All the tested anthracenes showed similar absorption profiles and their molar absorption coefficients (ε, M -1 cm -1 ) were found in the range 15000 ± 1500 for PABA, PFPA and PCPA, and about 28000 for DIPA (Figure ). Interestingly, shifting from two aromatic substituents (PABA, Amax = 375 nm) to one aromatic and one alkynyl group (PCPA, PFPA, Amax = 391 nm) and lastly to the two alkynyl groups (DIPA Amax = 431 nm), a bathochromic shift was observed in the absorption spectra, reflecting the effect of the extended conjugation on the aromaticity of these compounds.