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:

N-[9-(ortho-Fluorobenzyl)-2-Phenyl-8-Azapurin-6-yl]-Amides as Potent and Selective Ligands for A1 Adenosine Receptors. A series of N-[9-(ortho-fluorobenzyl)-2-phenyl-8-azapurin-6-yl]-amides were synthesised and tested for their affinity toward A1 , A2A and A3 adenosine receptor subtypes. Biological results demonstrated that the introduction of a fluorine atom at the ortho position of the 9-benzyl group generally enhanced affinity toward A1 subtype and did not significantly affect A2A and A3 affinity. Very interesting is the compound bearing a meta-fluorophenyl substituent on the carbonyl carbon of the amide group, which shows significantly high A1 /A2A -A3 selectivity. Compounds of this new series, together with the previously published analogs without the fluorine atom on the 9-benzyl group, constituted the starting dataset for the development of QSAR models. The models obtained were able to rationally describe the affinity trends resulting from biological testing, and to enable investigation of the role of different substituents on the 8-azapurine scaffold, as well as the influence of the newly introduced fluorine atom on the benzyl moiety. The said QSAR models can also assist in the design of new compounds selectively active on A1 adenosine receptors. Furthermore, a molecular docking study was carried out in order to assess hypothetical binding mode of N-[9-(ortho-fluorobenzyl)-2-phenyl-8-azapurin-6-yl]-amides to A1 adenosine receptors. © 2013 John Wiley & Sons A/S.
{"Chemical": ["8-azapurine", "9-benzyl", "fluorine", "carbonyl carbon", "amide", "Adenosine", "benzyl", "N-[9-(ortho-Fluorobenzyl)-2-Phenyl-8-Azapurin-6-yl]-Amides", "N-[9-(ortho-fluorobenzyl)-2-phenyl-8-azapurin-6-yl]-amides", "meta-fluorophenyl", "adenosine"]}