Synthesis, crystal structure, polymorphism and microscopic luminescence properties of anthracene derivative compounds

Abstract

Anthracene derivative compounds are currently investigated because of their unique physical properties (e.g. bright luminescence and emission tunability), which make them ideal candidates for advanced optoelectronic devices. Intermolecular interactions are the basis of the tunability of the optical and electronic properties of these compounds, whose prediction and exploitation benefit from knowledge of the crystal structure and the packing architecture. Polymorphism can occur due to the weak intermolecular interactions, requiring detailed structural analysis to clarify the origin of observed material property modifications. Here, two silylethyne-substituted anthracene compounds are characterized by single-crystal synchrotron X-ray diffraction, identifying a new polymorph in the process. Additionally, laser confocal microscopy and fluorescence lifetime imaging microscopy confirm the results obtained by the X-ray diffraction characterization, i.e. shifting the substituents towards the external benzene rings of the anthracene unit favoursinteractions, impacting on both the morphology and the microscopic optical properties of the crystals. The compounds with more isolated anthracene units feature shorter lifetime and emission spectra, more similar to those of isolated molecules. The crystallographic study, supported by the optical investigation, sheds light on the influence of non-covalent interactions on the crystal packing and luminescence properties of anthracene derivatives, providing a further step towards their efficient use as building blocks in active components of light sources and photonic networks.

Triplet Exciton Transfers and Triplet–Triplet Annihilation in Anthracene Derivatives via Direct versus Superexchange Pathways Governed by Molecular Packing

“…29 The efficiencies of SF, TTA, and exciton transfers depend on molecular packing structures, which can be tuned by chemical modifications and crystal polymorphism. 32 Several crystal polymorphs were found for TIPS−anthracene (TIPS-ANT) (Figure 2a), 32,33 for which SF 32 and photoluminescence 33 were investigated. Of particular interest is the impact of the packing structure on the mechanisms of TET and TTA, which would be governed by energetics of excited states and electronic couplings.…”

“…In this study, we theoretically analyze TET and TTA in anthracene derivatives, namely, TIPS-ANT (Figure 2a) and 1,2,3,4-tetrafluoro-5,8-bis(trimethylsilylethynyl)anthracene (F4-TMS-ANT) (Figure 2b). 33 We particularly focus on the TIPS-ANT crystal with a parallel packing structure (TIPS-ANTp). 33 The TET rate of the cofacially stacked F4-TMS-ANT is predicted to be faster than that of the slip-stacked TIPS-ANTp.…”

“…33 We particularly focus on the TIPS-ANT crystal with a parallel packing structure (TIPS-ANTp). 33 The TET rate of the cofacially stacked F4-TMS-ANT is predicted to be faster than that of the slip-stacked TIPS-ANTp. F4-TMS-ANT can exhibit an ultrafast TTA along the closely stacked (∼3.5 Å) a⃗ direction (Figure 2b) via the superexchange pathway, owing to strong electronic couplings and a moderate energy gap to the CT states.…”

Cyclodimers and Cyclotrimers of 2,3 ‐Bisalkynylated Anthracenes, Phenazines and Diazatetracenes

“…Ionization potential [ev] [b] HOMO [eV] [c] Electron affinity [a] First reduction potentials from cyclic voltammetry (CV) in CH 2 Cl 2 at room temperature with Bu 4 NPF 6 as the electrolyte against Fc/Fc + as an internal standard (À 5.10 eV) [14] at 0. volatile dichloromethane compared to the microcrystalline film of 3 c 2 from high-boiling toluene solution (see Figure S43 for polarization micrographs), and as a consequence of the higher transfer integrals (38.8 meV for 3 c 3 and 3.55 meV for 3 c 2 ) for electron transport (Figure S7). Although TIPS-ethynylated diazatetracene, [17] which was found to pack in a brick-wall motif, exhibited an electron mobility of μ lit = 5x10 À 2 cm 2 /V s, [18] the mobilities of trimer 3 c 3 are on the same order of magnitude and that despite bulkier (sBu) 3 Si-ethynyl groups being used to solubilize the material.…”

TIPS‐Ethynylated Naphthodiquinoline and Naphthodiacridine: Novel Diazabisacenes

“…Van‐der‐Waals contacts between the acene core and the silyl groups of two neighboring molecules dominate molecular packing, resulting in edge‐to‐face orientation of adjacent π‐systems and inhibiting π‐stacking. The crystal structure is isomorphous to that of the TIPS‐ethynylated anthracene (CCDC: 962668) sharing both space group and a similar unit cell [26] – the nitrogen atom of 8 is distributed statistically among the four possible atom positions and thus bond lengths can only represent mean values (see the Supporting Information). The extension of the arene backbone to bisacenes changes the packing in the solid state.…”