Symmetrically Backfolded Molecules Emulating the Self-Similar Features of Sierpinski Triangle

Novel branching motif in hierarchical self-similar molecules: we present an under-explored class of molecules featuring striking geometric resemblance to the famous fractal of Sierpinski triangle. Unlike the more traditional, starburst dendrimers, the centripetal-shaped Sierpinski molecules feature side branches symmetrically bent away from the growth direction of the main branch, thus contrasting the natural-tree shape. Molecule G3 exhibits three distinct levels of structural hierachy comprising the primary, secondary and tertiary branches, while the smaller G2 contains only features of the 1^st and 2^nd orders. In spite of the much larger conjugated backbone of G3, its UV-vis absorption remains little shifted in wavelength compared to G2, while the emission of G3 is curiously blue-shifted by over 50 nm from that of G2.