Single-Crystal Structures of Model Compounds for Poly(2,5-dialkoxy-1,4-phenylenevinylene)

Abstract

We report on the crystal structures of two alkoxy-substituted distyrylbenzene derivatives 4 and 5 which serve as model compounds for poly(1,4-phenylenevinylene)s and compare them to other known compounds 6-9 of similar structure. The obtained data are also related to two alkoxy-substituted stilbene derivatives 2 and 3 to recognize trends of torsion at the olefinic double bonds which are induced by substituents. Surprisingly, the direct impact of substituents on the torsion angles is negligible in comparison to crystal lattice effects. In contrast to quantum mechanical predictions, neither of the compounds 2-5 shows in the solid-state weak hydrogen bonding between the oxygen of the alkoxy side chains and the olefinic hydrogens.

Luminescent distyrylbenzenes: tailoring molecular structure and crystalline morphology

“…to a 'rolled' stack (Fig. 2); 16,17,19,23 this even holds for small substituents like methyl in the ortho-and meta-position of the terminal ring (3,4). 22,23 In this way, p-p-overlap is kept small through considerable slip along y (hence, excimers are not observed in these structures), and at the same time dense packing is ensured.…”

“…Much effort was dedicated to combine the cyano-vinylene functionality with substituents in the central ring, which allows for effective tuning of the solid state structure and, concomitantly, of the optical properties. A striking example is the series of compounds 18-21, which all carry methoxy-groups in the central rings, the cyano substitutions however are positioned once in the inner (18,19) or in the outer groups (20,21), and terminal butyloxy groups are added (19,21), where the latter establish a regular D-A-D-A-D motif in the chromophores. 39 While all molecules form slip-stacked arrangements, the donor-acceptor motif as well as local CN dipoles and H-bonding introduce increasing excitonic interactions in the series 18 / 19 / 20 / 21, Fig.…”

Direct Evidence for Secondary Interactions in Planar and Nonplanar Aromatic π-Conjugates and Their Photophysical Characteristics in Solid-State Assemblies

“…Thin-film FETs materials such as pentacene and acenes, − oligothiophenes, − fused thiophene aromatics, , and tetrathiafulvalenes , were reported to exhibit either a face-to-face or face-to-edge orientation as the most preferred configuration in the solid state. Surprisingly, these planar π-conjugates did not show any π–π stacking as expected in the crystal lattices. , Recent studies revealed that nonplanarity was observed in the aromatic cores of phenylene, naphthalene, and anthracene rings irrespective of the topology, size, and nature of the substitution. , Non-covalent interactions such as CH/π , and RCH 2 O/π − (R = H or alkyl) were reported to stabilize the packing of π-conjugated chromophores. Large numbers of π-conjugated materials belonging to phenylenevinylenes, fluorenes, and low-band-gap materials were found to be sluggish to produce good-quality single crystals.…”

Defined‐length Carbon‐rich Conjugated Oligomers

“…The 2,5-dipropoxy substituted OPVs 2a-j, shown in Scheme 11.5 [17][18][19][20][21][22][23][24][25], have been studied in detail.…”