[Epidemiological investigation of iron deficiency among preschool children in 10 provinces, autonomous regions, or municipalities in China]

Objective: To understand the current status of anemia, iron deficiency, and iron-deficiency anemia among preschool children in China. Methods: A cross-sectional study was conducted with a multi-stage stratified sampling method to select 150 streets or townships from 10 Chinese provinces, autonomous regions, or municipalities (East: Jiangsu, Zhejiang, Shandong, and Hainan; Central: Henan; West: Chongqing, Shaanxi, Guizhou, and Xinjiang; Northeast: Liaoning). From May 2022 to April 2023, a total of 21 470 children, including community-based children aged 0.5 to<3.0 years receiving child health care and kindergarten-based children aged 3.0 to<7.0 years, were surveyed. They were divided into 3 age groups: infants (0.5 to<1.0 year), toddlers (1.0 to<3.0 years), and preschoolers (3.0 to<7.0 years). Basic information such as sex and date of birth of the children was collected, and peripheral blood samples were obtained for routine blood tests and serum ferritin measurement. The prevalence rates of anemia, iron deficiency, and iron-deficiency anemia were analyzed, and the prevalence rate differences were compared among different ages, sex, urban and rural areas, and regions using the chi-square test. Results: A total of 21 460 valid responses were collected, including 10 780 boys (50.2%). The number of infants, toddlers, and preschoolers were 2 645 (12.3%), 6 244 (29.1%), and 12 571 (58.6%), respectively. The hemoglobin level was (126.7±14.8) g/L, and the serum ferritin level was 32.3 (18.5, 50.1) μg/L. The overall rates of anemia, iron deficiency, and iron-deficiency anemia were 10.4% (2 230/21 460), 28.3% (6 070/21 460), and 3.9% (845/21 460), respectively. The prevalence rate of anemia was higher for boys than for girls (10.9% (1 173/10 780) vs. 9.9% (1 057/10 680), χ2=5.58, P=0.018), with statistically significant differences in the rates for infants, toddlers and preschoolers (18.0% (475/2 645), 10.6% (662/6 244), and 8.7% (1 093/12 571), respectively, χ2=201.81, P<0.01), and the rate was significantly higher for children in rural than that in urban area (11.8% (1 516/12 883) vs. 8.3% (714/8 577), χ2=65.54, P<0.01), with statistically significant differences in the rates by region (χ2=126.60, P<0.01), with the highest rate of 15.8% (343/2 173) for children in Central region, and the lowest rate of 5.3% (108/2 053) in Northeastern region. The prevalence rates of iron deficiency were 33.8% (895/2 645), 32.2% (2 011/6 244), and 25.2% (3 164/12 571) in infants, toddlers, and preschoolers, respectively, and 30.0% (3 229/10 780) in boys vs. 26.6% (2 841/10 680) in girls, 21.7% (1 913/8 821), 40.0% (870/2 173), 27.1% (2 283/8 413), 48.9% (1 004/2 053) in Eastern, Central, Western, and Northeastern regions, respectively, and each between-group showed a significant statistical difference (χ2=147.71, 29.73, 773.02, all P<0.01). The prevalence rate of iron-deficiency anemia showed a significant statistical difference between urban and rural areas, 2.9% (251/8 577) vs. 4.6% (594/12 883) (χ2=38.62, P<0.01), while the difference in iron deficiency prevalence was not significant (χ2=0.51, P=0.476). Conclusions: There has been a notable improvement in iron deficiency and iron-deficiency anemia among preschool children in China, but the situation remains concerning. Particular attention should be paid to the prevention and control of iron deficiency and iron-deficiency anemia, especially among infants and children in the Central, Western, and Northeastern regions of China.

Two-dimensional spin-crossover coordination polymers based on the 1,1,2,2-tetra(pyridin-4-yl)ethene ligand

A series of two-dimensional (2D) spin-crossover coordination polymers (SCO-CPs) [FeII(TPE)(NCX)2]·solv (1: X = BH3, solv = H2O·2CH3OH·DMF; 2: X = Se, solv = H2O·2CH3OH·0.5DMF; 3: X = S, solv = H2O·2CH3OH·0.5DMF) were synthesized by employing 1,1,2,2-tetra(pyridin-4-yl)ethene (TPE) and pseudohalide (NCX-) coligands. Magnetic measurements indicated that complexes 1-3 exhibited SCO behaviors with diminishing thermal hysteresis (7/4/0 K) upon decreasing the ligand-field strength. The critical temperatures (Tc) during spin transition were found to be inversely proportional to the coordination ability parameters (a™) with a linear correlation. The guest effect was also investigated in the solvent-exchanged phases 1-SE/2-SE/3-SE wherein the DMF molecules were replaced by methanol molecules. Compared with 1-3, 1-SE/2-SE/3-SE displayed more abrupt and complete single-step SCO behaviors but narrower thermal hysteretic loops. The results reported here demonstrate that the Tc values of these two families were dominated by the ligand-field strength of the NCX- anions (NCBH3 > NCSe > NCS), whereas the guest effect only modulated the kinetic factor of the SCO nature in this system.

Cyanometallic charge engineering in spin crossover metal-organic frameworks

In this study, we successfully synthesize cationic/neutral/anionic inverse-Hofmann-type spin crossover (SCO) frameworks with 1,1,2,2-tetrakis(4-(pyridine-4-yl)phenyl)-ethene ligand by means of cyanometallic charge engineering strategy. The cationic and neutral frameworks exhibit single-step thermally induced spin transition behaviors, while the SCO capability of anionic framework can be aroused by partial desolvation. This strategy provides a new idea to construct ionic SCO frameworks and extends the toolkit for SCO materials.

Radical-Induced Photochromic Silver(I) Metal-Organic Frameworks: Alternative Topology, Dynamic Photoluminescence and Efficient Photothermal Conversion Modulated by Anionic Guests

Photogenerated radicals are an indispensable member of the state-of-the-art photochromic material family, as they can effectively modulate the photoluminescence and photothermal conversion performance of radical-induced photochromic complexes. Herein, two novel radical-induced photochromic metal‒organic frameworks (MOFs), [Ag(TEPE)](AC)⋅7/4H2O⋅5/4EtOH (1) and [Ag(TEPE)](NC)⋅3H2O⋅EtOH (2), are reported. Distinctly different topological networks can be obtained by judiciously introducing alternative π-conjugated anionic guests, including a new topological structure (named as sfm) first reported in this work, describing as 4,4,4,4-c net. EPR data and UV-Vis spectra prove the radical-induced photochromic mechanism. Dynamic photochromism exhibits tunability in a wide CIE color space, with a linear segment from yellow to red for 1, while a curved coordinate line for 2, resulting in colorful emission from blue to orange. Moreover, photogenerated TEPE* radicals effectively activate the near-infrared (NIR) photothermal conversion effect of MOFs. Under 1 W cm-2 808 nm laser irradiation, the surface temperatures of photoproducts 1* and 2* can reach ~160 ℃ and ~120 ℃, respectively, with competitive NIR photothermal conversion efficiencies η = 51.8% (1*) and 36.2% (2*). This work develops a feasible electrostatic compensation strategy to accurately introduce photoactive anionic guests into MOFs to construct multifunctional radical-induced photothermal conversion materials with tunable photoluminescence behavior.

NIR-II photothermal conversion and imaging based on a cocrystal containing twisted components

On account of the scarcity of molecules with a satisfactory second near-infrared (NIR-II) response, the design of high-performance organic NIR photothermal materials has been limited. Herein, we investigate a cocrystal incorporating tetrathiafulvalene (TTF) and tetrachloroperylene dianhydride (TCPDA) components. A stable radical was generated through charge transfer from TTF to TCPDA, which exhibits strong and wide-ranging NIR-II absorption. The metal-free TTF-TCPDA cocrystal in this research shows high photothermal conversion capability under 1064 nm laser irradiation and clear photothermal imaging. The remarkable conversion ability-which is a result of twisted components in the cocrystal-has been demonstrated by analyses of single crystal X-ray diffraction, photoluminescence and femtosecond transient absorption spectroscopy as well as theoretical calculations. We have discovered that space charge separation and the ordered lattice in the TTF-TCPDA cocrystal suppress the radiative decay, while simultaneously strong intermolecular charge transfer enhances the non-radiative decay. The twisted TCPDA component induces rapid charge recombination, while the distorted configuration in TTF-TCPDA favors an internal non-radiative pathway. This research has provided a comprehensive understanding of the photothermal conversion mechanism and opened a new way for the design of advanced organic NIR-II photothermal materials.

Single-Crystal Transformation Engineering the Spin Change of Metal-Organic Frameworks via Cluster Deconstruction

Spin crossover (SCO) materials with new architectures will expand and enrich the research in the SCO field. Here, we report two metal-organic frameworks (MOFs) containing tetradentate organic ligands and hexatopic linkers [Ag8 X8 (CN)6 ]6- (X=Br and I), which represents the first SCO MOF with clusters as building blocks. The silver halide cluster can be further removed after reacting with lithium tetracyanoquinodimethan (LiTCNQ). Such post-synthetic modification (PSM) is realized via single-crystal to single-crystal (SCSC) transformation from urk to nbo topology. Accordingly, the spin state and fluorescence properties are greatly modified by cluster deconstruction. Therefore, these achievements will provide new ideas for the design of new SCO systems and the development of PSM methods.

Lanthanide-radical single-molecule magnets: current status and future challenges

In the field of molecular magnetism, the lanthanide-radical (Ln-Rad) method has become one of the most appealing tactics for introducing strong magnetic interactions and has spurred on the booming development of heterospin single-molecule magnets (SMMs). The article is a timely retrospect on the research progress of Ln-Rad heterospin systems and special attention is invested on low dimensional Ln-Rad compounds with SMM behavior, primarily concerning with nitrogen-based radicals, semiquinone and nitroxide radicals. Rational design, molecular structures, magnetic behaviors and magneto-structural correlations are highlighted. Meanwhile, particular attention is focused on the influence of exchange couplings on the dynamic magnetic properties, with the purpose of helping to guide the design of prospective radical-based Ln-SMMs.

[Phonological processes in initial consonants of Putonghua in children in Jiangsu urban areas]

Objective: To explore the phonological processes in initial consonants of Putonghua-speaking children in Jiangsu urban areas. Methods: A status survey was applied. From December 2014 to September 2015, a stratified random sampling method was used to select 958 children aged 1 to 6 years with Putonghua as their mother tongue in the urban area of Nanjing, Changzhou, Yangzhou and Xuzhou to examine their phonological performance. Speech samples were collected by the method of picture naming. The children were divided into 9 age groups (1.5-<2.0, 2.0-<2.5, 2.5-<3.0, 2.5-<3.0, 3.0-<3.5, 3.5-<4.0, 4.0-<4.5, 5.0-<6.0, 6.0-<7.0 years). Descriptive analysis method was used to analyze the phonological processes in initial consonants at different age groups. Results: Among the 958 children, there were 482 boys and 476 girls. The age of the children was (3.8±1.4) years. The number of children in the 9 age groups (1.5-<2.0, 2.0-<2.5, 2.5-<3.0, 2.5-<3.0, 3.0-<3.5, 3.5-<4.0, 4.0-<4.5, 5.0-<6.0, 6.0-<7.0 years) is 100, 110, 110, 114, 114, 114, 111, 119, and 66, separately. The process of substitution was found in the speech of 701 children (73.2%), syllable structure simplification was found in 194 children (20.3%), distortion was found in 41 children (4.3%), and assimilation was found in 17 children (1.8%). Among these 4 types of processes, the occurrence of substitution was highest in all the age groups, ranging from 30.3% (20/66) to 94.5% (104/110). The occurrence of syllable structure simplification ranged from 27.3% (30/110) to 91.0% (91/100) in the age groups of 1.5-<3.0 years and 0.9% (1/114) to 7.9% (9/114) in the age groups of 3.0-<7.0 years. The occurrence of distortion ranged from 7.3% (8/110) to 19.1% (21/110) in the age groups of 1.5-<3.0 years and 0 (0/114) to 2.7% (3/111) in the age groups of 3.0-<7.0 years. The occurrence of assimilation was very low in all age groups, ranging from 0 (0/114) to 3.0% (3/100) among all age groups. For substitution, the occurrence order of mainly individual processes from high to low was listed as follows: retroflexion 35.4% (339/958), deretroflexion 31.6% (303/958), lateralization 27.9% (267/958), stopping 17.8% (171/958), backing 14.2% (136/958), palatalization 10.9% (104/958), fronting 10.6% (102/958), and nasalization 5.8% (56/958). From the 4.0-<4.5 years of age group onwards, the phonological processes in initial consonants all met suppression criteria (the occurrence of processes was reduced to<10%) except retroflexion, deretroflexion, and lateralization. Conclusions: The processes of syllable structure simplification and distortion mainly appears in the early stage of speech sound development, while substitution is the major form of phonological pattern in initial consonants found in developmental speech errors. By 4 years of age, phonological processes in initial consonants almost disappear. The remaining processes that persisted for a longer period of time are retroflexion, deretroflexion, and lateralization.

High-stability spherical lanthanide nanoclusters for magnetic resonance imaging

High-nuclear lanthanide clusters have shown great potential for the administration of high-dose mononuclear gadolinium chelates in magnetic resonance imaging (MRI). The development of high-nuclear lanthanide clusters with excellent solubility and high stability in water or solution has been challenging and is very important for expanding the performance of MRI. We used N-methylbenzimidazole-2-methanol (HL) and LnCl3·6H2O to synthesize two spherical lanthanide clusters, Ln32 (Ln = Ho, Ho32; and Ln = Gd, Gd32), which are highly stable in solution. The 24 ligands L- are all distributed on the periphery of Ln32 and tightly wrap the cluster core, ensuring that the cluster is stable. Notably, Ho32 can remain highly stable when bombarded with different ion source energies in HRESI-MS or immersed in an aqueous solution of different pH values for 24 h. The possible formation mechanism of Ho32 was proposed to be Ho(III), (L)- and H2O → Ho3(L)3/Ho3(L)4 → Ho4(L)4/Ho4(L)5 → Ho6(L)6/Ho6(L)7 → Ho16(L)19 → Ho28(L)15 → Ho32(L)24/Ho32(L)21/Ho32(L)23. To the best of our knowledge, this is the first study of the assembly mechanism of spherical high-nuclear lanthanide clusters. Spherical cluster Gd32, a form of highly aggregated Gd(III), exhibits a high longitudinal relaxation rate (1 T, r1 = 265.87 mM-1·s-1). More notably, compared with the clinically used commercial material Gd-DTPA, Gd32 has a clearer and higher-contrast T1-weighted MRI effect in mice bearing 4T1 tumors. This is the first time that high-nuclear lanthanide clusters with high water stability have been utilized for MRI. High-nuclear Gd clusters containing highly aggregated Gd(III) at the molecular level have higher imaging contrast than traditional Gd chelates; thus, using large doses of traditional gadolinium contrast agents can be avoided.

Magnetic and Luminescent Dual Responses of Photochromic Hexaazamacrocyclic Lanthanide Complexes

Herein, hexaazamacrocyclic ligand L^N6 was employed to construct a series of photochromic rare-earth complexes, [Ln(L^N6)(NO₃)₂](BPh₄) [1-Ln, Ln = Dy, Tb, Eu, Gd, Y; L^N6 = (3E,5E,10E,12E)-3,6,10,13-tetraaza-1,8(2,6)-dipyridinacyclotetradecaphane-3,5,10,12-tetraene]. The behavior of photogenerated radicals of hexaazamacrocyclic ligands was revealed for the first time. Upon 365 nm light irradiation, complexes 1-Ln exhibit photochromic behavior induced by photogenerated radicals according to EPR and UV-vis analyses. Static and dynamic magnetic studies of 1-Dy and irradiated product 1-Dy* indicate weak ferromagnetic interactions among Dy^III ions and photogenerated L^N6 radicals, as well as slow magnetization relaxation behavior under a 2 kOe applied field. Further fitting analyses show that the magnetization relaxation in 1-Dy* is markedly different from 1-Dy. Time-dependent fluorescence measurements reveal the characteristic luminescence quenching dynamics of lanthanide in the photochromic process. Especially for irradiated product 1-Eu*, the luminescence is almost completely quenched within 5 min with a quenching efficiency of 98.4%. The results reported here provide a prospect for the design of radical-induced photochromic lanthanide single-molecule magnets and will promote the further development of multiresponsive photomagnetic materials.

Redox-Programmable Spin-Crossover Behaviors in a Cationic Framework

Metal-organic frameworks (MOFs) provide versatile platforms to construct multi-responsive materials. Herein, by introducing the neutral tetradentate ligand and the linear dicyanoaurate(I) anion, we reported a rare cationic MOF [Fe^II(TPB){Au^I(CN)₂}]I·4H₂O·4DMF (TPB = 1,2,4,5-tetra(pyridin-4-yl)benzene) with hysteretic spin-crossover (SCO) behavior near room temperature. This hybrid framework with an open metal site (Au^I) exhibits redox-programmable capability toward dihalogen molecules. By means of post-synthetic modification, all the linear [Au^I(CN)₂]^- linkers can be oxidized to square planar [Au^III(CN)₂X₂]^- units, which results in the hysteretic SCO behaviors switching from one-step to two-step for Br₂ and three-step for I₂. More importantly, the stepwise SCO behaviors can go back to one-step via the reduction by l-ascorbic acid (AA). Periodic DFT calculations using various SCAN-type exchange-correlation functionals have been employed to rationalize the experimental data. Hence, these results demonstrate for the first time that switchable one-/two-/three-stepped SCO dynamics can be manipulated by chemical redox reactions, which opens a new perspective for multi-responsive molecular switches.

Single-Crystal to Single-Crystal Transformation of a Spin-Crossover Hybrid Perovskite via Thermal-Induced Cyanide Linkage Isomerization

Linkage isomers involving changes in the bonding mode of ambidentate ligands have potential applications in data storage, molecular machines, and motors. However, the observation of the cyanide-linkage-isomerism-induced spin change (CLIISC) effect characterized by single-crystal X-ray diffraction remains a considerable challenge. Meanwhile, the high-spin and low-spin states can be reversibly switched in spin-crossover (SCO) compounds, which provide the potential for applications to data storage, switches, and sensors. Here, a new perovskite-type SCO framework (PPN)[Fe{Ag(CN)₂}₃] (PPN⁺ = bis(trisphenylphosphine)iminium cation) is synthesized, which displays the unprecedented aging and temperature dependences of hysteretic multistep SCO behaviors near room temperature. Moreover, the thermal-induced cyanide linkage isomerization from Fe^II-N≡C-Ag^I to Fe^II-C≡N-Ag^I is revealed by single-crystal X-ray diffraction, Raman, and Mössbauer spectra, which is associated with a transition from the mixed spin state to the low-spin state and a dramatic volume shrinkage. Considering the wide use of cyanogen in magnetic systems, the association of CLIISC and SCO opens a new dimension to modulate the spin state and realize a colossal negative thermal expansion.

Discovery of a Dysprosium Metallocene Single-Molecule Magnet with Two High-Temperature Orbach Processes

Magnetic bistability in single-molecule magnets (SMMs) is a potential basis for new types of nanoscale information storage material. The standard model for thermally activated relaxation of the magnetization in SMMs is based on the occurrence of a single Orbach process. Here, we show that incorporating a phosphorus atom into the framework of the dysprosium metallocene [(Cp^iPr5)Dy(Cp^PEt4)]⁺[B(C₆F₅)₄]⁻ (Cp^iPr5 is penta-isopropylcyclopentadienyl, Cp^PEt4 is tetraethylphospholyl) leads to the occurrence of two distinct high-temperature Orbach processes, with energy barriers of 1410(10) and 747(7) cm^–1, respectively. These barriers provide experimental evidence for two different spin–phonon coupling regimes, which we explain with the aid of ab initio calculations. The strong and highly axial crystal field in this SMM also allows magnetic hysteresis to be observed up to 70 K, using a scan rate of 25 Oe s^–1. In characterizing this SMM, we show that a conventional Debye model and consideration of rotational contributions to the spin–phonon interaction are insufficient to explain the observed phenomena.

A phospholyl-ligated dysprosium metallocene single-molecule magnet shows two high-temperature Orbach relaxation processes with effective energy barriers of 1410(10) and 747(7) cm⁻¹, and magnetic hysteresis up to 70 K when using a scan rate of 25 Oe s⁻¹.

Synergistic Experimental and Theoretical Studies of Luminescent-Magnetic Ln2Zn6 Clusters

The present work is part of our ongoing quest for developing functional inorganic complexes using unorthodox pyridyl-pyrazolyl-based ligands. Accordingly, we report herein the synthesis, characterization, and luminescence and magnetic properties of four 3d-4f mixed-metal complexes with a general core of Ln₂Zn₆ (Ln = Dy, Gd, Tb, and Eu). In stark contrast to the popular wisdom of using a compartmental ligand with separate islands of hard and soft coordinating sites for selective coordination, we have vindicated our approach of using a ligand with overcrowded N-coordinating sites that show equal efficiency with both 4f and 3d metals toward multinuclear cage-cluster formation. The encouraging red and green photolumiscent features of noncytotoxic Eu₂Zn₆ and Tb₂Zn₆ complexes along with their existence in nanoscale dimension have been exploited with live-cell confocal microscopy imaging of human breast adenocarcinoma (MCF7) cells. The magnetic features of the Dy₂Zn₆ complex confirm the single-molecule-magnet behavior with befitting frequency- and temperature-dependent out-of-phase signals along with an U_eff value of ∼5 K and a relaxation time of 8.52 × 10^-6 s. The Gd₂Zn₆ complex, on the other hand, shows cryogenic magnetic refrigeration with an entropy change of 11.25 J kg^-1 K^-1 at a magnetic field of 7 T and at 2 K. Another important aspect of this work reflects the excellent agreement between the experimental results and theoretical calculations. The theoretical studies carried out using the broken-symmetry density functional theory, ORCA suite of programs, and MOLCAS calculations using the complete-active-space self-consistent-field method show an excellent synergism with the experimentally measured magnetic and spectroscopic data.

Opening Magnetic Hysteresis via Improving Planarity of Equatorial Coordination by Hydrogen Bonding

Through a mixed-ligand strategy, the structural change from a discrete dinuclear DyIII cluster to a one-dimensional polymeric chain was achieved, maintaining the two magnetic entities with the same {Dy(dppbO2)2(H2O)5} (dppbO2...

Light-induced hidden multistability in a spin crossover metal-organic framework

The pursuit of spin crossover (SCO) materials with photo-switchable multistability is driven by the fascinating perspectives toward light-response switches and opto-magnetic memory devices. Herein, we report a 3D Hofmann-type metal...

2D/3D spin crossover porous coordination polymers based on isomeric tetrapyridyl benzene ligands

By employing cyanoborohydride and isomeric tetrapyridyl benzene ligands, a new three-dimensional (3D) [Fe(3-tpb)(NCBH3)2] (1·2H2O, 3-tpb = 1,2,4,5-tetra(pyridin-3-yl)benzene) and a two-dimensional (2D) [Fe(4-tpb)(NCBH3)2] (2·2-NapSMe and 2·H2O·3DMF, 4-tpb = 1,2,4,5-tetra(pyridin-4-yl)benzene, 2-NapSMe =...

Single-Molecule Magnets beyond a Single Lanthanide Ion: The Art of Coupling

The promising future of storing and processing quantized information at the molecular level has been attracting the study of Single-Molecule Magnets (SMMs) for almost three decades. Although some recent breakthroughs are mainly about the SMMs containing only one lanthanide ion, we believe SMMs can tell a much deeper story than the single-ion anisotropy. Here in this Perspective, we will try to draw a unified picture of SMMs as a delicately coupled spin system between multiple spin centres. The hierarchical couplings will be presented step-by-step, from the intra-atomic hyperfine coupling, to the direct and indirect intra-molecular couplings with neighbouring spin centres, and all the way to the inter-molecular and spin–phonon couplings. Along with the discussions on their distinctive impacts on the energy level structures and thus magnetic behaviours, a promising big picture for further studies is proposed, encouraging the multifaceted developments of molecular magnetism and beyond.

In this Perspective, we draw a unified picture for single-molecule magnets as delicately coupled spin systems, discuss the hierarchical couplings (from intra-atomic to inter-molecular) and their distinctive impacts on the magnetic behaviours.

Magnetization Dynamics on Isotope-Isomorphic Holmium Single-Molecule Magnets

Here we reported the deuteration of the metal-binding equatorial water molecules in a reported Ho^III single-molecule magnet (SMM) with pentagonal-bipyramidal geometry, from [Ho(CyPh₂ PO)₂ (H₂ O)₅ ]³⁺ to [Ho(CyPh₂ PO)₂ (D₂ O)₅ ]³⁺ . The hyperfine structures originating from the nuclear spin of ¹⁶⁵ Ho^III can be clearly observed. Moreover, the resulting magnetization dynamics revealed the switch of the relative relaxation rates for the two isotope-isomorphic complexes-respectively faster/slower at low/high temperature. The noticeable isotope effect arises from not only the paramagnetic metal center but also the diamagnetic ligands, which can be explained by the ab initio calculated tunnel splitting and the involvement of the super-hyperfine interaction related to the difference in the nuclear spin number of protium (¹ H, I=¹ /₂ ) and deuterium (² H, I=1).

Fascinating interlocked triacontanuclear giant nanocages

We report herein three air, thermal and solvent stable interlocked triacontanuclear giant nanocages, generated using a node and spacer concept. Interestingly, the crystal structures of the cages are not only nano-dimensional but also exist in the nano-dimension range, which was corroborated with microscopic images. The combination of microscopic and crystallographic data, in effect, led us to a unique advantageous situation of generating nanomaterials with hard-to-come-by structural information at the molecular level.

Guest-Driven Light-Induced Spin Change in an Azobenzene Loaded Metal-Organic Framework

Stimuli-responsive materials that can be reversibly switched by light are of immense interest. Among them, photo-responsive spin crossover (SCO) complexes have great promises to combine the photoactive inputs with multifaceted outputs into switchable materials and devices. However, the reversible control the spin-state change by photochromic guests is still challenging. Herein, we report an unprecedented guest-driven light-induced spin change (GD-LISC) in a Hofmann-type metal-organic framework (MOF), [Fe(bpn){Ag(CN)₂ }₂ ]⋅azobenzene. (1, bpn=1,4-bis(4-pyridyl)naphthalene). The reversible trans-cis photoisomerization of azobenzene guest upon UV/Vis irradiation in the solid-state results in the remarkable magnetic changes in a wide temperature range of 10-180 K. This finding not only establishes a new switching mechanism for SCO complexes, but also paves the way toward the development of new generation of photo-responsive magnetic materials.

Tuning luminescence of didysprosium single-molecule magnets with a π-conjugated/non-conjugated bridging ligand

Herein, we reported two didysprosium single-molecule magnets constructed with {Dy(bbpen)(MeOH)} subunits and a π-conjugated tpb or non-conjugated tpcb bridging ligand. The former exhibits extremely weak luminescence that makes it difficult to simulate its emission spectra. However, the later shows obviously enhanced and well-resolved luminescence, which helps us to gain knowledge about the magneto-optical correlation and the relevant magnetic energy levels.

A spin-crossover phenomenon in a 2D heterometallic coordination polymer with [Pd(SCN)4]2- building blocks

Two new two-dimensional (2D) coordination polymers, [Fe^II(L)₂{Pd^II(SCN)₄}] (L₁ = 3-(9-anthracenyl)-pyridine (1) and L₂ = 4-(9-anthracenyl)-pyridine (2)), were constructed by employing square-planar [Pd(SCN)₄]^2- building blocks. Compound 1 exhibits a complete spin-crossover (SCO) behaviour under normal atmospheric pressure, and represents the first SCO example in a 2D system containing [Pd(SCN)₄]^2- units. In contrast, compound 2 only shows paramagnetic behaviour at measured temperatures. It is clear that the fine-tuning of the monodentate ligand can modulate the ligand field and packing fashions, which sheds light on developing new SCO materials.

Lanthanide clusters of phenanthroline containing a pyridine-pyrazole based ligand: magnetism and cell imaging

In this contribution, we report the synthesis, characterization and luminescence-magnetic properties of Ln-clusters (Ln = Gd3+, Eu3+ and Tb3+) using a new pyridine-pyrazole functionalized ligand fitted with a chromophoric phenanthroline backbone. The unorthodox N-rich ligand forms isostructural trinuclear lanthanide complexes with a topology that closely resembles two interdigitating hairpins. The clusters crystallize in chiral space groups and also exhibit chirality for bulk samples, which were further confirmed using solid state CD spectra. Magnetic studies on the complexes reveal their interesting features while the Gd cluster shows a significant cryogenic magnetic cooling behaviour with a moderately high magnetic entropy change of -23.42 J kg-1 K-1 at 7 T and 2 K. On the other hand, Eu and Tb complexes exhibit interesting fluorescence properties. The compounds were subsequently used as fluorescent probes for the imaging of human breast adenocarcinoma (MCF7) cells. Live cell confocal microscopy images show that the complexes penetrate beyond the usual cytoplasm region and can be useful in imaging the nucleus region of MCF7 cells.

Opening Magnetic Hysteresis by Axial Ferromagnetic Coupling: From Mono-Decker to Double-Decker Metallacrown

Combining Ising-type magnetic anisotropy with collinear magnetic interactions in single-molecule magnets (SMMs) is a significant synthetic challenge. Herein we report a Dy[15-MC_Cu -5] (1-Dy) SMM, where a Dy^III ion is held in a central pseudo-D_5h pocket of a rigid and planar Cu₅ metallacrown (MC). Linking two Dy[15-MC_Cu -5] units with a single hydroxide bridge yields the double-decker {Dy[15-MC_Cu -5]}₂ (2-Dy) SMM where the anisotropy axes of the two Dy^III ions are nearly collinear, resulting in magnetic relaxation times for 2-Dy that are approximately 200 000 times slower at 2 K than for 1-Dy in zero external field. Whereas 1-Dy and the Y^III -diluted Dy@2-Y analogue do not show remanence in magnetic hysteresis experiments, the hysteresis data for 2-Dy remain open up to 6 K without a sudden drop at zero field. In conjunction with theoretical calculations, these results demonstrate that the axial ferromagnetic Dy-Dy coupling suppresses fast quantum tunneling of magnetization (QTM). The relaxation profiles of both complexes curiously exhibit three distinct exponential regimes, and hold the largest effective energy barriers for any reported d-f SMMs up to 625 cm^-1 .

Sensitive magnetic-field-response magnetization dynamics in a one-dimensional dysprosium coordination polymer

A Dy(iii) coordination polymer shows significant single-molecule magnet behavior with a sensitive low-field response.

Reversible step spin crossover modulation via water absorption and dehydration in a 3D Hofmann-type framework

Reversible modulations of step spin crossover behaviors are achieved in a 3D Hofmann-type framework via water absorption and dehydration.

Magnetic dynamics of an open-ring tridysprosium complex employing mixed ligands

By employing mixed ligands, a new trinuclear dysprosium complex [Dy3(dbm)3(L)4](ClO4)2·CH2Cl2·2MeOH (1, Hdbm = dibenzoylmethane; HL = 2-methoxy-6-((quinolin-8-ylimino)methyl)phenol) was synthesized by a one-pot reaction. According to structural characterization, all the 8-coordinated Dy(iii) sites are well arranged with slightly distorted square antiprism (D4d) geometries. Magnetic measurements reveal that 1 exhibits typical single-molecule magnetic behavior at zero magnetic field and shows rarely open hysteresis loops up to 3 K among open-ring {Dy3} SMMs, where the relaxation time remains very stable under the protection from the Dy-Dy magnetic coupling in the open-ring arrangement of Ising spins.

[Survey on the stunting of children under seven years of age in nine cities of China]

Objective: To survey the children under 7 years of age in nine cities of China for a better understanding of the current situation of childhood stunting. Methods: According to a stratified cluster sampling design, a cross-sectional survey on children under 7 years of age was carried out in 9 cities (Beijing, Harbin and Xi'an in northern China; Shanghai, Nanjing and Wuhan in central China; and Guangzhou, Fuzhou and Kunming in southern China) from June to November in 2016. A total of 110 499 children were recruited. Height of children was evaluated using the growth standards for Chinese children (2009 edition) .Children with height less than the 3rd percentile of the growth standards were considered as stunting, and children with height between the 3rd and 10th percentiles of the growth standards were considered as relatively short stature. Chi-square test was used for comparison between data of boys and girls, urban and suburban, as well as among different ages and regions. Results: Totally 113 084 children under 7 years of age should be investigated and actually 110 499 children were investigated, with a rate of 97.7%. The prevalence of stunting was 1.9% (2 141/110 499) among all the children. The prevalence of stunting in urban children (1.6%, 904/55 524) was lower than that in suburban children (2.3%, 1 237/54 975, χ(2)=56.246, P<0.01). The gender difference in stunting prevalence was not statistically significant (1.9% (1 121/57 921) in boys and 1.9% (1 020/52 578) in girls, χ(2)=0.003, P=0.965). The prevalence of stunting decreased with age for children younger than 3 years, from 1.8% (312/17 080) in 0-<1 year of age group to 1.2% (168/13 740) in 2-<3 years of age group, but increased to 2.2% (240/11 073) at 6-<7 years group. Comparison among different regions showed that the stunting prevalence in southern region was higher than those in the central and northern regions (0.9% (193/20 374) in northern urban, 0.8% (154/18 486) in central urban, and 3.3% (557/16 664) in southern urban children), showing a statistical significance (χ(2)=437.736, P<0.01); 1.1% (241/21 924) in northern suburban, 1.4% (227/16 775) in central suburban and 4.7% (769/16 276) in southern suburban children, showing a statistical significance (χ(2)=646.533, P<0.01). In urban areas, the difference between the central and northern regions showed no statistical significance (χ(2)=1.429, P=0.232) and the stunting prevalence of central Chinese children was slightly higher than that of northern Chinese children in suburban areas (χ(2)=5.130, P=0.024). Among the nine cities, the stunting prevalence of Guangzhou (6.1%, 613/10 019) was higher than those of other cities (χ(2)=1 559.64, P<0.01). Among the stunting children, 78.4% (1 679/2 141) were classified as borderline or mild and only 7.2% (154/2 141) were classified as severe. The prevalence of relatively short stature was 5.2% (5 721/110 499). Conclusions: The prevalence of stunting among children under 7 years of age in nine cities of China is low and most of the stunting children were classified as mild; the prevalence of stunting in suburban children is higher than that in urban children; the gender difference show no statistical significance; and the prevalence of stunting in southern Chinese children is higher than those in central and northern Chinese children.

Light- and temperature-assisted spin state annealing: accessing the hidden multistability

Among responsive multistable materials, spin crossover (SCO) systems are of particular interest for stabilizing multiple spin states with various stimulus inputs and physical outputs. Here, in a 2D Hofmann-type coordination polymer, [Fe(isoq)₂{Au(CN)₂}₂] (isoq = isoquinoline), a medium-temperature annealing process is introduced after light/temperature stimulation, which accesses the hidden multistability of the spin state. With the combined effort of magnetic, crystallographic and Mössbauer spectral investigation, these distinct spin states are identified and the light- and temperature-assisted transition pathways are clarified. Such excitation-relaxation and trapping-relaxation joint mechanisms, as ingenious interplays between the kinetic and thermodynamic effects, uncover hidden possibilities for the discovery of multistable materials and the development of multistate intelligent devices.

Two new two-stage manipulation protocols, namely light- and temperature-assisted spin state annealing (LASSA/TASSA), are applied to a spin crossover coordination polymer, [Fe(isoq)₂{Au(CN)₂}₂], revealing the hidden multistability of spin states.

Isolation of a Perfectly Linear Uranium(II) Metallocene

Reduction of the uranium(III) metallocene [(η⁵ -C₅ ⁱ Pr₅ )₂ UI] (1) with potassium graphite produces the "second-generation" uranocene [(η⁵ -C₅ ⁱ Pr₅ )₂ U] (2), which contains uranium in the formal divalent oxidation state. The geometry of 2 is that of a perfectly linear bis(cyclopentadienyl) sandwich complex, with the ground-state valence electron configuration of uranium(II) revealed by electronic spectroscopy and density functional theory to be 5f³ 6d¹ . Appreciable covalent contributions to the metal-ligand bonds were determined from a computational study of 2, including participation from the uranium 5f and 6d orbitals. Whereas three unpaired electrons in 2 occupy orbitals with essentially pure 5f character, the fourth electron resides in an orbital defined by strong 7s-6d z 2 mixing.

Physical stimulus and chemical modulations of bistable molecular magnetic materials

In this Feature Article, we summarize the recent progress made in modulating the multifaceted magnetic behaviour of single-molecule magnets (SMMs) and spin-crossover (SCO) materials based on chemical modifications and external stimuli.

Tunable photoluminescence in flexible carboxylate ligand-based coordination polymers with interesting topologies and Fe3+ sensitivity

Complexes 1–5, showing different interesting topological networks from 1D ladder to 3D frameworks, exhibit selective and sensitive fluorescence quenching of Fe³⁺ ion.

Slow magnetic dynamics in centrosymmetric didysprosium and equilateral triangular tridysprosium molecules

Slow magnetic dynamics were investigated in centrosymmetric didysprosium and equilateral triangular tridysprosium molecules.

Asymmetric seven-/eight-step spin-crossover in a three-dimensional Hofmann-type metal–organic framework

An unprecedented hysteretic seven-/eight-step spin-crossover behavior is revealed. Most importantly, a molecular alloy based on a Hofmann-type framework is used as a strategy to explore multi-step spin-crossover materials for the first time.

A perfect triangular dysprosium single-molecule magnet with virtually antiparallel Ising-like anisotropy

A perfect triangular Dy₃ single-molecule magnet was reported. Each Dy(iii) magnetic axis is oriented almost normal to the plane of Dy₃, and the intramolecular magnetic dipole interaction gives rise to a virtually antiparallel Ising-like ground state.

The substituent guest effect on four-step spin-crossover behavior

The fluoro substituent strategy on the guest in a three-dimensional Hofmann-type metal–organic framework is explored for four-step spin-crossover properties.

Spin-crossover in an organic–inorganic hybrid perovskite

The first spin-crossover complex with an organic–inorganic hybrid perovskite structure is reported, which displays three-step spin-crossover, light-induced excited spin-state trapping and spin-state dependent fluorescence properties.