Two-dimensional supramolecular clusters and chains are observed upon submonolayer deposition of 1-nitronaphthalene (NN) onto reconstructed Au(111). The molecules become pseudochiral upon adsorption. Their handedness is determined from high-resolution scanning tunneling microscope images and local-density calculations. Modeling shows that hydrogen bonds cause the observed self-assembly. Clusters and chains mutually interact via electrostatic repulsion.