J. Fischer

Molecular recognition directed self-assembly of ordered supramolecular strands by cocrystallization of complementary molecular components

The interaction of two suitably designed complementary ditopic molecular components (1,2) and (3,4) generates spontaneously an organized supramolecular architecture displaying molecular sorting and orientation.

Crystal and molecular structure of μ-oxo-bis((5,10,15,20)tetrakispentafluorophenyl)porphinatoiron(III)

Abstract In this paper, we report the crystal and molecular structure of μ-oxo-bis(5,10,15,20)tetrakispentafluorophenyl)porphinatoiron(III) [(TPP(F5)Fe)2O]. The crystals belong to the tetragonal system, space group I41/a, with a =b = 26.362(7),c = 30.886(8)A,V = 21465A3,Z = 8 and Dcalc = 1.496. Discrepancy indices are R1 = 0.084 and R2 = 0.104 for 3320 reflections having I3σ(I). The Fe Np average distance, 2.088(11)A, is at the long end of the range of high-spin ferric porphyrin while the Fe O distances (1.775(1)A) are similar to those of the non-halogenated analog (TPPFe)2O. The Fe O Fe angle of 178.4(5)° shows an essentially linear oxo bridge. The 0.673(2)Adisplacement of the iron atom from the porphyrin mean plane is unusually large. The facing porphyrin rings are twisted 47° with respect of each other giving the molecule nearly exact D4d symmetry.

The structure and reactivity towards oxygen transfer of pyrazinedicarboxylato peroxo titanium derivatives. Molecular and crystal structure of peroxo(pyrazine 2-carboxylato 3-carboxyl)(acetylacetonato)(hexamethylphosphortriamide) titanium(IV)

Abstract The synthesis and properties, with respect to oxygen transfer to olefins, of four peroxo Ti(IV) complexes of pyrazine- and pyridinedicarboxylic acids, are reported. The X-ray structure of Ti- [pz(COO)(COOH)](acac)(HMPA), 1 , was performed; it essentially revealed that the pyrazine ligands are non-bridging: the carboxylate group at the 2 position is deprotonated while the other carboxylate forms intramolecular hydrogen bonds. Strong stabilization of the peroxo moiety precluded oxygen transfer from 1 to organic substrates. On the other hand, pyrazine- and pyridine-2,5-dicarboxylic acids yielded polymeric compounds 2–4 where both carboxylate groups of the ligands are deprotonated. Complexes 2–4 epoxidize tetramethylethylene; the reactivity thus revealed is attributed to the breaking of the pyrazine or pyridine bridges in solution, which liberates a vacant site on the metal. Crystal data for 1 : C 23 H 46 N 8 O 10 P 2 Ti 2 , triclinic, a = 16.295(6), b = 15.247(6), c = 15.398(6) A, a = 90.36(2)°, β= 115.50(2)°, γ = 89.21(2)°; space group P 1, Z = 4.

Molecular ribbons from molecular recognition directed self-assembly of self-complementary molecular components

The programmed self-association of the self-complementary nucleotide-like pyrimidinone 5 and pyrimidinedione 6, generates, as predicted, organized supramolecular ribbons. The crystal structure of such a species has been determined. A similar entity is obtained from the pyrimidinetriamine 12 with solvent participation, giving a quadruply hydrogen-bonded ribbon, whose crystal structure has also been determined. These processes give access to the designed generation of organized arrays of functional substituents.