New position-dependent conjugated hydrocarbon dyes containing a pyrene core and multi-fluorene moieties 3 have been synthesized and characterized by H-1/C-13 NMR spectroscopy, as well as by optical and theoretical studies. The solubility of mono-, bis- and tetra-fluorenyl-pyrene 3 tends to decrease and leads to varied thermal properties. The results of the optical studies and DFT calculations revealed that the energy gap can be easily modified or fine-tuned by either varying the substituent number or position. Remarkably, such pyrene-fluorene materials exhibited deep blue fluorescence (lambda(max) = 400-458 nm in CH2Cl2) with excellent quantum yields (approximate to 78%). These results suggest that these new pyrene-fluorene derivatives have potential application in OLED technology as blue host materials. (C) 2015 Elsevier B.V. All rights reserved.