title: Optical Response of Terpyridine Ligands to Zinc Binding: A Close Look at the Substitution Effect by Spectroscopic Studies at Low Temperature.
abstract: Terpyridine (tpy) ligands are popular building blocks to bind metal ions. Several tpy ligands with different substituents were synthesized and examined for their binding with zinc cation. The study revealed a large substituent effect on the zinc binding-induced fluorescence quenching. With the aid of a liquid nitrogen Dewar, the tpy molecules were frozen to their ground-state conformation, preventing (or minimizing) molecular reorganization in the photoinduced excited state. This allowed us to detect the fluorescence spectra from the locally excited state (having a minimum of charge transfer interaction) and the temperature-dependent fluorescence. The fluorescence response to low temperature provided useful information about the intramolecular charge transfer (ICT) interaction between the donor and acceptor groups. Furthermore, a strong donor substituent (such as Me2N) played an essential role in observed fluorescence quenching. The study also provides a useful example to elucidate the ICT mechanism by using low-temperature fluorescence spectroscopy.
authors.affiliation: Department of Chemistry & Maurice Morton Institute of Polymer Science, The University of Akron , Akron, Ohio 44325, United States.
authors.forename: Xiaoman
authors.initials: X
authors.lastname: Bi
authors.affiliation: Department of Chemistry & Maurice Morton Institute of Polymer Science, The University of Akron , Akron, Ohio 44325, United States.
authors.forename: Yi
authors.initials: Y
authors.lastname: Pang
mesh_terms: D001665:Binding Sites; D002413:Cations, Divalent / Q000737:chemistry; D003080:Cold Temperature; D005453:Fluorescence; D008024:Ligands; D008958:Models, Molecular; D011725:Pyridines / Q000737:chemistry*; D013050:Spectrometry, Fluorescence; D013696:Temperature; D015032:Zinc / Q000737:chemistry*
chemical_list: C512247:2,3',6',3''-terpyridine; D002413:Cations, Divalent; D008024:Ligands; D011725:Pyridines; D015032:Zinc