Modifying a graphene layer by a thymine or a uracil nucleobase: DFT studies Mahmoud Mirzaei a,⇑ , Saeedeh Ravi b , Mohammad Yousefi c a Laboratory of Nano Computations (LNC), Department of Nanotechnology, Pharmaceutical Sciences Branch, Islamic Azad University, Tehran, Iran b Young Researchers Club, Pharmaceutical Sciences Branch, Islamic Azad University, Tehran, Iran c Department of Chemistry, Shahre-Rey Branch, Islamic Azad University, Tehran, Iran article info Article history: Received 23 April 2012 Received in revised form 13 May 2012 Accepted 16 May 2012 Available online 23 May 2012 Keywords: Graphene Thymine Uracil Density functional theory Nano-bio hybrids abstract The hybridizations of a graphene layer by a thymine and a uracil nucleobase have been investigated by performing density func- tional theory (DFT) calculations. The isolated and hybrid structures have been firstly stabilized to reach the minimum energy and the electronic properties have been subsequently evaluated for the optimized structures. The structural and atomic scale parameters indicated that the tip of graphene is important in determining the properties of new hybrids. Moreover, different effects of thymine and uracil nucleobases have been identified in the hybrid structures. Quadrupole coupling constants have been evaluated to characterize the atomic scale properties, in which the most notable effects of hybridizations have been observed for the atoms close to the linking regions whereas negligible effects have been seen for other atoms. Ó 2012 Elsevier Ltd. All rights reserved. 1. Introduction Graphene, one type of nano-structures, is an isolated mono layer from the graphite with sp 2 hybrid- ization for carbon atoms [1]. Free-standing structures of graphene have been also synthesized [2]. The single or multi wall carbon nanotubes (CNTs) could be also constructed by rolling one or more layers of graphene [3]. The planar nature of graphene makes it a proper material for several applications in the fields of surface sciences, etc. [4]. However, its hydrophobic property is an obstacle for the use of graphene in the watery media [5]. To overcome this deficiency, the layers could be modified by 0749-6036/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.spmi.2012.05.010 ⇑ Corresponding author. Tel.: +98 912 8117305. E-mail address: mdmirzaei@iaups.ac.ir (M. Mirzaei). Superlattices and Microstructures 52 (2012) 306–311 Contents lists available at SciVerse ScienceDirect Superlattices and Microstructures journal homepage: www.elsevier.com/locate/superlattices