A Triptycene-Based Enantiopure Bis(Diazadibenzoanthracene) by a Chirality-Assisted Synthesis Approach.

By applying a chirality-assisted synthesis (CAS) approach enantiopure diaminodibromotriptycenes were converted to rigid chiral helical diazadibenzoanthracenes, which show besides pronounced Cotton effects in circular dichroism spectra higher photoluminescence quantum yields as comparable carbacyclic analogues. For the enantiopure building blocks, a protocol was developed allowing the large scale synthesis without the necessity of separation via HPLC.

Microporous Triptycene-Based Affinity Materials on Quartz Crystal Microbalances for Tracing of Illicit Compounds.

Triptycene-based organic molecules of intrinsic microporosity (OMIMs) with extended functionalized π-surfaces are excellent materials for gas sorption and separation. In this study, the affinities of triptycene-based OMIM affinity materials on 195 MHz high-fundamental-frequency quartz crystal microbalances (HFF-QCMs) for hazardous and illicit compounds such as piperonal and (-)-norephedrine were determined. Both new and existing porous triptycene-based affinity materials were investigated, resulting in very high sensitivities and selectivities that could be applied for sensing purposes. Remarkable results were found for safrole - a starting material for illicit compounds such as ecstasy. A systematic approach highlights the effects of different size of π-surfaces of these affinity materials, allowing a classification of the properties that might be optimal for the design of future OMIM-based affinity materials.

Attractive Dispersion Interactions Versus Steric Repulsion of tert-Butyl groups in the Crystal Packing of a D3h -Symmetric Tris(quinoxalinophenanthrophenazine).

The crystalline packing of a π-extended D3h -symmetric triptycene reveals a particular π stacking motif with an almost-eclipsed arrangement of adjacent π planes despite the steric repulsion of tert-butyl substituents. Four model compounds were analyzed by using single-crystal X-ray diffraction and theoretical calculations to study the influence of dispersion interactions of molecular parts and understand the relationship between the molecular structure and this unique packing motif.

Crystal Structures of a Molecule Designed Not To Pack Tightly.

Organic molecules of intrinsic microporosity (OMIMs) are structurally constructed to not pack tightly. Consequently, only weak interactions between OMIM molecules can occur, which is the reason that almost all OMIMs have been described and investigated in their amorphous states. For the same reason it is very difficult to grow single crystals of OMIMs for X-ray structural analysis. Here we describe four different polymorphs of an OMIM that was before only described in the amorphous state.

A pyrene-fused N-heteroacene with eleven rectilinearly annulated aromatic rings.

A highly soluble pyrene-fused undecacene is realized by end-capping the rectilinear aromatic π-plane with triptycenylene units. Besides the good solubility, the compound shows a high tendency to crystallize. Two polymorphs from dichlorobenzene and chloroform are described. In the polymorph from chloroform, half of the molecules are strongly bent out of the π-plane by 26.4°.

Selective even-numbered bromination of triptycene tris(thiadiazoles).

An unusual even-numbered bromination of triptycene tristhiadiazole is described, giving selectively dibromo-, tetrabromo-, and hexabromotriptycenes with two bromines each at the same phenyl ring. The new compounds can be used as precursors for extended π-conjugated systems and polymers.

Rigid π-extended triptycenes via a hexaketone precursor.

A high-yielding synthesis of a rigid hexaketone is presented that can be transformed into π-extended D3h-symmetric triptycene derivatives with high internal molecular free volumes (IMFVs). The products show excellent photophysical properties combined with high specific surface areas.