نتایج جستجو برای: crown ether addition
تعداد نتایج: 750363 فیلتر نتایج به سال:
Nitrobenzofurazan derivatives are well known for their fluorescence, whilst crown ethers complexing capacity toward cationic species. In this study, we present the synthesis and structural characterization of a new derivative containing both nitrobenzofurazan moieties ether core. The compound was obtained from dibenzo-18-crown-6 ether, which first nitrated, reduced to corresponding amine, subse...
Two procedures for the synthesis of benzo-21-crown-7 have been explored. The [1+1] macrocyclization with KBF₄ as the template was found to be more efficient than the intramolecular macrocyclization without template. Pseudorotaxanes form with secondary ammonium ions bearing at least one alkyl chain narrow enough to slip into the crown ether. Substitution on benzo-21-crown-7 or on the secondary a...
Chemiluminescence (CL) of firefly luciferin (Ln) consisting of red and green emission peaks can be generated by dissolving oxygen (O2) gas in deoxygenated dimethyl sulfoxide containing potassium tert-butoxide (t-BuOK) even without the enzyme luciferase. In this study, the characteristics of CL of Ln are examined by varying the concentrations of both Ln ([Ln]) and t-BuOK ([t-BuOK]). The time cou...
Novel 2-benzothiazole-, 4-pyridine-, and 2- and 4-quinoline-based styryl dyes containing an N-methylbenzoaza-15(18)-crown-5(6)-ether moiety were synthesized. A detailed electronic spectroscopy study revealed high performance of these compounds as optical molecular sensors for alkali and alkaline-earth metal cations. They were shown to considerably surpass analogous chromoionophores based on N-p...
deuterating reagent ultimately becomes detached from the complex, with the net effect of one hydrogen atom being replaced with a deuterium atom. This H/D exchange process may repeat multiple times in the gas phase. Other pathways that are independent of the charge site and involve the interaction of the deuterating reagent directly with the labile hydrogen atom are typically higher in energy an...
Conformational restriction imposed upon Ru(bpy)32+ crown ether complexes by metal ion binding leads to enhanced luminescence.
The title compound, C(29)H(33)NO(8), is a product of the Michael addition of the cyclic secondary amine subunit of the aza-14-crown-4 ether to dimethyl acetyl-enedicarboxyl-ate. The piperidinone ring exhibits a distorted chair conformation, and the dimethyl ethylenedicarboxylate fragment has a cis configuration with a dihedral angle of 78.96 (5)° between the two carboxyl-ate groups. The crystal...
The title compound, C(39)H(37)NO(8), is a product of the Michael addition of the cyclic secondary amine subunit of aza-14-crown-4 ether to dimethyl acetyl-enedicarboxyl-ate. The piperidinone ring exhibits a distorted chair conformation and the dimethyl acetyl-enedicarboxyl-ate fragment has a cis configuration with a dihedral angle of 56.61 (5)° between the two carboxyl-ate groups. The crystal p...
Direct enantioseparation of racemic amine, amino-thiophene-2-yl-acetonitrile (TAN), on chiral crown ether stationary phase [Crownpak CR (+)] is described in this study. The elution behavior and the effect of acid additives on resolution of racemic amine, TAN, is intensely investigated. Moreover, the chiral recognition mechanism in this specific system is proposed based on computational methods ...
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