Uranium coordination on clay surface at nanoscale: Integration of EXAFS data and Ab initio molecular dynamics

Krot A.; Evgeny V. Tararushkin; Trigub A.; Vlasova I.; Kalmykov S.

doi:10.1016/j.clay.2025.107863

Publications

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Uranium coordination on clay surface at nanoscale: Integration of EXAFS data and Ab initio molecular dynamics

Applied Clay Science. 2025. Vol. 274. Article 107863.

Krot A., Evgeny V. Tararushkin, Trigub A., Vlasova I., Kalmykov S.

Understanding the interactions between uranium and clay minerals at the molecular level is crucial for addressing environmental contamination and nuclear waste management. In this work we are focusing on the determination the molecular-level structure of uranium (VI) surface species on smectite using a combination of EXAFS spectroscopy and ab initio molecular dynamics simulations (AIMD). A set of samples was prepared with uranyl cation adsorbed on bentonite clay of three deposits at various pH and uranium concentrations. To elucidate the structure of the adsorbed species at nanoscale, AIMD simulations were carried out for uranyl coordination models at basal surface and on edge sites of clay mineral. Linear combination fitting of experimental EXAFS spectra with those calculated from AIMD trajectories allowed us to specify the fractions of each adsorbed complex configuration present at pH 3, 5 and 8. At low pH, the speciation of the adsorbed uranyl cation is mainly comprised of outer-sphere basal complex. When pH is increased to 5, edge complexes at (110) surface become predominant, and at pH 8 uranyl cation is mainly localized at (010) surface of clay mineral. With the implementation of advanced molecular dynamics simulations and spectroscopic techniques, the obtained results for the first time reveal the structure of the adsorbed uranyl complexes on clay mineral surfaces at nanoscale.

Research target: Chemistry

Keywords: Uranyl cation Clay surface X-ray absorption spectroscopy Molecular dynamics

Formation of Singly Bonded {CpCo(CO)-η 2 -C 60 – } 2 Dimers upon the Dimerization of the CpCo(CO)-η 2 -C 60 •– Radical Anions

sobov P., Yakushev I., Shestakov A. et al., Organometallics 2025 Vol. 44 No. 24 P. 2873–2881

Interaction of {Cryptand(K+)}(C60•–) with CpCo(CO)2 yields the air-sensitive crystalline salt {Cryptand(K+)}{CpCo(CO)-η2-C60•–} (1), in which C60•– replaces carbonyl group in CpCo(CO)2. Two Co–C bonds of 2.028(9) and 2.057(8)Å are formed. The magnetic moment of 1 is 1.72 μB, indicating a doublet S = 1/2 spin state of {CpCo(CO)-η2-C60•–} at 300 K. The compound shows a broad ...

Added: September 20, 2026

Water confined in heterogeneous clay–quartz pores: Structure and dynamics from atomistic simulations

Glushak A., Tararushkin E., Smirnov G., Colloids and Surfaces A: Physicochemical and Engineering Aspects 2027 Vol. 752 Article 141756

The molecular-scale behavior of water in heterogeneous clay–quartz systems is critical for understanding cementation processes in natural soils and compacted bentonite, which is crucial for oil recovery and nuclear waste disposal barriers construction. Here we investigate how heterogeneity of mixed Na-montmorillonite and α-quartz surfaces affect water structure and dynamics in nanopores of 2.5 to 60 Å ...

Added: September 15, 2026

Coordination-driven assemblies of thioindigo and phthalocyanine chromophores: tuning optical absorption and magnetic interactions

Kolin N., Nazarov D., Krivenko K. et al., Dyes and Pigments 2026 Vol. 254 Article 113957

Interaction of thioindigo dianions with metal phthalocyanines, MPc, where M = MgII, MnII, AlIIICl and SiIVCl2, in the presence of cryptand[2.2.2] produces anionic and neutral complexes: {Crypt(K+)}2{(trans-thioindigo2−)⋅(MgIIPc)2}2−⋅2C6H4Cl2 (1); {Crypt(Cs+)}2{(trans-thioindigo2−)⋅(MnIIPc)2}2− (2), {Crypt(K+)}{(cis-Hthioindigo−)2⋅(AlIIIPc)}− (3) and {(cis-Hthioindigo−)2⋅(SiIVPc)} (4). Bidentate thioindigo2− ligand forms symmetric binuclear dimers in 1 and 2 with short M-O(thioindigo2−) bonds of 1.899(2) and 1.984(6) Å length for ...

Added: September 14, 2026

Doubly Reduced Phthalocyanine Complexes of V(IV), Cu(II), and Sn(II): Synthesis, Structure, and Spin Dynamics

Faraonov M., Romanenko N., Ivanov T. et al., Dalton Transactions 2026 Vol. 55 No. 24 P. 9428–9438

Doubly reduced phthalocyanine complexes remain largely unexplored despite their potential relevance for molecular spin-based applications. Herein, we report the synthesis of a series of crystalline complexes, {cryptand(Cs + )} 2 [M(Pc) 4– ] 2–. ...

Added: September 14, 2026

Binuclear and trinuclear 3d-metal complexes of HATNA and HAT(CN)6 with unique magnetic behavior: from extremely strong antiferromagnetic coupling to opposite sign of zero-field splitting in the same complex

Mikhailenko M., Astakhova T., Timokhina E. N. et al., Inorganic Chemistry Frontiers 2026 Vol. 13 No. 14 P. 6145–6156

series of anionic bi- and trinuclear complexes of Co II , Fe II , and Mn II with hexaazatrinaphthylene (HATNA) and hexaazatriphenylenehexacarbonitrile (HAT(CN) 6 ), incorporating paramagnetic Cp* 2 Fe + cations ( S = 1/2), were obtained and investigated. ...

Added: September 14, 2026

1D and 2D coordination polymers based on ring-reduced freebase and copper-containing meso-tetra(4-pyridyl)porphyrins and M(III) (TMHD) 3 units (M = Dy, Tb and Gd; TMHD: 2,2,6,6-tetramethyl-3,5-heptanedionate)

Nazarov D., Yakushev I. A., Kuzmin A. V. et al., Inorganic Chemistry Frontiers 2026 Vol. 13 No. 11 P. 5039–5050

Reduced tetra(4-pyridyl)porphyrins (H 2 TPyP and Cu II TPyP) form polymers with M III (TMHD) 3 (M = Dy, Tb and Gd). Folded zigzag 2D and linear 1D polymers are obtained. Their structure, optical and magnetic properties are investigated. ...

Added: September 14, 2026

Singlet–Triplet Transitions in the Dianionic Complex of Fullerene C 60 with Iron Carbonyl: (TBA + ) 2 {[Fe 2 (CO) 6 ]-η 2 ,η 2 -C 60 } 2–

Sobov P. A., Yakushev I. A., Shestakov A. et al., Inorganic Chemistry 2026 Vol. 65 No. 16 P. 9107–9115

Interaction of fullerene C60 with Cs2Fe(CO)4 in the presence of two equivalents of tetrabutylammonium iodide (TBAI) yields the first dianionic coordination complex of fullerene: (TBA+)2{[Fe2(CO)6]-η2,η2-C60}2– (1). According to magnetic data and DFT calculations, complex 1 has a diamagnetic ground (S = 0) and a triplet excited state (S = 1) populated above 80 K. As ...

Added: September 14, 2026

Crystalline Trinuclear Exo- and Endocyclic Complexes of a Tetrapyrazinoporphyrazine Ligand with 3 d - and 4 f -Metals

Faraonov M., Romanenko N., Ivanov T. et al., Crystal Growth & Design 2026 Vol. 26 No. 7 P. 2792–2801

A redox-active tetrapyrazinoporphyrazine ligand was used as a platform for the design of multimetallic coordination complexes. The first paramagnetic homo- and heterotrimetallic complexes have been obtained as crystals through the reaction of iron(II) octaethyltetrapyrazinoporphyrazine, FeII(Et8TPyzPz), with 3d- (FeII, CoII) and 4f-metal (DyIII) iodides. In these conditions, tetrapyrazinoporphyrazine can coordinate to metals to form exo- and ...

Added: September 14, 2026

Complex of fullerene C60 with partial charge transfer: {(dppf)CpFe(CO)}+(C60)-⋅C6H4Cl2 (δ = 0.54–0.86), where dppf is bis(diphenylphosphino)ferrocene ligand

Sobov P. A., Khasanov S., Kuzmin A. V. et al., Inorganic Chemistry Communications 2026 Vol. 185 Article 116055

New complex {(dppf)CpFe(CO)}(C60)⋅C6H4Cl2 (1) was obtained when stoichiometric mixture of C60 and CoII(dppf)Cl2 is reduced by two equivalents of (Cs+){CpFe(CO)2−} (dppf: 1,1`-bis(diphenylphosphino)ferrocene). CpFe(CO)2− anion reduces CoII(dppf)Cl2 and CpFe(CO)2 abstracts the dppf ligand from Co(dppf) forming (dppf)CpFeI(CO). Electron transfer from (dppf)CpFeI(CO) to C60 is observed. As a result, the state of {(dppf)CpFe(CO)}δ+(C60)δ−⋅C6H4Cl2 (δ = 0.54–0.86) is intermediate between ...

Added: September 14, 2026

Mono- and binuclear complexes of iron(II) and cobalt(II) with deprotonated trans-indigo anions. Effect of cationic surrounding on structure and magnetic properties.

Krivenko K., Kuzmin A. V., Mikhailenko M. et al., Dyes and Pigments 2026 Vol. 246 Article 113342

Mono- and binuclear complexes of FeII and CoII with deprotonated trans-indigo were obtained. Reduction of indigo by metallic iron in the presence of crystal violet (CV) yields (CV+)[(FeCl2)HIndigo]−⋅C6H4Cl2 (1). The reaction of FeI2 and CoI2 with one equivalent of decamethylchromocene (Cp∗2Cr) and one or half equivalent of indigo yields mononuclear (Cp∗2Cr+)[(CoI2)HIndigo]−⋅C6H4Cl2 (2), (Cp∗2Cr+)[(FeI2)HIndigo]−⋅ xC6H4Cl2, where ...

Added: September 14, 2026

A 36-Nuclear Wheel-Shaped Heterometallic Cluster: Self-Assembly of Mixed-Valent Pt II /Pt IV and Mn II Centers

Sosunov E., Skabitsky I. V., Churakov A. et al., Crystal Growth & Design 2026 Vol. 26 No. 4 P. 1775–1782

Polynuclear 5d–3d assemblies represent a promising class of systems for exploring the interplay among electronic structure, magnetism, and self-assembly. Here, we report the synthesis and structural characterization of the first heterometallic wheel-shaped Pt–Mn cluster, [PtIV12PtII6Mn18(OAc)72(μ3-O)12]·43C6H6(1), which incorporates 36 metal centers. The giant ring is constructed from alternating PtIIMnII paddlewheel fragments and PtIV2Mn2 oxo-acetate units, bridged ...

Added: September 14, 2026

Effect of the size of the substituents in triptycene (TPC-X) on the magnetic and conducting properties of the layered 2D organic metals (MDABCO+)(C60•−)·(TPC-X), where X = H, Br, and I

Sobov P. A., Kuzmin A. V., Shevchun A. F. et al., Synthetic Metals 2025 Vol. 313 Article 117904

Modification of the neutral triptycene TPC-X molecule by increasing the size of the X substituent at the 9th position from X = H to Br and I affects the magnetic and conducting properties of the (MDABCO+)(C60•−)(TPC-X) salts (1–3, respectively), where MDABCO+ is N-methyldiazabicyclooctanium. These salts feature hexagonal fullerene layers composed of C60•−, which remain undimerized owing to ...

Added: September 14, 2026

Salts of Tetraselenatetracene and Bis(ethylenedithio)tetrathiafulvalene with Metal Hexafluoroacetylacetonate Anions: MnII(hfac)3–, CoII(hfac)2Cl–, and PrIII(hfac)4–

Flakina A. M., Nazarov D., Faraonov M. et al., Crystal Growth & Design 2025 Vol. 25 No. 15 P. 6332–6344

Oxidation of tetraselenatetracene (TSeT) and bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF) by p-chloranil in the presence of metal hexafluoroacetylacetonates: MnII(hfac)2, CoII(hfac)2 and PrIII(hfac)3 followed by precipitation of crystals by n-hexane produces (TSeT1.5)+{MnII(hfac)3–} (1), (TSeT1.5)+{PrIII(hfac)4–} (3), (TSeT2)+{CoII(hfac)2Cl–} (4), and (ET3)+{MnII(hfac)3–} (5). Thioindigo dye is introduced into (TSeT1.5)+ (Thioindigo1.5){MnII(hfac)3–} (2) due to the appearance of specific C═O···(Se–Se bond) interactions accompanied by ...

Added: September 14, 2026

Complex of copper(II) hexafluoroacetylacetonate with photochromic spiropyran in the merocyanine form: Field-induced slow magnetic relaxation and quantum coherence for Cu(II) (S = 1/2) and photoswitching of spiropyran ligand

Osipov N., Faraonov M., Yakushev I. A. et al., Dalton Transactions 2025 Vol. 54 No. 32 P. 12180–12188

The interaction of photochromic 8-methoxy-1′,3′,3′-trimethyl-6-nitro-spiro[chromene-2,2′-indole] (MNSP) spiropyran with copper(II) hexafluoroacetylacetonate yields a deep red–violet solution due to a coordination-induced transition of MNSP from its closed form to the colored, open merocyanine (MC) form. The crystal structure of {CuII(hfac)2·MNSP} (1) shows coordination of two oxygen atoms in MNSP to CuII, forming a distorted octahedral geometry with ...

Added: September 14, 2026

Complexes of d‐ and f‐metal Ions with Redox‐Active and Highly Symmetric Truxenone Ligand: Effect of Cations and Coordination on Distortions of Radical Anions and Singlet–Triplet Transition in Dianions

Krivenko K., Shestakov A., Faraonov M. et al., European Journal of Inorganic Chemistry 2025 Vol. 28 No. 14 Article e202400760

Truxenone (Tr) with high C3h symmetry forms crystalline radical anion and dianion salts. The {Bu3MeP+}(Tr⋅−) (1) and {Cp*2Co+)}(Tr⋅−)⋅2 C6H4Cl2 (2) show intense low‐energy absorption up to 2000 nm. Calculations predict Jahn–Teller distortions for Tr⋅−, which are enhanced by the asymmetric approach of cations to Tr⋅−, leading to C=O bond length alternation and EPR signal asymmetry in 2. ...

Added: September 14, 2026

Complexes (TBA+){(TMI-NPS)2·LnIIII4}− (Ln = Dy, Tb) with two axial photochromic spiropyran ligands: photoswitching and zero-field SIM behaviour with a high magnetization blocking barrier for the Dy complex

Osipov N., Faraonov M., Kuzmin A. V. et al., Inorganic Chemistry Frontiers 2025 Vol. 12 No. 5 P. 2092–2102

Two photochromic spiropyran molecules (1,3,3-trimethylindolino-β-naphthopyrylospiran, TMI-NPS) react in the open form with LnIII iodides (Ln = Dy, Tb) to form in the presence of TBAI crystalline (TBA+){(TMI-NPS)2·LnIIII4}−·0.5C6H4Cl2 (1 and 2, respectively). Two TMI-NPS ligands are coordinated to lanthanides (Ln) by oxygen atoms at the axial position, and four iodide anions located at the equatorial position ...

Added: September 14, 2026

Macrocycle- and metal-centered reduction of cobalt trithiadodecaazahexaphyrin (Hhp). Metal-to-ligand charge transfer in {(Co(I)2Co(II)O){Hhp(•4-))}(2-)

Nazarov D., Kuzmin A. V., Islyaikin M. et al., New Journal of Chemistry 2025 Vol. 49 No. 5 P. 1631–1639

Reduction of free-base trithiadodecaazahexaphyrin, H3Hhp, by potassium graphite in the presence of cobalt(II) acetylacetonate and cryptand[2.2.2] produces {Cryptand[2.2.2](K+)}2{(CoI2CoIIO)2+(Hhp˙4−)}2−·2C6H4Cl2 (1). Co atoms in Co3O have square-planar geometry with short Co–N and Co–O bonds of 1.852–1.898(3) Å length. A nearly planar shape of Hhp macrocycles in 1 with equal Nmeso–C bonds indicates the aromatic character of Hhp˙4−. ...

Added: September 14, 2026

Coordination complexes of iron(II) phthalocyanine with cationic, anionic and neutral ligands

Romanenko N., Faraonov M., Kuzmin A. V. et al., Journal of Porphyrins and Phthalocyanines 2024 Vol. 28 No. 09n10 P. A–k

A series of coordination complexes of iron(II) phthalocyanine (FeIIPc) with anionic, cationic and neutral ligands has been obtained in crystalline form. The salt of FeIIPc with MDABCO[Formula: see text] cations (MDABCO[Formula: see text][FeI(Pc[Formula: see text]][Formula: see text]⋅(I[Formula: see text]⋅2TPC⋅2C6H4Cl2 (1) contains FeIIPc reduced to [FeI(Pc[Formula: see text]][Formula: see text], and the FeI ion coordinates two ...

Added: September 14, 2026

Binuclear Coordination Assemblies of Metal Tetraphenylporphyrins (M = Mn, Fe, and In) with Anionic Thioindigo Bridges as Promising Magnetic Systems with Tunable Properties

Nazarov D., Faraonov M., Nations S. et al., Inorganic Chemistry 2024 Vol. 63 No. 48 P. 22677–22687

A series of hybrids comprising two metal (Mn, Fe, and In) tetraphenylporphyrins axially substituted with anionic bidentate trans-thioindigo ligands (TI) were obtained. Substitution of the axial chloride anion by an oxygen atom of the dye forms short M–O bonds. Crystalline binuclear assemblies (TI•–)·{[MnIITPP]0·[MnIIITPP]+}·xC6H4Cl2 (x = 2 for 1 or 1 for 2) and (TI2–){[MIIITPP]+}2·xC6H4Cl2 (M ...

Added: September 14, 2026

Effect of nuclearity and reduction state of the central ligand on magnetic properties of hexaazatrinaphthylene-based cobalt(ii) and iron(ii) complexes: from extremely weak to record-breaking antiferromagnetic exchange interaction

Mikhailenko M., Ivanov V. V., Faraonov M. et al., Inorganic Chemistry Frontiers 2024 Vol. 11 No. 21 P. 7563–7575

A series of hexaazatrinaphthylene (HATNA) and hexaazatrianthracene (HATA) complexes with high-spin four-coordinate cobalt(II) (S = 3/2) and iron(II) (S = 2) ions were synthesized. These compounds vary in charge of the central hexaazatriphenylene (HAT) ligand (L) and the number of coordinated metal atoms. The occupancy of the three coordinating sites on the HAT ligands greatly ...

Added: September 14, 2026

Single-Ion Magnetism of the [DyIII(hfac)4]− Anions in the Crystalline Semiconductor {TSeT1.5}●+[DyIII(hfac)4]− Containing Weakly Dimerized Stacks of Tetraselenatetracene

Flakina A. M., Nazarov D., Faraonov M. et al., International Journal of Molecular Sciences 2024 Vol. 25 No. 15 Article 8068

The oxidation of tetraselenatetracene (TSeT) by tetracyanoquinodimethane in the presence of dysprosium(III) tris(hexafluoroacetylacetonate), DyIII(hfac)3, produces black crystals of {TSeT1.5}●+[DyIII(hfac)4]− (1) salt, which combines conducting and magnetic sublattices. It contains one-dimensional stacks composed of partially oxidized TSeT molecules (formal averaged charge is +2/3). Dimers and monomers can be outlined within these stacks with charge and spin ...

Added: September 14, 2026

Mixing of real and quantum gases

Борщевский А. Я., Physical Chemistry Chemical Physics 2025 Vol. 27 No. 9 P. 4793–4803

Through the consistent application of quantum statistical thermodynamics, functions of isothermal mixing of real rarefied gases and quantum gases in states of varying degrees of degeneracy are obtained. The reasons for the emergence and resolution of the “Gibbs paradox” and other “paradoxes” are analyzed. Numerical calculations of entropy and pressure jumps were performed using the ...

Added: September 14, 2026

Coordination vs. oxidative rearrangement of photochromic spiropyrans upon reacting with FeIIICl3 and FeIIIBr3

Osipov N., Faraonov M., Kuzmin A. V. et al., New Journal of Chemistry 2024 Vol. 48 No. 30 P. 13526–13537

Photochromic 1,3,3-trimethylindolino-β-naphthopyrylospiran (TMI–NPS) and 1,3,3-trimethylindolinonaphthospirooxazine (TMI–NSO) spiropyrans transform into the open merocyanine (MC) form, which exhibits a red-violet color upon reacting with one equivalent of anhydrous FeIIICl3 or FeIIIBr3 in o-dichlorobenzene. Slow mixing with n-hexane precipitates black crystals of the coordination complexes: (TMI–NPS)·FeIIICl3 (1), (TMI–NPS)·FeIIIBr3·2C6H4Cl2 (2) and (TMI–NSO)·FeX3·0.5C6H4Cl2 (where X = Cl for 3 and ...

Added: September 14, 2026

Atomistic modeling of phengite and molecular mechanisms of NH4+ and K+ diffusional mobility in its structure

Tararushkin E., Glushak A., Rudmin M. et al., Applied Clay Science 2026 Vol. 291 Article 108288

Phengite is one of the important hydrous phyllosilicate minerals capable of transporting water and potassium in subducting slabs down to the Earth’s upper mantle. Being able to incorporate significant amounts of ammonium in its structure, phengite is also a major contributor to the nitrogen cycle in subduction zones. Employing classical molecular dynamic simulations with the ...

Added: June 6, 2026