Water as an Activator of Luminescence

Ewles, J.

doi:10.1038/125706b0

Cited by 30 publications

(18 citation statements)

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“…Recently, with the help of steady and transient absorption and emission spectrum, we unambiguously confirmed that SWs adsorbed or confined at nanoscale interface in the form of OH -•H 2 O could emit bright colors as non-conjugation luminophors [36][37][38][39] , which answers a century of debate on that water is colored or colorless liquid 40,41 . Differing from the traditional hydrogen bonding of water, the hydroxyl (hydroxide) groups and water molecules in structural water are mainly combined through the spatial interaction between the p orbitals of O atoms, which is a new kind of weak interaction with the characteristics of conjugated π bond and transient feature (Scheme 1c).…”

Section: Introductionsupporting

confidence: 59%

Activation of H2O tailored by interfacial electronic states at nanoscale interface for enhanced electrocatalytic hydrogen evolution

Zhang

Wang

Zhou

et al. 2022

Preprint

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Despite the fundamental and practical significance of the hydrogen evolution reaction (HER), the reaction kinetics at the molecular level is not clear, particularly in basic media. Here, with ZIF-67 derived Co-based carbon frameworks (Co/NC) as a model catalyst, we systematically investigated the effects of different reaction parameters on the HER kinetics, and surprise found that HER activity was not directly dependent on the type of nitrogen in the carbon framework, but on the relative content of surface hydroxyl and water (OH-/H2O) adsorbed on Co active sites embedded in carbon frameworks. When the ratio of the OH-/H2O was close to 1:1, Co/NC nanocatalyst showed the best reaction performance under the condition of high-pH electrolytes, e.g., with an overpotential of only 232 mV at a current density of 10 mA cm-2 in 1 M KOH electrolyte. We unambiguously identified that, the structural water molecules (SWs) in the form of hydrous hydroxyl complex absorbed on metal centers {OH-∙H2O@M+} were catalytic active sites for enhanced HER, where M+ could be transition and/or alkaline metal cations. Different from the traditional hydrogen bonding of water, the hydroxyl (hydroxide) groups and water molecules in SWs were mainly transiently bonded together through the spatial interaction between the p orbitals of O atoms, showing characteristics of delocalized π bond with dynamic feature. These new formed surface bonds or transient states could be a new weak interaction, which can act as an alternative channel for concerted electron and proton transfer at electrode surface. The capturing of new surface states not only answers pH-, cation- and transition metal- dependent hydrogen evolution kinetics, but also provides completely new insights into the understanding of other electrocatalytic reduction involved by other small moleculesm, including CO2, CO and N2 etc.

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Section: Introductionsupporting

confidence: 59%

Activation of H2O tailored by interfacial electronic states at nanoscale interface for enhanced electrocatalytic hydrogen evolution

Zhang

Wang

Zhou

et al. 2022

Preprint

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“…S6b). Some bright non-luminescent minerals like quartz emit bluish fluorescence after being wetted (Ewles 1930). This can explain the bright tiny objects in Fig.…”

Section: Discussionmentioning

confidence: 89%

Development of micro-zymography: Visualization of enzymatic activity at the microscopic scale for aggregates collected from the rhizosphere

et al. 2022

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Aims Visualization of enzymatic activity links microbial functioning to localization in heterogeneous soil habitats. To assess enzymatic reactions in soil thin layer at the microscopic level, we developed a micro-zymography approach and tested it by visualization of the potential activity of phosphomonoesterase for aggregates collected from the rhizosphere of Zea mays L. Methods We evaluated micro-zymography by applying fluorogenically-labeled substrate i) on individual soil aggregates freshly sampled from the rhizosphere, ii) on thin layers of aggregates (≈ 500 µm) saturated with substrate to assess the dynamics of phosphomonoesterase activity, and iii) on maize roots under laser scanning microscope upon the identified hotspots by membrane-based zymography. Results We found super transparent silicon as the most appropriate fixative to prevent sample drying. We optimized microscope settings to eliminate the soil auto-fluorescence. The fluorescent signal shifted from the free liquid phase towards the aggregate boundaries within 30 min after substrate addition and was finally detectable at the surface of a few aggregates. This was probably due to higher microbial abundance and enzymatic activity on the soil aggregates compared to the liquid phase. The enzymatic activity appeared patchy at the aggregate and root surfaces indicating heterogeneous distribution of hotspots. Conclusions The methodology including calibration, sample preparation, fixation, and monitoring was developed. The novel membrane-free micro-zymography approach is a promising tool to identify functional specificity and niche differentiation on roots and soil aggregates. This approach revealed unexplained complexity of competing processes (biochemical, hydrolytic, and physical) due to differently charged reaction products and enzyme-clay complexes.

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“…The emission properties can be tuned by the solvent [68], thermal annealing treatment [77] and cations [19,78,79], etc. which was highly related to the hydration state of silver NCs [20,80], and the emission was unambiguously attributed to the behavior of structural water molecules (SWs) confined in nanoscale interface and/or space [67][68][69][70][71]. Based on the fundamentals of SWs, these elusive results as above discussed can be well understood.…”

Section: Resultsmentioning

confidence: 99%

“…We can conclude that both quantum size effect or AIE effect is not a personality for a certain type of materials or molecules but a common feature for luminescent materials, and metal-thiolate complexes bound on metallic core in good solvent or aggregated in the poor solvent can emit identical phosphorescence [52], which established a connection between quantum size effect and AIE effect. We would ask whether the common luminescent properties may not originated from the quantum dots or aggregates itself but a common species, such as ubiquitous water molecules suggested and investigated in our previous researches [66][67][68][69][70][71], adsorbed or confined in the nanoscale interface and/or space? Understanding the luminescent fundamentals of metal(I)-thiolate complexes with AIE characteristics can give better insight to both quantum size effect and AIE effect on luminescence for low-dimension quantum dots and AIEgens, respectively.…”

Section: Introductionmentioning

confidence: 99%

Origin of the Bright Photoluminescence of Thiolate-protected Gold Nanoclusters: Confined Structural Water Molecules as Real Emitters

Peng

Zhang

2021

Preprint

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The availability of a range of excited states has enriched zero-, one- and two- dimensional quantum nanomaterials with interesting luminescence properties, in particular for noble metal nanoclusters (NCs) as typical examples. But, the elucidation and origin of optoelectronic properties remains elusive. In this report, using widely used Au(I)-alkanethiolate complex (Au(I)-SRs, R = -(CH2)12H) with AIE characteristics as a model system, by judiciously manipulating the delicate surface ligand interactions at the nanoscale interface, together with a careful spectral investigations and an isotope diagnostic experiment of heavy water (D2O), we evidenced that the structural water molecules (SWs) confined in the nanoscale interface or space are real emitter centers for photoluminescence (PL) of metal NCs and the aggregate of Au(I)-SRs complexes, instead of well-organized metal core dominated by quantum confinement mechanics. Interestingly, the aggregation of Au(I)-SRs generated dual fluorescence-phosphorescence emission and the photoluminescence intensity was independent on the degree of aggregation but showed strong dependency on the content and state of structural water molecules (SWs) confined in the aggregates. SWs are different from traditional hydrogen bonded water molecules, wherein, due to interfacial adsorption or spatial confinement, the p orbitals of two O atoms in SWs can form a weak electron interaction through spatial overlapping, which concomitantly constructs a group of interfacial states with π bond characteristics, consequently providing some alternative channels (or pathways) to the radiation and/or non-radiation relaxation of electrons. Our results provide completely new insights to understand the fascinating properties (including photoluminescence, catalysis and chirality, etc.) of other low-dimension quantum dots and even for aggregation-induced emission luminophores (AIEgens). This also answers the century old debate on whether and how water molecules emit bright color.

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Water as an Activator of Luminescence

Cited by 30 publications

References 0 publications

Activation of H2O tailored by interfacial electronic states at nanoscale interface for enhanced electrocatalytic hydrogen evolution

Activation of H2O tailored by interfacial electronic states at nanoscale interface for enhanced electrocatalytic hydrogen evolution

Development of micro-zymography: Visualization of enzymatic activity at the microscopic scale for aggregates collected from the rhizosphere

Origin of the Bright Photoluminescence of Thiolate-protected Gold Nanoclusters: Confined Structural Water Molecules as Real Emitters

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