The effects of anchoring groups on electron injection from adsorbate to nanocrystalline thin films were investigated by comparing injection kinetics through carboxylate versus phosphonate groups to TiO 2 and SnO 2 . In the first pair of molecules, Re(L A )(CO) 3 Cl (ReC1A) and Re(Lp)(CO)3Cl (ReC1P), [L A ) 2,2′-bipyridine-4,4′-bis-CH 2 -COOH, Lp) 2,2′-bipyridine-4,4′-bis-CH 2 -PO 3 H 2 ], the anchoring groups were insulated from the bipyridine ligand by a CH 2 group. In the second pair of molecules, Ru(dcbpyH 2 ) 2 (NCS) 2 (RuN3) and Ru(bpbpyH 2 ) 2 (NCS) 2 (RuN3P), [dcbpy ) 2,2′-bipyridine-4,4′-biscarboxylic acid, bpbpy ) 2,2′-bipyridine-4,4′-bisphosphonic acid], the anchoring groups were directly connected to the bipyridine ligands. The injection kinetics, as measured by subpicosecond IR absorption spectroscopy, showed that electron injection rates from ReC1P to both TiO 2 and SnO 2 were faster than those from ReC1A. The injection rates from RuN3 and RuN3P to SnO 2 films were similar. On TiO 2 , the injection kinetics from RuN3 and RuN3P were biphasic: carboxylate group enhances the rate of the <100 fs component, but reduces the rate of the slower components. To provide insight into the effect of the anchoring groups, the electronic structures of Re-bipyridyl-Ti model clusters containing carboxylate and phosphonate anchoring groups and with and without a CH 2 spacer were computed using density functional theory. With the CH 2 spacer, the phosphonate group led to a stronger electronic coupling between bpy and Ti center than the carboxylate group, which accounted for the faster injection from ReC1P than ReC1A. When the anchoring groups were directly connected to the bpy ligand without the CH 2 spacer, such as in RuN3 and RuN3P, their effects were 2-fold: the carboxylate group enhanced the electronic coupling of bpy π* with TiO 2 and lowered the energy of the bpy orbital. How these competing factors led to different effects on TiO 2 and SnO 2 and on different components of the biphasic injection kinetics were discussed.

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The combination of a novel trigonal metalloligand and linear linker affords the large non-interpenetrating honeycomb-like 2D [6,3] network in spite of the large hexagon lattice dimension.

Hollow, hexa-porphyrin prisms of two sizes were template-assembled and covalently locked, via cross-olefin metathesis, into permanent, torsionally rigid structures whose active sites (metal sites) can be both accessed and altered in a facile manner.

A second coordination sphere of six Nexo atoms in a trigonal‐antiprismatic arrangement allows the metalloligand [FeIII(L)2]+ (red spheres, L=hydrotris(1,2,4‐triazolyl)borate) to assemble with Rh2(OAc)4 linear spacers (blue rods) in an unprecedented noninterpenetrating 3D framework with 4669 topology. The metalloligand is reduced to the iron(II) state during the reaction by the borate ligand.

The coordination-directed self-assembly approach is an extremely powerful strategy for the synthesis of various 2-and 3D metallasupramolecules and can provide a structural and functional basis for its potential application toward molecular sensing and catalysis by using supramolecular chemistry.[1] In particular, discrete 3D self-assemblies derived from the multiple noncovalent interactions between monomeric metallo-subunits, such as chains, squares, and/or cages, are very intriguing because they are structurally complex but symmetrically simple and synthetically convenient to make. [2] Whereas various functional groups have been utilized for such purposes, little attention has been paid to metal-halide bonds, although they are well known as hydrogen-bond acceptors in molecular recognition and crystal engineering.[3] The halides are usually destined to be eliminated, presumably as a result of limited coordination sites on the metal center for incoming ligands.[1] These facts prompted us to explore the way to get the metal-halide groups to participate in both the coordination-directed and noncovalent self-assembly processes without their abstraction. Considering the molecular library model, [1g] we envisioned that the octahedral geometry of a transition metal might provide a novel approach for the use of metal-halide bonds as a self-assembly motif. For example, octahedral transition-metal centers with axial halide and cisprotecting ligands could serve as a 908 building block. The axial halide, then, may participate in hydrogen bonding with suitably functionalized bridging ligands.Herein, we demonstrate the unprecedented self-complementary dimer of Ru II metallamacrocycles which uses the intact metal-halide bonds in the coordination-directed selfassembly process and its reversible dissociation/association behavior, which is controlled by halide anions in solution.The ligand N,N'-bis(pyridin-4-yl)pyridine-2,6-dicarboxamide (1) was quite suitable for our purpose because it has central amide protons as hydrogen-bonding donors and is well known for bridging two metal centers, thus giving metallamacrocycles.[4] In addition, its bisamide configuration has proven to be very useful in hydrogen-bonding-mediated rotaxane formation [5] and anion recognition [6] with metallasupramolecules. As a precursor for the metal center, [RuCl 2 (PPh 3 ) 3 ] (2) was chosen for its ability to give a transCl 2 -cis-N 2 -cis-P 2 coordination environment around the Ru II center by reaction with a chelating phosphine and N-donor ligands. [7] Stirring equimolar amounts of 1, 2, and 1,3-bis(diphenylphosphino)propane (DPPP) in acetone at room temperature yielded the orange solid of 3 2 in good yield (87 %; Scheme 1).A single-crystal X-ray structure determination of 3 2 unambiguously revealed an interesting supramolecular association between two severely folded molecules of Ru II metallamacrocycle 3 (Figure 1). [8] The folded metallacycles 3, self-complementary monomers of 3 2 , are oriented orthogonally to each other. This orthogonal assembly s...

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