Novel azo octupoles with large first hyperpolarizabilitiesElectronic supplementary information (ESI) is available: molar absorptivity spectra of 1a,d,e, P1 and P2 in THF and plots of I2ω vs. number density for 1a,d,e and 2a,c,e in THF at 1064 nm. See http://www.rsc.org/suppdata/jm/b3/b300777d/

Novel two-dimensional octupoles containing azo groups and their oligomers have been synthesized and their first hyperpolarizabilities were determined. The λmax and β(0) values of azo octupoles are nearly the same regardless of the nature of the bridge or the conjugation length. On the other hand, 1,3,5-tricyano-2,4,6-tris[4-(p-diethylaminostyryl)styryl]benzene has a larger β(0) value than the corresponding azo analogue probably due to the more efficient conjugation ability of CC compared with the NN bond. The β(0)/MW of the octupoles are larger than the corresponding dipoles, whereas those of the azo octupoles are comparable to the latter. Also, retention of monomeric β(0) is observed in the octupolar oligomers.