m,m- and p,p-Cyclobis(biphenylphenylene) as the all-hydrocarbon neutral analogues of m,m-CBPQT4+ and the Bluebox: synthesis, structures, and photophysical properties.

m,m-CBPP and p,p-CBPP, neutral analogues of m,m-CBPQT4+ and the Bluebox, were synthesized via platinum-mediated homocoupling. The concave m,m-isomer and convex p,p-isomer display distinct ring strain and weak orbital interactions, with the latter showing a narrowed HOMO-LUMO gap and a red-shifted UV absorption, highlighting how connectivity governs cyclophane properties.