You will be shown an abstract from a biomedical research paper. Given this abstract, your task is to extract all unique entities of the following types: ["Chemical"].

Please return the output as a JSON object of the format: {"Chemical": ["Arsenic", ...]}. The keys should be entity types and values should be lists of extracted entities belonging to the corresponding type. If you cannot find entities belonging to a specific type, the value should be [].

Only output the JSON object and do not include any additional text.

Abstract:

Carbon nanotube functionalization with carboxylic derivatives: a DFT study. Chemical functionalization of a single-walled carbon nanotube (CNT) with different carboxylic derivatives including -COOX (X=H, CH3, CH2NH2, CH3Ph, CH2NO2, and CH2CN) has been theoretically investigated in terms of geometric, energetic, and electronic properties. Reaction energies have been calculated to be in the range of -0.23 to -7.07 eV. The results reveal that the reaction energy is increased by increasing the electron withdrawing character of the functional groups so that the relative magnitude order is -CH2NO2>-CH2CN>-H>-CH2Ph>-CH3>-CH2NH2. The chemical functionalization leads to an increase in HOMO/LUMO energy gap of CNT by about 0.32 to 0.35 eV (except for -H). LUMO, HOMO, and Fermi level of the CNT are shifted to lower energies especially in the case of -CH2NO2 and -CH2CN functional groups. Therefore, it leads to an increment in work function of the tube, impeding the field electron emission.
{"Chemical": ["COOX", "CH2CN", "carbon", "Carbon", "CH2NH2", "CH3Ph", "CH2Ph", "carboxylic", "H", "CH3", "CH2NO2"]}