Figure 12. The 1:1 hydrogen bond equilibrium between a donor molecule 4-fluorophenol (highlighted in blue) and the acceptor molecule acetone (highlighted in red) forming a donor-acceptor complex

From

It Is Important to Compute Intramolecular Hydrogen Bonding in Drug Design?

María J. R. Yunta

American Journal of Modeling and Optimization. 2017, 5(1), 24-57 doi:10.12691/ajmo-5-1-3