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We synthesized a series of novel macrocycles with diamide-diester groups (S,S)-1, (S,S)-2, (S,S)-3, and (R,R)-1, derived from dimethyloxalate and amino alcohols by high dilution technique, and evaluated enantiomeric recognition properties of these macrocycles toward primary alkyl ammonium salts by 1H NMR titration. Taking into account the host employed, important differences were observed in the Ka values of (R)-Am and (S)-Am for (S,S)-1 and (R,R)-1 hosts, KS/KR = 5.55 and KR/KS = 3.65, Delta Delta Go = 0.43 and -0.32 kJ mol-1, respectively. There seems a general tendency for the host to include the guests with the same absolute configuration. 相似文献
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C(2)-Symmetric two bis(amino alcohol)oxalamides (diamidediols) were synthesized and fully characterized. A new method was developed and successfully applied for the simultaneous preconcentration of both trace and toxic metals in water, by using C(2)-symmetric compounds. Under the optimum experimental conditions (i.e. pH = 10.0 +/- 0.2, 2.75 x 10(-3) mol L(-1) N,N'-bis[(1R)-1-ethyl-2-hydroxyethyl]ethanediamide (DAD1), 1.75 x 10(-3) mol L(-1) N,N'-bis[(1S)-1-benzyl-2-hydroxyethyl]-ethanediamide (DAD2), 0.10% w/v octylphenoxy-polyethoxyethanol (Triton X-114)), calibration graphs were linear in the range of 2.5 - 25.0 ng mL(-1) for Cu and Cd, 5.0 - 25.0 ng mL(-1) for Co and Ni. The enrichment factors were 18, 23, 18 and 20 for Cd, Cu, Co and Ni in the case of DAD1, respectively; 20, 22, 17 and 20 for Cd, Cu, Co and Ni in the case of DAD2. The limits of detection for DAD1 were found to be 0.45, 0.50, 1.25 and 0.60 ng mL(-1) for Cd, Cu, Co and Ni, respectively, and for DAD2 were found to be 0.44, 0.25, 0.60 and 1.55 ng mL(-1) for Cd, Cu, Co and Ni, respectively. The developed method was applied to the determination of Cu, Cd, Co and Ni in water samples and certified reference materials with satisfactory results. 相似文献
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Hayriye Ozer Şafak Ozhan Kocakaya Abuzer Akgun Halil Hoşgören Mahmut Togrul 《Tetrahedron: Asymmetry》2009,20(13):1541-1546
Pyridine-based macrocycles were prepared by treating 2,6-bis[[2′6′-bis(bromomethyl)-4′-methylphenoxy]methyl]pyridine 3 with the appropriate chiral aminoalcohols. The enantiomeric recognition of these macrocycles bearing aminoalcohol subunits of the pyridinocrown type ligand was evaluated for chiral organic ammonium salts by UV titration. The important differences were observed in the Ka values of (R)-Am2 and (S)-Am2 for (S,S,S)-1, (S,S,S)-2 and (S,S,S)-3 hosts, KS/KR = 5.0, KS/KR = 2.4 and KS/KR = 5.0, respectively. There seems to be a general tendency for hosts to recognise (S)-enantiomers for both Am1 and Am2. 相似文献
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Azobenzene moieties were incorporated into a synthetic receptor allowing its affinity for the guanidinium cation to be modulated ten-fold by photoirradiation and/or heating. 相似文献
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