronounced differences in each polymer's spectroscopic behavior upon interaction with each metal, ultimately producing better analytical information and improved differentiation. To demonstrate the environmental and biological utility, a simple two‐component sensing array is showcased that can differentiate nine metal cation species down to 500 × 10−12
Influence of spin state and electron configuration on the active site and mechanism for catalytic hydrogenation on metal cation catalysts supported on NU-1000: insights from experiments and microkinetic modeling
The mechanism of ethene hydrogenation to ethane on six dicationic 3d transition metal catalysts is investigated. Specifically, a combination of density functional theory (DFT), microkinetic modeling, and high throughput reactor experiments is used to interrogate the active sites and mechanisms for Mn@NU-1000, Fe@NU-1000, Co@NU-1000, Ni@NU-1000, Cu@NU-1000, and Zn@NU-1000 catalysts, where NU-1000 is a metal–organic framework (MOF) capable of supporting metal cation catalysts. The combination of experiments and simulations suggests that the reaction mechanism is influenced by the electron configuration and spin state of the metal cations as well as the amount of hydrogen that is adsorbed. Specifically, Ni@NU-1000, Cu@NU-1000, and Zn@NU-1000, which have more electrons in their d shells and operate in lower spin states, utilize a metal hydride active site and follow a mechanism where the metal cation binds with one or more species at all steps, whereas Mn@NU-1000, Fe@NU-1000, and Co@NU-1000, which have fewer electrons in their d shells and operate in higher spin states, utilize a bare metal cation active site and follow a mechanism where the number of species that bind to the metal cation is minimized. Instead of binding with the metal cation, catalytic species bind with oxo ligands from the NU-1000 support, as this enables more facile H 2 adsorption. The results reveal opportunities for tuning activity and selectivity for hydrogenation on metal cation catalysts by tuning the properties that influence hydrogen content and spin, including the metal cations themselves, the ligands, the binding environments and supports, and/or the gas phase partial pressures.
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- Award ID(s):
- 1725573
- NSF-PAR ID:
- 10201351
- Date Published:
- Journal Name:
- Catalysis Science & Technology
- Volume:
- 10
- Issue:
- 11
- ISSN:
- 2044-4753
- Page Range / eLocation ID:
- 3594 to 3602
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1039/d0cy00394h
