Investigations on the bottom-up fabrication of graphene with 1,3,5-triphenylbenzene as precursor on Ru(0 0 0 1) was carried out using scanning tunneling microscopy (STM) and density functional theory (DFT) calculations. Upon annealing 1,3,5-triphenylbenzene overlayer on Ru(0 0 01) at 550 degrees C, the precursors dehydrogenated and coalesced into graphitized flakes, and subsequent annealing up to 600 degrees C results in complete graphene conversion. The migration behavior and close-packing morphology of precursors were captured during STM measurements, and DFT calculations indicated that the inter-molecular interaction is responsible for the accumulation and close-packing of the precursors. The noticeable increment in the dehydrogenation barrier from 1.27 eV for monomer adsorption to 1.62 eV for dimer adsorption is well consistent with the observed drastic reduction of the graphitization temperature at lower precursor coverage, suggesting the crucial influence of inter-molecular vdW interaction on the dehydrogenation process. (C) 2016 Elsevier B.V. All rights reserved.