No abstract

Optical signals of pH probes mainly driven from the formation or rupture of covalent bonds, whereas the changes in covalent bonds usually require higher chemical driving forces, resulting in limited sensitivity and reversibility of the probes. The exploration of high-performance pH probes has been a subject of intense investigation. Herein, a new pH probe has been developed, with optical property investigation suggesting the probe has excellent signal-to-noise ratio, and fluorescence intensity shows exponential growth, combined with a visible color change, as pH increased from 5.1 to 6.0; Moreover, the probe has outstanding stability and reversibility, with more than 90% of the initial signal intensity remaining after 30 cycles. In order to better understand the special fluorescence behavior of the reported probe, the non-halogenated isomer is introduced for comparison, combined with the results of structural analysis, quantitative calculation and optical experiments, and the possible mechanism of the special supramolecular aggregation-caused quenching effect induced by the halogen atom is discussed.

To identify the effects of halogen bonding in the architecture of Schiff base complex supramolecular networks, we introduced halogenated Schiff-base 3-Br-5-Cl-salen as ligand and isolated a new salen-type manganese(III) complex [MnIII(Cl)(H2O)(3-Br-5-Cl-salen)] (1) where 3-Br-5-Cl-salen = N,N’-bis(3-bromo-5-chlorosalicylidene)-1,2-diamine. The complex was investigated in the solid-state for halogen bonds (XBs) by single crystal X-ray structure analysis. Meanwhile, theoretical calculations were carried out to rationalize the formation mechanism of different types of XBs in the complex. The analysis result of electronic structure of the halogen bonds indicated that the chlorine atom coordinated to the Mn(III) center possesses the most negative potential and acts as anionic XB acceptor (electron donor) to the adjacent substituted halogens on the ligand, meanwhile the intermolecular Mn-Cl···X-C halogen bonding plays a significant role in directing the packing arrangement of adjacent molecules and linking the 2D layers into a 3D network. In order to verify the above results and acquire detailed information, the title complex was further analyzed by using the Hirshfeld surface analyses.

With every subset selection Z for posets, there is associated a certain ideal completion Z . As shown by Erné, such completions help to extend classical results on domains and similar structures in the absence of the required joins. Some results about Z-predistributive or Z-precontinuous posets and Z -continuous functions are summarized and supplemented. In particular, several central results on function spaces in domain theory are extended to the setting of productive closed subset selections. The category FSBP, in which objects are finitely separated and upper bounded posets and arrows are D −continuous functions between them, is shown to be cartesian closed.