Tuning the antiaromatic character and charge transport of pentalene-based antiaromatic compounds by substitution

Abstract

Understanding structure−property relationships in antiaromatic molecules is crucial for controlling their electronic properties and designing new organic optoelectronic materials. Here we report the design, synthesis, and characterization of three new...

Increased Antiaromaticity through Pentalene Connection in [n]Cyclo-1,5-dibenzopentalenes

“…12−15 Depending on how DBP is incorporated into more extended π-systemsthrough the 5,10-positions at the five-membered rings or the 2,7-positions at the sixmembered rings (see atom numbering in Scheme 1)its antiaromaticity, conjugation, and electronic character can be influenced. 16,17 This has been demonstrated in not only small molecule DBPs 17 but also in DBP-based conjugated polymers, where a change in this connecting pattern altered their electronic properties. 18 Conjugation through the 5,10positions has a stronger influence on the LUMO energies, 19 while substituents in the 2,7-positions more strongly influence the HOMO energy.…”

“…Using polycyclic aromatic hydrocarbons (PAHs) often leads to an interesting interplay of conjugation localized within the PAHs or around the hoop. While replacing phenylene units in [ n ]­cyclopara­phenylenes ([ n ]­CPPs) by small PAHs with alternating π-systems usually leads to moderate shifts in the optoelectronics, incorporating nonalternating π-systems effects large changes, even when these are small π-systems. , An example is dibenzo­[ a , e ]­pentalene (DBP), which, due to its antiaromatic character, displays a relatively high HOMO and low LUMO energy considering the small size of its π-system (16 π-electrons). − Depending on how DBP is incorporated into more extended π-systemsthrough the 5,10-positions at the five-membered rings or the 2,7-positions at the six-membered rings (see atom numbering in Scheme )its antiaromaticity, conjugation, and electronic character can be influenced. , This has been demonstrated in not only small molecule DBPs but also in DBP-based conjugated polymers, where a change in this connecting pattern altered their electronic properties . Conjugation through the 5,10-positions has a stronger influence on the LUMO energies, while substituents in the 2,7-positions more strongly influence the HOMO energy .…”

Flexible and Stretchable Organic Electrochemical Transistors for Physiological Sensing Devices

“…The ion intake/outtake and the redox process vary the electronic carrier density in the semiconductor modulating the electronic conductivity of the channel upon application of V GS /V DS biases (Figure 1c). [89] Consequently, a volumetric capacitance is associated with OECT operation, which is typically orders of magnitude higher than that in typical OFETs/OEDLTs, [90][91][92][93][94] as well as solution processed metal oxide FETs/EDLTs, [95][96][97][98][99][100][101] leading to a large amplification capability at low driving voltages (typically <1 V for aqueous electrolyte). [42,71] Figure 1d compares the g m range of OFETs, OEDLTs, and OECTs versus driving voltage, but note, the driving voltages of OFETs are typically much larger than the 5 V reported in this figure . The most advanced OECTs reported to date are based on ptype (hole-transporting or electrochemically oxidized) semiconductors, while n-type (electron-transporting or electrochemically reduced)-semiconductor-based OECTs remain rare, are typically less stable, and exhibit much lower performance compared to their p-type counterparts.…”

Cascade Vinylation/8π-Electrocyclization and Cu(II)-Catalyzed Dehydrogenation toward Highly Stable Formally Antiaromatic Cycloheptatrienyl Anions

“…The notions of aromaticity and antiaromaticity are regarded as the fundamental concepts in organic chemistry. Antiaromatic compounds are usually referred to as unstable; however, researchers have found ways to inhibit the instability of antiaromatic systems, − which has further increased the interest in terms of their application as diverse functional materials, such as organic field-effect transistors, organic solar cells, and so forth. − Therefore, the methodology for the synthesis of antiaromatic molecules has gained considerable importance with both fundamental and applied organic chemistry. Despite the growing interest in this area, isolation of stable charged antiaromatic molecules remains challenging due to the higher reactivity of such species.…”