Synthesis and Supramolecular Assembly of Pentacyclic Dithienofluorene and Diselenophenofluorene Derivatives

Abstract

2,7-Diiodo-3,6-dibromofluorene and 2,7-dichloro-3,6-dibromofluorene have been successfully synthesized. The two key intermediates enable us to implement a regioselective Sonogashira reaction followed by intramolecular thiolate/acetylene cyclization, forming two regiospecific pentacyclic dithieno[2,3-b:7,6-b']fluorene (2,7-DTF) and dithieno[3,2-b:6,7-b']fluorene (3,6-DTF) isomeric molecules, respectively. By using a similar strategy, selenophene-based diselenopheno[2,3-b:7,6-b']fluorene (2,7-DSF) as well as diselenopheno[3,2-b:6,7-b']fluorene (3,6-DSF) were also prepared. The isomeric and sulfur/selenium effects determine the optical, electrochemical, and orbital properties. X-ray crystallography revealed that 2,7-DTF and 3,6-DTF molecules assemble into supramolecular helical structures.

Bigger and Brighter Fluorenes: Facile π‐Expansion, Brilliant Emission and Sensing of Nitroaromatics

“…3.1 eV) or much smaller than those of DTF/DSF derivatives (ca. 3.61 eV) reported earlier, indicative of the extensive π‐delocalization in these systems. Such wide band gap materials with brilliant blue emission are useful in white‐light generation with suitable dopants via fluorescence resonance energy transfer (FRET) mechanisms in OLEDs…”

“…The HOMO energy levels of 2 – 5 are slightly deeper (ca. 0.16–0.25 eV) than those of the previously reported thiophene/selenophene‐fused fluorenes (−5.60 to −5.75 eV), besides lowering of the LUMO energy levels (ca. 0.5–0.7 eV), which showcases the effect of extended π‐conjugation as well as the air‐stability gained by these systems .…”

“…300 nm and λ max (abs) of DTF/DSF in CHCl 3 is ca. 340 nm . To check whether the molecular properties (solution) of 1 – 5 are preserved in films, we carried out absorption spectral studies in an inert polymer, polystyrene (ps), matrix .…”

“…340 nm. [17] To check whethert he molecular properties (solution) of 1-5 are preserved in films, we carried out absorption spectral studies in an inert polymer,p olystyrene (ps), matrix. [29] The absorption spectrum of ps films of 1-5 (0.1 wt %) exhibited av ery similar behavior to their solutions in toluene; notably, 2 exhibited as light bathochromic shift (2-9 nm) when compared to other fluorenes (see the Supporting Information).…”

Side-chain modulation of dithienofluorene-based copolymers to achieve high field-effect mobilities

“…11 To this end, we recently designed and synthesized a fluorene-based dithieno[3,2- b :6,7- b ′]fluorene (DTF) in which the central fluorene is π-extended by fusing with two outer thiophene rings at its 2,3- and 6,7-junctions. 12 Structurally analogous to IDT, the pentacyclic DTF exhibits high coplanarity and rigidity which reduces the energetic disorder of the backbone and thus enhances 1-dimensional intramolecular charge transport. Furthermore, in comparison with the IDT unit having two dialkyl sp 3 -carbon bridges in the cyclopentadiene (CP) moieties, the singly dialkyl substituted CP ring in the middle of DTF would minimize the inter- and intramolecular steric hindrance between the aliphatic side chains attached to the polymer backbones, which is beneficial to the strength of the intermolecular interactions and maintenance of main-chain coplanarity.…”