Selectivity of Br/Li Exchange and Deprotonation of 4,4′-Dibromo-3,3′-bithiophene for Synthesis of Symmetrical and Unsymmetrical Dithienoheteroaromatic Rings

The novel selective synthesis of symmetrical and unsymmetrical dithienoheteroaromatic rings (<b>DTHA</b>s) has been developed via intramolecular cyclization of 4,4′-dibromo-3,3′-bithiophene (<b>3</b>). Four reaction conditions including <i>n</i>-BuLi/Et₂O, <i>n</i>-BuLi/THF, <i>s</i>-BuLi/Et₂O, and <i>t</i>-BuLi/Et₂O were employed to react with <b>3</b> for selective formation of two types of dicarbanions, which generate the symmetrical and unsymmetrical <b>DTHA</b>s after quenching with three electrophilic reagents (<b>4a</b>–<b>c</b>). The possible mechanism of formation of <b>DTHA</b>s was proposed. In addition, two unsymmetrical <b>DTHA</b>s were confirmed by X-ray single-crystal analyses

Planar Heptathienoacenes Based on Unsymmetric Dithieno­[3,2‑<i>b</i>:3′,4′-d]­thiophene: Synthesis and Photophysical Properties

The unsymmetric dithieno­[3,2-<i>b</i>:3′,4′-<i>d</i>]­thiophene (<i><b>ts</b></i><b>-DTT</b>) was efficiently synthesized, and two novel hepta­thieno­acenes with linear and bull’s horn shapes were designed and prepared via different ring cyclization connection manners. All intermediates and aimed hepta­thieno­acenes were fully characterized by ¹H NMR, ¹³C NMR, and HRMS. Their UV–vis absorption behavior, fluorescence, and electrochemical properties are characterized. In addition, DFT quantum calculation was employed to further understand the electron distribution and the origin of the absorption bands

Selectivity of Br/Li Exchange and Deprotonation of 4,4′-Dibromo-3,3′-bithiophene for Synthesis of Symmetrical and Unsymmetrical Dithienoheteroaromatic Rings

The novel selective synthesis of symmetrical and unsymmetrical dithienoheteroaromatic rings (<b>DTHA</b>s) has been developed via intramolecular cyclization of 4,4′-dibromo-3,3′-bithiophene (<b>3</b>). Four reaction conditions including <i>n</i>-BuLi/Et₂O, <i>n</i>-BuLi/THF, <i>s</i>-BuLi/Et₂O, and <i>t</i>-BuLi/Et₂O were employed to react with <b>3</b> for selective formation of two types of dicarbanions, which generate the symmetrical and unsymmetrical <b>DTHA</b>s after quenching with three electrophilic reagents (<b>4a</b>–<b>c</b>). The possible mechanism of formation of <b>DTHA</b>s was proposed. In addition, two unsymmetrical <b>DTHA</b>s were confirmed by X-ray single-crystal analyses

Selectivity of Br/Li Exchange and Deprotonation of 4,4′-Dibromo-3,3′-bithiophene for Synthesis of Symmetrical and Unsymmetrical Dithienoheteroaromatic Rings

The novel selective synthesis of symmetrical and unsymmetrical dithienoheteroaromatic rings (<b>DTHA</b>s) has been developed via intramolecular cyclization of 4,4′-dibromo-3,3′-bithiophene (<b>3</b>). Four reaction conditions including <i>n</i>-BuLi/Et₂O, <i>n</i>-BuLi/THF, <i>s</i>-BuLi/Et₂O, and <i>t</i>-BuLi/Et₂O were employed to react with <b>3</b> for selective formation of two types of dicarbanions, which generate the symmetrical and unsymmetrical <b>DTHA</b>s after quenching with three electrophilic reagents (<b>4a</b>–<b>c</b>). The possible mechanism of formation of <b>DTHA</b>s was proposed. In addition, two unsymmetrical <b>DTHA</b>s were confirmed by X-ray single-crystal analyses

Naphthotetrathiophene-Based Helicene-Like Molecules: Synthesis and Photophysical Properties

Two novel helicene-like molecules based on naphthotetrathiophene are successfully synthesized. All target molecules and intermediates are characterized by ¹H NMR, ¹³C NMR, IR, and HRMS. Their electrochemical and photophysical properties are studied. The configurations of the molecules are optimized by DFT quantum calculations and UV–vis behaviors are also predicted to further understand the origin of different absorption bands. We believe the current work illustrated an efficient way for the design and synthesis of sophisticated structures with naphthotetrathiophene as building blocks

Synthesis of Dendrimers Based on Tetrakis(thiophene-2-yl)ethene as New Dendron

Two novel dendrimers, <b>16T</b> and <b>20T</b>, based on 1,1,2,2-tetra(thiophen-2-yl)ethene (<b>4T</b>) as a new dendron, were efficiently synthesized via carbonylation, Suzuki, and McMurry reactions. All intermediates and title compounds were fully characterized by ¹H NMR, ¹³C NMR, and HRMS. <b>4T</b> and <b>16T</b> were confirmed by X-ray single crystal analyses. In addition, the absorption behaviors of two titled dendrimers are also described

Synthesis of Dendrimers Based on Tetrakis(thiophene-2-yl)ethene as New Dendron

Two novel dendrimers, <b>16T</b> and <b>20T</b>, based on 1,1,2,2-tetra(thiophen-2-yl)ethene (<b>4T</b>) as a new dendron, were efficiently synthesized via carbonylation, Suzuki, and McMurry reactions. All intermediates and title compounds were fully characterized by ¹H NMR, ¹³C NMR, and HRMS. <b>4T</b> and <b>16T</b> were confirmed by X-ray single crystal analyses. In addition, the absorption behaviors of two titled dendrimers are also described

Two-Dimensional Conjugated Polymer Based on sp²‑Carbon Bridged Indacenodithiophene for Efficient Polymer Solar Cells

Molecular electronic structure plays a vital role in the photovoltaic performances in polymer solar cells (PSCs) due to their influences on light-harvesting, charge carrier transfer, π–π stacking, etc. Indacenodithiophene as a star unit has been well studied in PSCs; various structural derivation methods have been tried, but they are still not efficient in improvement of power conversion efficiencies (PCE) due to the narrow optical absorptions. In this contribution, a novel planar DMIDT with extended lateral π-electron delocalization is efficiently synthesized via introduction of sp² hybrid carbons as the bridge atoms. Based on this novel building block, a two-dimensional conjugated polymer PDMIDT-TPD is prepared, and the unique structure improves the conjugation at the lateral direction, enlarges the electron delocalization area, and greatly broadens the absorption spectrum with a full coverage from 350 to 700 nm. Finally, a PCE of 8.26% is achieved when blended with PC₇₁BM, which is the highest result among the IDT-based polymer donors. Meanwhile, PDMIDT-TPD also presents good compatibility with the non-fullerene acceptor, and a preliminary PCE of 6.88% is obtained. In all, this work not only provides an excellent donor material but also offers a general and simple derivation strategy for fused aromatic building blocks

Two-Dimensional Conjugated Polymer Based on sp²‑Carbon Bridged Indacenodithiophene for Efficient Polymer Solar Cells

Molecular electronic structure plays a vital role in the photovoltaic performances in polymer solar cells (PSCs) due to their influences on light-harvesting, charge carrier transfer, π–π stacking, etc. Indacenodithiophene as a star unit has been well studied in PSCs; various structural derivation methods have been tried, but they are still not efficient in improvement of power conversion efficiencies (PCE) due to the narrow optical absorptions. In this contribution, a novel planar DMIDT with extended lateral π-electron delocalization is efficiently synthesized via introduction of sp² hybrid carbons as the bridge atoms. Based on this novel building block, a two-dimensional conjugated polymer PDMIDT-TPD is prepared, and the unique structure improves the conjugation at the lateral direction, enlarges the electron delocalization area, and greatly broadens the absorption spectrum with a full coverage from 350 to 700 nm. Finally, a PCE of 8.26% is achieved when blended with PC₇₁BM, which is the highest result among the IDT-based polymer donors. Meanwhile, PDMIDT-TPD also presents good compatibility with the non-fullerene acceptor, and a preliminary PCE of 6.88% is obtained. In all, this work not only provides an excellent donor material but also offers a general and simple derivation strategy for fused aromatic building blocks

Synthesis and Characterization of Cyclooctatetrathiophenes with Different Connection Sequences

Based on the selectivity of deprotonation of 5,5′-bistrimethylsilyl-2,3′-bithiophene (<b>4</b>) in the presence of <i>n</i>-BuLi, three new cyclooctatetrathiophenes (<b>COTh</b>s), <b>COTh-1</b>, <b>COTh-2</b>, and <b>COTh-3</b> have been efficiently developed via intermolecular or intramolecular cyclizations. Their crystal structures clearly show that the different connectivity sequence of the thiophene rings in the molecules. The CV data and UV–vis absorbance spectra of <b>COTh</b>s are also described. In addition, the time-dependent density functional theory (TDDFT) calculations accurately reproduce experimental observations and afford band assignment