A dynamic combinatorial library of metal ion Schiff-base complexes have been studied for the extraction of Zn(II) or Cd(II) from aqueous solution into chloroform. Library components consist of different aminophenols and 2-pyridinecarboxaldehyde. Extraction of both Zn(II) and Cd(II) into chloroform was observed from aqueous solutions containing 0.0500 mM M(NO3)2, 0.100 M aminophenol, 0.100 M 2-pyridinecarboxaldehyde, 0.100 M NaCl, and 5.00 mM buffer at pH 8.5. Extraction was dependent on pH but not on counterions including Cl-, Br-, or NO3-. Studies showed that equilibrium was attained between the Schiff-base complexes across the two-phase chloroform-water system after 24 h of stirring. Analysis of the extracted species by use of 1H NMR spectroscopy and mass spectrometry as well as solubility studies on characterized complexes suggested that the major extracted species is the neutral bis-Schiff-base metal ion complex. In libraries containing mixtures of two different aminophenols and 2-pyridinecarboxaldehyde, an enhanced extent of extraction of Zn(II) into chloroform is observed. Studies suggest that a Zn(II) complex, which is likely the mixed Schiff-base complex, has superior extraction properties compared to simple libraries with a single aminophenol component. The structures of two bis-Schiff-base complexes of Zn(II) and one of Cd(II) have been determined by X-ray crystallography. The geometries of the two Zn(II) complexes, which differ only by a methyl substituent on the Schiff-base ligand, are markedly different, supporting the use of combinatorial methods in coordination chemistry. Zn(SB14)2 crystallized as the sesquihydrate (C24H18N4O2Zn.1.5 H2O) in the space group C2/c, with cell dimensions a = 23.219(15) A, b = 11.299(7) A, c = 16.822(11) A, beta = 102.91(5) degrees, V = 4302(5) A3, and Z = 8. Zn(SB15)2 crystallized as a 1:1 methanol solvate (C26H22N4O2Zn.CH3OH) in the space group P2(1)/c with cell dimensions a = 13.981(5) A, b = 7.978(3) A, c = 22.568(8) A, beta = 104.53(3) degrees, V = 2436.8(15) A3, and Z = 4. Cd(SB14)2 crystallized as a 1:1 ethanol solvate (C24H18N4O2Cd.CH3CH2OH) in the space group R3 with unit cell dimensions of a = 36.423(2) A, c = 9.2930(10) A, V = 10678(2) A3, and Z = 18.
The interaction of three Eu(III) macrocyclic complexes Eu(THED)3+, Eu(ATHC)3+, and Eu(ATHC)3+, and Eu(S-THP)3+ with two 5'-cap model compounds, GpppG and m7GpppG is studied (THED = 1,4,7,10-tetrakis(2-hydroxyethyl)-1,4,7,-10-tetraazacyclododecane, ATHC = 1-(carbamoylmethyl)-4,7,10-tris(2-hydroxyethyl)-1,4,7,10- tetraazacyclododecane, S-THP = 1S,4S,7S,10S-tetrakis(2-hydroxypropyl)-1,4,7,10-tetraazacyclododecane). Laser-induced excitation luminescence spectroscopy is used to study the binding of Eu(S-THP)3+ to GpppG (K = 5.9 x 10(4) M-1) and to characterize the Eu(S-THP)-GpppG complex. Both Eu(THED)3+ and Eu(S-THP)3+ bind to m7GpppG as monitored by use of fluorescence spectroscopy with binding constants of 5.9 x 10(3) and 4.4 x 10(4) M-1, respectively. The kinetics of cleavage of GpppG by two macrocyclic complexes is studied. Cleavage of GpppG by Eu(THED)3+ is accelerated by 15-fold in the presence of an equivalent of Zn(NO3)2 at pH 7.3, 37 degrees C, suggesting that two metal ions accelerate the cap cleavage reaction. Eu(ATHC)3+ promotes cleavage of GpppG with a pseudo-first-order rate constant of 2.6 x 10(-5) s-1 at pH 7.3, 37 degrees C, and 0.30 mM complex.
OBJECTIVE: Pediatricians are required to perform quality improvement for board recertification. We developed an asthma project within the Pediatric Physicians' Organization at Children' s, an independent practice association affiliated with Boston Children' s Hospital, designed to meet recertification requirements and improve asthma care. METHODS:The program was based on the learning collaborative model. We developed practice-based registries of children 5 to 17 years of age with persistent asthma and helped physicians improve processes of asthma care through education, data feedback, and sharing of best practices. RESULTS:Fifty-six physicians participated in 3 cohorts; 594 patients were included in the project. In all cohorts, improvements occurred in the use of asthma action plans (62.4%-76.8% cohort 1, 50.6%-88.4% cohort 2, 53.0%-79.6% cohort 3) and Asthma Control Tests (4.6%-55.2% cohort 1, 9.0%-67.8% cohort 2, 15.2%-61.4% cohort 3). Less consistent improvements were observed in seasonal influenza vaccines, controller medications, and asthma follow-up visits. The proportion of patients experiencing $1 asthma exacerbation within the year declined in all 3 cohorts (37.8%-19.9%, P = .0002 cohort 1; 27.8%-20.7%, P = .1 cohort 2; 36.6%-26.9%, P = .1 cohort 3). For each cohort, asthma exacerbations declined to a greater extent than those of a comparison group.CONCLUSIONS: This asthma quality improvement project designed for maintenance of certification improved processes of care among patients with persistent asthma. The learning collaborative approach may be a useful model for other board-recertification quality improvement projects but requires a substantial investment of organizational time and staff. Pediatrics 2014;134:e242-e248
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