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At least 253 records · Page 14
All sourcesNASA NTRSDOE OSTI
DOE OSTI2013

Copper(II)-lanthanide(III) coordination polymers constructed from pyridine-2,5-dicarboxylic acid: Preparation, crystal structure and photoluminescence

A series of 3d-4f heterometallic coordination polymers, formulated as {l_brace} [Cu{sub 3}Ln{sub 2}(pydc){sub 6}(H{sub 2}O){sub 12}]{center_dot}4H{sub 2}O{r_brace} {sub n} [Ln=Tb (1), Eu (2), Dy (3), Ho (4), Lu (5)], {l_brace} [CuNd{sub 2}(pydc){sub 4}(H{sub 2}O){sub 3}]{center_dot}H{sub 2}O{r_brace} {sub n} (6) and {l_brace} [Cu{sub 3}Pr{sub 2}(pydc){sub 6}(H{sub 2}O){sub 13}]{center_dot}4H{sub 2}O{r_brace} {sub n} (7) (where H{sub 2}pydc=pyridine-2,5-dicarboxylic acid), have been hydrothermally prepared by reactions of H{sub 2}pydc ligand with lanthanide ions in the presence of Cu(II) ion. X-ray crystal structure analysis reveals that these compounds exhibit rich structural chemistry. 1-5 are isomorphous and present a two-dimensional network constructed from Ln{sub 2}Cu{sub 2}L{sub 2}(H{sub 2}O){sub 2} SBU rings and CuL{sub 2}(H{sub 2}O) building blocks. In 6, two-dimensional ladder-like layers based on Nd(III) belts and CuL{sub 2}O{sub 2} units are assembled by H{sub 2}pydc ligands into a three-dimensional open framework. Polymer 7 displays a two-dimensional wave-like layer structure containing two distinct ring units, in which a new coordination mode of the pydc{sup 2-} ligand is observed. The results indicate that the coordination flexibility of the pydc{sup 2-} ligand and lanthanide contraction effect play cooperative roles in the formation of coordination polymers with different polymeric architectures. Compounds 1-2 exhibit intense green and red luminescence emission characteristics of Tb(III) and Eu(III), respectively. Furthermore, elemental analyses (EA), infrared spectra (IR) and thermogravimetric analyses (TGA) of these compounds were also studied. - Graphical abstract: Seven 3d-4f heterometallic coordination polymers were synthesized by reactions of H{sub 2}pydc with lanthanide metal ions in the presence of Cu{sup 2+}, the effects of Cu{sup 2+} on the structures and photoluminescent properties of Ln-pydc{sup 2-} systems were investigated. Highlights: Black-Right-Pointing-Pointer Seven 3d-4f heterometallic compounds have been prepared and characterized. Black-Right-Pointing-Pointer 1-5 and 7 are constructed from Ln{sub 2}Cu{sub 2}L{sub 2}(H{sub 2}O){sub 2} rings and CuL{sub 2}(H{sub 2}O) building blocks. Black-Right-Pointing-Pointer One new coordination mode of the pydc{sup 2-} ligand is first observed. Black-Right-Pointing-Pointer 1-2 exhibit intense characteristic luminescence emission spectra of lanthanide ions.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Syntheses, structural analyses and luminescent property of four alkaline-earth coordination polymers

Four alkaline-earth coordination polymers, [Ba(Pzdc)(H{sub 2}O)]{sub n} (1), [Ba(Pzdc)]{sub n} (2), [AgSr(Pzdc)(NO{sub 3})(H{sub 2}O)]{sub n} (3), [Ag{sub 2}Ca(Pzdc){sub 2}(H{sub 2}O)]{sub n} (4) (H{sub 2}Pzdc=2, 3-pyrazinedicarboxylic acid) have been synthesized and characterized by single-crystal X-ray diffraction. Compounds 1 and 2 afford 2D layer networks generated by one-dimensional chains containing the [Ba{sub 2}O{sub 11}N] units. Compound 3 is of 2D mixed-metal coordination network formed by one-dimensional chain units, while 4 is of a 3D heterometallic framework. Interestingly, 1 and 2 can undergo reversible SCSC structural transformation upon dehydration/rehydration of coordinated water molecules. In addition, the π–π stacking interactions dominate fluorescent properties of compounds 1 and 2. - Graphical abstract: Four new coordination polymers [Ba(Pzdc)(H{sub 2}O)]{sub n} (1), [Ba(Pzdc)]{sub n} (2), [AgSr(Pzdc)(NO{sub 3})(H{sub 2}O)]{sub n} (3), [Ag{sub 2}Ca(Pzdc){sub 2}(H{sub 2}O)]{sub n} (4) (H{sub 2}Pzdc=2, 3-pyrazinedicarboxylic acid) have been synthesized. Compounds 1–3 display 2D topology structures and compound 4 exhibits a 3D topology structure. Fortunately, 1 and 2 undergo reversible dehydration/rehydration of coordinated water molecules. Display Omitted - Highlights: • All structures are generated by 1D chains. • 1 and 2 show reversible dehydration/rehydration of coordinated water molecules. • The π–π stacking interactions dominate fluorescent properties of compounds 1 and 2.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2014

Anion-controlled assembly of silver-di(aminophenyl)sulfone coordination polymers: Syntheses, crystal structures, and solid state luminescence

Five silver coordination polymers, namely, ([Ag(3,3′-daps){sub 2}]·BF{sub 4}){sub n} (1), ([Ag(3,3′-daps){sub 2}]·NO{sub 3}){sub n} (2), [Ag(3,3′-daps)(CF{sub 3}SO{sub 3})]{sub n} (3), ([Ag(4,4′-daps)]·CF{sub 3}SO{sub 3}){sub n} (4), and ([Ag(4,4′-daps)]·ClO{sub 4}){sub n} (5) (3,3′-daps=di(3′-aminodiphenyl)sulfone, and 4,4′-daps=di(4′-aminodiphenyl)sulfone) have been synthesized and structural characterized by elemental analyses, IR spectra, powder X-ray diffraction (PXRD) and single-crystal X-ray diffraction analyses. Complex 1 displays a 1D ladder-like chain with four-connected Ag ions and bridged 3,3′-daps. Complex 2 shows other 1D ladder chain modified by tentacles. Complex 3 is a 2D layer structure with both Ag ions and 3,3′-daps are 3-connected nodes. Complex 4 is another 1D ladder chain with three-connected Ag ions and 4,4′-daps. Complex 5 shows a 2D 4{sup 4}-sql net with Ag ions and 4,4′-daps as 4-connected nodes. Moreover, their solid state luminescence and thermal stabilities also have been investigated. - Graphical abstract: Pictogram: Synthetic procedures of the five anion controlled silver coordination polymers. We reported the synthetic procedures, structure, and luminescence property of the five anion controlled silver coordination polymers based on two novel di(aminophenyl)sulfone V-shaped ligands. Display Omitted - Highlights: • Five new silver coordination polymers were synthesized and characterized. • Two novel designed V-shaped di(aminophenyl)sulfone ligands were first introduced to coordination chemistry. • Anions play important roles in determining the five silver coordination polymers. • The structural diversity and photoluminescence property were also discussed.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2014

Syntheses, structures and properties of four 3D microporous lanthanide coordination polymers based on 3,5-pyrazoledicarboxylate and oxalate ligands

Four three-dimensional lanthanide coordination polymers with reversible structural interconversions, [Ln{sub 2}(Hpdc){sub 2}(C{sub 2}O{sub 4})(H{sub 2}O){sub 4}]{sub n}·2nH{sub 2}O [Ln=Sm (1), Eu (2), Tb (3) and Dy (4)], have been synthesized by hydrothermal reactions of lanthanide nitrates with 3,5-pyrazoledicarboxylic (H{sub 3}pdc) and oxalic acids. It is noteworthy that there is an in situ reaction in 1, in which H{sub 3}pdc was decomposed into (ox){sup 2−} with Cu(II)–Sm(III) synergistic effect under hydrothermal conditions. These compounds are isostructural and crystallized in the monoclinic P2{sub 1}/c space group. The Ln(III) ions are eight-coordinated with dodecahedron coordination geometry. These polyhedra are linked by oxalate groups to form 1D zigzag chain, which are further connected by 3,5-pyrazoledicarboxylate to extend similar 3D frameworks with channels along c-axis in 1–4. These coordination polymers display the characteristic emission bands of the Ln(III) ions in the solid state and possess good thermal stabilities. - Graphical abstract: Four 3D microporous lanthanide coordination polymers with reversible structural interconversion have been synthesized. They exhibit characteristic emission bands of the lanthanide ions and possess great thermal stability. - Highlights: • Four lanthanide coordination polymers have been hydrothermal synthesized. • There is an in situ reaction in 1 in which H{sub 3}pdc was decomposed into (ox){sup 2−} with the Cu(II)–Sm(III) synergistic effect under hydrothermal conditions. • TGA and XRD studies reveal that upon hydration–dehydration, compounds 1–4 undergo a reversible structural interconversion process through a cooling-heating cycle. • Compounds 1–4 exhibit characteristic lanthanide-centered luminescence.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2015

Solvent induced synthesis, structure and properties of coordination polymers based on 5-hydroxyisophthalic acid as linker and 1,10-phenanthroline as auxiliary ligand

Three new coordination polymers [Mn(hip)(phen) (H{sub 2}O)]{sub n} (1), [Co(hip)(phen) (H{sub 2}O)]{sub n} (2), and [Cd(hip) (phen) (H{sub 2}O)]{sub n} (3) (H{sub 2}hip=5-hydroxyisophthalic acid; phen=1,10-phenanthroline) have been synthesized by solvo-hydrothermal method using diethyl formamide-water (DEF-H{sub 2}O) as solvent system. Single-crystal X-ray diffraction analysis reveals that all three coordination polymers 1, 2 and 3 crystallize in monoclinic space group P2/n. Metal ions are inter-connected by hydroxyisophthalate anions forming zig-zag 1D chain. 1D chains are further inter-connected by hydrogen bonding and π–π stacking interactions leading to 3D supramolecular architecture. Hydrogen-bonding and π–π stacking provide thermal stability to polymers. Compounds 1 and 2 are paramagnetic at room temperature and variable temperature magnetic moment measurements revealed weak ferromagnetic interactions between metal ions at low temperature. Compound 3 exhibits excellent photoluminescence with large Stokes shift. - Graphical abstract: 1D helical chains of coordination polymers were synthesized by solvo-hydrothermal reaction of 5-hydroxyisopthalic acid and 1,10-phenanthroline with MnCl{sub 2}·4H{sub 2}O / CoCl{sub 2}·6H{sub 2}O / Cd(NO{sub 3}){sub 2}·6H{sub 2}O. - Highlights: • Solvent induced synthesis of three coordination polymers with 1D zig-zag structure. • Crystal structures of coordination polymers are reported and discussed. • 1,10-Phenanthroline influences magnetic and luminescent properties of polymers. • Coordination polymer of Cd is luminescent exhibiting large Stokes shift.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2016

Construction of New Coordination Polymers from 4’-(2,4-disulfophenyl)- 3,2’:6’3”-terpyridine: Polymorphism, pH-dependent syntheses, structures, and properties

Nine new coordination compounds, namely, [Co(HDSPTP){sub 2}(H{sub 2}O){sub 4}]·4H{sub 2}O (H{sub 2}DSPTP=4’-(2,4-disulfophenyl)-3,2’:6’3”-terpyridine, 1 and 2), {[Ni(DSPTP)(H_2O)_4]·3H_2O}{sub n} (3), {[Cu(HDSPTP)_2(H_2O)_3]·8H_2O}{sub n} (4), {[Cu(HDSPTP)_2(H_2O)_3]·6H_2O}{sub n} (5), {[Cu(DSPTP)(H_2O)_2]·H_2O}{sub n} (6), {[Zn(DSPTP)(H_2O)_2]·2H_2O}{sub n} (7), {[Cd(DSPTP)(H_2O)_2]·2H_2O}{sub n} (8), and [Ag{sub 2}(DSPTP)(H{sub 2}O)]{sub n} (9), were constructed based on a new ligand containing both terpyridyl and sulfo groups. The reactions of H{sub 2}DSPTP with Co(NO{sub 3}){sub 2}.6H{sub 2}O resulted in two mononuclear complexes (compounds 1 and 2). They are polymorphisms that display different hydrogen bonding networks. They are selectively synthesized by altering the added alkalis. The reaction of H{sub 2}DSPTP with Ni(NO{sub 3}){sub 2}·6H{sub 2}O resulted in a 1D “S-shaped” coordination chain (compound 3). The reactions of Cu(II) with H{sub 2}DSPTP at different pH value resulted in the following three compounds: two kinds of 1D chains obtained at pH 3.0 and 4.0 for compounds 4 and 5, respectively, and a 3D framework based on binuclear ring units with 4-connected sra topology (Compound 6). The reactions of H{sub 2}DSPTP with ds-block ions resulted in the following three compounds: a Zn(II) (compound 7) and a Cd(II) (compound 8) 3D frameworks with structures similar to that in compound 6, and a 3D framework based on tetranuclear Ag(I) SBUs with binodal (4,8)-connected flu type 3D framework topology. The structural diversity is mainly attributed to the rich coordination modes (from monodentate to µ{sub 7}-mode) and conformations (cis–cis and cis–trans) of HDSPTP{sup −}/DSPTP{sup 2−} ligands and the metal center and can be controllable synthesized by altering the alkalis, and pH value. Thermal stability of all compounds was performed, and the thermal behaviors of compounds 6 and 8 were further explored by PXRD. Compound 6 exhibits low thermal stability and undergo a crystalline–crystalline-amorphous phase transition as temperature increases from 25 °C to 200 °C, and show amorphous–crystalline phase transition when rehydrated. However, compound 8 exhibits high thermal stability above 500 °C. Its crystalline phase can retain above 300 °C and undergo a crystalline–crystalline phase transition as temperature increased to 400 °C, and transit back to compound 8 when rehydrated. Moreover, luminescence properties of compounds 7–9 were also investigated. - Graphical abstract: Series of coordination compounds based on a new terpyridine-based ligand, 4’-(2,4-disulfophenyl)-3,2’:6’3’’-terpyridine, were constructed. The syntheses, structural diversity, thermal stability, phase transition, and luminescent properties of selected compounds were explored. - Highlights: • Nine coordination polymers based on a new terpyridine-based ligand were obtained. • Both metal ion and coordination modes of H2DSPTP affect the structural diversity. • The Co(II) compounds are polymorphisms. • The pH-dependent syntheses of Cu(II) compounds were observed. • Compounds 6 and 8 exhibit phase transmission as temperature increased.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2016

Utilization of mixed ligands to construct diverse Ni(II)-coordination polymers based on terphenyl-2,2′,4,4′-tetracarboxylic acid and varied N-donor co-ligands

Three new coordination polymers, namely, {[Ni(H_2L)(bix)(H_2O)_2]·2h_2O}{sub n} (1), {[Ni(HL)(Hdpa)(H_2O)_2]·H_2O}{sub n} (2), {[Ni(L)_0_._5(bpp)(H_2O)]·H_2O}{sub n} (3) (H{sub 4}L=terphenyl-2,2′,4,4′-tetracarboxylic acid; bix=1,4-bis(imidazol-1-ylmethyl)benzene; dpa =4,4′-dipyridylamine; bpp=1,3-bis(4-pyridyl)propane), based on rigid H{sub 4}L ligand and different N-donor co-ligands, have been synthesized under hydrothermal conditions. Compound 1 features a 3D 4-connected 6{sup 6}-dia-type framework with H{sub 4}L ligand adopts a μ{sub 2}-bridging mode with two symmetry-related carboxylate groups in μ{sub 1}-η{sup 1}:η{sup 0} monodentate mode. Compound 2 displays a 1D [Ni(HL)(Hdpa)]{sub n} ribbon chains motif, in which the H{sub 4}L ligand adopts a μ{sub 2}-bridging mode with two carboxylate groups in μ{sub 1}-η{sup 1}:η{sup 1} and μ{sub 1}-η{sup 1}:η{sup 0} monodentate modes, while 3 possesses a (4,4)-connected 3D frameworks with bbf topology, with H{sub 4}L ligand displays a μ{sub 4}-bridging coordination mode. The H{sub 4}L ligand displays not only different deprotonated forms but also diverse coordination modes and conformations. The structural diversities among 1–3 have been carefully discussed, and the roles of N-donor co-ligands in the self-assembly of coordination polymers have been well documented. - Graphical abstract: Three nickel coordination polymers with different architectures based on mixed ligand system were synthesized and structurally characterized. Topology analyses indicate that 1 shows the 4-connected 6{sup 6}-dia net, 1D ribbon chains for 2 and 3D (4,4)-connected bbf network for 3. Display Omitted - Highlights: • Three Ni-based coordination polymers with distinct features have been prepared. • Compound 1 features a 3D 4-connected 66-dia-type framework, 2 displays a 1D [Ni(HL)(Hdpa)]{sub n} ribbon chains motif, while 3 possesses a (4,4)-connected 3D frameworks with bbf topology. • The “mixed ligand assembled” strategy is significant potential for network design.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2016

Two Zn coordination polymers with meso-helical chains based on mononuclear or dinuclear cluster units

Two zinc coordination polymers {[Zn_2(TPPBDA)(oba)_2]·DMF·1.5H_2O}{sub n} (1), {[Zn(TPPBDA)_1_/_2(tpdc)]·DMF}{sub n} (2) have been synthesized by zinc metal salt, nanosized tetradentate pyridine ligand with flexible or rigid V-shaped carboxylate co-ligands. These complexes were characterized by elemental analyses and X-ray single-crystal diffraction analyses. Compound 1 is a 2-fold interpenetrated 3D framework with [Zn{sub 2}(CO{sub 2}){sub 4}] clusters. Compound 2 can be defined as a five folded interpenetrating bbf topology with mononuclear Zn{sup 2+}. These mononuclear or dinuclear cluster units are linked by mix-ligands, resulting in various degrees of interpenetration. In addition, the photoluminescent properties for TPPBDA ligand under different state and coordination polymers have been investigated in detail. - Graphical abstract: Two zinc coordination polymers have been synthesized by zinc metal salt, nanosized tetradentate pyridine ligand with flexible or rigid V-shaped carboxylate co-ligands. Compound 1 is a 2-fold interpenetrated 3D framework with [Zn{sub 2}(CO{sub 2}){sub 4}] clusters. Compound 2 can be defined as a five folded interpenetrating bbf topology with mononuclear Zn{sup 2+}. In addition, the photoluminescent properties for TPPBDA ligand under different status and coordination polymers have been investigated in detail. Display Omitted - Highlights: • Two Zn coordination polymers based on mononuclear or dinuclear cluster units have been synthesized. • Compound 1 is a 2-fold interpenetrated 3D framework with [Zn{sub 2}(CO{sub 2}){sub 4}] clusters. • Compound 2 is a five folded interpenetrating bbf topology with mononuclear Zn{sup 2+}. • The photoluminescent properties for TPPBDA with different state and two coordination polymers have been investigated.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Nitroaromatic-detecting zinc and cadmium coordination polymers with methyl-substituted aliphatic dicarboxylate and 4,4′-dipyridylamine ligands and diverse topologies

Highlights: • Zinc and cadmium aliphatic coordination polymers with 4,4′-dipyridylamine. • Mutual inclined, 4-fold dia, and 2-fold pcu interpenetrated topologies. • “turn-off” luminescence detection of nitroaromatics in ethanol suspension. - Abstract: Hydrothermal reaction of a metal nitrate, a methyl-substituted aliphatic dicarboxylic acid, and the hydrogen-bonding capable 4,4′-dipyridylamine (dpa) ligand afforded four crystalline coordination polymers whose dimensionality, topology, and interpenetration scheme depends on the aliphatic tether length, methyl group position, and coordination geometry at the metal. The four new phases were structurally characterized via single-crystal X-ray diffraction. [Zn(22dmg)(dpa)]{sub n} (1, 22dmg = 2,2-dimethylglutarate) displays a system of mutually inclined interpenetrated (4,4) grid coordination polymer layers. [Zn(33dmg)(dpa)]{sub n} (2, 33dmg = 3,3-dimethylglutarate), in contrast to 1, displays a stacked arrangement of pairs of (4,4) grid coordination polymer layers, without any interpenetration. [Zn(3mad)(dpa)]{sub n} (3, 3mad = 3-methyladipate) possesses a system of four-fold interpenetrated 6{sup 6} dia topology coordination polymer networks. [Cd(33dmg)(dpa)]{sub n} (4) displays a 2-fold interpenetrated 4{sup 12}6{sup 3} pcu 3D topology, based on pillaring of dimer-based [Cd{sub 2}(33dmg){sub 2}]{sub n} layers by pairs of dpa ligands. Luminescent behavior in 1–4 is attributed to intra-ligand molecular orbital transitions within the dpa aromatic pyridyl rings. The new phases were also surveyed for the ability to detect nitroaromatics in ethanol suspension, with 4 providing optimum response for nitrobenzene detection. Thermal decomposition behavior is also discussed herein.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Plutonium and Cerium Perrhenate/Pertechnetate Coordination Polymers and Frameworks

Spent nuclear fuel (SNF) contains transuranic and lanthanide species, which are sometimes recovered and repurposed. One particularly problematic fission product, 99 TcO 4 – , hampers this recovery via coextraction with high valence metals, perhaps by complexation during aqueous reprocessing of SNF. There is limited molecular-level knowledge concerning the coordination chemistry between TcO 4 – or its well-known surrogate ReO 4 – and transuranic/lanthanide species. In the current study, we investigated the coordination of ReO 4 – /TcO 4 – with plutonium and cerium cations by structural and chemical characterization of a series of isolated extended solids. In this study, Ce represents both trivalent lanthanides and is considered a surrogate for Pu, respectively, in its common trivalent and tetravalent oxidation states. The structural elucidation of the seven isolated crystalline solids revealed that ReO 4 – /TcO 4 – directly connects to Pu IV , Pu VI O 2 2 + , Ce III , and Ce IV in the terminal and bridging coordination modes, leading to 1-, 2-, and 3-dimensional frameworks. For example, ReO 4 – coordination to Pu(IV) formed a 1D chain or 2D framework, isostructural with previously isolated Th(IV) compounds. However, Pu VI O 2 2 + alternating with ReO 4 – led to a unique 1D chain, different from the prior-reported U(VI)/Np(VI)-ReO 4 – /TcO 4 – structures. Coordination of ReO 4 – /TcO 4 – with Ce(III) promotes the assembly of 3D frameworks. Finally, attempted synthesis of a Ce(IV)-ReO 4 – compound resulted in a 2D framework with a mixed-valence Ce III/IV . The highly acidic reaction conditions supported the reduction of both Ce IV and Tc VII , challenging isolation of compounds featuring these species. Only one TcO 4 -containing structure was obtained in this study (Ce III –TcO 4 3D framework), vs the six total Ce/Pu-ReO 4 compounds. Furthermore, our three Pu-ReO 4 crystal structures are the first reported and translated to atomic-level information about Pu-TcO 4 coordination in nuclear fuel reprocessing scenarios, in addition to broadening our knowledge of bonding trends in the early, high-valence actinides.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2024

Influence of Aqueous Phase Acidity on Ln(III) Coordination by N , N , N ', N '-Tetraoctyldiglycolamide

Here, this study highlights the importance of combining distribution ratio measurements with multiple spectroscopic techniques to provide a more comprehensive understanding of organic phase Ln coordination chemistry. Solvent extraction investigations with N,N,N',N'-tetraoctyldiglycolamide (TODGA) in n-heptane reveal the sensitivity of Ln complexation to the HNO 3 concentration. Distribution ratio measurements in tandem with UV–Vis demonstrated that increasing the concentration of HNO3 above 0.5 M with a constant NO 3 – of 1 M increases the number of coordinating TODGA molecules, from a 1:2 to a 1:3 Ln:TODGA complex. At each concentration of HNO 3 considered herein (from 0.01 to 1 M), Eu lifetime analysis demonstrated no evidence of H 2 O coordination. Results from Fourier transform infrared investigations suggest the presence of inner-sphere NO 3 – under low concentrations of HNO 3 when the 1:2 Ln:TODGA complex is present. Increasing the HNO 3 concentration above 0.5 M increases the propensity for outer-sphere interactions by removing the coordinated NO 3 – and saturating the Ln coordination sphere with three TODGA molecules, resulting in the well-established cationic, trischelate homoleptic [Ln(TODGA) 3 ] 3+ complex. This work demonstrates the importance in considering the NO 3 – source for solvent extraction systems. In particular, for systems with an affinity for outer-sphere interactions with molar concentrations of HNO 3 , changing the NO 3 – source can change the inner-sphere coordination of the Ln complex, which, in turn, affects the separation efficacy.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Characterization of Uranyl Coordinated by Equatorial Oxygen: Oxo in UO 3 versus Oxyl in UO 3 +

Uranium trioxide, UO 3 , has a T-shaped structure with bent uranyl, UO 2 2+ , coordinated by an equatorial oxo, O 2– . The structure of cation UO 3 + is similar but with an equatorial oxyl, O •– . Neutral and cationic uranium trioxide coordinated by nitrates were characterized by collision induced dissociation (CID), infrared multiple-photon dissociation (IRMPD) spectroscopy, and density functional theory. CID of uranyl nitrate, [UO 2 (NO 3 ) 3 ] – (complex A1), eliminates NO 2 to produce nitrate-coordinated UO 3 + , [UO 2 (O • )(NO 3 ) 2 ]– (B1), which ejects NO 3 to yield UO 3 in [UO 2 (O)(NO 3 )] – (C1). Finally, C1 associates with H 2 O to afford uranyl hydroxide in [UO 2 (OH) 2 (NO 3 )] – (D1). IRMPD of B1, C1, and D1 confirms uranyl equatorially coordinated by nitrate(s) along with the following ligands: (B1) radical oxyl O •– ; (C1) oxo O 2– ; and (D1) two hydroxyls, OH – . As the nitrates are bidentate, the equatorial coordination is six in A1, five in B1, four in D1, and three in C1. Ligand congestion in low-coordinate C1 suggests orbital-directed bonding. Hydrolysis of the equatorial oxo in C1 epitomizes the inverse trans influence in UO 3 , which is uranyl with inert axial oxos and a reactive equatorial oxo. The uranyl ν 3 IR frequencies indicate the following donor ordering: O 2– [best donor] >> O •– > OH – > NO 3 – .

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Sulfur-Donor Solvents Strongly Coordinate Pb 2+ in Hybrid Organic–Inorganic Perovskite Precursor Solutions

Strong coordination between Lewis-basic processing additives and the Lewis-acidic lead halide in hybrid organic–inorganic perovskite (HOIP) precursor solutions is required to solubilize the lead halide, and subsequently access the appropriate crystallization kinetics and attain the desired morphology of perovskite active layers. While oxygen-donor solvents and additives, such as dimethylformamide and dimethyl sulfoxide, are widely used for perovskite processing, we demonstrate here that “soft” sulfur-donor solvents exhibit stronger coordination to the “borderline soft” Lewis acid Pb 2+ center of PbI 2 relative to “hard” O-donor solvents in the precursor solution. The stronger coordination of S-donor solvents compared to O-donor solvents to Pb 2+ implies that such compounds can be useful additives to HOIP precursor solutions. Density-functional calculations of the enthalpy change resulting from the coordination of solvents to Pb 2+ provide direct numerical comparison of the strength of O-donor and S-donor coordination with Pb 2+ and expands the library of candidate S-donor compounds. Our results provide a roadmap for processing additive selection and expand the previously limited choice of perovskite processing additives to include strongly coordinating S-donor compounds.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2017

Transitions in Al Coordination during Gibbsite Crystallization Using High-Field 27 Al and 23 Na MAS NMR Spectroscopy

Mechanisms of nucleation and growth of Al hydroxides such as gibbsite from aqueous solution, particularly in highly alkaline conditions, remain poorly understood. In this work, quantitative 27Al and 22Na MAS NMR experiments were conducted on solid samples extracted from the crystallization of gibbsite from an amorphous aluminum hydroxide gel precursor. The use of high magnetic field and fast sample spinning allowed transitional tetrahedral (AlT) and pentahedral (AlP) aluminum species to be observed along with the octahedral aluminum (AlO) that dominates the gibbsite product. Low-coordinated Al species could be detected at concentrations as low as 0.1% of the total Al sites. It is established that (a) AlT and AlP coexist on the surface of growing gibbsites even with a combined percentage over the total Al sites of less than 1%; (b) Different synthesis methods generate gibbsite with varying amounts of low-coordinated Al; (c) the amorphous gel precursor contains a significant amount of low-coordinated Al sites with AO: AlP: AlT ratios of approximately 4:2:1; (d) upon hydration, the external, low-coordinated Al sites become six-fold coordinated by interacting with the oxygen in H2O and the 27Al MAS NMR peak position shifts to that for the AlO sites; (e) gibbsite with increased long range order is synthesized over longer times by gradually incorporating residual AlP and AlT sites into octahedrally-coordinated AlO sites; (f) trace Na is predominantly a surface species on gibbsite particles. These findings provide a basis for understanding the gibbsite crystallization mechanism, along with a general means of characterizing gibbsite surface properties that are of equal importance for understanding related processes such as dissolution behavior.

Environmental Molecular Sciences Laboratory↗
DOE OSTI2015

Synthesis and Structural Characterization of Magnesium Based Coordination Networks in Different Solvents

Three magnesium based metal-organic frameworks, Mg{sub 3}(3,5-PDC){sub 3}(DMF){sub 3} {center_dot} DMF [1], Mg(3,5-PDC)(H{sub 2}O) {center_dot} (H{sub 2}O) [3], and Mg4(3,5-PDC)4(DMF){sub 2}(H{sub 2}O){sub 2} {center_dot} 2DMF {center_dot} 4.5H{sub 2}O [4], and a 2-D coordination polymer, [Mg(3,5-PDC)(H{sub 2}O){sub 2}] [2] [PDC = pyridinedicarboxylate], were synthesized using a combination of DMF, methanol, ethanol, and water. Compound 1 [space group P2{sub 1}/n, a = 12.3475(5) {angstrom}, b = 11.1929(5) {angstrom}, c = 28.6734(12) {angstrom}, {beta} = 98.8160(10){sup o}, V = 3916.0(3) {angstrom}{sup 3}] consists of a combination of isolated and corner-sharing magnesium octahedra connected by the organic linkers to form a 3-D network with a 12.2 {angstrom} x 4.6 {angstrom} 1-D channel. The channel contains coordinated and free DMF molecules. In compound 2 [space group C2/c, a = 9.964(5) {angstrom}, b = 12.0694(6) {angstrom}, c = 7.2763(4) {angstrom}, {beta} = 106.4970(6){sup o}, V = 836.70(6) {angstrom}{sup 3}], PDC connects isolated seven coordinated magnesium polyhedra into a layered structure. Compound 3 [space group P6{sub 1}22, a = 11.479(1) {angstrom}, c = 14.735(3) {angstrom}, V = 1681.7(4) {angstrom}{sup 3}] (previously reported) contains isolated magnesium octahedra connected by the organic linker with each other forming a 3D network. Compound 4 [space group P2{sub 1}/c, a = 13.7442(14) {angstrom}, b = 14.2887(15) {angstrom}, c = 14.1178(14) {angstrom}, {beta} = 104.912(2){sup o}, V = 2679.2(5) {angstrom}{sup 3}] also exhibits a 3D network based on isolated magnesium octahedra with square cavities containing both disordered DMF and water molecules. The structural topologies originate due to the variable coordination ability of solvent molecules with the metal center. Water molecules coordinate with the magnesium metal centers preferably over other polar solvents (DMF, methanol, ethanol) used to synthesize the coordination networks. Despite testing multiple desolvation routes, we were unable to measure BET surface areas greater than 51.9 m{sup 2}/g for compound 1.

Banerjee, Debasis↗
DOE OSTI2022

Fine-tuned local coordination environment of Pt single atoms on ceria controls catalytic reactivity

Constructing single atom catalysts with fine-tuned coordination environments can be a promising strategy to achieve satisfactory catalytic performance. Herein, via a simple calcination temperature-control strategy, CeO 2 supported Pt single atom catalysts with precisely controlled coordination environments are successfully fabricated. The joint experimental and theoretical analysis reveals that the Pt single atoms on Pt 1 /CeO 2 prepared at 550 °C (Pt/CeO 2 -550) are mainly located at the edge sites of CeO 2 with a Pt–O coordination number of ca. 5, while those prepared at 800 °C (Pt/CeO 2 -800) are predominantly located at distorted Ce substitution sites on CeO 2 terrace with a Pt–O coordination number of ca. 4. Pt/CeO 2 -550 and Pt/CeO 2 -800 with different Pt 1 -CeO 2 coordination environments exhibit a reversal of activity trend in CO oxidation and NH 3 oxidation due to their different privileges in reactants activation and H 2 O desorption, suggesting that the catalytic performance of Pt single atom catalysts in different target reactions can be maximized by optimizing their local coordination structures.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Catalytic reactions within the cavity of coordination cages

Natural enzymes catalyze reactions in their substrate-binding cavities, exhibiting high specificity and efficiency. In an effort to mimic the structure and functionality of enzymes, discrete coordination cages were designed and synthesized. These self-assembled systems have a variety of confined cavities, which have been applied to accelerate conventional reactions, perform substrate-specific reactions, and manipulate regio- and enantio-selectivity. Many coordination cages or cage–catalyst composites have achieved unprecedented results, outperforming their counterparts in different catalytic reactions. This tutorial review summarizes recent developments of coordination cages across three key approaches to coordination cage catalysis: (1) cavity promoted reactions, (2) embedding of active sites in the structure of the cage, and (3) encapsulation of catalysts within the cage. Special emphasis of the review involves (1) introduction of the structure and property of the coordination cage, (2) discussion of the catalytic pathway mediated by the cage, (3) elucidation of the structure–property relationship between the cage and the designated reaction. This work will summarize the recent progress in supramolecular catalysis and attract more researchers to pursue cavity-promoted reactions using discrete coordination cages.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Coordination and thermophysical properties of select trivalent lanthanides in LiCl–KCl

The coordination chemistry of various fission and decay products, such as actinides and lanthanides, are crucial to the commercial deployment of molten salt reactors as they can affect the thermophysical properties. In this report we examined the structure, coordination environment, and physical properties such as the density and the vibrational density of states for three lanthanide species, namely Ce, Eu, and Sm in the LiCl–KCl eutectic system using a combination of quantum mechanics simulations and spectroscopic experiments. Quantum mechanics molecular dynamics (QM-MD) modelling was employed to determine the physical properties of each system resulting in accurate local coordination of each species. Then, the vibrational density of states (DOS) was determined using a two-phase thermodynamic modelling which was then compared to the experimentally obtained Raman spectra of the species in molten LiCl–KCl having the eutectic composition. We find that Ce 3+ , Eu 3+ and Sm 3+ all adopt octahedral local coordination environments in the eutectic salt composition in good agreement with experimental results. Ce3+ is found to fluctuate between an octahedral six-coordinated and a seven-coordinated structure due to the increased local proximity of Cl in the eutectic salt, resulting in a lower fluidicity/diffusivity than the other trivalent lanthanides studied. The thermophysical properties of the eutectic composition with trivalent lanthanides were not significantly different from the pure eutectic salt composition, but several changes were noted.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗