title: Energy band gap and optical transition of metal ion modified double crossover DNA lattices.
abstract: We report on the energy band gap and optical transition of a series of divalent metal ion (Cu(2+), Ni(2+), Zn(2+), and Co(2+)) modified DNA (M-DNA) double crossover (DX) lattices fabricated on fused silica by the substrate-assisted growth (SAG) method. We demonstrate how the degree of coverage of the DX lattices is influenced by the DX monomer concentration and also analyze the band gaps of the M-DNA lattices. The energy band gap of the M-DNA, between the lowest unoccupied molecular orbital (LUMO) and the highest occupied molecular orbital (HOMO), ranges from 4.67 to 4.98 eV as judged by optical transitions. Relative to the band gap of a pristine DNA molecule (4.69 eV), the band gap of the M-DNA lattices increases with metal ion doping up to a critical concentration and then decreases with further doping. Interestingly, except for the case of Ni(2+), the onset of the second absorption band shifts to a lower energy until a critical concentration and then shifts to a higher energy with further increasing the metal ion concentration, which is consistent with the evolution of electrical transport characteristics. Our results show that controllable metal ion doping is an effective method to tune the band gap energy of DNA-based nanostructures.
authors.affiliation: Department of Physics and Sungkyunkwan Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University , Suwon 440-746, Korea.
authors.forename: Sreekantha Reddy
authors.initials: SR
authors.lastname: Dugasani
authors.forename: Taewoo
authors.initials: T
authors.lastname: Ha
authors.forename: Bramaramba
authors.initials: B
authors.lastname: Gnapareddy
authors.forename: Kyujin
authors.initials: K
authors.lastname: Choi
authors.forename: Junwye
authors.initials: J
authors.lastname: Lee
authors.forename: Byeonghoon
authors.initials: B
authors.lastname: Kim
authors.forename: Jae Hoon
authors.initials: JH
authors.lastname: Kim
authors.forename: Sung Ha
authors.initials: SH
authors.lastname: Park
mesh_terms: D003460:Crystallization; D004247:DNA / Q000737:chemistry*; D007477:Ions; D008670:Metals / Q000737:chemistry*; D018625:Microscopy, Atomic Force; D009690:Nucleic Acid Conformation; D055620:Optical Phenomena; D013816:Thermodynamics
chemical_list: D007477:Ions; D008670:Metals; D004247:DNA
keywords: DNA; HOMO−LUMO; M−DNA; energy band gap; lattices; optical transition