3D ZnII-Based coordination polymer: Synthesis, structure and fluorescent sensing property for nitroaromatic compounds.

A water-stable ZnII-based coordination polymer (CP) with excellent photophysical behavior, namely [Zn2L(atez)(H2O)2] (compound 1; H3L = 4-(2',3'-dicarboxylphenoxy); atez = 5-aminotetrazole), was successfully prepared by the solvothermal reaction of Zn ions with a π-conjugated and semi-rigid multicarboxylate ligand H3L in the presence of N-containing linker atez. Compound 1 displays a hierarchically pillared three-dimensional (3D) (3,4,5)-connected (4·62) (42·64) (43·64·83) net which is based on two-dimensional (2D) multicarboxylate- ZnII layers strutted by the atez ligands. Sensing investigations of compound 1 reveal that this material can selectively and sensitively detect nitroaromatic compounds in water suspension through fluorescence quenching effect. In particular, it is worth noting that it shows highly specific detection of nitrobenzene (NB) and 2,4,6-trinitrophenol (TNP) with remarkable quenching constants (KSV = 7.5 × 104 M-1 for NB and KSV = 1.9 × 105 M-1 for TNP) and low limit of detection (LOD = 0.93 µM for NB and LOD = 0.36 µM for TNP). Investigations reveal that the probable mechanisms for such sensing processes are the concurrent presence of fluorescence resonance energy transfer (FRET) as well as photoinduced electron transfer (PET) between the CP and nitroaromatic molecules. This work not only offers an effective route to improve the application of fluorescent CPs but also provide one novel probable fluorescence probe for nitroaromatic compounds.

Multifunctional Cd-CP for fluorescence sensing of Cr(VI), MnO4-, acetylacetone and ascorbic acid in aqueous solutions.

The development of multifunctional fluorescent chemosensors for the detection of multiple targets remains challenging but of great importance. In this paper, one novel coordination polymer (CP), denoted as [Cd2(edda)(phen)2]∙H2O (compound 1, H4edda = 5,5' (ethane-1,2-diylbis(oxy)) diisophthalic acid, phen = 1,10-phenanthroline) is successfully designed and prepared under hydrothermal conditions. Structural analysis indicates that compound 1 possesses a one-dimensional (1D) double chain structure, then self-assembles into a three-dimensional (3D) supramolecular framework via π…π interactions between phen molecules. Interestingly, compound 1 is found to be tolerant in wide range of acidic to alkaline aqueous solutions (pH = 2-13). Fluorescent spectral investigations reveal that compound 1 exhibits highly selective and sensitive fluorescence responses toward MnO4-, Cr(VI) ions, acetylacetone (acac) and ascorbic acid (AA) by fluorescence quenching in the aqueous phase. The detection limits are in the very low range, reaching µM level for the detection of MnO4-, Cr(VI) ions, nM for AA and ppm for acac detection. The distinguished multi-responsive performance suggests compound 1 to be a potential multifunctional probe. Furthermore, the possible quenching mechanisms have also been systematically investigated in this work.

A water-stable dual-responsive Cd-CP for fluorometric recognition of hypochlorite and acetylacetone in aqueous media.

One novel cadmium(II)-coordination polymer [Cd3L2(datrz)(H2O)3] (CP 1) is controllably synthesized by surmising the astute combination of semi-rigid tricarboxylate acid 4-(2',3'-dicarboxylphenoxy) benzoic acid (H3L) and auxiliary ligand 3,5-diamino-1,2,4-triazole (datrz). Structure analysis shows that CP 1 has a two-dimensional (2D) layer structure with a 5-nodal (43) (44·62) (45·64·8) (45·6) (47·66·82) topology. Further investigations reveal that CP 1 shows superordinary water stability and good thermal stability. The fluorescent explorations suggest that the as-synthesized CP 1 could emit blue light centered at 485 nm, attributing to ligand-based emission. In terms of sensing investigations, CP 1 could act as a fluorescent sensor for detecting hypochlorite (ClO-) and acetylacetone (acac) through fluorescence turn-off process in aqueous solution, and the detection limit could reach 0.18 µM and 0.056 µM, respectively. Further research reveals that it is more likely the N-H···O-Cl hydrogen bonds between -NH2 groups of the triazole ligands and O atoms of ClO- plays the key role in the system, which may serve as a bridge for the energy transfer, leading to fluorescence quenching of the chemosensor. While the photoinduced electron transfer (PET) combined with inner filter effect (IFT) should be responsible for the turn-off fluorescence of CP 1 triggered by acac.

A dual luminescent sensor coordination polymer for simultaneous determination of ascorbic acid and tryptophan.

Simultaneous high sensitivity detection of biomolecules is important for research in medicine, living cells and environmental samples. In this work, a water stable coordination polymer, [Cd2(bptc)(4,4'-bpy)(H2O)3]ˑH2O 1 (H4bptc = 2,3,3',4'-biphenyl tetracarboxylic acid, 4,4'-bpy = 4,4'-bipyridine), was designed and successfully synthesized as a luminescent sensor for simultaneous recognition of Ascorbic Acid (AA) and L-Tryptophan (L-Trp) based on luminescent -OFF and -ON, respectively. Importantly, the proposed sensing system showed an excellent performance with high KSV values of 4.85 × 104 M-1, 9.60 × 107 M-1 and low limit of detection (LOD) of 0.28 nM, 63 nM, respectively. In addition, the probable mechanisms are also discussed. The luminescent quenching behavior by AA can be mainly attributed to the static resonance energy transfer between complex 1 and the analytes. Whereas the enhancing effect of L-Trp comes from the intrinsic strong luminescence for L-Trp itself and photo-competitive mechanism between CP 1 sensor and L-Trp, supposedly. In addition, the repeatability of both systems were also investigated.

Ln-CPs constructed from unsymmetrical tetracarboxylic acid ligand: Tunable white-light emission and highly sensitive detection of CrO42-, Cr2O72-, MnO4- in water.

A series of isostructural lanthanide coordination polymers (Ln-CPs), [Ln(Hbptc)(H2O)4]·H2O [Ln = Er (1), Pr (2), Dy (3), Sm (4), Gd (5), Nd (6) and Tb(7); H4bptc = 2,3,3',4'-biphenyl tetracarboxylic acid] have been isolated based on an unsymmetrical tetracarboxylic acid. Single-crystal X-ray diffraction analysis reveals that all CPs featured a two dimensional (2D) layer with (6, 6, 6)-connected 63 topology. Luminescent spectra demonstrate that CPs 1-7 exhibit impressive UV-visible luminescence in the solid state at room temperature. More significantly, a single-component white-light material with International Commission on Illumination (CIE) coordinates of (0.335, 0.334) for 4 (Sm-CP), very closing to the pure white-light of (0.333, 0.333) was obtained by finely tuning of the excitation wavelength. In addition, the luminescent detection for anions of 7 is investigated. Fluorescence measurements show that 7 can detect oxoanion pollutants Cr2O72-, CrO42-, and MnO4- anions in aqueous solutions with high selectivity and sensitivity, which suggests that the Tb-CP is a promising functional luminescence probe for toxic oxoanions. The possible mechanisms of the quenching effect were also discussed in detail.

Acute spontaneous intracerebral hemorrhage and traumatic brain injury are the most common causes of critical illness in the ICU and have high early mortality.

BACKGROUND: Critical care covers multiple disciplines. However, the causes of critical illness in the ICU, particularly the most common causes, remain unclear. We aimed to investigate the incidence and the most common causes of critical illness and the corresponding early mortality rates in ICU patients. METHODS: A retrospective cohort study was performed to examine critically ill patients (aged over 15 years) in the general ICU in Shuyang County in northern China (1/2014-12/2015). The incidences and causes of critical illnesses and their corresponding early mortality rates in the ICU were determined by an expert panel. RESULTS: During the 2-year study period, 1,211,138 person-years (PY) and 1645 critically ill patients (mean age, 61.8 years) were documented. The median Glasgow Coma Scale (GCS) score was 6 (range, 3-15). The mean acute physiology and chronic health evaluation II (APACHE II) score was 21.2 ± 6.8. The median length of the ICU stay was 4 days (range, 1-29 days). The most common causes of critical illness in the ICU were spontaneous intracerebral hemorrhage (SICH) (26%, 17.6/100,000 PY) and traumatic brain injury (TBI) (16.8%, 11.4/100,000 PY). During the first 7 days in the ICU, SICH was the most common cause of death (42.2%, 7.4/10,000 PY), followed by TBI (36.6%, 4.2/100,000 PY). Based on a logistic analysis, older patients had a significantly higher risk of death from TBI (risk ratio [RR], 1.7; 95% CI, 1.034-2.635), heart failure/cardiovascular crisis (RR, 0.2; 95% CI, 0.083-0.484), cerebral infarction (RR, 0.15; 95% CI, 0.050-0.486), or respiratory failure (RR, 0.35; 95% CI, 0.185-0.784) than younger patients. However, the risk of death from SICH in the two groups was similar. CONCLUSIONS: The most common causes of critical illness in the ICU were SICH and TBI, and both critical illnesses showed a higher risk of death during the first 7 days in the ICU.

Risk factors for nosocomial nontraumatic coma: sepsis and respiratory failure.

BACKGROUND: Coma's are a major cause of clinical deterioration or death. Identification of risks that predispose to coma are important in managing patients; however, the risk factors for nosocomial nontraumatic coma (NNC) are not well known. Our aim was to investigate the risk factors in patients with NNC. METHODS: A retrospective case-control design was used to compare patients with NNC and a control group of patients without coma in a population-based cohort of 263 participants from the neurological intensive care unit in Shuyang County People's Hospital of Northern China. Coma was diagnosed by a Glasgow Coma Scale score ≤8. Adjusted odds ratios for patients with NNC were derived from multivariate logistic regression analyses. RESULTS: A total of 96 subjects had NNC. The prevalence of NNC was 36.5% among the subjects. Among these, 82% had acute cerebrovascular etiology. Most of the NNC usually occurred at day 3 after admission to the neurological intensive care unit. Patients with NNC had higher hospital mortality rates (67.7% vs 3%, P<0.0001) and were more likely to have a central herniation (47.9% vs 0%, P<0.001) or uncal herniation (11.5% vs 0%, P<0.001) than those without NNC. Multiple logistic regression showed that systemic inflammatory response syndrome-positive sepsis (odds ratio =4, 95% confidence interval =1.875-8.567, P<0.001) and acute respiratory failure (odds ratio =3.275, 95% confidence interval =1.014-10.573, P<0.05) were the factors independently associated with a higher risk of NNC. CONCLUSION: Systemic inflammatory response syndrome-positive sepsis and acute respiratory failure are independently associated with an increased risk of NNC. This information may be important for patients with NNC.