The even double helicenes with 4-12 phenyl groups in each helix were examined at B3LYP-D3/6-311G (d). The double helicenes with 4-10 phenyl rings are less than twice as strained as their component helicenes; the strain results from twisting about the shared naphthyl moiety, with accompanying loss of aromaticity. These compounds should be reasonable synthetic targets, and computed NMR shifts are provided to aid in their characterization. (C) 2016 Elsevier B. V. All rights reserved.