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author:("begin, uwes")
1.  3-Methyl­ideneoxolane-2,5-dione 
The title compound (itaconic anhydride), C5H4O3, consists of a five-membered carbon–oxygen ring in a flat envelope conformation (the unsubstituted C atom being the flap) with three exocyclic double bonds to two O atoms and one C atom. In contrast to the bond lengths, which are very similar to those in itaconic acid in its pure form or in adducts with other mol­ecules, the bond angles differ significantly because of the effect of ring closure giving rise to strong distortions at the C atoms involved in the exocyclic double bonds. In the crystal, C—H⋯O inter­actions link the mol­ecules, forming an extended three-dimensional network.
doi:10.1107/S1600536813002924
PMCID: PMC3588448  PMID: 23476519
2.  Dimer/tetramer motifs determine amphiphilic hydrazine fibril structures on graphite 
Summary
Fibril structures are produced at a solvent–graphite interface by self-assembly of custom-designed symmetric and asymmetric amphiphilic benzamide derivatives bearing C10 aliphatic chains. Scanning tunnelling microscopy (STM) studies reveal geometry-dependent internal structures for the elementary fibrils of the two molecules that are distinctly different from known mesophase bulk structures. The structures are described by building-block models based on hydrogen-bonded dimer and tetramer precursors of hydrazines. The closure and growth in length of building units into fibrils takes place through van der Waals forces acting between the dangling alkyl chains. The nanoscale morphology is a consequence of the basic molecular geometry, where it follows that a closure to form a fibril is not always likely for the doubly substituted hydrazine. Therefore, we also observe crystallite formation.
doi:10.3762/bjnano.3.75
PMCID: PMC3458612  PMID: 23019562
fibrils; graphite; hydrazide; hydrazine; interface; self-assembly; STM

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