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:

(4,4')-Bipyridine in vacuo and in solvents: a quantum chemical study of a prototypical floppy molecule from a molecular transport perspective. We report results of quantum chemical calculations for the neutral and anionic species of (4,4')-bipyridine (44BPY), a prototypical molecule with a floppy degree of freedom, placed in vacuo and in solvents. In addition to equilibrium geometries and vibrational frequencies and spectra, we present adiabatic energy curves for the vibrational modes with significant intramolecular reorganization upon charge transfer. Special attention is paid to the floppy strongly anharmonic degree of freedom of 44BPY, which is related to the most salient structural feature, namely the twist angle θ between the two pyridine rings. The relevance of the present results for molecular transport will be emphasized. We show that the solvent acts as a selective gate electrode and propose a scissor operator to account for solvent effects on molecular transport. Our result on the conductance G vs. cos(2)θ is consistent with a significant transmission in perpendicular conformation indicated by previous microscopic analysis.
{"Chemical": ["pyridine", "44BPY", "(4,4\u0027)-bipyridine", "(4,4\u0027)-Bipyridine"]}