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A new series of lanthanide (1-5) and uranyl (6) complexes with a tetra-substituted bifunctional calixarene ligand H₂L is described.The coordination environment for the Ln³+ and UO₂²+ ions is provided by phosphoryl and salicylamidefunctional groups appended to the lower rim of the p-tert-butylcalix[4]arenescaffold. Ligand interactions with lanthanide cations (light: La³+, Pr³+; intermediate: Eu³+and Gd³+; and heavy: Yb³+), as well as the uranyl cation (UO₂²+) is examined in the solution and solid state, respectively with spectrophotometric titration and single crystal X-ray diffractometry. The ligand is fully deprotonated in the complexation of trivalent lanthanide ions forming di-cationic complexes 2:2 M:L, [Ln2(L)2(H2O)]2+(1-5), in solution, whereas uranyl formed a 1:1 M:L complex [UO2(L)(MeOH)]∞(6) that demonstrated very limited solubility in 12 organic solvents. Solvent extraction behaviour is examined for cation selectivity and extraction efficiency. H₂L was found to be an effective extracting agent for UO₂²+ over La³+ and Yb³+ cations. The separation factors at pH 6.0 are: ß UO₂²+/La³+ = 121.0 and ß UO₂²+/Yb³+ = 70.0.

Radioactive materials require special management and considerations. From a non-proliferation standpoint, their presence may indicate a nuclear security threat. Whether they are elements to be recovered from used nuclear fuel or contaminants to be removed from a body of water, the separation, concentration and identification of these materials is imperative for nuclear energy and security to succeed. Functionalized sorbent materials can be designed for enhanced sequestration of radioactive materials present in these aqueous environments. The salophen Schiff base has demonstrated potential as a selective actinyl ion (U, Np, Pu) chelator during solvent extraction. Incorporating this ligand into a solid sorbent material may increase its potential by facilitating the concentration and containment of radioactive ions into a compact solid. In this work, a salophen Schiff-base sorbent material if formed through silica xerogel sol-gel co-condensation polymerization and a (triethoxysilyl)propyl modification to one side of the salophen for covalent inclusion. The nonsymmetrical ligand is therefore tethered to the xerogel at only one point, forming an actinyl ion-selective hybrid sorbent material. This sorbent has shown superior uptake to its symmetrically tethered counterpart as well as a commercial material for the removal of uranium from aqueous solutions. In addition, the sorbent can be further adapted utilizing a phenylene bridged polysilsesquioxane sol-gel polymerization. This sorbent material demonstrates potential to lessen the effects of ionizing radiation on the Schiff base ligand for the reprocessing of used nuclear fuel or the containment of high level radioactive waste. In the interest of nuclear security and owing to the chromophoric shift of the salophen ligand as it binds actinyl ions, the nonsymmetrical ligand can also be utilized as a solid optical thin film sensor for the detection of aqueous uranyl ions.

This thesis presents the results of synthetic and structural investigations of novel cyclotricatechylene-based supramolecular assemblies. Cyclotricatechylene is a bowl-shaped tris-catechol that has been shown to associate with other chemical species through hydrogen bonding and metal coordination. The research focuses on the synthesis and characterisation of novel crystalline supramolecular assemblies of cyclotricatechylene. The compounds described in the four experimental chapters include assemblies of cyclotricatechylene and its related anions with s, p, d and f-block elements of the periodic table. The compounds have been characterised X-ray crystallography. Synthetic and structural investigations of compounds formed from the combination of cyclotricatechylene with s-block metal cations reveal a diverse array of network materials, with cyclotricatechylene in various protonation states. The s-block cations are commonly found to associate with the oxygen atoms of the ligand, however Rb+ and Cs+ also exhibit an affinity for the inner and outer aromatic surfaces of the ligand. Two compounds containing cyclotricatechylene ‘clams’, H[Cs(ctcH5)(ctcH5)] and [Cs(ctcH6)2]+ are reported, in which cyclotricatechylene is found in different protonation states. In these compounds, the large group 1 metal cation Cs+ associates with the electron-rich aromatic surfaces of the cyclotricatechylene bowls, an interaction present in many structures described in this thesis. Metal-cyclotricatechylene polymeric structures are reported, in which s-block metal cations are chelated by catechol(ate) oxygen atoms. These structures include 2D sheets containing Ca2+, Sr2+ and Ba2+ cations, [Cs2Li4(ctcH3)4]6- metallocycles that hydrogen bond to each other to form a 3D network that has the topology of diamond, undulating ‘honeycomb’ networks with Cs+ or Rb+, and a 3D network with the topology of the (10,3)-a net, containing Cs+ in cyclotricatechylene bowls and Sr2+ chelated by catecholate units.

Radioactive materials require special management and considerations. From a non-proliferation standpoint, their presence may indicate a nuclear security threat. Whether they are elements to be recovered from used nuclear fuel or contaminants to be removed from a body of water, the separation, concentration and identification of these materials is imperative for nuclear energy and security to succeed. Functionalized sorbent materials can be designed for enhanced sequestration of radioactive materials present in these aqueous environments. The salophen Schiff base has demonstrated potential as a selective actinyl ion (U, Np, Pu) chelator during solvent extraction. Incorporating this ligand into a solid sorbent material may increase its potential by facilitating the concentration and containment of radioactive ions into a compact solid. In this work, a salophen Schiff-base sorbent material if formed through silica xerogel sol-gel co-condensation polymerization and a (triethoxysilyl)propyl modification to one side of the salophen for covalent inclusion. The nonsymmetrical ligand is therefore tethered to the xerogel at only one point, forming an actinyl ion-selective hybrid sorbent material. This sorbent has shown superior uptake to its symmetrically tethered counterpart as well as a commercial material for the removal of uranium from aqueous solutions. In addition, the sorbent can be further adapted utilizing a phenylene bridged polysilsesquioxane sol-gel polymerization. This sorbent material demonstrates potential to lessen the effects of ionizing radiation on the Schiff base ligand for the reprocessing of used nuclear fuel or the containment of high level radioactive waste. In the interest of nuclear security and owing to the chromophoric shift of the salophen ligand as it binds actinyl ions, the nonsymmetrical ligand can also be utilized as a solid optical thin film sensor for the detection of aqueous uranyl ions.

[Abstract] The release of uranyl(VI) is a hazardous environmental issue, with limited ways to monitor accumulation in situ. Here, we present a method for the detection of uranyl(VI) ions through the utilization of a unique fluorescence energy transfer process to europium(III). Our system displays the first example of a “turn‐on” europium(III) emission process with a small, water‐soluble lanthanide complex triggered by uranyl(VI) ions.

The coordination chemistry of radionuclides (RN) with organic components is of great interest since latter can affect the mobility as well as the sorption behavior adversely. Acetate (AcO-) can be a biotic or abiotic degradation product of organic material present in nuclear waste. Additionally it is often declared as model compound for more complex organic structures. A large number of studies is available which investigated the speciation of uranium(VI) in the presence of acetate under acidic conditions. From potentiometric titrations it seems to be very clear that three uranyl-acetate species are formed under acidic conditions: UO2AcO+ (1:1), UO2(AcO)2 (1:2) and UO2(AcO)3- (1:3). Spectroscopic methods (e.g. IR and EXAFS) provide no certainty whether the 1:3 complex exists or not. TRLFS and UV-vis spectroscopy were mainly applied to characterize the formation of the 1:1 complex. In this study TRLFS, ATR-FT-IR and UV-vis spectroscopy were applied to determine the speciation of uranium(VI) in the presence of acetate and to fill the gap of missing spectroscopic data for the other formed species. Experimental conditions were chosen so that all three previous identified species should be formed. Data evaluation was performed on the basis of factor analysis resulting in single component spectra and stability constants. The findings led us to the conclusion that the 1:3 complex was not formed. In addition the detailed evaluation of ATR-FT-IR spectra show that an approximation used in potentiometric studies should be treated with caution. All these indications reinforce the doubts with respect to the existence of the UO2(AcO)3- species.

The coordination chemistry of radionuclides (RN) with organic components is of great interest since latter can affect the mobility as well as the sorption behavior adversely. Acetate (AcO-) can be a biotic or abiotic degradation product of organic material present in nuclear waste. Additionally it is often declared as model compound for more complex organic structures. A large number of studies is available which investigated the speciation of uranium(VI) in the presence of acetate under acidic conditions. From potentiometric titrations it seems to be very clear that three uranyl-acetate species are formed under acidic conditions: UO2AcO+ (1:1), UO2(AcO)2 (1:2) and UO2(AcO)3- (1:3). Spectroscopic methods (e.g. IR and EXAFS) provide no certainty whether the 1:3 complex exists or not. TRLFS and UV-vis spectroscopy were mainly applied to characterize the formation of the 1:1 complex. In this study TRLFS, ATR-FT-IR and UV-vis spectroscopy were applied to determine the speciation of uranium(VI) in the presence of acetate and to fill the gap of missing spectroscopic data for the other formed species. Experimental conditions were chosen so that all three previous identified species should be formed. Data evaluation was performed on the basis of factor analysis resulting in single component spectra and stability constants. The findings led us to the conclusion that the 1:3 complex was not formed. In addition the detailed evaluation of ATR-FT-IR spectra show that an approximation used in potentiometric studies should be treated with caution. All these indications reinforce the doubts with respect to the existence of the UO2(AcO)3- species.

Tot de mineralen die indirect door menselijke activiteit zijn ontstaan, behoren enkele soorten die een uranylgroep bevatten. Ze zijn prachtig gekleurd, maar ook bijzonder vanwege de omstandigheden waaronder ze zijn gevormd.

Typically, the staff of a nonreactor nuclear facility or a processing facility involving nuclear material are not expected to have a strong technical background in nuclear criticality physics, as that is not the purpose of these sites, yet handle material with the potential to undergo a criticality excursion. Such excursions have occurred 22 times in the past, 21 of which involved an aqueous solution material. Therefore, it would be useful to have a general model capable of providing a quick estimation of the consequences of a criticality excursion in a processing plant. To this end, correlations developed utilizing experimental data from previous tests were analyzed, from which it was determined that two bounding empirical correlations are applicable to such a system with a relatively high degree of accuracy. Additionally, a computational model was adapted using Monte Carlo nuclear physics and a time- and volume-element discretization scheme. This model was used to predict the evolution and estimate the consequences of first-pulse excursions from both a SILENE experimental excursion and the historical Wood River Junction accident. The model was able to predict the power peak and total energy from the SILENE experiment when a pressure gradient damping factor was applied. Further work is needed to adequately account for the reactivity feedback from volume changes and balance the pressure effects with density effects.

The understanding of reduction and remediation of uranyl (UO22+) in the environment is a crucial consideration when planning for storage of spent nuclear fuel, as uranyl is a water-soluble environmental contaminant. This dissertation will focus on the development of new synthetic methods for the reduction of uranyl(VI) to U(IV), utilizing a synergistic relationship between a silylating reagent and a reductant. These methods provide controlled one-pot transformations at ambient temperatures and pressures, where the fates of the substituted oxo ligands have been explicitly determined. The uranyl moiety has a strictly linear O=U=O geometry, and a cis-uranyl ion is currently unknown. Isolating a cis-uranyl complex could provide some unique insights into actinide covalency and f-orbital participation in bonding. This dissertation discuses the coordination of small macrocycles to the uranyl fragment, which generates perturbed uranyl complexes with O-U-O bond angles ranging from 168° - 162°. These are some of the smallest O-U-O bond angles yet reported.

The understanding of reduction and remediation of uranyl (UO22+) in the environment is a crucial consideration when planning for storage of spent nuclear fuel, as uranyl is a water-soluble environmental contaminant. This dissertation will focus on the development of new synthetic methods for the reduction of uranyl(VI) to U(IV), utilizing a synergistic relationship between a silylating reagent and a reductant. These methods provide controlled one-pot transformations at ambient temperatures and pressures, where the fates of the substituted oxo ligands have been explicitly determined. The uranyl moiety has a strictly linear O=U=O geometry, and a cis-uranyl ion is currently unknown. Isolating a cis-uranyl complex could provide some unique insights into actinide covalency and f-orbital participation in bonding. This dissertation discuses the coordination of small macrocycles to the uranyl fragment, which generates perturbed uranyl complexes with O-U-O bond angles ranging from 168° - 162°. These are some of the smallest O-U-O bond angles yet reported.

A wide range of uranyl-peroxide nanocapsules have been synthesized using very simple reactants in basic media; however, little is known about the process to form these species. We have performed a density functional theory study of the speciation of the uranyl ions under different experimental conditions and explored the formation of dimeric species via a ligand exchange mechanism. We shed some light onto the importance of the excess of peroxide and alkali counterions as a thermodynamic driving force towards the formation of larger uranyl-peroxide species.

Europe currently holds a substantial nuclear legacy arising from fission activities, with a large proportion of high activity wastes that pose a radiological threat to natural and engineered environments. The decision to dispose of these high level wastes (following separation) in a suitable geological disposal facility (GDF) has provided some of the most demanding technical, and environmental challenges facing the EU in the coming century. In order to address these issues, we have begun a programme of work to establish a comprehensive understanding of the electronic properties and physical and chemical properties of the radioactive actinide metals using state of the art emission spectroscopic techniques in combination with NMR and computational methods.[1,2] Our approach to this is to firstly use coordination chemistry to synthesise uranium compounds with ligands that model environmentally complexed species and use optical spectroscopy to understand and map both the chemical and physical behaviour of these species (Figure 1). We have recently established that U(IV) complexes are emissive and will demonstrate that uranium in the +IV and +VI oxidation states can be detected simultaneously at relatively low concentrations. Time gating techniques enable the long lived uranyl(VI) species to be separated from the shorter lived uranium(IV) species. Furthermore, the form of the emission spectra of uranyl(VI) compounds are extremely sensitive to the nature of the ligand bound in the equatorial plane and the complex nuclearity (extent of aggregation), potentially giving a sensitive method of assessing the solution forms of uranium in environmental conditions. We will next discuss how the optical properties of these model compounds can be extended to the trans-uranics and applied to disproportionation reactions and redox events in solution. Financial support for this research was provided by the UK Engineering and Physical Sciences Research Council (EPSRC) and The Leverhulme

Sean Woodall, Louise Natrajan, Peter Kaden and Andrew Kerridge highlight recent advances in the chemistry of actinide elements that have been made possible through the collaborative efforts of industry and academia

Europe currently holds a substantial nuclear legacy arising from fission activities, with a large proportion of high activity wastes that pose a radiological threat to natural and engineered environments. The decision to dispose of these high level wastes (following separation) in a suitable geological disposal facility (GDF) has provided some of the most demanding technical, and environmental challenges facing the EU in the coming century. In order to address these issues, we have begun a programme of work to establish a comprehensive understanding of the electronic properties and physical and chemical properties of the radioactive actinide metals using state of the art emission spectroscopic techniques in combination with NMR and computational methods.[1,2] Our approach to this is to firstly use coordination chemistry to synthesise uranium compounds with ligands that model environmentally complexed species and use optical spectroscopy to understand and map both the chemical and physical behaviour of these species (Figure 1). We have recently established that U(IV) complexes are emissive and will demonstrate that uranium in the +IV and +VI oxidation states can be detected simultaneously at relatively low concentrations. Time gating techniques enable the long lived uranyl(VI) species to be separated from the shorter lived uranium(IV) species. Furthermore, the form of the emission spectra of uranyl(VI) compounds are extremely sensitive to the nature of the ligand bound in the equatorial plane and the complex nuclearity (extent of aggregation), potentially giving a sensitive method of assessing the solution forms of uranium in environmental conditions. We will next discuss how the optical properties of these model compounds can be extended to the trans-uranics and applied to disproportionation reactions and redox events in solution. Financial support for this research was provided by the UK Engineering and Physical Sciences Research Council (EPSRC) and The Leverhulme

Raman spectrum of the mineral derriksite Cu4UO2(SeO3)2(OH)6⋅H2O was studied and complemented by the infrared spectrum of this mineral. Both spectra were interpreted and partly compared with the spectra of demesmaekerite, marthozite, larisaite, haynesite and piretite. Observed Raman and infrared bands were attributed to the (UO2)2+, (SeO3)2−, (OH)− and H2O vibrations. The presence of symmetrically distinct hydrogen bonded molecule of water of crystallization and hydrogen bonded symmetrically distinct hydroxyl ions was inferred from the spectra in the derriksite unit cell. Approximate U–O bond lengths in uranyl and O–H⋯O hydrogen bond lengths were calculated from the Raman and infrared spectra of derriksite.

Biogenic mackinawite (FeS) produced by Shewanella putrefaciens CN32 is submicron in size but nanosized in one dimension (film-like morphology) Biogenic FeS is very reactive evident by its propensity to reduced U(VI) and rapid oxidation to form lepidocrocite upon exposure to air. U(VI) reduction is observed in the pasteurized control indicative of a non-enzymatic redox process. XAS and nanodiffraction techniques (bulk and nanoscale analyses) confirm the formation of UO2. UO2 particles are nanoparticulate measuring c.a. 2.5 nm in size. The present work suggests that a remediation strategy could potentially incorporate subsurface abiotic redox interactions between biogenic Fe(II)-bearing minerals such as mackinawite & contaminant U(VI) to immobilize U as UO2 – an in-situ waste form.

The interaction of hexavalent U with a freshly synthesized nanoparticulate magnetite ((FeFe2O4)-Fe-II-O-III) (stochiometric ratio x(Fe(II)/Fe-TOT) = 0.25-0.33), a partly oxidized synthetic nanoparticulate magnetite (x = 0.11-0.27) and maghemite nanoparticles (x = 0-1) under anoxic conditions and exclusion of CO2 as function of pH, contact time and total U concentration (3 x 10(-5) M and 1 x 10(-7) M) has been examined. Short term kinetic batch experiments (contact time of 90 d) for four different pH values have been conducted. Moreover, classical batch pH sorption edges have been prepared for two different uranium concentrations for a contact time of 550 d. Spectroscopic techniques (XPS, XAS) were applied to probe for the presence and amount of reduced U on the magnetite surface. Batch kinetic studies revealed a fast initial U removal from aqueous solution with >90% magnetite associated U after 24 h within the pH range 5-11. Long-term contact time batch experiments (550 d) showed neither a U removal below pH < 3 nor a decrease in the magnetite associated U at pH >= 9. Redox speciation by XPS verifies the presence of reduced U (both U(IV) and U(V) were resolved if the satellite structures were used in the fitting procedure) at the near surface of magnetite up to a contact time of 550 d and a clear correlation of the amount of available Fe(II) on the magnetite surface and the amount of reduced U is observed. XANES investigation supports presence of U(V)/U(VI) uranate and U(IV). Interpretation of the EXAFS for one sample is consistent with incorporation of U into an Fe oxide phase, after long reaction times. Thermodynamic calculations based on the experimentally determined redox potentials corroborate the spectroscopic findings of U oxidation states. Overall, the results reflect the importance of structurally bound Fe(II) as redox partner for uranyl reduction.

The retardation of contaminants in aquifers is mainly determined by chemical reactions occurring at the solid/liquid interface. For a more detailed understanding of the molecular reactions of uranium(VI) at Al-hydroxide surfaces, the surface speciation of the radionuclide on gibbsite was studied in aqueous medium by a combined spectroscopic approach using time-resolved Attenuated Total Reflection Fourier-Transform Infrared (ATR FT-IR) and Extended X-ray Absorption Fine Structure (EXAFS) spectroscopy. For the first time, the impact of the surface morphology and of atmospherically derived carbonate on the uranyl surface speciation was systematically investigated under environmentally relevant conditions, namely in the near neutral pH range, at maximum initial U(VI) concentrations of 20 µM, and at different surface loadings. Concordantly, the formation of a monomeric binary inner-sphere surface complex is derived from vibrational spectroscopic and EXAFS data irrespective of the prevailing atmospheric condition and surface loading. In addition, from infrared spectra it was found that U(VI) surface precipitation occurs at a micromolar concentration level after a relatively short contact time in an inert gas atmosphere. However, this is circumvented by lowering the initial U(VI) concentration or in the presence of atmospheric CO2 due to the formation of ternary uranyl carbonato surface complexes. The ternary complex was identified as a dimeric inner-sphere uranyl surface species containing a bidentately coordinated carbonate ligand. The results of this work might be of relevance for a comprehensive description of the dissemination of uranium in groundwater systems.

The sorption reactions of uranium(VI) at the ferrihydrite(Fh)-water interface were investigated in the absence and presence of atmospherically derived CO2 by time-resolved in situ vibrational spectroscopy. The spectra clearly show that a single uranyl surface species, most probably a mononuclear bidentate surface complex, is formed irrespective of the presence of atmospherically derived CO2. The character of the carbonate surface species correlates with the presence of the actinyl ions and changes from a monodentate to a bidentate binding upon sorption of U(VI). From the in situ sorption experiments under mildly acid conditions, the formation of a ternary surface complex is derived where the carbonate ligands coordinate bidentately to the uranyl moiety (≡UO2(O2CO)x). Furthermore, the release reaction of the carbonate ligands from the ternary surface complex is found to be considerably retarded compared to those from the pristine surface suggesting a tighter bonding of the carbonate ions in the ternary complex. Simultaneous sorption of U(VI) and atmospherically derived carbonate onto pristine Fh shows formation of binary monodentate carbonate surface complexes prior to the formation of the ternary complexes.

Biogenic mackinawite (FeS) produced by Shewanella putrefaciens CN32 is submicron in size but nanosized in one dimension (film-like morphology) Biogenic FeS is very reactive evident by its propensity to reduced U(VI) and rapid oxidation to form lepidocrocite upon exposure to air. U(VI) reduction is observed in the pasteurized control indicative of a non-enzymatic redox process. XAS and nanodiffraction techniques (bulk and nanoscale analyses) confirm the formation of UO2. UO2 particles are nanoparticulate measuring c.a. 2.5 nm in size. The present work suggests that a remediation strategy could potentially incorporate subsurface abiotic redox interactions between biogenic Fe(II)-bearing minerals such as mackinawite & contaminant U(VI) to immobilize U as UO2 – an in-situ waste form.

Uranium forms analogous minerals with phosphate and arsenate. In aqueous solutions an analogy is expected to govern the complexes that uranium builds with these ligands. Three uranyl arsenate complexes UO2H2AsO4+, UO2HAsO4 0 and UO2(H2AsO4)2 0 were identified and reported previously with TRLFS in the pH range 1 to 3. Using a similar detection system and elevating the pH range a negatively charged fourth uranyl-arsenate complex, UO2AsO4- was found under circum neutral pH. Determining the complex formation constant for this complex was not possible due to the susceptibility of the fluorescence intensity to external influences and the difficulty of resolving the measured spectra into individual fluorescence contributions. By immediate shock-freezing to 15K we succeeded to measure a reproducible EXAFS spectrum of a uranyl-arsenate species in an aqueous solution at pH 2.

Raman spectra of the uranyl containing mineral coconinoite, Fe2Al2(UO2)2(PO4)4(SO4)(OH)2•20H2O, are presented and compared with the mineral’s infrared spectra. Bands connected with (UO2)2+, (PO4)3- , (SO4)2-, (OH)- and H2O stretching and bending vibrations, are assigned. Approximate U-O bond lengths in uranyl, (UO2)2+, and O-H...O hydrogen bond lengths are calculated from the wavenumbers of the U-O stretching vibrations and (OH)- and H2O stretching vibrations, respectively, and compared with published data for similar natural and synthetic compounds.

Raman spectra of the uranyl titanate mineral brannerite were analysed and related to the mineral structure. A comparison is made with the Raman spectra of uranyl oxyhydroxide hydrates. Observed bands are attributed to the TiO and (UO2)2+ stretching and bending vibrations, U-OH bending vibrations, H2O and (OH)- stretching, bending and libration modes. U-O bond lengths in uranyls and O-H…O bond lengths are calculated from the wavenumbers assigned to the stretching vibrations. Raman bands of brannerite are in harmony with those of the uranyl oxyhydroxides. The mineral brannerite is metamict as is evidenced by the intensity of the UO stretching and bending modes being of lower intensity than expected and with bands that are significantly broader.

Raman spectra of the uranyl titanate mineral holfertite CaxU2-xTi(O8-xOH4x)•3H2O were analysed and related to the mineral structure. Observed bands are attributed to the TiO and (UO2)2+ stretching and bending vibrations, U-OH bending vibrations, H2O stretching, bending. The mineral holfertite is metamict as is evidenced by order/disorder of the mineral. Unexpectedly the Raman spectrum of holfertite does not show any metamictization. The intensity of the UO stretching and bending modes show normal intensity and the bands are sharp.

Raman spectra of the uranyl titanate mineral euxenite were analyzed and related to the mineral structure. A comparison is made with the Raman spectra of uranyl oxyhydroxide hydrates. The obsd. bands are attributed to the Ti[n.63743]O and (UO2)2+ stretching and bending vibrations, as well as lattice vibrations of rare-earth ions. The Raman bands of euxenite are in harmony with those of the uranyl oxyhydroxides. The mineral euxenite is metamict as is evidenced by the intensity of the U[n.63743]O stretching and bending modes, which are of lower intensity than expected, and with bands that are significantly broader.

Raman spectra of the uranyl titanate mineral davidite-(La) (La,Ce)(Y,U,Fe2+)(Ti,Fe3+)20(O,OH)38 were analysed and related to the mineral structure. Observed bands are attributed to the TiO and (UO2)2+ stretching and bending vibrations, U-OH bending vibrations, H2O and (OH)- stretching, bending and libration modes. U-O bond lengths in uranyls and O-H…O bond lengths are calculated from the wavenumbers assigned to the stretching vibrations. Raman bands of davidite-(La) are in harmony with those of the uranyl oxyhydroxides. The mineral davidite-(La) is metamict as is evidenced by the intensity of the UO stretching and bending modes being of lower intensity than expected and with bands that are significantly broader.

Die Komplexierung von Uran(VI) und Cm(III) mit den Zellwandkompartimenten Lipopolysaccharid und Peptidoglycan, charakterisiert durch TRLFS, EXAFS und FT-IR, wird dargestellt.

Uranyl(V) species are normally unstable in solutions but are here shown to be stable in high-temperature chloride melts. Reactions leading to the formation of UO2Cl4 3- ions were studied, including thermal decomposition and chemical reduction of uranyl(VI) chlorospecies in various alkali chloride melts (LiCl, 3LiCl-2KCl, NaCl-KCl, and NaCl-2CsCl) at 550-850 °C. Decomposition of UO2Cl4 2- species under reduced pressure, with inert gas bubbling through the melt or using zirconium getter in the atmosphere results in the formation of UO 2Cl4 3- and UO2. Elemental tellurium, palladium, silver, molybdenum, niobium, zirconium, and hydrogen, as well as niobium and zirconium ions were tested as the reducing agents. The outcome of the reaction depends on the reductant used and its electrochemical properties: uranyl(VI) species can be reduced to uranyl(V) and uranium(IV) ions, and to uranium dioxide. © 2010 IUPAC.

Raman spectra of the uranyl titanate mineral betafite were obtained and related to the mineral structure. A comparison is made with the spectra of uranyl oxyhydroxide hydrates. Observed bands are attributed to the (UO2)2+ stretching and bending vibrations, U-OH bending vibrations, H2O and (OH)- stretching, bending and libration modes. U-O bond lengths in uranyls and O-H…O bond lengths are calculated from the wavenumbers assigned to the stretching vibrations. Raman bands of betafite are comparable with those of the uranyl oxyhydroxides. The mineral betafite is metamict as is evidenced by the intensity of the UO stretching and bending modes being of lower intensity than expected and with bands that are significantly broader.

Raman and infrared spectroscopies were used to characterise two samples of triclinic ejkaite Na4[UO2(CO3)3] and its synthetic trigonal analogue. The v3 (UO2)2+ mode is not Raman active, whereas both the v3 and v1 (UO2)2+ modes are infrared active. U--O bond lengths in uranyls were calculated from the spectra obtained and compared with bond lengths derived from crystal structure analyses. From the higher number of bands related to the uranyl and carbonate vibrations, the presence of symmetrically distinct (UO2)2+ and (CO3)2- units in both structures is proposed.

In crystal structure of the title compound, {[UO2NO3(C4H7NO)2]2O2}, two UO22+ ions are connected by mu-ita2:ita2-O22–. An inversion center is located at the middle point of a O—O bond in the O2 moiety. As a result, the centrosymmetrically expanded dimeric structure is afforded. The O2 unit shows "side-on" coordination and connects two U, i.e., mu-ita2:ita2-O2. The bond lengths between U and the axial O are 1.78 Å (mean), indicating that oxidation state of U is exclusively 6+, i.e., UO22+. Furthermore, the O—O distance in the dioxy­gen moiety is 1.491 Å, which is typical of the peroxide, O22–. Each U atom is eight-coordinate in a hexagonal-bipyramidal geometry. The coordinating atoms of nitrate, pyrrolidine-2-one and mu-ita2:ita2-O22– are located on the equatorial plane, and form an irregular hexagon. The inter­molecular hydrogen bonds are found between N—H of 2-pyrrolidone and the coordinating O of the same ligand in the neighboring complex.

The complexation of uranium(VI) with glucose was studied in the pH range from pH 2 to 6 by time resolved laser-induced fluorescence spectroscopy (TRLFS) at room temperature (RT) and for the first time under cryogenic conditions of 153 K (cryo-TRLFS). A uranyl(VI) glucose complex was spectroscopically identified by cryo-TRLFS measurements at pH 5. At lower pH values only the free uranyl(VI) ion was identified. The study revealed that quenching effects severely influenced the TRLFS measurements conducted at RT and significantly reduced the uranium(VI) fluorescence signal. This decrease in U(VI) fluorescence intensity is usually used to calculate complex formation constants of non-fluorescent uranyl(VI) organic complexes. However, our cryo-TRLFS results clearly showed that the observed decrease in U(VI) fluorescence intensity at RT for the samples at pH 2 to 4 is not attributed to the formation of such a non-fluorescent U(VI) glucose complex, i.e. to static quenching, but related to dynamic quenching of glucose on the uranyl(VI) fluorescence. At higher pH values the formation of uranyl(VI) glucose complexes were suppressed by the formation of uranyl(VI) carbonate species. The detected uranyl(VI) glucose complex was characterized by five emission bands at 499.0, 512.1, 525.2, 541.7, and 559.3 nm. The respective fluorescence lifetime determined at 153 K was 20.9 ± 2.9 µs. The uranyl(VI) glucose complex formation constant was calculated for the first time to be logßI = 0.1 M = 15.35 ± 0.91. Comparing this constant with formation constants of other important environmentally relevant inorganic ligands, in particular carbonate, it became evident that glucose only may influence the transport behaviour of uranium in a very small pH region of about 5. Our cryo-TRLFS investigation opens up new possibilities for the determination of complex formation constants since interfering quenching effects often encounter at RT are suppressed by measurements at cryogenic conditions.

This paper describes, for the first time, a simple method for the synthesis of uranyl aluminate (URAL) nanoparticles. URAL was prepared by U(VI) hydrolytic precipitation with ammonia at pH = 11 in the presence of mesoporous alumina MSU-X under 20 kHz of sonication followed by annealing of the obtained solids at 800 C. TEM, XAFS, powder XRD, and 27Al MAS NMR studies revealed that the speciation of uranium in this system strongly depends on uranium concentration. The sample with 5 wt % of uranium yields air-stable nanoparticles (∼5 nm) of URAL. Presumably, UO2 2þ cations in this compound are coordinated with bidentate AlO2 - groups. The increase of uranium concentration to 30 wt % causes mostly formation of U3O8 fine particles (∼50 nm) and small amounts of URAL.

The fabrication of novel uranyl (UO2 2+) binding protein based sensors is reported. The new biosensor responds to picomolar levels of aqueous uranyl ions within minutes using Lysinibacillus sphaericus JG-A12 S-layer protein tethered to gold electrodes. In comparison to traditional self assembled monolayer based biosensors the porous bioconjugated layer gave greater stability, longer electrode life span and a denser protein layer. Biosensors responded specifically to UO2 2+ ions and showed minor interference from Ni2+, Cs+, Cd2+ and Co2+. Chemical modification of JG-A12 protein phosphate and carboxyl groups prevented UO2 2+ binding, showing that both moieties are involved in the recognition to UO2 2+.

Uranium(VI) mobility in groundwater is strongly affected by sorption of mobile U(VI) species (e.g. uranyl, UO22+) to mineral surfaces, precipitation of U(VI) compounds, such as schoepite (UO2)(4)O(OH)(6)center dot 6H(2)O), and by reduction to U(IV), forming sparingly soluble phases (uraninite; UO2). The latter pathway, in particular, would be very efficient for long-term immobilization of U. In nature, Fe(II) is an important reducing agent for U(VI) because it frequently occurs either dissolved in natural waters, sorbed to matrix minerals, or structurally bound in many minerals. Redox reactions between U(VI) and Fe(II) depend not only on the availability of Fe(II) in the environment, but also on the chemical conditions in the aqueous solution. Under natural groundwater condition U(VI) forms complexes with many anionic ligands, which strongly affect its speciation. Carbonate, in particular, is known to form stable complexes with U, raising the question, if U(VI), when complexed by carbonate, can be reduced to UO2. The goal of this study was to find out if Fe(II) when structurally bound in a mineral (as magnetite, Fe3O4) or sorbed to a mineral surface (as corundum, Al2O3) can reduce U(VI) to U(IV) in the presence of HCO3-. Batch experiments were conducted under anaerobic conditions to observe U removal from the aqueous phase by the two minerals depending on HCO3- addition (1 mM), U concentration (0.01-30 mu M) and pH value (6-10). Immediately after the experiments, the mineral surfaces were analyzed by X-ray photoelectron spectroscopy (XPS) to obtain information on the redox state of U bound to the solid surfaces. XPS results gave evidence that U(VI) can be reduced both by magnetite and by corundum amended with Fe(II). In the presence of HCO3 the amount of reduced U on the mineral surfaces increased compared to carbonate-free solutions. This can be explained by the formation of Fe(II) carbonates on the mineral surfaces which represent an easily available Fe(II) pool f, QC 20100525

Raman spectra of jáchymovite, (UO2)8(SO4)(OH)14•13H2O, were studied, complemented with infrared spectra, and compared with published Raman and infrared spectra of uranopilite, [(UO2)6(SO4)O2(OH)6(H2O)6] •6H2O. Bands related to the stretching and bending vibrations of (UO2)2+, (SO4)2-, (OH)- and water molecules were assigned. U-O bond lengths in uranyl and O-H…O hydrogen bond lengths were calculated from the Raman and infrared spectra.

Raman spectra of natrouranospinite complemented with infrared spectra were studied and related to the structure of the mineral. Observed bands were assigned to the stretching and bending vibrations of (UO2)2+ and (AsO4)3- units and of water molecules. U-O bond lengths in uranyl and O-H…O hydrogen bond lengths were calculated from the Raman and infrared spectra.

Raman spectra of dumontite were measured at 298 and 77 K. Observed bands were attributed to the stretching and bending vibrations of uranyl and phosphate units and OH stretching vibrations of water molecules. U-O bond lengths in uranyls and approximate O-H…O bond lengths were calculated. The values of the U-O bond lengths are in agreement with the data from the single crystal structure analysis of dumontite.

Previous spectroscopic research suggested that uranium(VI) adsorption to iron oxides is dominated by ternary uranyl-carbonato surface complexes across an unexpectedly wide pH range. Formation of such complexes would have significant impact on the sorption behavior and mobility of uranium in aqueous environments. We therefore re-investigated the identity and structural coordination of uranyl sorption complexes using a combination of U LIII-edge Extended X-ray Absorption Fine-Structure (EXAFS) spectroscopy and Iterative Transformation Factor Analysis, which enhances the resolution in comparison to conventional EXAFS analysis. A range of conditions (pH, CO2 partial pressure, ionic strength) made it possible to quantify the variations in surface speciation. In the resulting set of spectral data (N=11), the variance is explained by only two components, which represent two structurally different types of surface complexes: (1) a binary uranyl surface complex with a bidentate coordination to edges of Fe(O,OH)6 octahedra, and (2) a uranyl triscarbonato surface complex where one carbonate ion bridges uranyl to the surface. This ternary type B complex differs from a type A complex where uranyl is directly attached to surface atoms, and carbonate is bridged by uranyl to the surface. Both surface complexes agree qualitatively and quantitatively with predictions by a charge distribution (CD) model. According to this model, the edge-sharing uranyl complex has equatorial ligands (–OH2, -OH or one -CO3 group) that point away from the surface. The monodentate uranyl triscarbonato surface complex (type B) is relevant only at high pH and elevated pCO2. At these conditions, however, it is responsible for significant uranyl sorption, whereas standard models would predict only weak sorption. This paper presents the first spectroscopic evidence of this ternary surface complex, which has significant implications for the immo

We investigated the structure of uranyl sorption complexes on gibbsite (pH 5.6 - 9.7) by two independent methods, density functional theory (DFT) calculations and extended X-ray absorption fine structure (EXAFS) spectroscopy at the U-LIII edge. To model the gibbsite surface with DFT, we tested two Al (hydr)oxide clusters, a dimer and a hexamer. Based on polarization, structure, and relaxation energies during geometry optimization, the hexamer cluster was found to be the more appropriate model. An additional advantage of the hexamer model is that it represents both edges and basal faces of gibbsite. The DFT calculations of (monomeric) uranyl sorption complexes show an energetic preference for the corner-sharing versus the edge-sharing configuration on gibbsite edges. The energy difference is so small, however, that possibly both surface species may coexist. In contrast to the edge sites, sorption to basal sites was energetically not favorable. EXAFS spectroscopy revealed in all investigated samples the same interatomic distances of the uranyl coordination environment (RU-Oax ≈ 1.80 Å, RU-Oeq ≈ 2.40 Å), and towards the gibbsite surface (RU-O ≈ 2.87 Å, RU-Al ≈ 3.38 Å). In addition, two U-U distances were observed, 3.92 Å at pH 9.7 and 4.30 Å at pH 5.6, both with coordination numbers of ~ 1. The short U-U distance is close to that of the aqueous uranyl hydroxo dimer, UO2(OH)2, reported as 3.875 Å in the literature, but significantly longer than that of aqueous trimers (3.81-3.82 Å), suggesting sorption of uranyl dimers at alkaline pH. The longer U-U distance (4.30 Å) at acidic pH, however, is not in line with known aqueous uranyl polymer complexes. Based on the EXAFS findings we further refined dimeric surface complexes with DFT. We propose two structural models: in the acidic region, the observed long U-U distance can be explained with a distortion of the uranyl dimer to form both a corner-sharing and an edge-sharing linkage to neighboring Al octahedra, leading to RU-U

A multisite surface complexation (MUSIC) model for ferrihydrite has been developed. The surface structure and composition are described for ferrihydrite in terms of site densities, molar mass, bulk density and reactive surface area, all linked to ion binding and surface charge development. Singly coordinated surface groups dominate the surface of ferrihydrite. These groups are present in two structural configurations, each linked to different surface patches. The configurations either form bidentate complexes by edge sharing coordination or form double-corner complexes. Both types of configurations react differently in terms of binding of ions such as uranyl and carbonate. The adsorption of uranyl (UO22+) on ferrihydrite has been evaluated with the Charge Distribution (CD) model. Modeling shows that uranyl forms bidentate innersphere complexes at binding sites that do not react with carbonate ions. This observation is used to develop a surface structural model for ferrihydrite. Uranyl is bound by singly coordinated surface groups present at particular edges of Fe-octahedrons of ferrihydrite while another set of singly coordinated surface groups may form double-corner bidentate complexes with for instance carbonate ions. The uranyl surface speciation strongly changes in the presence of carbonate due to the specific adsorption of carbonate ions as well as the formation of ternary uranyl-carbonate surface complexes. The CD model reveals the formation of a uranyl-triscarbonato surface complex, i.e. ≡ (UO2)(CO3)34-, particularly present in systems with a high pH and carbonate concentration. This finding remarkably differs from results from previous interpretations made in literature. The presence of this surface species agrees quantitatively with a recent interpretation of EXAFS data (Rossberg et al. 2008). In the specific case of a high pH value, but at low carbonate level, as can be prepared in CO2-closed systems, the model suggests the presence of a ternary uranyl-mon

Previous spectroscopic research suggested that uranium(VI) adsorption to iron oxides is dominated by ternary uranyl-carbonato surface complexes across an unexpectedly wide pH range. Formation of such complexes would have significant impact on the sorption behavior and mobility of uranium in aqueous environments. We therefore re-investigated the identity and structural coordination of uranyl sorption complexes using a combination of U LIII-edge Extended X-ray Absorption Fine-Structure (EXAFS) spectroscopy and Iterative Transformation Factor Analysis, which enhances the resolution in comparison to conventional EXAFS analysis. A range of conditions (pH, CO2 partial pressure, ionic strength) made it possible to quantify the variations in surface speciation. In the resulting set of spectral data (N=11), the variance is explained by only two components, which represent two structurally different types of surface complexes: (1) a binary uranyl surface complex with a bidentate coordination to edges of Fe(O,OH)6 octahedra, and (2) a uranyl triscarbonato surface complex where one carbonate ion bridges uranyl to the surface. This ternary type B complex differs from a type A complex where uranyl is directly attached to surface atoms, and carbonate is bridged by uranyl to the surface. Both surface complexes agree qualitatively and quantitatively with predictions by a charge distribution (CD) model. According to this model, the edge-sharing uranyl complex has equatorial ligands (–OH2, -OH or one -CO3 group) that point away from the surface. The monodentate uranyl triscarbonato surface complex (type B) is relevant only at high pH and elevated pCO2. At these conditions, however, it is responsible for significant uranyl sorption, whereas standard models would predict only weak sorption. This paper presents the first spectroscopic evidence of this ternary surface complex, which has significant implications for the immo

Previous spectroscopic research suggested that uranium(VI) adsorption to iron oxides is dominated by ternary uranyl-carbonato surface complexes across an unexpectedly wide pH range. Formation of such complexes would have significant impact on the sorption behavior and mobility of uranium in aqueous environments. We therefore re-investigated the identity and structural coordination of uranyl sorption complexes using a combination of U LIII-edge Extended X-ray Absorption Fine-Structure (EXAFS) spectroscopy and Iterative Transformation Factor Analysis, which enhances the resolution in comparison to conventional EXAFS analysis. A range of conditions (pH, CO2 partial pressure, ionic strength) made it possible to quantify the variations in surface speciation. In the resulting set of spectral data (N=11), the variance is explained by only two components, which represent two structurally different types of surface complexes: (1) a binary uranyl surface complex with a bidentate coordination to edges of Fe(O,OH)6 octahedra, and (2) a uranyl triscarbonato surface complex where one carbonate ion bridges uranyl to the surface. This ternary type B complex differs from a type A complex where uranyl is directly attached to surface atoms, and carbonate is bridged by uranyl to the surface. Both surface complexes agree qualitatively and quantitatively with predictions by a charge distribution (CD) model. According to this model, the edge-sharing uranyl complex has equatorial ligands (–OH2, -OH or one -CO3 group) that point away from the surface. The monodentate uranyl triscarbonato surface complex (type B) is relevant only at high pH and elevated pCO2. At these conditions, however, it is responsible for significant uranyl sorption, whereas standard models would predict only weak sorption. This paper presents the first spectroscopic evidence of this ternary surface complex, which has significant implications for the immo

Two-dimensional (2D) correlation spectroscopy was used to resolve the positions and correlations among U4f primary peaks and satellite structures of UIV, UV and UVI components on a dry mica surface. These different species resulted from the reduction of UVI, initially sorbed/precipitated from solution, upon exposure to a high flux of monochromatic Al Kα X-rays during X-ray photoelectron spectroscopy. Synchronous and asynchronous 2D maps of these results are consistent with previous assignments to UIV, UV and UVI components of the solid. The synchronous spectra confirmed the negative correlation between UVI and UIV components and the asynchronous spectra confirmed the role of UV as a reactive intermediate in the reduction reaction of UVI to UIV. Simulations of 2D correlation maps using synthetic spectra of the primary peaks showed that the presence of highly overlapped peaks centered within 2 eV of each other cannot be distinguished without the presence of additional cross-peaks. The maps have therefore confirmed the existence of three dominant oxidation states, and identified positions of UIV, UV and UVI U4f primary peaks and satellite structures that are consistent with previous peak-fitting efforts. Satellite structures also showed out-of-phase correlations among the different oxidation states, further confirming their use as reliable indicators of oxidation state.

Raman spectra of phosphuranylite and yingjiangite were measured, interpreted and compared with published infrared spectra of both minerals. U-O bond lengths were calculated using the Bartlett-Cooney‘s empirical relations and the O-H-O hydrogen bond lengths were inferred on the basis of Libowitzky's empirical relation. The presence of oxonium and (H3O)+ ions, expected from the single crystal structure analysis of phosphuranylite, was not inferred from the Raman spectra. It was assumed that phosphuranylite and yingjiangite are identical and the name yingjiangite should be discarded because the name phosphuranylite has priority.

Raman spectra of the uranyl oxyhydroxy hydrated mineral compreignacite, K2[(UO2)3O2(OH)3]2.7H2O, were measured and interpreted. Observed bands were attributed to the stretching and bending vibrations of uranyl units, molecular water and hydroxyl ions. U-O bond lengths in uranyl and O-H…O hydrogen bond lengths were inferred from the spectra and compared with those from the X-ray single crystal structure data. The importance of this spectroscopic study rests with the ability to analyze very small amounts of mineral.

Synchrotron-based EXAFS spectroscopy is a powerful technique to obtain structural information on radionuclide bioligand species in solution. As an example pyoverdin-type siderophores are a unique class of bioligands, with a high potential to dissolve, bind, and thus transport uranium in the environment. Pyoverdins are secreted from fluorescent Pseudomonas species which are ubiquitous soil bacteria. The functional groups of the pyoverdin molecule, LH4, participating in metal binding are the catechol group of the chromophore and two ligand sites in the peptide chain, i.e., one or two hydroxamate groups and one or two -hydroxy acid moieties [1]. The formation of complexes of UO22+ with pyoverdins released by the groundwater bacterium Pseudomonas fluorescens (CCUG 32456) isolated at a depth of 70 m in the Äspö Hard Rock Laboratory, Sweden, was investigated in our previous study [2]. Two UO22+-P. fluorescens pyoverdin species, UO2LH2 and UO2LH-, could be distinguished on the basis of UV-vis spectroscopy and fs-TRLFS. Little structural information is available regarding the U(VI) pyoverdin species formed in aqueous solutions. We therefore performed U LIII-edge EXAFS measurements of test solutions containing 5x10-4 or 0.001 M UO22+ and pyoverdins or related model compounds at an ionic strength of 0.1 M NaClO4. The pH was varied between 2 and 8 depending on the bioligand. EXAFS measurements were carried out on the Rossendorf Beamline (ROBL) BM20 at the ESRF [3]. The samples were measured at room temperature using a water-cooled Si(111) double-crystal monochromator in channel cut mode (5-35 keV). The spectra were collected either in fluorescence mode using a 13-element Ge solid-state detector or in transmission mode using Ar filled ionization chambers. The model compounds simulate the hydroxamate function (simple hydroxamate and a trihydroxamate compound) and the chromophore of the pyoverdin molecule. The obtained structural information for the axial and equatorial oxygen a

Synchrotron-based EXAFS spectroscopy is a powerful technique to obtain structural information on radionuclide bioligand species in solution. As an example pyoverdin-type siderophores are a unique class of bioligands, with a high potential to dissolve, bind, and thus transport uranium in the environment. Pyoverdins are secreted from fluorescent Pseudomonas species which are ubiquitous soil bacteria. The functional groups of the pyoverdin molecule, LH4, participating in metal binding are the catechol group of the chromophore and two ligand sites in the peptide chain, i.e., one or two hydroxamate groups and one or two -hydroxy acid moieties [1]. The formation of complexes of UO22+ with pyoverdins released by the groundwater bacterium Pseudomonas fluorescens (CCUG 32456) isolated at a depth of 70 m in the Äspö Hard Rock Laboratory, Sweden, was investigated in our previous study [2]. Two UO22+-P. fluorescens pyoverdin species, UO2LH2 and UO2LH-, could be distinguished on the basis of UV-vis spectroscopy and fs-TRLFS. Little structural information is available regarding the U(VI) pyoverdin species formed in aqueous solutions. We therefore performed U LIII-edge EXAFS measurements of test solutions containing 5x10-4 or 0.001 M UO22+ and pyoverdins or related model compounds at an ionic strength of 0.1 M NaClO4. The pH was varied between 2 and 8 depending on the bioligand. EXAFS measurements were carried out on the Rossendorf Beamline (ROBL) BM20 at the ESRF [3]. The samples were measured at room temperature using a water-cooled Si(111) double-crystal monochromator in channel cut mode (5-35 keV). The spectra were collected either in fluorescence mode using a 13-element Ge solid-state detector or in transmission mode using Ar filled ionization chambers. The model compounds simulate the hydroxamate function (simple hydroxamate and a trihydroxamate compound) and the chromophore of the pyoverdin molecule. The obtained structural information for the axial and equatorial oxygen a

The bonding of uranium with glucose and alpha cyclodextrin were investigated by time resolved laser fluorescence spectroscopy (TRLFS), attenuated total reflectance fourier transform infrared spectroscopy (ATR-FTIR) and confocal laser scanning microscopy (CLSM). Two different uranyl-sugar complexes could be synthesized. Both complexes show a strong fluorescence signal by excitation with 266 nm. The emission maxima were detected at 497 nm for the uranyl-glucose complex and 494 nm for the uranyl-alpha-cyclodextrin complex respectively. The time resolved investigations show a fluorescence lifetime of 36 µs for the uranyl-glucose complex and 37 µs for the uranyl-alpha-cyclodextrin complex.