Katharina M. Fromm

Toposelective and Chiroselective Self-Assembly of [2×2] Grid-Type Inorganic Arrays Containing Different Octahedral Metallic Centers

The introduction of different metal ions in specific positions is achieved in the synthesis of [2×2] grid-type heterometallic complexes (see schematic representation; the black bars symbolize the ditopic ligands, and the circles the different metals ions). This novel method for the construction of inorganic architectures opens the way to a number of developments.

Multiple Expression of Molecular Information: Enforced Generation of Different Supramolecular Inorganic Architectures by Processing of the Same Ligand Information through Specific Coordination Algorithms

The multisubunit ligand 2 combines two complexation substructures known to undergo, with specific metal ions, distinct self-assembly processes to form a double-helical and a grid-type structure, respectively. The binding information contained in this molecular strand may be expected to generate, in a strictly predetermined and univocal fashion, two different, well-defined output inorganic architectures depending on the set of metal ions, that is, on the coordination algorithm used. Indeed, as predicted, the self-assembly of 2 with eight CuII and four CuI yields the intertwined structure D1. It results from a crossover of the two assembly subprograms and has been fully characterized by crystal structure determination. On the other hand, when the instructions of strand 2 are read out with a set of eight CuI and four MII (M = Fe, Co, Ni, Cu) ions, the architectures C1-C4, resulting from a linear combination of the two subprograms, are obtained, as indicated by the available physico-chemical and spectral data. Redox interconversion of D1 and C4 has been achieved. These results indicate that the same molecular information may yield different output structures depending on how it is processed, that is, depending on the interactional (coordination) algorithm used to read it. They have wide implications for the design and implementation of programmed chemical systems, pointing towards multiprocessing capacity, in a one code/ several outputs scheme, of potential significance for molecular computation processes and possibly even with respect to information processing in biology.

{Ag(isonicotinamide)2NO3}2 — a Stable Form of Silver Nitrate

[Ag(isonicotinamide)2NO3]2, featuring a short Ag···Ag contact and a strong hydrogen-bonding network in the solid state, is a light-stable and still readily soluble form of silver nitrate, showing little complex formation in solution but a counter-intuitive decrease in dissolution rate with decrease of pH.

Hydrogen-bonding and metal-ion-mediated self-assembly of a nanoporous crystal lattice.

Hydrogen-bonding and metal-ion coordination are utilized to assemble a nanoporous crystal lattice. In the initial step of the assembly process, tecton 1 (4b,5,7,7a-tetrahydro-4b,7aepiminomethanoimino-6H-imidazo[4,5-f][1,10]phenanthroline-6,13-dione) forms an octahedrally coordinated secondary building block with FeII, which in the final step assembles through hydrogen-bonding interactions to a nanoporous network. The secondary building blocks hydrogen-bond such that ribbons with two-membered channels are formed. Sheets are generated through hydrogen-bonding of the ribbons, which results in four-membered channels. In the crystal, the sheets are stacked parallel to each other, which results in a three-dimensional porosity.

A Logical Concept of Structure Prediction Derived from Supramolecular Polymers of Alkaline Earth Metal Halides Formed by Hydrogen Bonding and Complexation of the Metal Ion

Several different dimensional polymers derived from alkaline earth metal iodides are obtained as a result of supramolecular noncovalent bonding modes of the metal ion, namely complexation and hydrogen bonding. These polymers consist of complex cations linked to the halide ions by hydrogen bonds of the water ligands coordinated to the metal. They are built up in a logical way, depending on the ratio of complexing ligands to complexing and hydrogen-bonding ligands so that their dimensionality and, to a certain extent, their structure can be predicted.

H-bonded polymer structures of different dimensionality: syntheses and crystal structures of [Ca(DME)n(H2O)m]I2·(DME)x (1: n=3, m=3, x=1; 2: n=2, m=4, x=0) and [Ca{CH3(OCH2)3OCH3}(H2O)4]I2

Abstract From the non-covalent binding modes used in supramolecular chemistry, metal ion complexation and hydrogen bonding are combined in order to synthesise new inorganic polymers as precursors for thin layer deposition. With the same coordinating ligands, DME and water, but in varying stoichiometries, two different dimensional compounds are obtained. The synthesis and crystal structures of the one- and three-dimensional polymers are described together with a third example for better control of the supramolecular products formed.

Structural relationship of two coordination polymers of Cu(I) with the ligand ethanediyl bis(isonicotinate)

The flexible ligand ethanediyl bis(isonicotinate), L, is used as linking unit for Cu(I) ions in a coordination polymer. Two different structures of one-dimensional chains can be obtained, mainly depending on the co-crystallising solvent. Weak interactions such as hydrogen bonding and pi–stacking, and the exclusion of solvent molecules are responsible for the slow transformation of one compound into the other in the mother liquor.

How many structures are there for {[AgL](NO3)(H2O)n}? Water-content dependent variations in the structure of {[AgL](NO3)(H2O)n}, n= 0, 1, 2; L = ethanediyl bis(isonicotinate)

Three compounds of the composition [AgL](NO3)(H2O)n, n = 0 (1), 1 (2), 2 (3) have been obtained with different structures each. Whereas 1 builds single chains of ...–Ag–L–Ag–L–... crosslinked by NO3− anions to form two-dimensional layers, the conformation of L changes from anti to syn in 2, yielding pairs of chains with close Ag–Ag contacts. The anti conformation of the ligand L is again adopted in 3, and pairs of chains are now arranged in a parallel fashion. Calculations give a qualitative understanding of involved forces.

On the coordination behaviour of NO3- in coordination compounds with Ag+

The influence of the solubility of AgNO3 in three solvent systems is studied for the reaction between AgNO3 and the ligand L (= ethanediyl bis(isonicotinate)). Three solid state structures are obtained, differing in the relative ratio Ag : L in the first case, and in polymorphism in the second. The Ag–O(NO3−) distance correlates strongly with the solubility of AgNO3 in the used solvent. Solution studies prove indeed the existence of close ion contact pairs in the less good solvents, where as ion solvation is observed in good solvents for AgNO3. The three different structures are compared to two solvated structures in which H2O demonstrates coordination to the nitrate anion via H-bonding.

Chiral S-1,1′-bi-2-naphthol (S-BINOL) as a synthon for supramolecular hydrogen-bonded {(S-BINOLATn−)(S-BINOL)n}-strands with naphthyl-paneled cavities or channels for a Cd(NH3)4-fragment (n= 2) or [Ag(NH3)2]+(n= 1). Part 2

The molecule 1,1′-bi-2-naphthol (BINOL) shows a propensity for supramolecular, hydrogen-bonded strand formation when crystallized with its deprotonated form BINOLAT2− or BINOLAT− (in conc. ammonia). The strand adapts from racemic rac-BINOL to enantiomeric S-BINOL and from di- to monocationic metal ions but keeps the overall strand feature. The structure of [Cd2+(S-BINOLAT2−-κ2O,O′)(NH3)4](S-BINOL)2(H2O)(MeOH)2 (1) can be correlated to the known structures of [M(NH3)6]2+(rac-BINOLAT2−)(rac-BINOL)2 (M = Ni, Cd) despite the direct Cd-O,O′-BINOLAT chelate coordination in the former. With Ag+ as a monocationic metal structures of the formula [Ag(NH3)2]+(S-BINOLAT−)(S-BINOL)(EtOH) (2) and [Ag(NH3)2]+(S-BINOLAT−)(S-BINOL)(H2O)2(MeOH) (3) are formed from ethanol or methanol, respectively. Crystallization of Ag+/NH3 with rac-BINOL from EtOH also yields 2 with a spontaneous resolution to an enantiomeric excess of ca. 40%. Simultaneous differential thermoanalysis, thermogravimetry and mass spectrometry (DTA-TG-MS) show that the EtOH, MeOH and H2O solvent of crystallization together with the NH3 ligands can be removed before the BINOL moieties. X-Ray powder diffraction (XRPD) still shows the sample of 1 to be crystalline after the loss of solvent of crystallization. Upon heating to 130 °C the needle-shaped crystals of 2 keep their shape, yet darken (formation of Ag by XRPD) and turn amorphous, with small crystal “prickles” (BINOL by XRPD) forming on the surface. The difference in metal coordination between 1 and [Cd(NH3)6]2+(rac-BINOLAT2−)(rac-BINOL)2 is evidenced by a strong maximum at 591 nm in the emission spectrum of 1 which is absent in the emission spectra of both BINOL and [Cd(NH3)6]2+(rac-BINOLAT2−)(rac-BINOL)2. This maximum is assigned to a metal–ligand transition due to the direct Cd-O,O′-BINOLAT chelate coordination in 1.