title: Synthesis, optical properties, and electronic structures of nucleobase-containing π-conjugated oligomers.
abstract: The molecular recognition properties of the nucleobases instruct the formation of complex three-dimensional architectures in natural and synthetic systems; relatively unexplored is their use as building blocks for π-conjugated materials where they might mutually tune electronic and supramolecular structures. Toward this goal, an introductory set (1a-d and 2a-d) of six purine-terminated and two pyrimidine-terminated π-conjugated oligomers has been synthesized and used to develop experimental electronic and photophysical structure-property trends. Unlike 2,2':5',2″-terthiophene (TTT) derivatives 2a-d, intramolecular charge transfer dominates oligomers 1a-d bearing a 4,7-bisthienylbenzothiadiazole (TBT) spacer due to the strong electron-accepting ability of its benzothiadiazole (BTD) ring. The resulting donor-acceptor-donor systems feature lower HOMO-LUMO gaps than the terthiophene-linked nucleobases (ΔE(g) ∼ 1.8 eV vs 2.4 eV based on electrochemical measurements), and the lowest so far for π-conjugated molecules that include nucleobases within the π-framework. Experiments reveal a dependence of photophysical and electronic structure on the nature of the nucleobase and are in good agreement with theoretical calculations performed at the B3LYP/6-31+G** level. Overall, the results show how nucleobase heterocycles can be installed within π-systems to tune optical and electronic properties. Future work will evaluate the consequences of these information-rich components on supramolecular π-conjugated structure.
authors.affiliation: Department of Chemistry, University of Florida , P.O. Box 117200, Gainesville, Florida 32611, United States.
authors.forename: Raghida
authors.initials: R
authors.lastname: Bou Zerdan
authors.forename: Pamela
authors.initials: P
authors.lastname: Cohn
authors.forename: Egle
authors.initials: E
authors.lastname: Puodziukynaite
authors.forename: Matthew B
authors.initials: MB
authors.lastname: Baker
authors.forename: Maud
authors.initials: M
authors.lastname: Voisin
authors.forename: Céline
authors.initials: C
authors.lastname: Sarun
authors.forename: Ronald K
authors.initials: RK
authors.lastname: Castellano
mesh_terms: D004583:Electrons; D006571:Heterocyclic Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D008958:Models, Molecular; D015394:Molecular Structure; D020135:Peptide Nucleic Acids / Q000138:chemical synthesis / Q000737:chemistry; D011789:Quantum Theory; D013830:Thiadiazoles / Q000138:chemical synthesis* / Q000737:chemistry; D013876:Thiophenes / Q000138:chemical synthesis* / Q000737:chemistry
chemical_list: D006571:Heterocyclic Compounds; D020135:Peptide Nucleic Acids; D013830:Thiadiazoles; D013876:Thiophenes; C015700:benzo-1,2,3-thiadiazole