Rigidly Tethered Bis‐phosphoric Acids: Generation of Tunable Chiral Fluorescent Frameworks and Unexpected Selectivity for the Detection of Ferric Ions

• Published in: Chemistry : a European journal 2017-07, Vol.23 (42), p.10058-10067
• Main Authors: Octa‐Smolin, Frescilia, Mitra, Raja, Thiele, Maike, Daniliuc, Constantin G., Stegemann, Linda, Strassert, Cristian, Niemeyer, Jochen
• Format: Article
• Language: English
• Subjects: Acids; Cadmium; Chemical synthesis; Chemistry; Ferric ions; Fluorescence; Ions; Iron; Metal ions; Phosphoric acid; phosphoric acids; Quenching; Selectivity; Self-association; sensors; Spectroscopy; supramolecular chemistry
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.201700954

We describe the straightforward synthesis of a series of bis‐phosphoric acids (R,R)‐1 a–d, featuring two chiral 1,1′‐binaphthyl‐phosphoric acid units that are tethered by rigid, π‐conjugated linkers. The nature of the linker has a profound influence on the properties of the bis‐phosphoric acids, such as their self‐association behavior and their interaction with metal ions. This led to the identification of one preferred bis‐phosphoric acid (R,R)‐1 d, which shows selective fluorescence quenching in the presence of ferric ions (Fe3+). Thus, (R,R)‐1 d could be applied for the detection of Fe3+, even in the presence of a variety of other metal ions. The chiral nature of the bis‐phosphoric acid enables the interaction with Fe3+ to be followed by CD spectroscopy, providing a complementary detection mode with the same probe. Iron turns me off: The preparation and analysis of a series of rigidly tethered 1,1′‐binaphthyl‐phosphoric acids led to the identification of a novel probe for ferric ions (see figure). The presence of Fe3+ can be detected by means of CD or fluorescence spectroscopy with high chemoselectivity.