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The coordination properties of the ligand 2,2'-bipyrimidine-4,4'-dicarboxylic acid (H2bpd) with lanthanide(III) ions (Ln = Eu, Tb, or Lu) were investigated. The syntheses of the H2bpd ligand and its salts, [K2(bpd)(H2O)2] (1) and [(AlkNH)Lu(bpd)2] (Alk = Et, Hex, or en), are described. In the presence of LnCl3 salts (Ln = Lu, Eu, or Tb), the formation of [Ln(bpd)2]- and [Ln(bpd)(H2O)x]+ species was assessed by 1H nuclear magnetic resonance (NMR), spectrophotometry, and spectrofluorometric titrations in aqueous solution. The solid state structure of 1, [K(H2O)2][Lu(bpd)2] (2), and [(Et3NH)Lu(bpd)2] (3) could be determined by X-ray diffraction, showing the ligand to act as a tetradentate unit with formation of three five-membered chelate rings around the central Ln(III). With the aim of building polynuclear assemblies, the coordination between [Lu(bdp)2]- and [Lu(tta)3(H2O)] units (tta = thenoyltrifluoroacetylacetonate) was also investigated. In methanol, 1H NMR titration experiments revealed the formation of complex mixtures from which two new species could be identified, [Lu2(bpd)(tta)4] (4) and H[Lu(bpd)(tta)2] (5), as confirmed by their solid state structure analysis. Using highly lipophilic cations in chloroform, the octametallic complex [enH]4[Lu8(bpd)4(tta)18] (6) could be isolated and its X-ray structure determined.In spite of the comprehensive study of the metal-mediated conversion of NO to N2O disclosing the conceivable processes/mechanism in biological and biomimetic studies, in this study, the synthesis cycles and mechanism of NO reduction to N2O triggered by the electronically localized dinuclear Fe(NO)210-Fe(NO)29 dinitrosyl iron complex (DNIC) [Fe(NO)2(μ-bdmap)Fe(NO)2(THF)] (1) (bdmap = 1,3- bis(dimethylamino)-2-propanolate) were investigated in detail. Reductive conversion of NO to N2O triggered by complex 1 in the presence of exogenous ·NO occurs via the simultaneous formation of hyponitrite-bound [Fe2(NO)4(μ-bdmap)]2(κ4-N2O2) (2) and [NO2]--bridged [Fe2(NO)4(μ-bdmap)(μ-NO2)] (3) (NO disproportionation yielding N2O and complex 3). EPR/IR spectra, single-crystal X-ray diffraction, and the electrochemical study uncover the reversible redox transformation of Fe(NO)29-Fe(NO)29 [Fe2(NO)4(μ-bdmap)(μ-OC4H8)]+ (7) ↔ Fe(NO)210-Fe(NO)29 1 ↔ Fe(NO)210-Fe(NO)210 [Fe(NO)2(μ-bdmap)Fe(NO)2]- (6) and characterize the formation of complex 1. Also, the synthesis study and DFT computation feature the detailed mechanism of electronically localized Fe(NO)210-Fe(NO)29 DNIC 1 reducing NO to N2O via the associated hyponitrite-formation and NO-disproportionation pathways. Presumably, the THF-bound Fe(NO)29 unit of electronically localized Fe(NO)210-Fe(NO)29 complex 1 served as an electron buffering reservoir for accommodating electron redistribution, and the Fe(NO)210 unit of complex 1 acted as an electron-transfer channel to drive exogeneous ·NO coordination to yield proposed relay intermediate κ2-N,O-[NO]--bridged [Fe2(NO)4(μ-bdmap)(μ-NO)] (A) for NO reduction to N2O.This research addresses a subject discussed controversially for almost 70 years. The interactions between the uranyl(VI) ion, U(VI), and citric acid, H3Cit, were examined using a multi-method approach comprising nuclear magnetic resonance (NMR), ultraviolet-visible (UV-vis), attenuated total reflectance Fourier-transform infrared (ATR FT-IR), and extended X-ray absorption fine-structure (EXAFS) spectroscopies as well as density functional theory (DFT) calculations. Combining 17O NMR spectroscopy and DFT calculation provided an unambiguous decision on complex configurations, evidencing for the first time that the dimeric complex, (UO2)2(HCit-H)22-, exists as two diastereomers with the syn-isomer in aqueous solution strongly favored over the anti-isomer. Both isomers interconvert mutually with exchange rates of ∼30 s-1 at -6 °C and ∼249 s-1 at 60 °C in acidic solution corresponding to an activation barrier of about 24 kJ mol-1. Upon increasing the pH value, ternary dimeric mono- and bis-hydroxo as well as trimeric complexes form, that is, (UO2)2(HCit-H)2(OH)3-, (UO2)2(HCit-H)2(OH)24-, (UO2)3(O)(Cit-H)38-, and (UO2)3(O)(OH)(Cit-H)25-, respectively. Stability constants were determined for all dimeric and trimeric species, with log β° = -(8.6 ± 0.2) for the 33 species being unprecedented. Additionally, in the 66 sandwich complex, formed from two units of 33 species, the 17O NMR resonance of the trinuclear uranyl(VI) core bridging μ3-O is shown for the first time. https://www.selleckchem.com/products/msa-2.html Species distribution calculations suggest that the characterized polynuclear U(VI)-citrate species do not significantly increase uranium(VI) mobility in the environment. Furthermore, we revise the misconceptions in the aqueous U(VI)-citric acid solution chemistry, that is, structures proposed and repeatedly taken up, and outline generalized isostructural considerations to provide a basis for future U(VI) complexation studies.
A retrospective study of prospectively collected clinical data.
To identify preoperative psychological factors associated with patient satisfaction after surgery for lumbar spinal stenosis (LSS).
Associations between depressive symptoms, anxiety, and worse surgical outcome or patient dissatisfaction have been reported in LSS patients. However, the influence of preoperative pain catastrophizing and fear-avoidance beliefs on postoperative satisfaction is not well understood.
LSS patients who underwent decompression surgery with or without fusion were included. Clinical outcomes were measured before surgery and 6 months postoperatively using the Zurich Claudication Questionnaire (ZCQ); Visual Analog Scale (VAS) of low back pain, leg pain, and leg numbness; Japanese Orthopaedic Association Back Pain Evaluation Questionnaire; and the Medical Outcomes Study 36-item Short-Form General Health Survey (SF-36). The Hospital Anxiety and Depression Scale (HADS), Pain Catastrophizing Scale, and Pain Anxiety Symptompostoperative psychological status should be assessed carefully and managed appropriately.
Preoperative less severe low back pain, lower mental health, and higher anxiety are associated with patient dissatisfaction with lumbar surgery, not depression, pain catastrophizing, or fear-avoidance beliefs. Pre- and postoperative psychological status should be assessed carefully and managed appropriately.
Website: https://www.selleckchem.com/products/msa-2.html
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