NIR-II emissive anionic copper nanoclusters with intrinsic photoredox activity in single-electron transfer.

Ultrasmall copper nanoclusters have recently emerged as promising photocatalysts for organic synthesis, owing to their exceptional light absorption ability and large surface areas for efficient interactions with substrates. Despite significant advances in cluster-based visible-light photocatalysis, the types of organic transformations that copper nanoclusters can catalyze remain limited to date. Herein, we report a structurally well-defined anionic Cu40 nanocluster that emits in the second near-infrared region (NIR-II, 1000-1700 nm) after photoexcitation and can conduct single-electron transfer with fluoroalkyl iodides without the need for external ligand activation. This photoredox-active copper nanocluster efficiently catalyzes the three-component radical couplings of alkenes, fluoroalkyl iodides, and trimethylsilyl cyanide under blue-LED irradiation at room temperature. A variety of fluorine-containing electrophiles and a cyanide nucleophile can be added onto an array of alkenes, including styrenes and aliphatic olefins. Our current work demonstrates the viability of using readily accessible metal nanoclusters to establish photocatalytic systems with a high degree of practicality and reaction complexity.

Evolution of Polynuclear Gold(I) Sulfido Complexes from Clusters and Cages to Macrocycles.

Two unprecedented tetratriacontanuclear and tetraicosanuclear gold(I) sulfido clusters (denoted as Au34-LMe and Au24-LCbz) with different temperature-induced stimulus-responsive behavior and emission property have been constructed by taking advantage of the judiciously designed bidentate phosphine ligand. Au34-LMe represents the highest nuclearity of the gold(I) sulfido cluster with more than a thousand atoms in the molecule. Octagonal macrocycles based on metal-cluster nodes have been assembled for the first time. The self-assembly and temperature-induced stimulus-responsive processes were monitored by 1H and 31P{1H} NMR spectroscopy, and the identities of the discrete gold(I) complexes were established by single-crystal structural analysis and high-resolution electrospray ionization mass spectrometry data. The steric effects exerted by the substituents on the V-shaped 1,3-bis(diphenylphosphino)benzene ligand have been shown to govern the self-assembly from the 1D cluster and 3D cage to 2D macrocycles. This work not only offers a new strategy to construct and regulate the structure of 2D macrocyclic gold(I) sulfido complexes but also lays the foundation for the future precise design and controlled construction of higher polygonal and cluster-node macrocycles.

Application of intravoxel incoherent motion diffusion-weighted imaging for preoperative knowledge of lymphovascular invasion in gastric cancer: a prospective study.

PURPOSE: To investigate the potential of intravoxel incoherent motion diffusion-weighted imaging (IVIM) for preoperative prediction of lymphovascular invasion (LVI) in gastric cancer (GC). METHODS: This study prospectively enrolled 90 patients (62 males, 28 females, 60.79 ± 9.99 years old) who received radical gastrostomy. Abdominal MRI examinations including IVIM were performed within 1 week before surgery. Patients were divided into LVI-positive and -negative group according to pathological diagnosis after surgery. The apparent diffusion coefficient (ADC) and IVIM parameters, including true diffusion coefficient (D), pseudodiffusion coefficient (D*), and pseudodiffusion fraction (f), were compared between the two groups. The relationship between MRI parameters and LVI was studied by Spearman's correlation analysis. Multivariable logistic regression analysis was used to screen independent predictors of LVI. Receiver-operating characteristic curve analyses were applied to evaluate the efficacy. RESULTS: The ADC, D in LVI-positive group were lower, whereas tumor thickness and f parameter in LVI-positive group were higher than those in LVI-negative group, and they were statistically correlated with LVI (p < 0.05). D, f and tumor thickness were independent risk factors of LVI. The area under the curve of ADC, D, f, thickness, and the combined parameter (D + f + thickness) were 0.667, 0.754, 0.695, 0.792, and 0.876, respectively. The combined parameter demonstrated higher efficacy than any other parameters (p < 0.05). CONCLUSION: The ADC, D, and f can effectively distinguish LVI status of GC. The D, f and thickness were independent predictors. The combination of the three predictors further improved the efficacy.

Photo- and Temperature-Induced Reversible Structural Transformation between Dodecanuclear and Pentadecanuclear Gold(I) Sulfido Complexes.

Stimuli-responsive structural transformation has attracted much attention for its potential to mimic the behavior of biological transformations and functions. Here, two unprecedented dodecanuclear and pentadecanuclear gold(I) sulfido clusters (denoted trans-Au12 and trans-Au15, respectively) with impressive stimuli-responsive interconversion have been obtained by taking advantage of the judiciously designed tridentate phosphine ligand Ltrans as the building block. Both UV light and temperature can be applied to trigger the structural conversions between trans-Au12 and trans-Au15. In addition, NMR, high-resolution electrospray ionization mass spectrometry, and UV-vis absorption spectroscopy have been employed to monitor the transformation process and decipher the mechanism of structural conversion. This work not only provides a paradigm to investigate photo-induced cluster-to-cluster transformation based on polydentate phosphine ligands but also offers a new direction for the construction of the stimuli-responsive materials.

Stimuli-Induced Reversible Transformation between Decanuclear and Pentanuclear Gold(I) Sulfido Complexes.

Decanuclear and pentanuclear gold(I) sulfido complexes of phenanthrene- and dibenzothiophene-based diphosphine ligands were synthesized and characterized. Unprecedented stimuli-induced reversible transformation between decanuclear and pentanuclear gold(I) sulfido complexes was observed, which could be readily monitored by NMR and UV-vis absorption spectroscopy in solution. Remarkably, the decanuclear gold(I) sulfido complex (Au10-LPh) was found to show a highly reversible transformation process, which is stable for over 10 successive cycles in solution. The stimuli-induced reversible transformation behavior of the gold(I) sulfido complexes was found to depend on the P-P bite distance of the bidentate phosphine ligands.

Dynamic contrast-enhanced and diffusion-weighted MR imaging in early prediction of pathologic response to neoadjuvant chemotherapy in locally advanced gastric cancer.

PURPOSE: To investigate the efficacy of diffusion-weighted imaging (DWI) and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) for the early prediction of the pathologic response to neoadjuvant chemotherapy (NAC) in patients with locally advanced gastric cancer (LAGC). METHODS: Fifty patients with LAGC who were treated with NAC followed by radical gastrectomy were enrolled. Uncontrasted and DCE-MRI were performed within 1 week before NAC. According to tumor regression grading (TRG), patients were labeled as responders (TRG = 0 + 1) and non-responders (TRG = 2 + 3). Apparent diffusion coefficients (ADC) and DCE-MRI kinetics (Ktrans, Ve, and Kep) were compared between the two groups. Logistic regression analysis was performed to screen independent factors to predict the NAC efficacy. The relationship between MRI parameters and TRG was studied by Spearman's correlation analysis. Receiver-operating characteristic curve analyses were applied to evaluate the efficacy. RESULTS: ADC, Ktrans, and Kep values were higher in responders than in non-responders (p < 0.05) and correlated with TRG (p < 0.05). The ADC and Kep values were independent markers for predicting TRG. The area under the curve, sensitivities, specificities of ADC, Ktrans, Kep, and ADC + Kep were 0.813, 0.699, 0.709, 0.886;73.64%, 65.54%, 63.21%, 70.37%; 86.47%, 54.97%, 79.47%, 95.65%; respectively. ADC + Kep demonstrated a higher efficacy than Ktrans and Kep (p = 0.012, 0.011), but without improvement compared with ADC (p > 0.05). CONCLUSION: Both DWI and DCE-MRI can effectively predict the pathologic response to NAC in LAGC. A combination of ADC and Kep increased the efficacy, and ADC is the most valuable imaging parameter.

Impact of minimally invasive mitral valve surgery on sexual dysfunction in male patients.

BACKGROUND: Sexual dysfunction after cardiac surgery can seriously affect patients' quality of life, but the impact of cardiac surgery on sexual function has long been neglected. Compared with conventional cardiac surgery, minimally invasive cardiac surgery has the advantages of aesthetic appearance and no disruption of the sternal structure, which can greatly improve the patient's quality of life. However, studies focusing on the effects of minimally invasive mitral valve surgery (MIMVS) on sexual function have not been reported. The objective of this research was to investigate the effects of totally endoscopic mitral valve surgery on health-related quality of life and sexual function in male patients and to provide possible recommendations. METHODS: Patients who underwent median sternotomy or totally endoscopic mitral valve surgery at our institution from January 2019 to December 2020 were selected using an electronic medical record system. Data were collected by questionnaires, including the MOS 36-item short-form health survey and the International Erectile Function Questionnaire. RESULTS: There were 156 male patients who participated in our study. Of these, 112 patients completed all questionnaires. Forty-five patients (40.18%) developed postoperative sexual dysfunction, including 15 patients (29.41%) in the MIMVS group and 30 patients (49.18%) in the conventional MVS group, indicating that the incidence of sexual dysfunction could be reduced by MIMVS and that the MIMVS group scored better on the International Erectile Function Questionnaire (P < 0.05). On the evaluation of health-related quality of life, the MIMVS group scored better than the MVS group on the mental health and bodily pain subscales of the MOS 36-item short-form health survey. In addition, our study showed that postoperative sexual dysfunction was associated with physical functioning and mental health. CONCLUSIONS: In our study, totally endoscopic mitral valve surgery had less adverse effects on sexual function in male patients than conventional mitral valve surgery. In terms of health-related quality of life, totally endoscopic mitral valve surgery was superior to conventional surgery. Patients who opt for totally endoscopic mitral valve surgery may have a more satisfying and healthier sexual life than those who undergo conventional mitral valve surgery.

Stimuli-Responsive and Structure-Adaptive Three-Dimensional Gold(I) Cluster Cages Constructed via "De-aurophilic" Interaction Strategy.

Self-assembly of three-dimensional (3D) metallosupramolecular cages has drawn increasing attention for their potential to interconvert between different architectures due to the dynamic and reversible features of the coordination bond. These supramolecular transformations can provide unique approaches for the construction of stimuli-responsive supramolecular model systems to mimic biological transformation processes. While gold(I) clusters have attracted much interest due to their propensity to exhibit aurophilic interactions, the construction of 3D gold(I) cluster cages has remained a challenging and daunting task. Here, we proposed a "de-aurophilic" interaction strategy, which involves the prevention of aurophilic interaction formation between the basic [(µ3-S)Au3]+ units, to construct 3D gold(I) cluster cages. Through the judicious design of diphosphine ligands, an unprecedented class of gold(I) cluster cages with adaptive structures has been constructed. These gold(I) cluster cages are found to show intriguing stimuli-responsive structure transformation and interconversion. This work not only provides a strategy for the design and construction of novel 3D supramolecular cages based on cluster nodes but also offers a paradigm to study the stimuli-responsive structural interconversion between the unique structures of these gold(I) cluster cages.

Quality of life: modified triple-branched stent graft implantation versus frozen elephant trunk technique.

OBJECTIVE: To compare the effects of modified triple-branched stent implantation and frozen elephant trunk technique on the quality of life (QoL) of acute Stanford Type A aortic dissection (AAAD) patients at different follow-up times. METHODS: Data from 175 AAAD survivors was collected which were divided into two groups according to different surgical techniques: (group A): modified triple-branched stent graft implantation; (group B): frozen elephant trunk. The SF-36 were used to assess the QoL at discharge (AD), the third postoperative month (POM3), and the twelfth postoperative month (POM12). RESULTS: (1) The total scores at each time of both groups showed lower than the normal level; Group A scored higher than group B at some time points in terms of some items (role physical, role emotion and mental health; all P = 0.000), and some items at POM3 or POM12 scored higher than at discharge (role physical, social function; both P = 0.000). (2) There were less patients with heavy self-perceived burden in group A than group B at discharge (P = 0.032) and patients with heavy self-perceived burden decreased over time. (3) Young postoperative AAD patients (P = 0.002) in group B (P = 0.005) with heavy self-perceived burden (P = 0.000), acute renal failure (P = 0.008), long LOS (P = 0.026) and blood loss (> 1000 mL/24 h) (P = 0.039) seemed to get a worse QoL. CONCLUSION: The impact on QoL of the modified triple-branched stent graft implantation technique seemed to be better than those of frozen elephant trunk surgery in role physical, role emotion and mental health.

Association between Health-Related Physical Fitness and Risk of Dyslipidemia in University Staff: A Cross-Sectional Study and a ROC Curve Analysis.

BACKGROUND: This study aimed to assess the relationship between dyslipidemia (DL) risk and health-related physical fitness (HPF) and evaluated the prognostic value of HPF for risk of DL. METHODS: A total of 776 university staff members were recruited, of which 407 were females, and 369 males. Blood samples and HPF tests were collected from all participants after 12 h fasting. RESULTS: The prevalence of DL was 41.77% and 51.49% in female and male university staff members, respectively, and there was no significant difference between genders (χ2 = 2.687, p = 0.101). According to the logistic regression analysis, age, male sex, GLU, hypertension, BMI, BF, WHtR, and LAP were significant risk factors for DL (p < 0.05), VCI and, SAR were significant protective factors for DL (p < 0.05), and SMI, GS, and VG were not significantly associated with the risk of DL. The area under the receiver-operating characteristic (ROC) curve (AUC) analysis indicated that, LAP (AUC: 0.730, 95CI%: 0.697-0.762), WHtR (AUC: 0.626, 95CI%: 0.590-0.660), and BMI (AUC: 0.599, 95CI%: 0.563-0.634) are valid predictors of DL, and LAP and WHtR perform better than BMI (Z = 8.074, p < 0.001) in predicting DL in male and female university staff members. CONCLUSION: The risk of DL is significantly related to body composition, cardiorespiratory fitness, and flexibility. LAP and WHtR perform better than BMI in predicting risk of DL in male and female university staff members.

Patch Neointima Technique in Acute Type A Aortic Dissection: Midterm Results of 147 Cases.

BACKGROUND: The patch neointima technique is a modified valve-sparing aortic root repair surgery for acute type A aortic dissection and the short-term outcomes are satisfactory. The midterm outcomes have not been reported. METHODS: From January 2009 to December 2012, 147 patients underwent valve-sparing aortic root repair with the patch neointima technique for type A aortic dissection in our center. The midterm outcomes of the patients were evaluated by echocardiography and aortic computed tomography angiography. RESULTS: Of 147 patients, 32 patients (21.8%) underwent proximal arch repair, and 115 patients (78.2%) underwent proximal arch repair combined with triple-branched stent graft implantation. The perioperative mortality was 5.4%. Preoperative aortic insufficiency (AI) was observed in 94 patients (63.9%); 131 patients (89.1%) left the operating room with 0 AI; the remaining 16 patients (10.9%) had trace or less than 1+ AI. A total of 128 patients (87.1%) completed 7-year follow-up. The mean follow-up time was 5.7 ± 1.2 years. As many as 82% of patients (105) were 0 AI and 15.6% of patients (20) were 0.5+ trace or less than 1+ AI. No reoperation was performed for the aortic root. The diameters of sinotubular junction and sinus were reduced to the normal range (28.3 ± 4.2 mm and 30.5 ± 3.6 mm, respectively) and remained stable (28.9 ± 5.6 mm, P = .300, and 30.8 ± 4.2 mm, P = .540, respectively) during 7 years of follow-up. CONCLUSIONS: Valve-sparing aortic root repair with patch neointima technique was associated with stable function of the aortic valves and no expansion of the aortic root in the midterm.

Exploring DNA Methylation Profiles Altered in Cryptogenic Hepatocellular Carcinomas by High-Throughput Targeted DNA Methylation Sequencing: A Preliminary Study for Cryptogenic Hepatocellular Carcinoma.

BACKGROUND: Hepatocellular carcinoma (HCC) includes cryptogenic hepatocellular carcinomas (CR-HCC) that lack a defined cause. Specific DNA methylation patterns and comparisons of the aberrant alterations in DNA methylation between CR-HCC and adjacent peritumor tissues (APTs) have not yet been reported. METHODS: The SureSelectXT Methyl-Seq Target Enrichment System was used to sequence targeted DNA methylation in three paired CR-HCC tissues and APTs. Gene Ontology (GO) enrichment and KEGG pathway analysis were performed to investigate the DNA methylation mechanism of CR-HCC. The mRNA expression levels of HOXB-AS3, HOXB6, HOXB3, USP18, MAP3K6, TIRAP, TNNI2, SHC3, CTTN, and TFAP2A, selected from the identified signaling pathways, were evaluated by quantitative real-time PCR (qPCR). RESULTS: A total of 1728 differentially methylated regions (DMRs) were identified in tumor tissues compared with non-tumor tissues, of which 868 DMRs were hypermethylated and 860 were hypomethylated. The DMRs were mapped within 2091 DMR-associated genes (DMGs). The mRNA expression of HOXB-AS3, HOXB3, and MAP3K6 was downregulated in CR-HCC tissues compared to the APTs. However, the mRNA expression of TIRAP, SHC3, and CTTN was upregulated in the CR-HCC tissues. Differences between the mRNA expression of HOXB6, USP18, TNNI2, and TFAP2A in the CR-HCC and APTS tissues were not statistically significant. GO analysis showed that the molecular functions of "binding", "protein binding", and "cytoskeletal protein binding" were the main categories for the hypermethylated DMGs. The hypomethylated DMGs were mostly enriched in the molecular functions "binding", "protein binding", "calcium ion binding", among others. KEGG pathway analysis showed that the hypermethylated DMGs were enriched in several pathways such as "estrogen signaling pathway", while hypomethylated DMGs were enriched in several pathways such as "proteoglycans in cancer", suggesting that epigenetic modifications play important roles in the cryptogenic hepatocarcinogenesis. CONCLUSION: These results provide useful information for future work to characterize the functions of epigenetic mechanisms on CR-HCC.

Efficacy of interleukin-6 in combination with D-dimer in predicting early poor postoperative prognosis after acute stanford type a aortic dissection.

BACKGROUND: We studied early poor postoperative prognosis in acute Stanford type A aortic dissection (ATAAD) patients and investigated the predictive effect of interleukin-6 (IL-6) combined with D-dimer in the early poor postoperative prognosis after ATAAD. METHODS: Data on 141 ATAAD patients, who underwent emergency surgery between January 2018 and December 2018 at our hospital, were studied. We analyzed early postoperative prognosis using two patient groups. Patients with good prognosis were included in group A and those with poor prognosis were in group B. Univariate logistic and multivariable logistic regression analysis were performed for poor early postoperative prognosis. RESULTS: Preoperative IL-6 level was lower (57.8 ± 39.0 vs 211.0 ± 153.7 pg/mL, p < 0.001) and the D-dimer was also lower (7.3 ± 6.1 vs. 16.7 ± 5.8 µg/mL, p < 0.001) in group A than in B. The cut-off points, determined by the ROC curve, were preoperative IL-6 > 108 pg/mL (area under the curve: AUC = 0.901) and D-dimer > 14.0 µg/mL (AUC = 0.817). Univariate logistic regression analysis showed that IL-6 > 108 pg/mL, D-dimer > 14.0 µg/mL, prothrombin time > 15 s, creatinine > 135 mmol/mL, and operation time > 306 min for ATAAD appeared to be early postoperative risk factors of poor prognosis. Multivariable logistic regression analysis showed that IL-6 > 108 pg/mL and D-dimer > 14.0 µg/mL were early postoperative risk factors for poor prognosis after ATAAD, and the odds ratios (ORs) of IL-6 > 108 pg/mL and D-dimer > 14.0 µg/mL were 24.937 (6.837, 90.931) and 18.757 (5.094, 69.075), respectively. When IL-6 was > 108 pg/mL (AUC = 0.901), the sensitivity and specificity of predicting early postoperative prognosis after ATAAD were 79.4 and 89.7%, respectively (95% confidence interval [CI] 0.839 to 0.963). When D-dimer was > 14.0 g/mL (AUC = 0.817), the sensitivity and specificity were 82.4 and 84.1%, respectively (95% CI 0.731 to 0.903). When combined with D-dimer (AUC = 0.936) (95% CI 0.793 to 0.979), the AUC values were more predictive than those for the individual marker. CONCLUSION: IL-6 > 108 pg/mL and D-dimer > 14.0 µg/mL is of high predictive value for the assessment of early poor postoperative prognosis after ATAAD. And IL-6 > 108 pg/mL in combination with D-dimer > 14.0 µg/mL is of higher predictive value.

Concentration- and Solvation-Induced Reversible Structural Transformation and Assembly of Polynuclear Gold(I) Sulfido Complexes.

A series of polynuclear gold(I) sulfido complexes of bis(diphenylphosphino)amine ligands has been synthesized and characterized. A rather small variation in the conformation of the bis(diphenylphosphino)amine ligands has led to distinct differences in the identity of the polynuclear gold(I) sulfido complexes formed. Unprecedented concentration-dependent and solvation-dependent reversible cluster-to-cluster transformation between a dodecanuclear gold(I) sulfido complex (LMe-Au12) and a hexanuclear gold(I) sulfido complex (LMe-Au6) has been observed. The transformation process has been monitored not only by 1H and 31P{1H} NMR spectroscopy but also by UV-vis absorption spectroscopy and high-resolution electrospray ionization mass spectrometry (HR-ESI-MS) in the solution state. This work has provided a simple approach to achieve structure modulation of gold(I) sulfido complexes and an understanding of supramolecular transformations via external stimuli.

Efficiency of Modified Triple-Branched Stent Graft in Type I Aortic Dissection: Two-Year Follow-up.

BACKGROUND: The efficacy of hemiarch replacement combined with a modified triple-branched stent graft in Debakey type I aortic dissection remains to be confirmed. METHODS: From January 2016 to December 2017, 167 patients with acute Debakey type I aortic dissection underwent hemiarch replacement combined with a modified triple-branched stent graft. The clinical and imaging data were retrospectively analyzed. The early composite endpoint was defined to comprise perioperative mortality, permanent neurologic deficits, and renal failure requiring hemodialysis at discharge. RESULTS: The overall 30-day mortality was 4.2% (7 of 167). The incidence of the composite endpoint was 11.4% (19 of 167). The risk factors for the composite endpoint were malperfusion syndrome (odds ratio 5.17; 95% confidence interval, 1.46 to 18.35; P = .011) and creatine greater than 1.5 mg/dL (odds ratio 5.44; 95% confidence interval, 2.27 to 13.06; P < .001). The overall survival was 94% at 1 year and 92.2% at 2 years during a median follow-up of 20.9 ± 9.6 months. Three patients required distal aorta reintervention. Complete thrombosis in the false lumen of the descending aorta at the level of the pulmonary bifurcation and at the level of the celiac trunk was observed in 98.8% and 10.8% of the patients, respectively. CONCLUSIONS: Hemiarch replacement combined with a modified triple-branched stent graft is a reliable technique for acute Debakey type I aortic dissection as indicated by 2 years of follow-up.

Stereocontrolled self-assembly and photochromic transformation of lanthanide supramolecular helicates.

Stereocontrolled self-assembly of a dinuclear triple-stranded europium helicate (Eu2L3) based on DTE-functionalized ligands has been achieved via the chiral-induction strategy. The point-chirality of the ligands is transferred to give either Δ or Λ metal-centers and hence leads to the overall P or M helical senses. CD spectroscopy and NMR enantiomeric differentiation experiments have confirmed the formation of enantiomers. Moreover, the helicates in solution feature reversible photocyclization and cycloreversion, offering an opportunity to develop as chiroptical switches.

A supramolecular lanthanide separation approach based on multivalent cooperative enhancement of metal ion selectivity.

Multivalent cooperativity plays an important role in the supramolecular self-assembly process. Herein, we report a remarkable cooperative enhancement of both structural integrity and metal ion selectivity on metal-organic M4L4 tetrahedral cages self-assembled from a tris-tridentate ligand (L1) with a variety of metal ions spanning across the periodic table, including alkaline earth (CaII), transition (CdII), and all the lanthanide (LnIII) metal ions. All these M4L14 cages are stable to excess metal ions and ligands, which is in sharp contrast with the tridentate (L2) ligand and bis-tridentate (L3) ligand bearing the same coordination motif as L1. Moreover, high-precision metal ion self-sorting is observed during the mixed-metal self-assembly of tetrahedral M4L4 cages, but not on the M2L3 counterparts. Based on the strong cooperative metal ion self-recognition behavior of M4L4 cages, a supramolecular approach to lanthanide separation is demonstrated, offering a new design principle of next-generation extractants for highly efficient lanthanide separation.

Evolution of Luminescent Supramolecular Lanthanide M2nL3n Complexes from Helicates and Tetrahedra to Cubes.

Lanthanide-containing molecules have many potential applications in material science and biology, that is, luminescent sensing/labling, MRI, magnetic refrigeration, and catalysis among others. Coordination-directed self-assembly has shown great power in the designed construction of well-defined supramolecular systems. However, application of this strategy to the lanthanide edifices is challenging due to the complicated and greatly labile coordination numbers and geometries for lanthanides. Here we demonstrate a sensitive structural switching phenomenon during the stereocontrolled self-assembly of a group of Ln2nL3n (Ln for lanthanides, L for organic ligands, and n = 1, 2, 4) compounds. Systematic variation of the offset distances between the two chelating arms on the bis(tridentate) ligands dictated the final outcomes of the lanthanide assembly, ranging from Ln2L3 helicates and Ln4L6 tetrahedra to Ln8L12 cubes. Remarkably, the borderline case leading to the formation of a mixture of the helicate and the tetrahedron was clearly revealed. Moreover, the concentration-dependent self-assembly of an unprecedented cubic Ln8L12 complex was also confirmed. The luminescent lanthanide cubes can serve as excellent turn-off sensors in explosives detection, featuring high selectivity and sensitivity toward picric acid. All complexes were confirmed by NMR, ESI-TOF-MS, and single crystal X-ray diffraction studies. Our results provide valuable design principles for the coordination self-assembly of multinuclear functional lanthanide architectures.

Stereocontrolled Self-Assembly and Self-Sorting of Luminescent Europium Tetrahedral Cages.

Coordination-directed self-assembly has become a well-established technique for the construction of functional supramolecular structures. In contrast to the most often exploited transition metals, trivalent lanthanides Ln(III) have been less utilized in the design of polynuclear self-assembled structures despite the wealth of stimulating applications of these elements. In particular, stereochemical control in the assembly of lanthanide chiral cage compounds is not easy to achieve in view of the usually large lability of the Ln(III) ions. We report here the first examples of stereoselective self-assembly of chiral luminescent europium coordination tetrahedral cages and their intriguing self-sorting behavior. Two pairs of R and S ligands are designed on the basis of the pyridine-2,6-dicarboxamide coordination unit, bis(tridentate) L1 and tris(tridentate) L2. Corresponding chiral Eu4(L1)6 and Eu4(L2)4 topological tetrahedral cages are independently assembled via edge- and face-capping design strategies, respectively. The chirality of the ligand is transferred during the self-assembly process to give either Δ or Λ metal stereochemistry. The self-assembled cages are characterized by NMR, high-resolution ESI-TOF-MS, and in one case by X-ray crystallography. Strict control of stereoselectivity is confirmed by CD spectroscopy and NMR enantiomeric differentiation experiments. Narcissistic self-sorting is observed in the self-assembly process when two differently shaped ligands L1 and L2 are mixed. More impressively, distinct self-sorting behavior between Eu4(L1)6 and Eu4(L2)4 coordination cages is observed for the first time when racemic mixtures of ligands are used. We envisage that chiral luminescent lanthanide tetrahedral cages could be used in chiroptical probes\sensors and enantioselective catalysis.