The programmed self-assembly of a multimetallic grid-type supramolecular architecture and its hierarchical organization on graphite are described. The doubly functionalized 4,6-bis(2,2'-bipyridyl-6-yl)-2-phenylpyrimidine derivative 1, equipped with CH2OC16H33 moieties at the terminal pyridine rings, was designed as a new bis(tridentate) ligand and synthesized using Stille-type coupling reactions. Treatment of ligand 1 with Fe(BF4)2·6H2O in CHCl3/CH3CN led to the spontaneous formation of a [2 × 2]-grid-type FeII complex 2 in quantitative yield. The self-assembled tetranuclear complex 2 was adsorbed onto highly oriented pyrolytic graphite (HOPG) and studied by scanning tunneling microscopy (STM), which showed two morphologies of highly ordered two-dimensional arrays of the metallo-supramolecular architectures. The resulting monolayers of the grid-type complex 2 are much more stable than that obtained from the corresponding unsubstituted grid-type complex owing to the additional attractive forces between the hexadecyl moieties in 2 and the HOPG surface. Moreover, the reproducibility of the STM images of the hexadecyl-substituted grid 2 was strongly improved compared to the unsubstituted one. These results suggest that the introduction of long alkyl chains into metallo-supramolecular architectures would have general advantages for their organization and STM investigation on HOPG. Details of the preparation and the STM investigation of ligand 1 are also presented. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

The magnetism of a series of tetranuclear complexes of the [FeII4L4](BF4)8[2×2]-grid-type was investigated, revealing the occurrence of spin-transition (ST) behavior within this class of compounds. The phenomenon depends directly on the nature of the substituent R1 of the ligand L. All FeII ions in compounds with R1 substituents favoring strong ligand fields (R1=H;OH) remain completely in the diamagnetic low-spin state. Only the complex bearing R1=Ph exhibits thermally induced ST behavior.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

The magnetism of a series of tetranuclear complexes of the [Fe4IIL4]8+ [2x2]-grid-type was investigated, revealing the occurrence of spin transition behavior within this class of compounds. The phenomenon depends directly on the nature of the substituent R(1) in the 2-position on the central pyrimidine group of the ligand L. All Fe(II) ions in compounds with R(1) substituents favoring strong ligand fields (R(1)=H; OH) remain completely in the diamagnetic low-spin state. Only complexes bearing R(1) substituents attenuating the ligand field by steric (and to a lesser extent electronic) effects (R(1)=Me; Ph) exhibit spin transition behavior triggered by temperature. In general, gradual and incomplete transitions without hysteresis were observed for magnetically active complexes. The systems described provide approaches to the development of (supra)molecular spintronics.

The self-assembly of new multimetallic complexes of grid-type architecture is described. The binding of a set of tris-terdentate ligands, 1 a-1 d, based on terpyridine-like subunits, with different octahedrally coordinated metal ions leads to the formation of species whose structure depends strongly on the ligand, the metal ion, the counterion, the solvent, and the reaction conditions. Under suitable conditions, the [3 x 3] grid was obtained from the reaction of ligand 1 a with zinc tetrafluoroborate and from ligand 1 b with mercury triflate. The other ligands led to the formation of mainly one compound of composition [M(6)L(5)](12+), which has the structure of an incomplete [2 x 3] grid. The crystal structure of such a [2 x 3] grid, [Co(6)(1 d)(5)](12+), has been determined. In this complex, the three central pyrimidine-pyridine-pyrimidine non-coordinating sites adopt transoid NCbond;CN conformations. The much less stable cisoid conformations, the "pinching" of the coordination sites in the complex, the weaker donor strength of the central binding site, and the steric demand of the substituents are all factors contributing to the reluctance to produce the [3 x 3] structure. A subtle interplay between the nature of the metal, the steric demand of the ligand, the reaction conditions, and the type of counterion determine the product of self-assembly. The results obtained show that by tuning the parameters, complexes containing six or nine octahedrally coordinated metal ions in a well-defined grid-type arrangement are accessible. Both types of arrays, [2 x 3] and [3 x 3 ], are of interest as self-assembled inorganic architectures of well-defined structure and nuclearity that may be suitable prototypes for selective information storage media.

The self-assembly of the terdentate ligands 1a-h, based on terpyridine-like binding sites, with octahedrally coordinated metal ions, such as Fe(II), Co(II), Cu(II), Zn(II), Cd(II), Hg(II) and Pb(II), leads to the formation of the supramolecular grid-type complexes 2a-c(M(II)), 3d-g(M(II)) and 4h(M(II)). The structures and compositions of these coordination complexes in solution were deduced from electrospray mass spectrometry (ESMS) measurements. The results agree with the data available from x-ray radiocrystallography in the solid state and/or NMR spectroscopy in solution. ESMS may be applied in cases where other methods are difficult to use or inconclusive. This study stresses the power of ESMS in supramolecular chemistry.

The [M(4)(II)L(4)](8+) [2 x 2]-grid-type complexes 1-8 present a set of features of particular interest for potential applications. All complexes exhibit multiple reduction levels at low reduction potentials paired with rather high stability. The modulation of the reduction potentials is possible by introduction of appropriate substituents on the ligands. The Co(II)(4) complexes 1-5 present a remarkable regularity in the disposition of the reduction levels, indicating the ability of the Co(II) sites to transmit electronic interactions between reduced ligands. In general, all investigated molecular systems 1-8 show characteristics typical for multilevel supramolecular electronic devices.

Here we report on the synthesis and characterisation of four new complexes of the [2x2] M-4(II) grid-type (M = Co, Fe, Zn) with oligopyridine-derived ligands. The presence of aminopyrazine and aminopyrimidine moieties at the edge of the ligands potentially enables the formation of infinite hydrogen-bonded multi-grid networks. The Ligands were synthesised by subsequent stannylations and Stille-type coupling reactions. The complexes were obtained by self-assembly of the ligand with the metal salt. The single-crystal X-ray structure was determined for the Co complex 7 containing aminopyrimidine as the hydrogen-bonding moiety [P (1) over bar; a = 15.4976(4), b = 18.2114(6), c = 31.9538(10) Angstrom, a = 86.9809(13) beta = 83.4137(18), gamma = 67.2828(16)degrees]. The crystal structure reveals hydrogen bonding in one direction, thus forming infinite chains of grids, whereas in the second direction of a layer, only weak attractive interactions are found. Anions and solvent molecules are situated between the layers, thus inhibiting any direct interaction between them. Cocrystallisation of the complementary complexes should enable the recognition-controlled alternating arrangement of grids incorporating different metal ions in a chessboard-like manner.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Das Titelbild zeigt, wie sich sowohl die bildende Kunst als auch die exakte Wissenschaft zum Austausch ihrer Erkenntnisse eines Systems miteinander verwobener symbolischer und ikonischer Darstellungen bedienen. Dabei greifen beide auf den gleichen Satz abstrahierter Zeichen zurück. So schuf Wassily Kandinsky bereits im Jahre 1925 ein Gemälde (unten), welches nun, 75 Jahre später, als Vorlage für ein wissenschaftliches Projekt dient. Kandinsky kombinierte in diesem Gemälde ein gitterförmiges Zeichen mit runden Gebilden unterschiedlicher Größe und Farbe, welche heute an einen existierenden molekularen Schalter erinnern. Anscheinend einer rätselhaften Vorschrift folgend, gelang es den Arbeitsgruppen um Lehn und Gütlich (siehe die Zuschrift auf Seite 2563 ff.), ein gitterartiges anorganisches System zu konstruieren (Bildmitte), das als ein molekularer Schalter mit drei magnetischen Niveaus anzusehen ist, steuerbar durch drei externe Einflüsse (p, T, hν). Das Funktionsprinzip des Schalters basiert auf der Änderung des Spinzustands von FeII–Ionen, wobei der Schaltvorgang durch Mößbauer-Spektroskopie (links) und magnetische Messungen (im Hintergrund) verfolgt werden kann.

A multiplex electronic switch on the molecular level has been realized by using a tetranuclear FeII complex of the [2×2] grid type. The four metal ions can be switched stepwise between their high-spin and low-spin states by temperature, pressure, and light, thus representing a triple level, triple switch system as illustrated in the picture.

The synthesis and X-ray structures of three metal complexes with terpyridine-derived ligands that contain amino-pyrimidine and amino-pyrazine moieties are presented. They have been designed in view of directing their self-assembly into specific supramolecular arrays through molecular recognition interactions. The solid-state structures indeed reveal extensive hydrogen-bonded networks. The Co complex 4a with PF6- counterions builds a two-dimensional infinite interwoven grid through strong double hydrogen bonds (d(N-H-N) =2.918-3.018 A) between the amino groups and the N atoms of the rings, with all H-bonding sites saturated. Changing the anions to BF4- in 4b leads to a similar infinite but partially broken grid with a quarter of the H-bonding sites unsaturated (d(N-H-N)=2.984-3.206 A). In the case of the Zn complex 12 with triflate anions, half of the hydrogen bonds are formed. Only one of the two orthogonal ligands has hydrogen bonds (d(N-H-N) = 3.082, 3.096 A) to the neighbouring complexes and thus builds linear, supramolecular, polymeric chains. These structural differences are mainly attributed to crystal-packing effects caused by the different anions. The data presented here may also be regarded as a prototype for the generation of organised arrays through sequential self-assembly processes.

Die bisher höchste Zahl gut aufgelöster, reversibler Reduktionswellen einer molekularen Verbindung wird bei der schrittweisen Reduktion des vierkernigen Co-[2×2]-Gitterkomplexes 1 (R=Ph) durch insgesamt elf Elektronen beobachtet. Die zehn gut aufgelösten, vollkommen reversiblen Reduktionsschritte im zugehörigen (differentiellen) Cyclovoltammogramm (siehe Diagramm) stehen für zehn reduzierte Spezies von überraschender Stabilität.

Angewandte Chemie International EditionVolume 39, Issue 22 p. 4139-4142 Communication Multilevel Molecular Electronic Species: Electrochemical Reduction of a [2×2] Co Grid-Type Complex by 11 Electrons in 10 Reversible Steps Mario Ruben Dr., Mario Ruben Dr. Laboratoire de Chimie Supramoléculaire ISIS-Université Louis Pasteur 4, rue Blaise Pascal, 67000 Strasbourg (France) Fax: (+33) 388-411 020Search for more papers by this authorEsther Breuning, Esther Breuning Laboratoire de Chimie Supramoléculaire ISIS-Université Louis Pasteur 4, rue Blaise Pascal, 67000 Strasbourg (France) Fax: (+33) 388-411 020Search for more papers by this authorJean-Paul Gisselbrecht Dr., Jean-Paul Gisselbrecht Dr. Laboratoire d'Electrochimie et de Chimie-Physique du Corps Solide UMR 7512,CNRS-Université Louis Pasteur 4, rue Blaise Pascal, 67000 Strasbourg (France) Fax: (+33) 388-611 553Search for more papers by this authorJean-Marie Lehn Prof. Dr., Jean-Marie Lehn Prof. Dr. lehn@chimie.u-strasbg.fr Laboratoire de Chimie Supramoléculaire ISIS-Université Louis Pasteur 4, rue Blaise Pascal, 67000 Strasbourg (France) Fax: (+33) 388-411 020Search for more papers by this author Mario Ruben Dr., Mario Ruben Dr. Laboratoire de Chimie Supramoléculaire ISIS-Université Louis Pasteur 4, rue Blaise Pascal, 67000 Strasbourg (France) Fax: (+33) 388-411 020Search for more papers by this authorEsther Breuning, Esther Breuning Laboratoire de Chimie Supramoléculaire ISIS-Université Louis Pasteur 4, rue Blaise Pascal, 67000 Strasbourg (France) Fax: (+33) 388-411 020Search for more papers by this authorJean-Paul Gisselbrecht Dr., Jean-Paul Gisselbrecht Dr. Laboratoire d'Electrochimie et de Chimie-Physique du Corps Solide UMR 7512,CNRS-Université Louis Pasteur 4, rue Blaise Pascal, 67000 Strasbourg (France) Fax: (+33) 388-611 553Search for more papers by this authorJean-Marie Lehn Prof. Dr., Jean-Marie Lehn Prof. Dr. lehn@chimie.u-strasbg.fr Laboratoire de Chimie Supramoléculaire ISIS-Université Louis Pasteur 4, rue Blaise Pascal, 67000 Strasbourg (France) Fax: (+33) 388-411 020Search for more papers by this author First published: 14 November 2000 https://doi.org/10.1002/1521-3773(20001117)39:22<4139::AID-ANIE4139>3.0.CO;2-YCitations: 83 This work was supported by a postdoctoral scholarship of the “Deutscher Akademischer Austauschdienst” (DAAD) (M.R.) and by the “Ministère de l'Education Nationale, de la Recherche et de la Technologie” (E.B.). We thank Dr. Eliseo Ruiz for carrying out the theoretical calculations and for fruitful discussions. AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Abstract The highest number, so far, of well-resolved, completely reversible reduction waves of a molecular compound is found during the stepwise reduction of the tetranuclear [2×2] Co grid-type complex 1 (R=Ph) by a total of 11 electrons. The associated (differential) cyclic voltammogram (see picture) shows ten reduction waves, which represent ten reduced species of remarkable stability. Citing Literature Volume39, Issue22November 17, 2000Pages 4139-4142 RelatedInformation

Resorcin[4]arene tetracarboxylic acids 5,6 (A) and resorcin[4]arene tetrapyridines 2,3 (P) self-assemble in chloroform solution to form stable heterotopic AP dimers. Data from NMR titration and dilution experiments, as well as from vapor-pressure osmometry (VPO), indicate that the AP dimer is formed with an association constant greater than 10(7) M-1 Solid-solution extraction experiments are indicative of the formation of a 2:1 trimer (A(2)P), while self-associated homotopic species (A(2) and A(3)) can be detected by NMR and VPO. Analysis of the heterotopic noncovalent assembly process over a range of compositions shows that these other species are much less stable than the AP heterodimer, which is the exclusive species at an A/P concentration ratio of 1:1 (> 99.7% of the total at 10 mM).