"Golgi-customized Trojan horse" nanodiamonds impair GLUT1 plasma membrane localization and inhibit tumor glycolysis.

Nutrient or energy deprivation, especially glucose restriction, is a promising anticancer therapeutic approach. However, establishing a precise and potent deprivation strategy remains a formidable task. The Golgi morphology is crucial in maintaining the function of transport proteins (such as GLUT1) driving glycolysis. Thus, in this study, we present a "Golgi-customized Trojan horse" based on tellurium loaded with apigenin (4',5,7-trihydroxyflavone) and human serum albumin, which was able to induce GLUT1 plasma membrane localization disturbance via Golgi dispersal leading to the inhibition of tumor glycolysis. Diamond-shaped delivery system can efficiently penetrate into cells as a gift like Trojan horse, which decomposes into tellurite induced by intrinsically high H2O2 and GSH levels. Consequently, tellurite acts as released warriors causing up to 3.8-fold increase in Golgi apparatus area due to the down-regulation of GOLPH3. Further, this affects GLUT1 membrane localization and glucose transport disturbance. Simultaneously, apigenin hinders ongoing glycolysis and causes significant decrease in ATP level. Collectively, our "Golgi-customized Trojan horse" demonstrates a potent antitumor activity because of its capability to deprive energy resources of cancer cells. This study not only expands the applications of tellurium-based nanomaterials in the biomedicine but also provides insights into glycolysis restriction for anticancer therapy.

Protective Effect of Isopulegol in Alleviating Neuroinflammation in Lipopolysaccharide-Induced BV-2 Cells and in Parkinson Disease Model Induced with MPTP.

BACKGROUND: Parkinson's disease (PD) is the most prevalent disease linked with age-associated neuronal degeneration. Phytotherapeutic compounds or agents have gained increased importance because of their increased specificity and minimal side effects. Isopulegol, a monoterpene, was utilized in the present study because of its wide range of therapeutic properties. Our aim was to examine the underlying mechanism of anti-neuroinflammatory action and neuroprotective efficacy of isopulegol in cell lines and in an experimental animal model of PD. METHODS: The MTT assay was performed in microglial BV-2 cells subjected to lipopolysaccharides (LPS). The release of NO and synthesis of ROS intracellularly in BV-2 cells were detected. C57BL/6 mice induced with MPTP were examined for motor function and coordination. Expression of proinflammatory mediators was also assessed both in vivo and in vitro. Histopathological sections of brain and expression of iNOS and COX-2 were also analyzed. RESULTS: BV-2 cells did not exhibit noticeable toxicity at selected concentrations and LPS-incubated cells showed marked elevation of NO levels and increased production of intracellular ROS. Increased expression of proinflammatory cytokines was also observed. Motor function and coordination deficits were observed in mice induced with MPTP. Histopathological abnormalities and increased iNOS and COX-2 expression were noted in MPTP-induced mice. Administration of isopulegol reversed the changes brought about by LPS and MPTP. CONCLUSION: The study indicated that isopulegol is a potential therapeutic drug against clinical complications of PD.

Antibody Profiling and Prevalence in the US population during the SARS-CoV2 Pandemic

BackgroundAntibody diagnostics play an important role in disease detection and can potentially aid in monitoring of the immune responses to see if an individual has developed immunity. Developing high throughput diagnostics which does not involve handling of infectious material becomes imperative in the case of pandemics such as the recent outbreak of SARS-CoV2. MethodsA protein microarray technology was used to detect the plurality of antibody response to four novel antigens namely S1 glycoprotein, Receptor binding domain (RBD), S2 glycoprotein and Nucleoprotein of the novel coronavirus named SARS-CoV2 using serum samples. A DBS card was additionally used to compare its performance with a venipuncture-based serum separator tube (SST) draw. ResultsThe three main subclasses of antibodies IgM, IgA and IgG were analyzed to see the variations in immune responses in the affected population and compared to their microbial RT-PCR based NP swab results. The clinical sensitivity and specificity were determined to be 98.1% and 98.6%. In the matrix comparison study, which would enable patients to test without risk of transmitting the virus, DBS matched with higher than 98% accuracy to a venipuncture-based SST collection. ConclusionMultiplex testing enables higher sensitivity and specificity which is essential while establishing exposure on a population scale. This flexible platform along with a discrete collection methodology would be crucial and broadly useful to scale up testing in current and future pandemics. Minimum sample volume that can be collected using DBS cards can be processed in this multiplex pillar plate format enabling the capacity to provide the reliability of high throughput analyzers while having the ease of collection similar to rapid tests.

Comorbid SUNCT Syndrome and Opalski Syndrome Caused by Dorsolateral Medullary Infarction.

Opalski syndrome is a rare variation of lateral medullary syndrome (LMS) accompanied by ipsilateral hemiparesis. Short-lasting unilateral neuralgiform headaches with conjunctival injection and tearing (SUNCT) is a rare headache syndrome which belongs to the trigeminal autonomic cephalalgias. SUNCT syndrome has been previously described in association with LMS. We here describe a case of SUNCT syndrome with Opalski syndrome caused by dorsolateral medullary infarction.

Evaluation of the Braak staging of brain pathology with 1H-MRS in patients with Parkinson's disease.

The Braak staging of Parkinson's disease (PD) pathology is usually based on the brain autopsy, which has not been confirmed in living patients of PD. In this study, we investigated the metabolites of medulla oblongata, substantia nigra (SN), putamen, and motor cortex by measuring N-acetylaspartate (NAA), choline-containing compounds (Cho) and creatine (Cr) in 22 patients of PD and 15 age-matched healthy controls, using single-voxel 1H-magnetic resonance spectroscopy (1H-MRS). The results showed that NAA/Cr in SN was lower in PD group than that in control group (p=0.006), however, there was no difference for NAA/Cr and Cho/Cr between PD group and control group in other regions. In SN, NAA/Cr was negatively correlated with Unified Parkinson's Disease Rating Scale (UPDRS) (r=-0.743, p=0.002) and Hoehn-Yahr staging (r=-0.714, p=0.003), while Cho/Cr was positively correlated with UPDRS (r=0.850, p<0.001) and Hoehn-Yahr staging (r=0.647, p=0.009). In PD group, the variance of NAA/Cr in SN was significantly larger than that in other regions (p=0.005), but there was no difference for the variance of Cho/Cr among regions of interesting (ROIs) (p=0.267). These results indicate that SN is the most seriously injured region in PD, and the metabolites in SN measured by 1H-MRS is correlated with the severity of PD. However, the Braak staging of PD pathology is not validated by 1H-MRS.

Ape1 protects against MPP+-induced neurotoxicity through ERK1/2 signaling in PC12 cells.

Oxidative stress, induced by reactive oxygen species (ROS), is an apoptosis activator. Oxidative stress causes dopaminergic neuron loss and plays a pivotal role in the pathogenesis of Parkinson's disease (PD). A recent study showed that apurinic/apyrimidinic endonuclease 1 (Ape1) decreases cytotoxicity and promotes neuron survival under oxidative stress. Furthermore, it has been proven that Ape1 is involved in the pathogenesis of PD. However, little is known about the contribution of Ape1 toward the development of PD. Thus, the present study was designed to define a critical pathway by which Ape1 mediates neurotoxicity in a model of PD. The results show that Ape1 was upregulated in MPP-treated PC12 cells. Ape1 overexpression significantly increased cell viability and inhibited apoptosis compared with MPP treatment, whereas Ape1 knockdown showed the opposite effect. Ape1 overexpression markedly suppressed ROS levels, whereas Ape1 knockdown significantly elevated ROS levels. Furthermore, Ape1 overexpression markedly upregulated the p-ERK1/2 protein expression level and inhibited ERK1/2 signaling. The ERK1/2 inhibitor PD98059 significantly decreased cell viability and increased apoptosis and the ROS level compared with the Ape1 overexpression group. Taken together, these results suggest that Ape1 protects against neuron death by activating the ERK1/2 signaling pathway.

A Label-free, Highly Sensitive and Selective Detection of Hemin Based on the Competition between Hemin and Protoporphyrin IX Binding to G-Quadruplexes.

Herein is reported a simple and label-free fluorescent detection method for hemin based on using protoporphyrin IX (PPIX) as a fluorescent signal reporter. PPIX emits weak fluorescence in an aqueous solution. When PPIX binds to G-quadruplexes, the fluorescence intensity of PPIX is greatly increased. While in the presence of target hemin, hemin competes with PPIX toward G-quadruplexes because its affinity to G-quadruplexes is higher than that of PPIX. With the formation of the hemin-G-quadruplex complex, PPIX is released to the solution from the G-quadruplex accompanied by quenching of the fluorescence of the system. This fluorescence change of the system can be used to monitor hemin with a low detection limit of 36 nM. In addition, the possible binding sites for PPIX binding to the G-quadruplex are discussed based on competition between hemin and PPIX. What is more, this method might pave the way for applying G-quadruplexes and PPIX to more sensing systems.

Thiazole orange as a fluorescent probe: Label-free and selective detection of silver ions based on the structural change of i-motif DNA at neutral pH.

Silver ions have been widely applied to many fields and have harmful effects on environments and human health. Herein, a label-free optical sensor for Ag(+) detection is constructed based on thiazole orange (TO) as a fluorescent probe for the recognition of i-motif DNA structure change at neutral pH. Ag(+) can fold a C-rich single stranded DNA sequence into i-motif DNA structure at neutral pH and that folding is reversible by chelation with cysteine (Cys). The DNA folding process can be indicated by the fluorescence change of TO, which is non-fluorescent in free molecule state and emits strong fluorescence after the incorporation with i-motif DNA. Thus, a rapid, sensitive, and selective method for the detection of Ag(+) and Cys is developed with a detection limit of 17 and 280nM, respectively. It is worth noting that the mechanism underlying the increase of the fluorescence of thiazole orange in the presence of i-motif structure is explained. Moreover, a fluorescent DNA logic gate is successfully designed based on the Ag(+)/Cys-mediated reversible fluorescence changes. The proposed detection strategy is label-free and economical. In addition, this system shows a great promise for i-motif/TO complex to analyze Ag(+) in the real samples.

MicroRNA-143-3p inhibits hyperplastic scar formation by targeting connective tissue growth factor CTGF/CCN2 via the Akt/mTOR pathway.

Post-traumatic hypertrophic scar (HS) is a fibrotic disease with excessive extracellular matrix (ECM) production, which is a response to tissue injury by fibroblasts. Although emerging evidence has indicated that miRNA contributes to hypertrophic scarring, the role of miRNA in HS formation remains unclear. In this study, we found that miR-143-3p was markedly downregulated in HS tissues and fibroblasts (HSFs) using qRT-PCR. The expression of connective tissue growth factor (CTGF/CCN2) was upregulated both in HS tissues and HSFs, which is proposed to play a key role in ECM deposition in HS. The protein expression of collagen I (Col I), collagen III (Col III), and α-smooth muscle actin (α-SMA) was obviously inhibited after treatment with miR-143-3p in HSFs. The CCK-8 assay showed that miR-143-3p transfection reduced the proliferation ability of HSFs, and flow cytometry showed that either early or late apoptosis of HSFs was upregulated by miR-143-3p. In addition, the activity of caspase 3 and caspase 9 was increased after miR-143-3p transfection. On the contrary, the miR-143-3p inhibitor was demonstrated to increase cell proliferation and inhibit apoptosis of HSFs. Moreover, miR-143-3p targeted the 3'-UTR of CTGF and caused a significant decrease of CTGF. Western blot demonstrated that Akt/mTOR phosphorylation and the expression of CTGF, Col I, Col III, and α-SMA were inhibited by miR-143-3p, but increased by CTGF overexpression. In conclusion, we found that miR-143-3p inhibits hypertrophic scarring by regulating the proliferation and apoptosis of human HSFs, inhibiting ECM production-associated protein expression by targeting CTGF, and restraining the Akt/mTOR pathway.

pH-Mediated Fluorescent Polymer Particles and Gel from Hyperbranched Polyethylenimine and the Mechanism of Intrinsic Fluorescence.

We report that fluorescence properties and morphology of hyperbranched polyethylenimine (hPEI) cross-linked with formaldehyde are highly dependent on the pH values of the cross-linking reaction. Under acidic and neutral conditions, water-soluble fluorescent copolymer particles (CPs) were produced. However, under basic conditions, white gels with weak fluorescence emission would be obtained. The water-soluble hPEI-formaldehyde (hPEI-F) CPs show strong intrinsic fluorescence without the conjugation to any classical fluorescent agents. By the combination of spectroscopy and microscopy techniques, the mechanism of fluorescence emission was discussed. We propose that the intrinsic fluorescence originates from the formation of a Schiff base in the cross-linking process between hPEI and formaldehyde. Schiff base bonds are the fluorescence-emitting moieties, and the compact structure of hPEI-F CPs plays an important role in their strong fluorescence emission. The exploration on fluorescence mechanism may provide a new strategy to prepare fluorescent polymer particles. In addition, the investigation shows that the hPEI-F CPs hold potential as a fluorescent probe for the detection of copper ions in aqueous media.

Enzyme-free fluorescent biosensor for the detection of DNA based on core-shell Fe3O4 polydopamine nanoparticles and hybridization chain reaction amplification.

A novel, highly sensitive assay for quantitative determination of DNA is developed based on hybridization chain reaction (HCR) amplification and the separation via core-shell Fe3O4 polydopamine nanoparticles (Fe3O4@PDA NPs). In this assay, two hairpin probes are designed, one of which is labeled with a 6-carboxyfluorescein (FAM). Without target DNA, auxiliary hairpin probes are stable in solution. However, when target DNA is present, the HCR between the two hairpins is triggered. The HCR products have sticky ends of 24 nt, which are much longer than the length of sticky ends of auxiliary hairpins (6 nt) and make the adsorption much easier by Fe3O4@PDA NPs. With the addition of Fe3O4@PDA NPs, HCR products could be adsorbed because of the strong interaction between their sticky ends and Fe3O4@PDA NPs. As a result, supernatant of the solution with target DNA emits weak fluorescence after separation by magnet, which is much lower than that of the blank solution. The detection limit of the proposed method is as low as 0.05 nM. And the sensing method exhibits high selectivity for the determination between perfectly complementary sequence and target with single base-pair mismatch. Importantly, the application of the sensor for DNA detection in human serum shows that the proposed method works well for biological samples.

Sensitive and selective turn-on fluorescence method for cetyltrimethylammonium bromide determination based on acridine orange-polystyrene sulfonate complex.

This work proposed a rapid and novel fluorescence-sensing system using a complex of acridine orange (AO) and polystyrene sulfonate (PSS) to sensitively recognize and monitor cetyltrimethylammonium bromide (CTAB) in an aqueous medium. AO can interact with PSS and a complex is formed via electrostatic attraction and hydrophobic interaction. The fluorescence of AO is greatly quenched after the introduction of PSS. Upon its subsequent addition, CTAB can interact and form a complex with PSS because the electrostatic attraction between CTAB and PSS is much stronger than that between AO and PSS, which results in significant fluorescence recovery. Interestingly, the proposed method can be applied for the discrimination and detection of surfactants with different hydrocarbon chain lengths due to their different binding affinity toward PSS. The detection limit for CTAB is as low as 0.2 µg/mL and the linear range is from 0.5 to 3.5 µg/mL. Moreover, we applied the sensor to the successful detection of CTAB in water samples. Copyright © 2015 John Wiley & Sons, Ltd.

bFGF and VEGF improve the quality of vitrified-thawed human ovarian tissues after xenotransplantation to SCID mice.

PURPOSE: The aim of this research is to study whether basic fibroblast growth factor (bFGF) alone or in combination with vascular endothelial growth factor (VEGF) could improve the quality of vitrified-thawed human ovarian tissue xenotransplanted to severe combined immune deficiency (SCID) mice. METHODS: After collection and cryopreservation, thawed human ovarian tissue were cultured in vitro for 2 days and then xenografted to severe combined immune deficiency (SCID) mice for 7 days. The in vitro culture medium was separated into six groups, including (A) the blank control group, (B) the human recombinant bFGF (150 ng/ml) group, (C) the bFGF (150 ng/ml)+human recombinant VEGF (25 ng/ml) group, (D) bFGF (150 ng/ml)+VEGF (50 ng/ml) group, (E) bFGF (150 ng/ml)+ VEGF (75 ng/ml) group and (F) bFGF (150 ng/ml) + VEGF (100 ng/ml) group. In addition, eight pieces of thawed ovarian tissue were transplanted without in vitro culture, which serve as the fresh control group. The effect of transplantation was assessed by histological analysis, immunohistochemical staining for CD34, Ki-67, and AC-3 expression, and microvessel density (MVD). RESULTS: There was no significant difference between the fresh and blank control group. Compared to the blank control group, the number of follicles, MVD, and rate of Ki-67-positive cells increased significantly in groups B, C, D, E, and F, while apoptosis decreased significantly. Compared to the bFGF treatment group, no significant difference appeared in group C, D, E, and F. CONCLUSIONS: The administration of bFGF alone or in combination with VEGF improved the quality of postgraft human ovarian tissue, though VEGF, regardless of different concentrations, did not influence effect of bFGF.

Discrete and infinite 1D, 2D/3D cage frameworks with inclusion of anionic species and anion-exchange reactions of Ag3L2 type receptor with tetrahedral and octahedral anions.

Complexes [PF6 subset(Ag3(titmb)2](PF6)2 (8) and {SbF6 subset[Ag3(titmb)2](SbF6)2}.H2O.1.5 CH3OH (9) are obtained by reaction of titmb and Ag+ salts with different anions (PF6(-) and SbF6(-)), and crystal structures reveal that they are both M3L2 cage complexes with short Ag...F interactions between the silver atoms and the fluorine atoms of the anions. In complex 8, a novel cage dimer is formed by weak Ag...F contacts; an unique cage tetramer formed via Ag...pi interactions (Ag...eta5-imidazole) between dimers and an infinite 1D cage chain is presented. However, each of the external non-disordered SbF6(-) anions connect with six cage 9s via Ag...F contacts, and each cage 9 in turn connects with three SbF6(-) anions to form a 2D network cage layer; and the layers are connected by pi-pi interactions to form a 3D network. The anion-exchange reactions of four Ag3L2 type complexes ([BF4 subset(Ag3(titmb)2](BF4)2 (6), [ClO4 subset(Ag3(titmb)2](ClO4)2 (7b), [PF6 subset(Ag3(titmb)2](PF6)2 (8) and [SbF6 subset(Ag3(titmb)2](SbF6)2.1.5CH3OH (9)) with tetrahedral and octahedral anions (ClO4(-), BF4(-), PF6(-) and SbF6(-)) are also reported. The anion-exchange experiments demonstrate that the anion selective order is SbF6(-) > PF6(-) > BF4(-), ClO4(-), and this anion receptor is preferred to trap octahedral and tetrahedral anions rather than linear or triangle anions; SbF6(-) is the biggest and most preferable one, so far. The dimensions of cage complexes with or without internal anions, anion-exchange reactions, cage assembly and anion inclusions, silver(I) coordination environments, Ag-F and Ag-pi interactions of Ag3L2 complexes 1-9 are discussed.

Formation of two (6,3) networks showing structural diversity, Borromean topology and conformational chirality in the same crystal.

Reaction of two tripodal ligands, 2,4,6-tris(4-((2-methyl-benzimidazol-1-yl)methyl)phenyl)-1,3,5-triazine (L1) and 1,3,5-tris(4-((2-methyl-benzimidazol-1-yl)methyl)phenyl)benzene (L2), with AgSbF6 led to formation of two types (6,3) networks in one single crystal, of which one is three-fold Borromean topologically entangled while the other is independent, showing the same chirality and sandwiched Borromean stacking.

3D coordination polymers with nitrilotriacetic and 4,4'-bipyridyl mixed ligands: structural variation based on dinuclear or tetranuclear subunits assisted by Na-O and/or O-H...O interactions.

The reactions of Cu(II) with the mixed nitrilotriacetic acid (H3NTA) and 4,4'-bipyridyl (4,4'-bpy) ligands in different metal-to-ligand ratios in the presence of NaOH and NaClO4 afforded two complexes, Na3[Cu2(NTA)2(4,4'-bpy)]ClO4 x 5H2O (1) and [Cu2(NTA) (4,4'-bpy)2]ClO4 x 4H2O (2). The two complexes have been characterized by elemental analysis, IR, XRD, and single-crystal X-ray diffraction. 1 contains a basic doubly negatively charged [Cu2(NTA)2(4,4'-bpy)]2- dinuclear unit which was further assembled via multiple Na-O and O-H...O interactions into a three-dimensional (3D) pillared-layer structure. 2 features a two-dimensional (2D) undulated brick-wall architecture containing a basic doubly positively charged [Cu4(NTA)2(4,4'-bpy)2]2+ tetranuclear unit. The 2D network possesses large cavities hosting guest molecules and was further assembled via O-H...O hydrogen bonds into a 3D structure with several channels running in different directions.

A noninterpenetrated 1D molecular ladder and 2D butterfly network: effect of positional isomerism of semirigid bis(pyridylmethyl)pyromellitic diimide ligands on the architecture of their metal(II) complexes.

Three new complexes [Cd(4-pmpmd)1.5 (NO3)2] x CHCl3 (1), [Cd(3-pmpmd)1.5 (NO3)2] x EtOH (2), and [Zn(3-pmpmd)1.5 (NO3)2] x MeOH (3) (3- or 4-pmpmd = N,N'-bis(3- or 4-pyridylmethyl)pyromellitic diimide) containing T-shaped building blocks have been obtained from reactions between the long semirigid ligands 3- or 4-pmpmd and either cadmium or zinc nitrate. 1 forms noninterpenetrated 1D molecular ladders that are linked via multiple, complementary intermolecular C-H...O hydrogen bonds that effect the 3D alignment. 2 and 3 are isostructural and feature a noninterpenetrated 2D butterfly-shaped network with (6,3) topology. Multiple intermolecular C-H...O hydrogen bonds exist between the 2D layers and generate the 3D framework. The structural differences between 1 and 2 or 3 are attributed to the different conformations adopted by the ligands, which illustrate the influence of positional isomerism on the resultant supramolecular architectures of metal complexes.

Multidimensional frameworks assembled from silver(I) coordination polymers containing flexible bis(thioquinolyl) ligands: role of the intra- and intermolecular aromatic stacking interactions.

The two flexible multidentate ligands 1,3-bis(8-thioquinolyl)propane (C3TQ) and 1,4-bis(8-thioquinolyl)butane (C4TQ) were reacted with AgX (X = CF(3)SO(3)(-) or ClO(4)(-)) to give four new complexes: ([Ag(C3TQ)](ClO(4)))(n)() 1, ([Ag(C3TQ)](CF(3)SO(3)))(n)() 2, ([Ag(2)(C4TQ)(CF(3)SO(3))(CH(3)CN)](CF(3)SO(3)))(n)() 3, and ([Ag(C4TQ)](ClO(4)))(n)() 4. All complexes have been characterized by elemental analysis, IR, and (1)H NMR spectroscopy. Single-crystal X-ray analysis showed that chain structures form for all complexes in which the quinoline rings interact via various intra- (1) or intermolecular (2, 3, and 4) pi-pi aromatic stacking interactions, which in the latter cases results in multidimensional structures. Additional weak interactions, such as Ag.O and Ag.S contacts and C-H.O hydrogen bonding, are also present and help form stable, crystalline materials. It was found that the (CH(2))(n) spacers (n = 3 or 4) affect the orientation of the two terminal quinolyl rings, thereby significantly influencing the specific framework structure that forms. If the same ligand is used, on the other hand, then the different counteranions have the greatest effect on the final structure.

Formation of racemate and mesocate complexes from an achiral tripodal ligand containing three benzimidazole groups.

Two complexes of the achiral tripodal ligand tris(1-benzimidazolylethyl)amine (nteb), viz., [Mn(nteb)(2)(H(2)O)(2)](ClO(4))(2).CH(3)OH, 1, and [Ag(2)(nteb)(2)](CF(3)CO(2))(2).2H(2)O, 2, have been synthesized and characterized by IR, (1)H NMR, and EPR spectroscopy (1), electrospray mass spectrometry, thermogravimetric analysis, and X-ray crystallography. Compound 1 contains chiral complex cations due to the same handedness of two nteb ligands (deltadelta or lambdalambda) but crystallizes as a racemate, while 2 contains a dinuclear mesocate because of the opposite handedness (deltalambda) of two nteb ligands. Crystal data for 1: space group P(-)1 with a = 9.471(4) A, b = 16.884(7) A, c = 19.906(8) A, alpha = 77.930(7) degrees, beta = 88.063(7) degrees, gamma = 89.706(7) degrees, V = 3111(2) A(3), and Z = 2. Crystal data for 2: space group P(-)1 with a = 9.3390(12) A, b = 10.2168(13) A, c = 16.382(2) A, alpha = 75.721(3) degrees, beta = 87.857(3) degrees, gamma = 71.738(3) degrees, V = 1437.2(3) A(3), and Z = 1. In 1, water serves as an auxiliary ligand, connected to one imidazole N atom of each nteb ligand through a H-bridge; the cationic complexes are associated intermolecularly via pi.pi interactions. In contrast to 1, the coordination to the Ag(+) ions in 2 occurs in a heterochiral manner and produces a dinuclear mesocate.

Syntheses, crystal structures, and luminescent properties of lanthanide complexes with tripodal ligands bearing benzimidazole and pyridine groups.

Two tripodal ligands, bis(2-benzimidazolylmethyl)(2-pyridylmethyl)amine (L(1)) and bis(2-pyridylmethyl)(2-benzimidazolylmethyl)amine (L(2)), were synthesized. With the third chromophoric ligand antipyrine (Antipy), three series of lanthanide(III) complexes were prepared: [LnL(1)(Antipy)(3)](ClO(4))(3) (series A), [LnL(1)(Antipy)Cl(H(2)O)(2)]Cl(2)(H(2)O)(2) (series B), and [LnL(2)(NO(3))(3)] (series C). The nitrate salt of the free ligand H(2)L(1).(NO(3))(2) and six complexes were structurally characterized: Pr(3+)A, Y(3+)A, Eu(3+)B, Eu(3+)C, Gd(3+)C and Tb(3+)C, in which the two A and three C complexes are isomorphous. Crystallographic studies showed that tripodal ligands L(1) and L(2) exhibited a tripodal coordination mode and formed 1:1 complexes with all lanthanide metal ions. The coordination numbers of the lanthanide metal ions for the A, B, and C complexes were 7, 8, and 10, respectively. Conductivity studies on the B and C complexes in methanol showed that, in the former, the coordinated Cl(-) dissociated to give 3:1 electrolytes and, in the latter, two coordinated NO(3)(-) ions dissociated to give 2:1 electrolytes. Detailed photophysical studies have been performed on the free ligands and their Gd(III), Eu(III), and Tb(III) complexes in several solvents. The results show a wide range in the emission properties of the complexes, which could be rationalized in terms of the coordination situation, the (3)LC level of the complexes, and the subtle variations in the steric properties of the ligands. In particular the Eu(3+)A and Tb(3+)A complexes, in which the central metal ions were wholly coordinated by chromophoric ligands of one L(1) and three antipyrine molecules, had relatively higher emission quantum yields than their corresponding B and C complexes.