Fluorescent and Electroactive Monoalkyl BTD-Based Liquid Crystals with Tunable Self-Assembling and Electronic Properties

Abstract

We report here on a series of redox active benzothiadiazole-based luminophores functionalized on one edge with a phenyl-nonyl substituent, which confers these molecules a rodlike shape and a tendency to self-assemble into layered superstructures. On the other edge, the molecules are endowed with different p-substituted phenyl rings, which allows the modulation of their redox and optical properties on the basis of the electronic nature of the terminal substituents. We have found that just one lateral alkyl chain is sufficient to induce mesomorphism in these molecules, which present nematic or smectic mesophases upon thermal treatment. Single-crystal analysis allows us to get an insight into the nature of the forces responsible for different supramolecular assemblies in these derivatives, and point to a strong contribution of the terminal groups in the different arrangements observed. The interesting redox and optical properties together with their self-assembling tendencies render these new materials interesting candidates for optoelectronics.

Electrochemical and Solvent‐Mediated Visible‐to‐Near‐Infrared Spectroscopic Switching of Benzoselenadiazole Fluorophores

“…The same trend can be derived between 2 and its structurally similar 5. [17] In this series, the emission of the selenium counterpart is red-shifted by 85 nm relative to its sulfur counterparti nb oth dichloromethane and THF,a nd red-shifted by 75 nm in hexane. The larger Stokess hift observed with 1 implies that its exciteds tate is more polar than its sulfur counterpart 4.I ng eneral, the emission of 1 and 2 can be tuned with solvent polarity with broad emissions spanning the visible to the NIR regions being possible.…”

“…The symmetric 3 was obtained in ao ne-step coupling reaction by applying synthetic protocols similar to known methods. [15,17] Unequivocal confirmation of the fluorophore structure is possible by single crystal X-ray diffraction. This methoda lso provides key information about the packing andi nteractions between molecules that occur in the solid state.…”

“… Synthetic scheme for the preparation of the benzoselenadiazole derivatives 1 – 3 examined in this study„ and the numbering scheme for their previously representative benzothiadiazole counterparts 4 – 6 [12a, 17] against which to benchmark both their spectroscopic and electrochemical properties.…”

Donor–Acceptor–Donor Copolymers with 3,4-Ethylenedioxythiophene Moiety: Electropolymerization and Effect on Optoelectronic and Electrochromic Properties

“…Recently, copolymers have attracted significant interest due to their tunable physical and chemical properties, namely, band gap, highest occupied molecular orbital (HOMO), lowest unoccupied molecular orbital (LUMO), optical absorption, morphology, solubility, stability, etc. 8 It is also noted that nowadays a large variety of donor and acceptor units are available for tuning the optoelectronic properties. 9 Among them, thiophene (Th), benzothiadiazole (BTZ), and their derivatives have been the most used chromophores for the synthesis of DAD conjugated polymer.…”

“…28,29 Although, the DAD polymer has interesting optoelectronic properties for different possible applications. 8,30 According to the recent investigation, regio-irregular polymer synthesized from the unsymmetrical monomer unit enhances the charge-transport properties. 31 Thus, these results created our interest to consider the three unsymmetrical DAD monomer units M1 – M3 for electrochemical copolymerization with EDOT moiety (Scheme 1).…”