**Enhancement of Haloperidol Binding Affinity to Dopamine Receptor via Forming a Charge-Transfer Complex with Picric Acid and 7,7,8,8-Tetracyanoquinodimethane for Improvement of the Antipsychotic Efficacy**

**Abdulhakeem S. Alamri 1,2 , Majid Alhomrani 1,2 , Walaa F. Alsanie 1,2, Hussain Alyami <sup>3</sup> , Sonam Shakya <sup>4</sup> , Hamza Habeeballah <sup>5</sup> , Abdulwahab Alamri <sup>6</sup> , Omar Alzahrani <sup>7</sup> , Ahmed S. Alzahrani <sup>2</sup> , Heba A. Alkhatabi 8,9,10 , Raed I. Felimban 8,11 , Abdulhameed Abdullah Alhabeeb <sup>12</sup>, Bassem M. Raafat <sup>13</sup>, Moamen S. Refat 14,\* and Ahmed Gaber 2,15,\***


**Abstract:** Haloperidol (HPL) is a typical antipsychotic drug used to treat acute psychotic conditions, delirium, and schizophrenia. Solid charge transfer (CT) products of HPL with 7,7,8,8 tetracyanoquinodimethane (TCNQ) and picric acid (PA) have not been reported till date. Therefore, we conducted this study to investigate the donor–acceptor CT interactions between HPL (donor) and TCNQ and PA (π-acceptors) in liquid and solid states. The complete spectroscopic and analytical analyses deduced that the stoichiometry of these synthesized complexes was 1:1 molar ratio. Molecular docking calculations were performed for HPL as a donor and the resulting CT complexes with TCNQ and PA as acceptors with two protein receptors, serotonin and dopamine, to study the comparative interactions among them, as they are important neurotransmitters that play a large role in mental health. A molecular dynamics simulation was ran for 100 ns with the output from AutoDock Vina to refine docking results and better examine the molecular processes of receptor–ligand interactions. When compared to the reactant donor, the CT complex [(HPL)(TCNQ)] interacted with serotonin and dopamine more efficiently than HPL only. CT complex [(HPL)(TCNQ)] with dopamine (CTtD)

**Citation:** Alamri, A.S.; Alhomrani, M.; Alsanie, W.F.; Alyami, H.; Shakya, S.; Habeeballah, H.; Alamri, A.; Alzahrani, O.; Alzahrani, A.S.; Alkhatabi, H.A.; et al. Enhancement of Haloperidol Binding Affinity to Dopamine Receptor via Forming a Charge-Transfer Complex with Picric Acid and 7,7,8,8-Tetracyanoquinodimethane for Improvement of the Antipsychotic Efficacy. *Molecules* **2022**, *27*, 3295. https://doi.org/10.3390/molecules 27103295

Academic Editors: Tanveer A. Wani, Seema Zargar and Afzal Hussain

Received: 3 April 2022 Accepted: 18 May 2022 Published: 20 May 2022

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showed the greatest binding energy value among all. Additionally, CTtD complex established more a stable interaction with dopamine than HPL–dopamine.

**Keywords:** charge transfer; haloperidol; π-acceptors; antipsychotics
