2,2'-{(1E,1'E)-[Ethane-1,2-diylbis(aza-nylyl-idene)]bis-(methanylyl-idene)}bis-(4-iodo-phenol).

The title compound, C20H14I2N2O2, a di-iodo-Schiff base, crystallizes in space group Pbca with one mol-ecule per asymmetric unit. The mol-ecular structure reveals two intra-molecular O-H⋯N hydrogen bonds that give the mol-ecule a twisted structure with non-coplanar rings. In the crystal structure, the mol-ecular packing is stabilized by π-π stacking, hydrogen- and halogen-bonding (C-H⋯I; O⋯I) inter-actions.

Water-Soluble Sulfonate Schiff-Base Ligands as Fluorescent Detectors for Metal Ions in Drinking Water and Biological Systems.

The ability to detect and selectively identify trace amounts of metal ions is of major importance for drinking water identification and biological studies. Herein, we report a series of water-soluble Schiff-base ligands capable of being fluorescent and colorimetric sensors for metal ions. Upon coordination of the metal ion to the ligand, quenching of fluorescence is observed, typically in a 1:1 ratio. The selectivity of metal ions Cu2+, Ni2+, Cr3+, and Co2+ is exhibited via fluorescence quenching accompanied by colorimetric changes, whereas that of Ag+ and Co2+ is observed through colorimetric changes alone. Additionally, pH sensing studies were performed for the potential use of these ligands in biological applications.

Stereoinversion of Unactivated Alcohols by Tethered Sulfonamides.

The direct, catalytic substitution of unactivated alcohols remains an undeveloped area of organic synthesis. Moreover, catalytic activation of this difficult electrophile with predictable stereo-outcomes presents an even more formidable challenge. Described herein is a simple iron-based catalyst system which provides the mild, direct conversion of secondary and tertiary alcohols to sulfonamides. Starting from enantioenriched alcohols, the intramolecular variant proceeds with stereoinversion to produce enantioenriched 2- and 2,2-subsituted pyrrolidines and indolines, without prior derivatization of the alcohol or solvolytic conditions.

Chemical cross-linking of a variety of green fluorescent proteins as Förster resonance energy transfer donors for Yukon orange fluorescent protein: A project-based undergraduate laboratory experience.

Förster resonance energy transfer (FRET) is the basis for many techniques used in biomedical research. Due to its wide use in molecular sensing, FRET is commonly introduced in many biology, chemistry, and physics courses. While FRET is of great importance in the biophysical sciences, the complexity and difficulty of constructing FRET experiments has resulted in limited usage in undergraduate laboratory settings. Here, we present a practical undergraduate laboratory experiment for teaching FRET using a diverse set of green-emitting fluorescent proteins (FPs) as donors for a cross-linked Yukon orange FP. This laboratory experiment enables students to make the connection of basic lab procedures to real world applications and can be applied to molecular biology, biochemistry, physical chemistry, and biophysical laboratory courses. Published 2018. This article is a U.S. Government work and is in the public domain in the USA., 46(5):516-522, 2018.

Iron-catalyzed arene alkylation reactions with unactivated secondary alcohols.

A simple, iron-based catalytic system allows for the inter- and intramolecular arylation of unactivated secondary alcohols. This transformation expands the substrate scope beyond the previously required activated alcohols and proceeds under mild reaction conditions, tolerating air and moisture. Furthermore, the use of an enantioenriched secondary alcohol provides an enantioenriched product for the intramolecular reaction, thereby offering a convenient approach to nonracemic products.