Dalton Transactions最新文献

{"title":"A novel ratiometric fluorescent probe for the detection of co-existing Fe3+ and Ag+ ions: characterization and mechanism exploration","authors":"Qi Wu, Qianwei Wang, Jinhu Guo, Mengxuan Fang, Xinyu Yang, Yichong Cheng, Dalai Jin, Longcheng Wang","doi":"10.1039/d5dt00012b","DOIUrl":"https://doi.org/10.1039/d5dt00012b","url":null,"abstract":"A novel white-light-emitting Ln-MOF composite, g-C₃N₄@TbEu(cpioa), was developed as a ratiometric fluorescent probe for the qualitative and quantitative analysis of metal ions. Among the tested ions, only Fe³⁺ and Ag⁺ exhibited distinct quenching behaviors. Mechanistic studies revealed that Fe³⁺ and Ag⁺ quench luminescence via dynamic and static processes, respectively, involving energy competitive absorption (ECA), photoinduced electron transfer (PET), Förster resonance energy transfer (FRET), and intramolecular weak interactions. The probe demonstrated high sensitivity with limits of detection (LOD) of 0.117 μM for Fe³⁺ and 0.383 μM for Ag⁺. Notably, the observable chromaticity variations enabled differentiation of co-existing Fe³⁺ and Ag⁺ in solutions—a first-reported achievement. Empirical equations derived from orthogonal experiments and multiple regression analysis validated the probe’s capability for dual-ion detection. This work pioneers the application of Ln-MOF-based probes in analyzing mixed analytes, offering significant potential for environmental monitoring, clinical diagnostics, and industrial applications.","PeriodicalId":71,"journal":{"name":"Dalton Transactions","volume":"26 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143660772","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Alkylamido Lutetium Complexes as Prospective Lutetium Imido Precursors: Synthesis, Characterization and Ligand Design","authors":"Jackson P. Knott, Shou-Jen Hsiang, Paul G. Hayes","doi":"10.1039/d5dt00338e","DOIUrl":"https://doi.org/10.1039/d5dt00338e","url":null,"abstract":"Mixed alkyl-amido lutetium complexes, L<small><sup><em>i</em></sup></small><small><sup>Pr</sup></small>Lu(CH<small><sub>2</sub></small>SiMe<small><sub>3</sub></small>)(NHCPh<small><sub>3</sub></small>) (<strong>7</strong><strong><small><sub>CPh3</sub></small></strong>) and L<small><sup><em>i</em></sup></small><small><sup>Pr</sup></small>Lu(CH<small><sub>2</sub></small>SiMe<small><sub>3</sub></small>)(NHDipp) (<strong>7</strong><strong><small><sub>Dipp</sub></small></strong>) (L<small><sup><em>i</em></sup></small><small><sup>Pr</sup></small> = 2,5-[<small><sup><em>i</em></sup></small>Pr<small><sub>2</sub></small>P=N(4-<small><sup><em>i</em></sup></small>PrC<small><sub>6</sub></small>H<small><sub>4</sub></small>)]<small><sub>2</sub></small>C<small><sub>4</sub></small>H<small><sub>2</sub></small>N<small><sup>–</sup></small>), were synthesized by addition of a bulky primary amine, NH<small><sub>2</sub></small>R (R = CPh<small><sub>3</sub></small>, Dipp) (Dipp = 2,6-<small><sup><em>i</em></sup></small>Pr<small><sub>2</sub></small>C<small><sub>6</sub></small>H<small><sub>3</sub></small>) to the dialkyl complex L<small><sup><em>i</em></sup></small><small><sup>Pr</sup></small>Lu(CH<small><sub>2</sub></small>SiMe<small><sub>3</sub></small>)<small><sub>2</sub></small> (<strong>6</strong>). Unlike complexes supported by the related pincer ligand L<small><sup>Ph</sup></small> (L<small><sup>Ph</sup></small> = 2,5-[Ph<small><sub>2</sub></small>P=N(4-<small><sup><em>i</em></sup></small>PrC<small><sub>6</sub></small>H<small><sub>4</sub></small>)]<small><sub>2</sub></small>C<small><sub>4</sub></small>H<small><sub>2</sub></small>N<small><sup>–</sup></small>) these species proved resistant to C–H cyclometalative processes. Attempts to access lutetium imdes via addition of 4-dimethylaminopyridine (DMAP) to <strong>7</strong><strong><small><sub>CPh3</sub></small></strong> and <strong>7</strong><strong><small><sub>Dipp</sub></small></strong> promoted disproportionation, affording 0.5 equivalents of the corresponding bisamide complexes L<em><small><sup>i</sup></small></em><small><sup>Pr</sup></small>Lu(NHCPh<small><sub>3</sub></small>)<small><sub>2</sub></small> (<strong>8</strong><strong><small><sub>CPh3</sub></small></strong>) and L<em><small><sup>i</sup></small></em><small><sup>Pr</sup></small>Lu(NHDipp)<small><sub>2</sub></small> (<strong>8</strong><strong><small><sub>Dipp</sub></small></strong>), respectively, as well as 0.5 equivalents of L<em><small><sup>i</sup></small></em><small><sup>Pr</sup></small>Lu(CH<small><sub>2</sub></small>SiMe<small><sub>3</sub></small>)<small><sub>2</sub></small>, which decomposed in the presence of DMAP. Incorporation of internal Lewis bases was accomplished by replacing the N-aryl substituents in L<em><small><sup>i</sup></small></em><small><sup>Pr</sup></small> with 4,6-dimethylpyrimidine groups (L<small><sup>Pm</sup></small>, <strong>11</strong>). The corresponding dialkyl lutetium complex L<small><sup>Pm</sup></small>Lu(CH<small>","PeriodicalId":71,"journal":{"name":"Dalton Transactions","volume":"56 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143660732","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Influence of imidazole functionalization on the properties of small molecule models of the LPMO active site","authors":"Ugo Gilbert, Xiao Mu, Sarah Lam, Gaël De Leener, Martin Schoenauen, Maëlle Bottin, Koen Robeyns, Michel Luhmer, Raphaël Robiette, Michael L Singleton","doi":"10.1039/d4dt03424d","DOIUrl":"https://doi.org/10.1039/d4dt03424d","url":null,"abstract":"A series of small molecule Cu(II) complexes based on tridentate N3 ligands relevant to the histidine brace of the active site of lytic polysaccharide monooxygenase were synthesized and characterized by X-ray crystallography and spectroscopic studies. In order to better understand the role of different structural features and to help bridge the differences between previously reported models, the methylation patterns, imidazole connectivity, linker nature, and type of heterocycle were systematically varied across the series. These modifications lead to important differences in the electrochemical properties of the complexes and their reactivity towards the oxidation of a model substrate.","PeriodicalId":71,"journal":{"name":"Dalton Transactions","volume":"20 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143660768","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Synthesis and characterization of 15N-labeled tetranuclear Ir complexes via Li2C15N2","authors":"Xuechao Yan, Shu-Xiao Ji, Shengyuan Zhang, Qianru Wang, Jianping Guo, Ping Chen, Zhenfeng Xi, Junnian Wei","doi":"10.1039/d5dt00644a","DOIUrl":"https://doi.org/10.1039/d5dt00644a","url":null,"abstract":"The synthesis of 15N-labeled organometallic complexes is challenging due to limited suitable 15N-labeled precursors. Herein, we report the preparation of a 15N-labeled tetranuclear iridium complex, 15N-1, from Li2C15N2, with nitrogen atoms originally from 15N2 gas. Mono-methylation and single-electron oxidation of 15N-1 yield the corresponding ate complexes, 15N-2 and 15N-3. These complexes were characterized by 1H, 13C, and 15N NMR spectroscopy and X-ray diffraction.","PeriodicalId":71,"journal":{"name":"Dalton Transactions","volume":"33 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143660776","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"C–C bond-forming reactions of 2-isocyanobiphenyl·BX3 adducts: spontaneous construction of polycyclic heteroaromatics","authors":"Yu-Tsen Kuo, Chia-Yu Yao, Yi-Hung Liu, Mu-Jeng Cheng, Jeffrey M. Farrell","doi":"10.1039/d5dt00210a","DOIUrl":"https://doi.org/10.1039/d5dt00210a","url":null,"abstract":"The syntheses and reactivities of 2-isocyanobiphenyl·BX<small>₃</small> adducts (X = I, Br, Cl) are reported. These adducts undergo unexpected C–H bond-functionalizing cyclization upon heating, yielding phenanthridinium-6-trihaloborate zwitterions. Where X = Cl, an unexpected helical polycyclic boronium salt is formed <em>via</em> a competing pathway. Mechanistic details are probed experimentally and computationally.","PeriodicalId":71,"journal":{"name":"Dalton Transactions","volume":"87 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143654022","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Dioxocobaltate(II)-anion in calcium vanadate apatite: partial ordering, magnetic anisotropy, and slow relaxation of magnetization","authors":"Timur Z. Sharifullin, Alexander V. Vasiliev, Robert E. Dinnebier, Reinhard Kremer, Konstantin Lyssenko, Stanislav Bezzubov, Shuqi Huang, Ivan O. Shavrin, Andrei A. Eliseev, Dmitry Tsymbarenko, Pavel E Kazin","doi":"10.1039/d5dt00059a","DOIUrl":"https://doi.org/10.1039/d5dt00059a","url":null,"abstract":"Polycrystalline ceramic and small single-crystal samples of Co-containing calcium vanadate(V) with apatite structure were prepared for the first time. The Co<small>²⁺</small> ions enter the apatite trigonal channels formally substituting protons of the OH<small>^-</small> groups and form separate O-Co-O atomic groups elongated in the <em>c</em> direction, Co being additionally weakly coordinated to an oxygen atom of a VO<small>₄</small> group. At a high Co content, the hexagonal apatite structure undergoes a triclinic distortion followed by partial ordering of the Co<small>²⁺</small> ions. The dc magnetic data fit well to a model of a zero-field split <em>S</em> = 3/2 state with a large negative <em>D</em> of -22 - -25 cm<small>^-1</small>, suggesting a strong easy-axis magnetic anisotropy. The ac susceptibility measurements below <em>T</em> = 10 K reveal a multichannel slow relaxation of the magnetization in non-zero dc field. The temperature dependence of the relaxation time can be described by an Orbach process with the remagnetization energy barrier <em>U<small>_eff</small></em> being equal to experimentally determined 2|<em>D</em>|. Modelling of the electronic structure shows that, with a small increase of the crystal field strength, the high-spin Co<small>²⁺</small> ion changes its ground state from one with an unquenched orbital moment <em>L</em> = 3 to a fully orbitally quenched one. Both states are characterized by easy-axis magnetization vectors directed approximately perpendicular to each other with a smooth rotation of the vector at intermediate crystal fields. The model explains the weak magnetic anisotropy observed in the triclinic single crystal as well as the earlier reported ability of the dioxocobaltate(II) ion to behave like a single-ion magnet with either a high <em>U<small>_eff</small></em> of hundreds of cm<small>^-1</small> or a moderate one of tens of cm<small>^-1</small>. To the best of our knowledge that represents the first instance of the conversion of the d-element ground electronic state from orbitally degenerate to non-degenerate by a slight variation of the crystal field.","PeriodicalId":71,"journal":{"name":"Dalton Transactions","volume":"86 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143654234","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Quantum Chemical Elucidation of the Luminescence Mechanism in Europium (III) co-doped UiO-66 Chemosensor Selective to Mercury (II)","authors":"Yoan Hidalgo-Rosa, Yoslainy Echevarria-Valdés, Mario Saavedra-Torres, Dayán Páez-Hernández, Eduardo Schott, Ximena Zárate","doi":"10.1039/d4dt03285c","DOIUrl":"https://doi.org/10.1039/d4dt03285c","url":null,"abstract":"Lanthanide (III) ions can be incorporated into Metal-Organic Frameworks (MOFs) through post-synthetic procedures (Ln@MOF). This makes the MOFs efficient luminescent chemical sensors for detecting trace amounts of heavy metals. In this report a quantum chemical theoretical protocol has been carried out to elucidate the detection principle of the turn-off luminescence mechanism in a Eu@UiO-66(DPA)-type MOF selective to Hg2+ ions. UiO-66-(DPA) is an iso-reticular MOF of the UiO-66 constructed by the Zr6-clusters ([Zr6(μ3-O)4(μ3-OH)4]12+) and ligands (1,4-benzene- dicarboxylate (BDC) and 2,6-pyridinedicarboxylate (DPA)) as linkers. The sensitization and energy transfer (ET) in UiO-66(DPA) doped with Eu3+ were analyzed using multireference ab initio CASSCF/NEVPT2 methods and time-dependent density functional theory (TD-DFT). The cluster model used in the calculations comprises the fragment (Z6-cluster/BDC/DPA) with the DPA ligand coordinating to Eu3+ or Hg2+ ions. The proposed sensitization pathway involves intersystem crossing from S1(DPA) to T1(DPA), a plausible subsequent energy transfer from T1(DPA) to the 5D1 state of Eu3+, and then vibrational relaxation to the emissive 5D0 state. These results also suggest that the electronic states of BDC ligand can be strengthened the population of the T1 electronic states of the DPA antenna via ET. Periodic-DFT calculations confirm the electronic state mixture of BDC and DPA linkers in the conduction bands, just above the electronic state of Eu3+ ions, which is in concordance with the proposed Eu3+ sensitization pathways. The assessed optical properties (absorption and emission) of Hg2+@UIO-66(DPA) explain the experimental behavior of this chemosensor when the Hg2+ ion replaces the Eu3+ and the luminescence diminished.","PeriodicalId":71,"journal":{"name":"Dalton Transactions","volume":"183 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143660774","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Precipitation of morphology-controlled uranium(VI) peroxide in nitric acid media","authors":"Lucas Muller, Paul Estevenon, Christelle Tamain, Nicolas Dacheux, Nicolas Clavier","doi":"10.1039/d4dt03467h","DOIUrl":"https://doi.org/10.1039/d4dt03467h","url":null,"abstract":"The precipitation of U(VI) peroxide (UO2(O2).4H2O, known as studtite) has been extensively studied in mildly acidic media (i.e. pH &gt; 1). However, few studies have investigated the influence of highly acidic conditions (i.e. pH &lt; 1) on the precipitation of studtite, particularly regarding the morphology of the final powder. The influence of high acidity (0.1 M &lt; C(HNO3)ini &lt; 2.0 M) and C(H2O2)ini/C(U)ini molar ratio (ranging from 10 to 70) on the precipitation kinetics, as well as the morphological and crystallographic properties of U(VI) peroxide was thus investigated in this study. Decreasing the acidity and increasing C(H2O2)ini/C(U)ini molar ratio significantly enhance both the final precipitation yield and the reaction kinetics. Furthermore, a correlation was established between the initial saturation index of the reaction mixture and the final morphology and crystallite size of the precipitated U(VI) peroxide, regardless of the initial precipitation conditions. These results demonstrate that in highly acidic nitric media, it is possible to control the morphology of the precipitated U(VI) peroxide by simply adjusting the initial saturation index. This correlation opens up interesting perspectives for the synthesis of powders with specific morphologies, particularly uranium peroxide or corresponding oxide powders obtained after thermal treatment. This morphology control is of great interest in the nuclear fuel fabrication field, as it allows obtaining oxide powders with optimized properties for sintering.","PeriodicalId":71,"journal":{"name":"Dalton Transactions","volume":"40 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143660773","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"K2SO4(NH3SO3)2 and Cs2SO4(NH3SO3)3: Two Deep-UV Transparent Sulfamate-Sulfates with Moderate Birefringence","authors":"Yun Ji, Huili Zhang, Xin Wen, Jindong Chen, Guangsai Yang, Yuchen Yan, Guang Peng, Ning Ye","doi":"10.1039/d5dt00401b","DOIUrl":"https://doi.org/10.1039/d5dt00401b","url":null,"abstract":"In this work, polar tetrahedron [NH3SO3] and non-polar tetrahedron [SO4]2- were combined to synthesize two deep-UV transparent crystals K2SO4(NH3SO3)2 and Cs2SO4(NH3SO3)3 based on solution evaporation method. Due to the presence of two types of tetrahedral groups with wide bandgap and alkali metal cations without d-d or f-f transitions, both crystals exhibit a deep-UV cutoff edge, approximately 190 nm. Significantly, the birefringence of K2SO4(NH3SO3)2 and Cs2SO4(NH3SO3)3 are 0.0123 and 0.0153 @546 nm, respectively, which are remarkably improved compared to many conventional sulfate crystals. In addition, theoretical calculations were performed to analyze the relationships between the structures and optical properties.","PeriodicalId":71,"journal":{"name":"Dalton Transactions","volume":"91 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143654237","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ca7Mg1.8Zn0.2Ga6O18:Bi3+/Mn4+ phosphor: energy transfer enables tunable colour emission and high sensitivity in optical thermometry","authors":"Gonggui Yan, Yuxuan Qi, Rihong Cong, Pengfei Jiang, Tao Yang","doi":"10.1039/d5dt00530b","DOIUrl":"https://doi.org/10.1039/d5dt00530b","url":null,"abstract":"Recent advancements in optical thermometry utilizing the fluorescence intensity ratio (FIR) technology have attracted tremendous attention in real-time temperature measurements due to its numerous advantages, such as high sensitivity. In this work, we rationally designed an FIR-type thermometer by utilizing the distinctive thermal responses of the blue and far-red emissions from Bi3+ and Mn4+ activators, respectively. To achieve a broad range of FIR values, we first optimized the blue emission of Ca7Mg2-xZnxGa6O18:0.05Bi3+ (CMZxGO:0.05Bi3+) through Zn2+-to-Mg2+ substitution and then utilized Bi3+/Mn4+ codoping into the optimal composition to realize dual emission. The blue emission of CMZxGO:0.05Bi3+ was improved significantly, which is associated with complex spectroscopic red and blue shifts due to the competitive effect of crystal field splitting and centroid shift for Bi3+-emitters. Additionally, Bi3+/Mn4+-codoped CMZ0.2GO:0.05Bi3+/yMn4+ phosphors exhibit tunable colour emission from blue to deep-red, arising from an increased energy transfer efficiency from Bi3+ to Mn4+ upon increasing the Mn4+-content. Benefitting from this energy transfer, Bi3+ and Mn4+ activators display severe thermal quenching and high thermal stability, respectively, thereby resulting in a high relative sensitivity (Sr) of 1.64% K-1 to temperature measurement. This Sr value surpasses that of most Bi3+/Mn4+- and Bi3+/Eu3+-codoped optical thermometers, implying the promising application potential of CMZ0.2GO:0.05Bi3+/0.001Mn4+ as an optical thermometer.","PeriodicalId":71,"journal":{"name":"Dalton Transactions","volume":"19 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143654203","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}