Chirally Organized Oligothiophenes: Towards Modeling Interchain Interactions Within π‐Conjugated Systems

Abstract

Interchain modeling: A model is proposed to compare the strength of the interaction between two conjugated oligomers (see graphic). It consists of probing changes in the angle between the parts of a binaphthalene hinge, invoked by the interaction between the oligomers. This allows the strength of the interaction between any set of oligomers to be compared or changes in the interactions upon oxidation or deprotonation to be monitored.

Interchromophoric Interactions in Chiral X-type π-Conjugated Oligomers: A Linear and Nonlinear Optical Study

“…However, while at λ < 380 nm the CD spectrum of such oligothiophene-substituted binaphthalene is constituted of Cotton effects arising from transitions located on the binaphthalene pincer and the oligomers, the CD spectrum λ >380 nm solely originates from the oligomer's π-π* transition. 9 It is clear that in this region a bisignate Cotton effect is observed, which is fully in agreement with the theory of chiral exciton coupling. Therefore, this observation unambiguously demonstrates the chiral arrangement of the p-type and n-type oligomer.…”

“…Except for BN1-2 , none of the samples showed interfering multiphoton fluorescence at the second-harmonic wavelength. 1 , 2 , ( S ) -5 , 6 , 11 , BN2-2 , BN1-2 , 13 , and 14 were synthesized according to literature procedures.…”

“…The synthesis of the electron-poor and the electron-neutral phosphonate 1 and 2 have already been reported. 9 The synthesis of the p-type phosphonate 3 is depicted in Scheme 2 and starts with the selective deprotonation and a subsequent stannylation of 2-morpholinethiophene (6) in the 5-position. It is worth noting that t-BuLi had to be used instead of n-BuLi to obtain a quantitative conversion and that the tributyltin functional group assured a better stability than the trimethyltin analogue.…”

“…This chiral X-type geometry was preferred, because it better ensures chiral exciton coupling between the two oligothiophene moieties, as previously demonstrated by CD experiments . By further exploiting the chirality of the binaphthalene unit, we could qualitatively monitor the strength of any type of (induced) interchain interaction through chiroptical evaluation of the dihedral angle of the binaphthalene hinge …”

“…8 By further exploiting the chirality of the binaphthalene unit, we could qualitatively monitor the strength of any type of (induced) interchain interaction through chiroptical evaluation of the dihedral angle of the binaphthalene hinge. 9 Perhaps the most compelling feature of -conjugated systems as active elements in new generations of organic light-emitting diodes (oLEDs) and organic photovoltaic devices (oPVDs) comprises the charge transfer interaction between a p-type and a n-type -conjugated system. Wang et al studied the intermolecular charge transfer interaction by mixing an excess of N,N-dimethylaniline (p-type) with a series of distyrylbenzene derivatives (n-type) to invoke exciplex formation.…”