Torsionally Responsive Tropone-Fused Conjugated Polymers

Abstract

Torsionally responsive molecular systems can change their electronic properties according to the dihedral angles and can be utilized as sensory materials. We have designed and synthesized novel tropone-fused conjugated polymers PBTr, PBTr-T, and PBTr-Tz that showed interesting dihedral-angledependent variations in UV−vis absorptions. Tropone-fused thiophene derivatives were prepared from one-step condensation of thiophene-3,4-dialdehyde and aliphatic ketones via a modular, facile, and high-yielding method. Subsequent halogenation and Stille cross-coupling polymerization with a bis(stannyl)benzodithiophene resulted in a tropone-fused conjugated polymer PBTr. We were also able to prepare thiophene-and thiazolebridged polymers, PBTr-T and PBTr-Tz, respectively, using similar synthetic methods. Electronic absorptions of the newly synthesized PBTrs were measured in solutions and in films states. Substantial red-shifts occurred in the case of thiophene-bridged PBTr-T, whereas almost no shift was observed for thiazolebridged PBTr-Tz. We attributed this to the substantial change in the torsional angle between the tropone-fused thiophene moiety and thiophene, which was further supported by density functional theory (DFT) calculations. Similar spectral changes of UV−vis absorptions were observed when a poor solvent (methanol) was introduced to a chloroform solution of PBTr-T. Reverse torsional angle variations were realized with initially planar PBTr-Tz by introducing steric hindrance through protonation on the thiazole rings. We believe that torsionally responsive tropone-fused conjugated polymers are promising as novel platforms for sensory applications.

A Highly Crystalline and Wide-Bandgap Polydiarylfluorene with β-Phase Conformation toward Stable Electroluminescence and Dual Amplified Spontaneous Emission

“…Results of the computation performed via the density functional theory (DFT) method at the B3LYP/6-31d (g) level (the methyl was used instead of the octyl, for the sake of simplification) revealed that the most stable torsional angles energetically are ∼36° and ∼142° (Figure c), which correspond to the amorphous state. Moreover, an energy difference of 1.32 kcal/mol between angles of 142° and 165° indicated that a planar conformation can be realized flexibly with a low energy barrier during the conformational transition. , As shown in Figure d, various contents of β-phase films were prepared through the following steps: the pristine films without β-phase were spin-coated on quartz substrates from chloroform solution (10 mg/mL) at a spin rate of 1000 rpm for 30 s. Increasing contents of β-phase films were obtained by adjusting the annealing temperature from 180 °C to 240 °C, and the annealing time was 5 min, respectively. The corresponding UV-vis spectra are shown in Figure S4 in the Supporting Information, and only when the films were treated at a temperature above 210 °C could we observe the well-split peak at 440 nm, which further confirmed that a significant conformational transition region exists at ∼210 °C for the β-phase.…”

Heterophenoquinones: Tuning Optoelectronics and Electrochromicity

“…combining the synthesis of thioquinones by Takahashi and the synthesis of the tropone moiety by Bordwell [19,20,23] . The tropones were generated by an aldol condensation of thiophene‐3,4‐dicarbonyl with symmetrically functionalized ketones bearing alkyl groups, fluorine or (hetero)aromatic systems, which tune the optoelectronics of the targets [23a,24] . Iodination of the heteroazulene derivatives furnished diiodides 1 a – e (Scheme 1a).…”

Novel Water-Soluble Cyclodextrin-Based Conjugated Polymer for Selective Host–Guest Interactions of Cationic Surfactant CTAB and Reverse FRET with Rhodamine B Tagged Adamantyl Guest

“…Furthermore, advantageous properties associated with conjugated polymers over small molecules can be derived through the collective properties of conjugated polymers, which are sensitive toward very minor perturbation conditions due to either the alterations into their microenvironments or the presence of guest analytes. Therefore, there are several reports on the utilization of conjugated polymers as sensory materials with high transduction signals gained through efficient exciton energy migrations along their backbones by employing various analytes with electron or energy donating or accepting capabilities. − The utilization of CD units in conjugated polymers as pendant group has been less explored, and thus up to date few examples can be found in the literature, where such polymers were utilized for the selective recognitions of adamantly derivatives and as polyrotaxanes. − In addition, there are few examples of utilizing rhodamines as a donor in the FRET donor–acceptor pairs. − Therefore, further investigations utilizing rhodamine as a donor are still required. As reported in the literature, the inclusion complexation of RhB bearing adamantyl guest demonstrated energy transfer via spirocyclic ring switching in the presence of metal ion.…”