Dalton Transactions

doi: 10.1039/b607315hpmid: N/A

doi: 10.1039/b607316fpmid: N/A

Humphrey, Jamie; O'Connor, Niamh

doi: 10.1039/b606629cpmid: N/A

Crespo-Biel, Olga; Jan Ravoo, Bart; Huskens, Jurriaan; Reinhoudt, David N.

doi: 10.1039/b517699apmid: 16751880

Nanotechnology aspires to create functional materials with characteristic dimensions of the order 1–100 nm. One requirement to make nanotechnology work is to precisely position molecules and nanoparticles on surfaces, so that they may be addressed and manipulated for bottom-up construction of nanoscale devices. Here we review the concept of a “molecular printboard”. A molecular printboard is a monolayer of host molecules on a solid substrate on which guest molecules can be attached with control over position, binding strength, and binding dynamics. To this end, cyclodextrins were immobilized in monomolecular layers on gold, on silicon wafers and on glass. Guest molecules (for example, adamantane and ferrocene derivatives) bind to these host surfaces through supramolecular, hydrophobic inclusion interaction. Multivalent interactions are exploited to tune the binding strength and dynamics of the interaction of guest molecules with the printboard. Molecules can be positioned onto the printboard using supramolecular microcontact printing and supramolecular dip-pen nanolithography due to the specific interaction between the ‘ink’ and the substrate. In this way, nanoscale patterns can be written and erased on the printboard. Currently, the molecular printboard is exploited for nanofabrication, for example in combination with electroless deposition of metals and by means of supramolecular layer-by-layer deposition.

Miller, Joel S.

doi: 10.1039/b515974apmid: 16751881

The development of molecules and assemblies of molecules exhibiting technologically important bulk properties, such as magnetic ordering, is an important worldwide research focus. Organic- and molecule-based magnets have been discovered and several families have been reported with magnetic ordering temperatures exceeding room temperature and as high as ∼125 °C. Examples of both hard and soft magnets have been reported with coercivities as high at 27 000 Oe (and exceeding commercially available magnets) have been reported. Several examples are based on the radical anion of tetracyanoethylene, = 1/2 [TCNE]˙. The include ionic zero-dimensional (0-D) [FeCp*]˙[TCNE]˙ (Cp* = pentamethylcyclopentadienide), 1-D [MnTPP][TCNE]˙ [TPP = -tetraphenylporphinato] coordination polymers, and 3-D extended network structured M[TCNE]·Solvent (M = V, Mn, Fe, Co, Ni, Dy). This Perspective focuses on work in our laboratory that will be discussed at the Dalton Discussion 9 meeting entitled “Functional Molecular Assemblies.” In addition to the overview of TCNE-based organic magnets, the targeted design, preparation, and chemical as well as magnetic characterization of a new family of magnets based on = 3/2 mixed-valent [Ru(OCR)] (R = Me, Bu) is described. In particular [Ru(OCMe)][Cr(CN)] prepared from aqueous media possess two interpenetrating cubic lattices and magnetically orders at 33 K. In contrast, [Ru(OCBu)][Cr(CN)] forms a 2-D layered lattice and orders at 37.5 K. Both exhibit hysteretic behavior, however, this is quite anomalous for the former cubic lattice. This as well as other anomalous magnetic behaviors is attributed to the presence of the second interpenetrating lattice.

Maurizot, Victor; Yoshizawa, Michito; Kawano, Masaki; Fujita, Makoto

doi: 10.1039/b516548mpmid: 16751882

Coordination self-assembly entities have been demonstrated to be useful and powerful alternatives for the construction of predefined and well-organized architectures. Self-assembled coordination cages, which possess an inner hydrophobic cavity, can be utilized to move substrates closer by encapsulation so enabling their interaction with each other and exhibiting of non-classical physical properties.

Pandya, Shashi; Yu, Junhua; Parker, David

doi: 10.1039/b514637bpmid: 16751883

Emissive f-block coordination complexes constitute an important class of optical probes, with applications ranging from sensing of bioactive species, high throughput assays and screening protocols , to time-resolved imaging studies or The key chemistry issues to be addressed in complex design and characterisation are defined, with an emphasis on the use of emissive europium and terbium complexes and their conjugates in molecular imaging. Both luminescent ‘tags’ useful in energy transfer studies and ‘responsive’ systems for sensing are discussed.

Weidner, Tobias; Krämer, Andreas; Bruhn, Clemens; Zharnikov, Michael; Shaporenko, Andrey; Siemeling, Ulrich; Träger, Frank

doi: 10.1039/b515727gpmid: 16751884

The new tridentate thioether ligands PhSi(CHSMe) () and Ph--CHSi(CHSMe) () have been synthesised and used for the preparation of the chelates -[W(κ-)(CO)] and -[W(κ-)(CO)], which were characterised by single-crystal X-ray diffraction. and were used as tripodal adsorbate molecules for the fabrication of self-assembled monolayers (SAMs) on gold. Film formation from solution was investigated by second harmonic generation (SHG) and ellipsometry, which revealed a two-stepped process (fast adsorption, followed by slow film ordering). SAMs of on gold were further investigated by methods, high-resolution X-ray photoelectron spectroscopy (HRXPS), Fourier transform infrared reflection absorption spectroscopy (FTIRRAS), and scanning tunneling microscopy (STM). The latter two methods indicated dense packing of the tripodal anchor groups on the surface, with a substantially lower density of the biphenyl pricks. HRXPS showed three different binding states of sulfur, including a standard thiolate-type and a coordination-type state.

Advincula, Rigoberto C.

doi: 10.1039/b517601hpmid: 16751885

In this work, the synthesis, characterization, and applications of branched oligothiophene dendrons that act as electroactive surfactants for the capping of Au metal nanoparticles and CdSe quantum dots are described. Two distinct methods have been employed for synthesis: a ligand exchange process and a direct-capping synthesis approach. The coverage of the dendrons per nanocrystal, the nature of the surface coordination interactions, and energy transfer interactions were studied in detail using UV-vis absorbance, FT-IR, AFM, TEM, and photoluminescence spectroscopy. The competition/displacement in ligand metathesis is highlighted by the size of the dendron and nature of binding on semiconductor nanocrystals. In the other system using the direct capping method, the size of the Au nanoparticle is mediated by the dimensions of the ligand, alkyl chain spacer and dendron branching or size. These hybrid dendron/nanoparticle complexes are generally very soluble and stable in non-polar solvents. They exhibit energy transfer, surface plasmon resonance effects, and photoinduced charge transfer interactions between the metal/semiconductor and conjugated ligands. Adsorption on mica and graphite surfaces was observed. A one-layer photovoltaic cell was fabricated to demonstrate the potential for device applications.

Cooper, Rachel J.; Camp, Philip J.; Gordon, Ross J.; Henderson, David K.; Henry, Dorothy C. R.; McNab, Hamish; De Silva, Sonali S.; Tackley, Daniel; Tasker, Peter A.; Wight, Paul

doi: 10.1039/b518260cpmid: 16751886