Synthesis, conformational studies, and inclusion properties of tris((2-pyridylmethyl)oxy)hexahomotrioxacalix(3)arenes

Article Abstract:

O-Alkylation of a flexible macrocycle with 2-(chloromethyl)pyridine in the presence of Cs2CO3 has yielded a partial cone, preferentially. With K2CO3, cone-to-partial-cone ratio increased. The alkali metal cations act as a template, which has an important part in this O-alkylation reaction. Synergism of cyclophane moiety and 2-3 lower-rim side chains with pyridyl groups has a plays a significant part in complexation of tris((2-pyridylmethyl)oxy) derivatives, the cone and the partial cone with n-butylammonium ion and Ag+ ion. Calixarene and related macrocycles have been of interest because of their host-guest chemistry when they are ionophoric receptors. In biology they can potentially be enzyme mimics

Observations, Nitrogen (Chemical element), Cations, Nitrogen, Alkylation, Alkylation (Petroleum refining), Ionophores

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Precise measurement of fluorescence from uranium taken up in sodium fluoride

Article Abstract:

Fluorescence signals from multiple samples of uranium in fused sodium fluoride beads, read in the customary way, do not display normal distribution. The signal from one bead shows considerable sinusoidal variation as the bead is rotated. The superposition of this sinusoidal variation on the normal variation between beads that leads to widened or even bimodal distribution among replicates. If each bead is read again after a half rotation, the average of the two readings gives the actual signal underlying the sinusoidal variation.

Methods, Uranium, Fluorimetry, Sodium fluoride

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Escherichia coli beta-galactosidase is hetrogeneous with respect to the activity of individual molecules

Article Abstract:

Escherichia coli beta-galactosidase molecules have been placed in a fluorogenic substrate in a capillary and incubated. Activities of individual enzyme molecules were detected using laser-induced fluorescence detection. The molecules differed in activity and showed a 23-fold distribution of activities. The majority were within a 4-fold distribution.

Usage, Escherichia coli, Electrophoresis, Structure-activity relationships (Biochemistry), Enzyme kinetics

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