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Crystal chemistry of layered structures formed by linear rigid silyl-capped molecules.

Lumpi D, Kautny P, Stöger B, Fröhlich J - IUCrJ (2015)

Bottom Line: Further increase of steric demand in the case of a dimethoxythiophene restored periodicity along [010] but resulted in a doubling of the c vector.The analogously oxidized EDOT-based molecule crystallized as systematic twins owing to its OD polytypism.Shortening of the backbone by removal of the aryl core resulted in an enantiomorphic structure and a further shortening by removal of a methylthio-ene fragment again in a systematically twinned OD polytype.

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Affiliation: Institute of Applied Synthetic Chemistry, Vienna University of Technology, Vienna, Austria.

ABSTRACT
The crystallization behavior of methylthio- or methylsulfonyl-containing spacer extended Z,Z-bis-ene-yne molecules capped with trimethylsilyl groups obtained by (tandem) thiophene ring fragmentation and of two non-spacer extended analogs were investigated. The rigid and linear molecules generally crystallized in layers whereby the flexibility of the layer interfaces formed by the silyl groups leads to a remarkably rich crystal chemistry. The molecules with benzene and thiophene spacers both crystallized with C2/c symmetry and can be considered as merotypes. Increasing the steric bulk of the core by introduction of ethylenedioxythiophene (EDOT) gave a structure incommensurately modulated in the [010] direction. Further increase of steric demand in the case of a dimethoxythiophene restored periodicity along [010] but resulted in a doubling of the c vector. Two different polytypes were observed, which feature geometrically different layer interfaces (non-OD, order-disorder, polytypes), one with a high stacking fault probability. Oxidation of the methylthio groups of the benzene-based molecule to methylsulfonyl groups led to three polymorphs (two temperature-dependent), which were analyzed by Hirshfeld surface d e/d i fingerprint plots. The analogously oxidized EDOT-based molecule crystallized as systematic twins owing to its OD polytypism. Shortening of the backbone by removal of the aryl core resulted in an enantiomorphic structure and a further shortening by removal of a methylthio-ene fragment again in a systematically twinned OD polytype.

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Layer contacts in the polymorphs (a) I and (b) of oxBSEM (1b) projected on the layer plane (100). Only the TMS groups are shown. Atoms of the lower layer are gray and blurred, color codes of the top layer as in Fig. 7 ▸. H atoms have been omitted for clarity.
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fig22: Layer contacts in the polymorphs (a) I and (b) of oxBSEM (1b) projected on the layer plane (100). Only the TMS groups are shown. Atoms of the lower layer are gray and blurred, color codes of the top layer as in Fig. 7 ▸. H atoms have been omitted for clarity.

Mentions: Thus, the I II phase transition has to be considered reconstructive, which is consistent with the destruction of large single crystals on cooling. The transformation is accompanied by an inclination of the molecules with respect to the stacking direction (Figs. 21 ▸b and 21 ▸d). In consequence, the layer interfaces are fundamentally different in the two polytypes (Fig. 22 ▸), demonstrating again the flexibility in layer arrangements allowed by the TMS groups.


Crystal chemistry of layered structures formed by linear rigid silyl-capped molecules.

Lumpi D, Kautny P, Stöger B, Fröhlich J - IUCrJ (2015)

Layer contacts in the polymorphs (a) I and (b) of oxBSEM (1b) projected on the layer plane (100). Only the TMS groups are shown. Atoms of the lower layer are gray and blurred, color codes of the top layer as in Fig. 7 ▸. H atoms have been omitted for clarity.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4547826&req=5

fig22: Layer contacts in the polymorphs (a) I and (b) of oxBSEM (1b) projected on the layer plane (100). Only the TMS groups are shown. Atoms of the lower layer are gray and blurred, color codes of the top layer as in Fig. 7 ▸. H atoms have been omitted for clarity.
Mentions: Thus, the I II phase transition has to be considered reconstructive, which is consistent with the destruction of large single crystals on cooling. The transformation is accompanied by an inclination of the molecules with respect to the stacking direction (Figs. 21 ▸b and 21 ▸d). In consequence, the layer interfaces are fundamentally different in the two polytypes (Fig. 22 ▸), demonstrating again the flexibility in layer arrangements allowed by the TMS groups.

Bottom Line: Further increase of steric demand in the case of a dimethoxythiophene restored periodicity along [010] but resulted in a doubling of the c vector.The analogously oxidized EDOT-based molecule crystallized as systematic twins owing to its OD polytypism.Shortening of the backbone by removal of the aryl core resulted in an enantiomorphic structure and a further shortening by removal of a methylthio-ene fragment again in a systematically twinned OD polytype.

View Article: PubMed Central - HTML - PubMed

Affiliation: Institute of Applied Synthetic Chemistry, Vienna University of Technology, Vienna, Austria.

ABSTRACT
The crystallization behavior of methylthio- or methylsulfonyl-containing spacer extended Z,Z-bis-ene-yne molecules capped with trimethylsilyl groups obtained by (tandem) thiophene ring fragmentation and of two non-spacer extended analogs were investigated. The rigid and linear molecules generally crystallized in layers whereby the flexibility of the layer interfaces formed by the silyl groups leads to a remarkably rich crystal chemistry. The molecules with benzene and thiophene spacers both crystallized with C2/c symmetry and can be considered as merotypes. Increasing the steric bulk of the core by introduction of ethylenedioxythiophene (EDOT) gave a structure incommensurately modulated in the [010] direction. Further increase of steric demand in the case of a dimethoxythiophene restored periodicity along [010] but resulted in a doubling of the c vector. Two different polytypes were observed, which feature geometrically different layer interfaces (non-OD, order-disorder, polytypes), one with a high stacking fault probability. Oxidation of the methylthio groups of the benzene-based molecule to methylsulfonyl groups led to three polymorphs (two temperature-dependent), which were analyzed by Hirshfeld surface d e/d i fingerprint plots. The analogously oxidized EDOT-based molecule crystallized as systematic twins owing to its OD polytypism. Shortening of the backbone by removal of the aryl core resulted in an enantiomorphic structure and a further shortening by removal of a methylthio-ene fragment again in a systematically twinned OD polytype.

No MeSH data available.


Related in: MedlinePlus