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Publication Abstract from PubMed

When strands of DNA encapsulate silver clusters, supramolecular optical chromophores develop. However, how a particular structure endows a specific spectrum remains poorly understood. Here, we used neutron diffraction to map protonation in (A(2)C(4))(2)-Ag(8), a green-emitting fluorophore with a "Big Dipper" arrangement of silvers. The DNA host has two substructures with distinct protonation patterns. Three cytosines from each strand collectively chelate handle-like array of three silvers, and calorimetry studies suggest Ag(+) cross-links. The twisted cytosines are further joined by hydrogen bonds from fully protonated amines. The adenines and their neighboring cytosine from each strand anchor a dipper-like group of five silvers via their deprotonated endo- and exocyclic nitrogens. Typically, exocyclic amines are strongly basic, so their acidification and deprotonation in (A(2)C(4))(2)-Ag(8) suggest that silvers perturb the electron distribution in the aromatic nucleobases. The different protonation states in (A(2)C(4))(2)-Ag(8) suggest that atomic level structures can pinpoint how to control and tune the electronic spectra of these nanoscale chromophores.

Mapping H(+) in the Nanoscale (A(2)C(4))(2)-Ag(8) Fluorophore.,David F, Setzler C, Sorescu A, Lieberman RL, Meilleur F, Petty JT J Phys Chem Lett. 2022 Dec 8;13(48):11317-11322. doi: , 10.1021/acs.jpclett.2c03161. Epub 2022 Dec 1. PMID:36453924^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.