z Electro, Physical & Theoretical Chemistry Electronic Properties of Acetaminophen Adsorbed on 2D Clusters: A First Principles Density Functional Study Ujjal Saikia, [a, b] Nabanita Saikia,* [a] Kevin Waters, [a] Ravindra Pandey,* [a] and Munima Bora Sahariah [b] The interaction of acetaminophen (N-acetyl-para-aminophenol), a prominent analgesic and antipyretic, with 2D clusters was investigated using density functional theory with inclusion of van der Waals dispersion correction. The implicit solvation model with three different solvents; water, ethanol and carbon tetrachloride were utilized to observe the trends in binding energy as a function of solvent polarity. The calculated results demonstrate that interactions are not solely dependent on solvent polarity, but inherent properties of the 2D clusters drive the nature of the interaction; i. e. physisorbed states were favored for graphene, boron nitride (BN), and phosphorene, whereas a chemisorbed state is preferred for silicene. Analysis of the frontier orbitals and density of states (DOS) show that the acetaminophen functionalization induces mid-gap energy states in BN. Chemisorbed acetaminophen on silicene induces a 2p core level shift in silicon. The calculated results provide atomistic insights on the nature of interactions of acetamino- phen with the new class of 2D materials beyond graphene for potential sensing applications. Introduction Acetaminophen (N-acetyl-para-aminophenol), commonly known as paracetamol, is a widely prescribed analgesic and antipyretic medication administered for medium to severe pains related to backache, headache, arthritis and postoper- ative pains. [1–4] For acetylsalicylic acid (aspirin) sensitive patients, acetaminophen is a preferred therapeutic. [5] Long term admin- istration or overdose of acetaminophen can cause serious health issues which includes fatal hepatoxicity, nephrotoxicity, liver disorders, skin rashes, and inflammation of the pan- creas. [4, 7–8] The other cause of concern is the reported acetaminophen contamination in drinking water. A recent survey on pharmaceuticals in drinking water stressed the requirement of extensive research on health hazards associated with long-term exposure to low concentrations of pharmaceut- icals and/or combined effects of mixtures of pharmaceuticals. [9] Therefore, development of a viable method for the detection of acetaminophen in drinking water has become important to meet environment standards. Graphene, a single atomic thick 2D carbon allotrope has been foreseen as a versatile material for several applications, [10– 13] with significant potential as a sensor for hazardous gases, [14– 16] organic molecules, [17] bio- and chemotherapeutic drug molecules. [18] Recently, it has been shown that electrochemical detection of acetaminophen molecule is possible with electro- chemically reduced graphene (ERG) deposited onto a glassy carbon electrode (GCE). [19] Given the substantial applications of graphene, interest has been shifted to a new class of 2D nanomaterials like boron nitride (BN), silicene, and phosphorene. The sensing properties of BN has been reported using experimental and theoretical methods to investigate its applications as molecular sensors. [20– 24] Likewise, silicene, a buckled honeycombed structure of Si atoms is currently being considered as sensors for gas molecules like CO, NH 3 , NO, NO 2 . [25, 26] Unlike graphene which is stabilized by sp 2 hybridization along the carbon lattice, silicene is stabilized by a mixed sp 2 -sp 3 hybridization [27, 28] which leads to the puckered morphology. Phosphorene, is an sp 3 hybridized material [29] with a highly buckled morphology which is respon- sible for its anisotropic electronic properties. [30, 31] The novel aspects of 2D materials beyond graphene have provided the motivation to investigate the potential applica- tion of a few experimentally synthesized 2D materials as sensing materials for acetaminophen. In a recent study, the electronic and optical response of graphene based 2D nano- materials towards functionalization of pyrazinamide (PZA) [32] was investigated which highlighted the inherent properties of the nanomaterials governing the nature and extent of inter- action. In the present study, density functional theory (DFT) calculations were performed to investigate the response of graphene, boron nitride (BN), silicene and phosphorene towards acetaminophen in a solvated phase. The solvent phase is represented by the continuum model using the following solvents; water (H 2 O), ethanol (C 2 H 5 OH) and carbon tetrachlor- [a] U. Saikia, Dr. N. Saikia, K. Waters, Prof. R. Pandey Department of Physics Michigan Technological University Houghton, MI 49931-1295, USA Tel: 906–487-2086 Fax: 906–487-2933 E-mail: nsaikia@mtu.edu pandey@mtu.edu [b] U. Saikia, Dr. M. B. Sahariah Institute of Advanced Study in Science and Technology Guwahati 781035, Assam, India Supporting information for this article is available on the WWW under https://doi.org/10.1002/slct.201601593 Full Papers DOI: 10.1002/slct.201601593 3613 ChemistrySelect 2017, 2, 3613 – 3621  2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim