A novel positive homotropic allosteric system 1 based on 3-methylpyrozole-5-one-4-one-2′,4′-dinitrophenylhydrazone was designed, synthesized and characterized. Colorimetric and fluorescent sensing of anions was achieved in physiological condition (pH 7.4), resulting from the positive homotropic allosterism of 1 induced by anions tested. In particular, the compound 1 exhibited a two-step response to the strong basic anions such as F−. In the first step, the hydrazone form of 1 interacted with anions through hydrogen bonding with an obvious color change from yellow to orange upon addition of 0.3 equiv. of anions. In the second step, with further addition of anions, the hydrazone form of 1 was shifted to the azophenol form, whose anion binding was accompanied with an orange-to-purple color change. In addition, the receptor 1 exhibited a fluorescent enhancement response to anions exploiting two possible signaling transduction mechanisms: (1) inhibition of photoinduced electronic transfer (PET) and (2) binding-induced rigidity of the host molecule. 相似文献
The values of the second dissociation constant, pK2, and related thermodynamic quantities of 3-[N,N-bis (2-hydroxyethyl)amino]-2-hydroxypropanesulfonic acid (DIPSO) have already
been reported over the temperature range 5 to 55 °C including 37 °C. This paper reports the pH values of four NaCl-free buffer
solutions and four buffer composition containing NaCl salt at I=0.16 mol⋅kg−1. Conventional paH values are reported for all eight buffer solutions. The operational pH values have been calculated for four buffer solutions
recommended as pH standards, at 25 and 37 °C after correcting the liquid junction potentials with the flowing junction cell. 相似文献
The optimum pH range for synthesizing barium strontium titanate (Ba0.5Sr0.5TiO3, BST) nanopowders by sol–gel auto-combustion method was calculated based on the principles of matter balance and charge balance.
The effectiveness of the calculation was proved by the successful synthesis of highly dispersive, spherically shaped and pure
BST nanoparticles with setting the pH in the range pre-decided by theoretical evaluation. Ours might have provided an effective
path for pre-deciding the solution pH in synthesizing various oxide nanopowders by sol–gel auto-combustion method. 相似文献
The degree of aggregation of silver nanoparticles can be controlled via a pH sensitive peptide coating (see figure). As the peptide not only controls the colloidal properties, but also influences the crystal structure of the individual nanoparticles, peptide/silver particle hybrid materials can be viewed as flexible and simple building blocks for the construction of new meta‐materials with tunable properties.