Showing papers by "Yunxiang Lu published in 2018"

Theoretical Exploration of Halogen Bonding Interactions in the Complexes of Novel Nitroxide Radical Probes and Comparison with Hydrogen Bonds.

Abstract: In this work, halogen bonding interactions in the complexes of two new nitroxide radicals, which contain both a halogen-bond-donor group and an electron-spin-resonance-active radical unit, were investigated using density functional theory calculations. For comparison, the corresponding hydrogen-bonded complexes were also examined. Halogen bonds in these systems are predicted to be linear and much stronger than hydrogen bonds. To further understand the nature of these interactions, many theoretical methods, such as atoms in molecules, noncovalent interaction index, localized orbital locator, energy decomposition analysis, electron density difference, and electron spin densities, were employed. Compared with hydrogen bonds, halogen bonds have more open shell and covalent interaction components. Particularly, the formation of halogen bonds changes the ratio of different conformations, leading to spin density shift on certain atoms. The results reported herein will assist in the design of new functional probe...

A novel naphthalimide-based probe for highly sensitive and selective recognition of fluoride ion

Abstract: Considering the excessive ingestion of fluoride ion (F−) may result in many diseases, herein, by introducing 2-hydroxy-1-naphthaldehyde azine framework to 1,8-naphthalimide derivatives, we have developed a unique colorimetric/fluorometric probe (NYL) for detection of fluoride. The response of NYL toward F− is an integration of ESIPT and PET processes with a large stokes’ shift (173 nm). The striking color change from yellow to light-purple and fluorescent quenching of probe NYL can be observed only in the presence of fluoride ions. Furthermore, 1H NMR titration indicates the probe undergoes the deprotonation of hydroxyl through the Hydrogen-bond interaction between phenolic O H and F− ions.

Ion-pair recognition based on halogen bonding: a case of the crown-ether receptor with iodo-trizole moiety

Abstract: The development of halogen-bond-based ditopic receptors capable of binding simultaneously both a cation and an anion has attracted recent research interest. In this work, the crown-ether receptor 1, which consists of an iodo-trizole moiety for anion recognition through halogen bonding and a Lewis-basic center for cation binding, was investigated using density functional theory calculations. The structural and energetic features for the complexes of 1 with single cations, single halide anions, and ion pairs were explored. Intermolecular interactions in these complexes were systematically analyzed by the atoms in molecules and noncovalent interaction index methods. The presence of the coordinated cation significantly increases the anion-binding affinity, while the binding of halide anions has a slight influence on the cation-binding affinity. Anti-cooperative effects were found in the ion-pair recognition of 1, due to the strong attraction between the two counterions in the complexes. The solvent weakens the interaction strength considerably, and anti-cooperativity becomes very small in solvent. The results reported in this work are of fundamental importance in the design of ion-pair receptors based on halogen bonding.