Torsional Influences within Disordered Organic Electronic Materials Based upon Non-Benzenoid 1,6-Methano[10]annulene Rings

Abstract

Conjugated polymers and small molecules containing the nonplanar aromatic 1,6-methano [10]annulene were synthesized in an effort to understand how torsional differences between planar and nonplanar πelectron components influence the electronic properties of π-conjugated materials. The polymers and small molecule model systems contain commonly employed aromatic subunits such as thiophene, diketopyrrolopyrrole, and 2,1,3benzothiadiazole, leading to electron donor and donor−acceptor polymers. The curved geometry of 1,6-methano[10]annulene can lead to reduced local torsional strain in semiconducting polymers relative to large planar aromatics, potentially increasing intrapolymer conjugation. The relative amount of effective conjugation length increase granted by the annulene in each system of regioisomers was interrogated through the use of UV−vis and photoluminescence spectroscopy and electrochemistry, and it was found that 1,6methano[10]annulene relieves some torsional strain associated with solubilizing alkyl chains clashing with aromatic rings along the polymer backbone. The polymers were also found to be highly disordered in thin films yet still provided reasonable hole mobilities (ca. 10 −4 cm 2 /(V s)) in OFET devices. These results suggest that methano [10]annulene or other curved aromatics may prove useful in the future development of organic electronics.

Prospecting in Hückel‐space: From Hinokitiol to Non‐benzenoid Organic Electronics

“…Figure , top) . Our more recent investigations examined the amorphous nature of annulene‐containing polymers as thin films relevant for semiconductor device fabrication, properties deduced by thermal and X‐ray diffraction measurements (Figure , bottom) . It should be noted here that the latter report describes a unique example that is NOT relying on the inherent electronics or aromaticity of the annulene core; rather, the structural aspects concerning non‐planarity, the methylene bridge, and the racemic nature of the annulen‐2,7‐diyl linkages within the monomer building block all lead to a frustration of extended crystallization that commonly accompanies typical rigid‐rod conjugated polymers designed for high‐performance applications.…”

Corrigendum: An Unusually Small Singlet–Triplet Gap in a Quinoidal 1,6‐Methano[10]annulene Resulting from Baird's 4n π‐Electron Triplet Stabilization

“…TheS 0 geometry of TMQT in Figure 4s hows ap artial rotation of the outer thiophenes relative to M10A in accordance with the single character of the connecting bond (structure A). [29] TheR aman spectrum with the 532 nm laser excitation in Figure 3d isplays an ew peak at 1483 cm À1 together with that at 1441-1445 cm À1 typical of the 1064/785/633 nm laser Raman excitations.H ence,t he growth of an ew band in the 532 nm Raman spectrum displaced at higher wavenumber, 1445!1482 cm À1 ,i si nl ine with the up-shift of the Raman bands from the Q3TCN quinoidal to the T3CN aromatic, 1430!1456 cm À1 ,and suggests achange toward amuch more aromatic core such as in the triplet structure D in Scheme 4. TheM 10A shows ac ontorted structure,o rM çbius-like aromatic shape.…”

“…[33] Thes odium salt of malononitrile was coupled to dibromo-TMT [29] under Pd catalysis and the coupling product was oxidized with Br 2 in water. [33] Thes odium salt of malononitrile was coupled to dibromo-TMT [29] under Pd catalysis and the coupling product was oxidized with Br 2 in water.…”

An Unusually Small Singlet–Triplet Gap in a Quinoidal 1,6‐Methano[10]annulene Resulting from Baird’s 4n π‐Electron Triplet Stabilization

“…Bond 5 in T 1 is very long as a result of steric/torsional strain (structure A). [29] The Raman spectrum with the 532 nm laser excitation in Figure 3 displays a new peak at 1483 cm À1 together with that at 1441-1445 cm À1 typical of the 1064/785/633 nm laser Raman excitations. Hence, the growth of a new band in the 532 nm Raman spectrum displaced at higher wavenumber, 1445!1482 cm À1 , is in line with the up-shift of the Raman bands from the Q3TCN quinoidal to the T3CN aromatic, 1430!1456 cm À1 , and suggests a change toward a much more aromatic core such as in the triplet structure D in Scheme 4.…”