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Ajuts: This work has been supported by the EC Program IHP- 99 (HPMF-CT-2002-01698) The exciton wave function of a trichromophoric system is investigated by means of single molecule spectroscopy at room temperature. Individual trimers exhibit superradiance and loss of vibronic structure in emission spectrum, features proving exciton delocalization. We identify two distinct photodegradation pathways for single trimers upon sequential photobleaching of the chromophores. The rate of each pathway is a measure for the contribution of the separate dyes to the collective excited state of the system, in this way probing the wave function of the delocalized exciton.

During the Calix2015 conference that took place in Giardini Naxos in July of this year, the first C. David Gutsche Award for Calixarene Chemistry was awarded to one of the founders of the field, Professor Rocco Ungaro of the University of Parma. In this paper, Rocco Ungaro’s seminal contributions to the field are described. His collaborations with many other groups, his role in the European supramolecular chemistry community and his most important scientific results are briefly summarised. Probably the first time I saw Rocco was in August 1978 at the Conference on Macrocyclization organised by Illuminati and Mandolini in Castel Gandolfo (Italy). We were both there but I do not recall meeting him personally. A few years later, we did meet in Stresa where we discussed our chemistry. In 1982, Rocco invited David Gutsche and myself to the Inclusion Phenomena meeting in Parma

This work describes the synthesis and photophysical characterization of Ir(III) and Ru(II) complexes bearing terminal amino groups, which act as anchoring units for the attachment to quantum dots, QDs. The photophysical properties of the metal complexes in combination with different types of QDs, allows directional photoinduced processes in the assemblies. In particular, we show photoinduced energy transfer from the luminescent excited Ir(III) unit to the CdTe nanocrystals, with an efficiency of 40%. The directionality was then inverted by employing an emitting Ru(II) complex as energy acceptor, in combination with photoluminescent CdSe/ZnS quantum dots. The efficiency of the photoinduced energy transfer from the nanocrystals to the Ru(II) center was estimated to be as high as 75%. This work provides model systems for nanoassemblies based on quantum dots and metal complexes for optoelectronic applications, and as active light-harvesting systems.

This study describes that the current rectification ratio, R h equivalent to vertical bar J vertical bar(+2.0 V)/vertical bar J vertical bar(+2.0 V) for supramolecular tunneling junctions with a top-electrode of eutectic gallium indium (EGaIn) that contains a conductive thin (0.7 nm) supporting outer oxide layer (Ga2O3), increases by up to four orders of magnitude under an applied bias of >+1.0 V up to +2.5 V; these junctions did not change their electrical characteristics when biased in the voltage range of +/- 1.0 V. The increase in R is caused by the presence of water and ions in the supramolecular assemblies which react with the Ga2O3/EGaIn layer and increase the thickness of the Ga2O3 layer. This increase in the oxide thickness from 0.7 nm to similar to 2.0 nm changed the nature of the monolayer-top-electrode contact from an ohmic to a non-ohmic contact. These results unambiguously expose the experimental conditions that allow for a safe bias window of +/- 1.0 V (the range of biases studies of charge transport using this technique are normally conducted) to investigate molecular effects in molecular electronic junctions with Ga2O3/EGaIn top-electrodes where electrochemical reactions are not significant. Our findings also show that the interpretation of data in studies involving applied biases of >1.0 V may be complicated by electrochemical side reactions which can be recognized by changes of the electrical characteristics as a function voltage cycling or in current retention experiments.

In this study, we describe the development of a sensing system for the real-time analysis of the pH and pH gradients at the solid/liquid interface. A pH-sensitive fluorescent platform has been developed by ‘clicking’ an alkyne-modified N-methylpiperazine naphthalimide onto an azide monolayer on glass. The surface immobilisation of the molecular probe was assessed by X-ray photoelectron spectroscopy, while sensitivity and reversibility were demonstrated by fluorescence microscopy and contact angle goniometry. The pH titration of the platform allowed for the determination of the pKa value of the pH-sensitive probe at the solid/liquid interface. The platform was employed for the real-time interfacial analysis of micron-scale pH gradients at the solid/liquid interface induced by the electrolysis of water as exerted by an interdigitated microelectrode array. The calibration by the platform titration allowed the visualisation and quantification of the pH gradient with a dynamic range of about three pH units and...

Pt top contacts have been deposited by pulsed laser deposition (PLD) onto bare and tetradecylphosphate (TDP) self-assembled monolayer (SAM)-modified Nb-doped SrTiO3 (Nb-STO) substrates. For the SAM-modified substrates, electrochemical Cu deposition occurred only at the places where electrical shorts existed between the top contact and the substrate. A nearly perfect yield of top contacts without shorts was obtained, which shows the dense packing and robustness of the SAM. The SAM decreased the leakage current about 500 times compared to the bare substrate. Alkylphosphate SAMs on conducting metal oxide substrates can therefore be used as dielectric thin films for device fabrication.

Item does not contain fulltext Dip-pen nanolithography (DPN) is an atomic force microscopy (AFM)-based lithography technique, which has the ability to fabricate patterns with a feature size down to approximately 15 nm using both top-down and bottom-up approaches. DPN utilizes the water meniscus formed between an AFM tip and a substrate to transfer ink molecules onto surfaces. A major application of this technique is the fabrication of micro- and nano-arrays of patterned biomolecules. To achieve this goal, a variety of chemical approaches has been used. This review concisely describes the development of DPN in the past decade and presents the related chemical strategies that have been reported to fabricate biomolecular patterns with DPN at micrometer and nanometer scale, classified into direct- and indirect DPN methodologies, discussing tip-functionalization strategies as well.

The kinetics of multivalent (multisite) interactions at interfaces is poorly understood, despite its fundamental importance for molecular or biomolecular motion and molecular recognition events at biological interfaces. Here, we use fluorescence microscopy to monitor the spreading of mono-, di- and trivalent ligand molecules on a receptor-functionalized surface, and perform multiscale computer simulations to understand the surface diffusion mechanisms. Analogous to chemotaxis, we found that the spreading is directional (along a developing gradient of vacant receptor sites) and is strongly dependent on ligand valency and concentration of a competing monovalent receptor in solution. We identify multiple surface diffusion mechanisms, which we call walking, hopping and flying. The study shows that the interfacial behaviour of multivalent systems is much more complex than that of monovalent ones.

Item does not contain fulltext PNAs (peptide nucleic acids) have been immobilized onto surfaces in a fast, accurate way by employing reactive microcontact printing. Surfaces have been first modified with aldehyde groups to react with the amino end of the synthesized PNAs. When patterning fluorescein-labeled PNAs by reactive microcontact printing using oxygen-oxidized polydimethylsiloxane stamps, homogeneous arrays were fabricated and characterized using optical methods. PNA-patterned surfaces were hybridized with complementary and mismatched dye-labeled oligonucleotides to test their ability to recognize DNA sequences. The stability and selectivity of the PNA-DNA duplexes on surfaces have been verified by fluorescence microscopy, and the melting curves have been recorded. Finally, the technique has been applied to the fabrication of chips by spotting a PNA microarray onto a flat PDMS stamp and reproducing the same features onto many slides. The chips were finally applied to single nucleotide polymorphism detection on oligonucleotides.

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This review gives an overview of the recent literature regarding lateral molecular interactions in monolayers. The first part (Section 3) focuses on systems of self-assembled monolayers on metal surfaces, discussing the covalent and noncovalent interactions of the terminal functionality or between the molecular chains of the molecules. The second part (Section 4) highlights the intermolecular interactions of monolayers on silicon and metal oxide surfaces. The third part (Section 5) presents examples of lateral interactions on receptor surfaces. A focus in all parts is on examples of lateral interactions in monolayers in which electron or energy transfer occurs.

We report here the use of nanomolding in capillaries (NAMIC) coupled with dithiocarbamate (DTC) chemistry to fabricate sub-50 nm quasi-1D arrays of 3.5 nm core gold nanoparticles (Au NPs) over large areas. Owing to chemical immobilization via the DTC bond, the patterned NP systems are stable in water and organic solvents, thus allowing the surface modification of the patterned Au NP arrays through thiol chemistry and further orthogonal binding of proteins. The electrical properties of these patterned Au NP wires have also been studied. Our results show that NAMIC combined with surface chemistry is a simple but powerful tool to create metal NP arrays that can potentially be applied to fabricate nanoelectronic or biosensing devices.

The concept of bioreductive alkylation as a mechanism of action of aziridinylquinoid anticancer agents has been investigated. The influence of quinone substituents on quinone reduction, on protonation of the aziridines prior to and following quinone reduction and on partitioning properties of the compound was examined. Parameters obtained from a combined electrochemical, chemical-stability and lipophilicity study describing these processes were determined and correlated quantitatively in a Hansch-type QSAR study with biological data obtained from three experimental tumor models. Poor quantitative correlations between cytotoxicity in a L1210 clonogenic assay and the parameters were obtained. Good linear relationships, however, between antitumor activity in vivo (vs. L1210 leukemic mice and vs. B16 melanoma-bearing mice) and the lipophilic properties of the quinone were found. These relationships, showing a negative correlation between antitumor activity and lipophilicity, can be used to predict the activity of new, unknown compounds. No trend was evident between antitumor activity and other parameters, although some indications for potential importance of electronic and steric properties of the substituents and of their ability to form hydrogen bonds were found.

Two different routes are described for the synthesis of the 2,2,2‐trifluoro‐l‐[2‐(dialkyl‐amino)phenyl]ethanones 2 and 9 and their hydrates 3 and 10, respectively, via trifluoroacetylation of the N,N‐dialkylanilines 1 and via a Barbier reaction of 2‐fluorobenzaldehyde. These compounds were thermally converted into a mixture of cis‐ and trans‐pyrrolo‐ and pyrido[1,2‐a] [3,1]benzoxazines, (11: cis; 12: trans). The structure of these compounds was proven by X‐ray analysis (11a) and 1H NOE difference spectroscopy. Cyclization of (R)‐9b (R1 = CH3) gave predominantly one enantiomer (12f, 70%) and in addition two diastereomers of 17a and two of 18a (total yield ≈ 17%), while cyclization of (S)‐9c (R1 = CH2OCH3) gave a mixture of 12g (18%), two diastereomers of 17b (36%) and two diastereomers of 18b (18%). The benzaldehyde 19a (R3 = H), acetophenone 19d (R3 = CH3), trifluoroacetophenones 19b,c (R3 = CF3) and benzophenone 19e (R3 = C6H5) reacted with Lawesson's reagent to yield exclusively the trans‐pyrrolo[1,2‐a] [3,1]benzothiazines 21a‐e in yields of 33‐77%. Reaction of 19f (R1 = CH3, R3 = H), 19g (R1 = CH3, R3 = CF3) and 19h (R1 = CH3, R3 = CH3) with Lawesson's reagent resulted in the formation of mixtures of isomers 21‐24.

The [3 + 3] macrocyclic compounds 2a–2c were easily prepared by cyclization of the dialdehyde 8 with the appropiate diamines in refluxing CH3CN/MeOH (1/1), in the presence of Ba2+ as a template ion. These macrocycles contain three salen units and are therefore, in combination with the crown ether interior, potentially tetranucleating. The length of the diamine bridge and the temperature at which the reaction is carried out, appear to influence the size of the macrocycle formed. In this way, the [4 + 4] macrocycle 2d could be formed selectively over the [3 + 3] macrocycles by carrying out the reaction at room temperature.

Neutral macrocyclic alkali‐cation receptors have been covalently linked to one or more molecules of the membrane solvent 2‐nitrophenyl n‐octyl ether (NPOE). These compounds are all highly lipophilic and soluble in NPOE. The flux of alkali‐perchlorate salts through supported liquid membranes (SLMs) has been optimized by variation of the carrier content in the membrane and the temperature. With all carriers, the optimum flux is reached at carrier contents of about 20% (w/w) in NPOE. Above this carrier content the flux decreases because of an increase in the viscosity of the membrane solutions. Relatively low activation energies for transport indicate that the transport is diffusion‐limited. The excellent compatibility between the carriers and the membrane solvent leads to very stable membranes (NPOE/Accurel®). The mechanism of alkali perchlorate transport has been investigated by variation of the source‐phase salt activity and the carrier concentration. Indications about ion pair formation and 2/1 carrier/cation complexation have been obtained from variation of the carrier concentration and transport selectivity measurements.

A general method has been developed for the preparation of bis(syn‐proximally) functionalized calix[4]arenes (6, 8–10). Starting from p‐tert‐butylcalix[4]arene 1a and calix[4]arene 1b syn‐proximally dialkylated calix[4]arenes 2a and 2b, 4, and 5, respectively, were obtained by treatment with 4.2 equiv of NaH and 2.2 equiv of alkylating reagent in DMF. The syn‐proximal substitution pattern was unequivocally proven by an X‐ray structural determination of 2b. Furthermore the influence of different bases on the functionalization of the free hydroxyl groups of 2b with chloroacetone was studied. Cs2CO3 as the base gave the bis(syn‐proximally) functionalized calix[4]‐arene 6 in the highest yield (82%). Cation complexation studies, with the picrate extraction method, showed that subtle changes in regioselective functionalization influences the selectivity for Na4 considerably.

Molecular‐mechanics (MM) and molecular‐dynamics (MD) simulations (in MeOH) were performed on Eu3+ complexes of two derivatized calix[4]arenes (2b and 2d) and a bislariat diazacrown ether (3). The Quanta/CHARMm Lennard‐Jones parameters of Ca2+ proved suitable as a model for the Lennard‐Jones parameters of Eu3+. The radial distribution function (RDF) of Eu3+ … MeOH (O) agrees well with experimental data. The MD of 2b · Eu3+ showed that the phenolic oxygens cannot compete with the solvent, although they are preorganized. Three molecules of MeOH are within the first coordination shell. The MD of 2d · Eu3+ showed two transitions. After the first the Eu3+ was coordinated by one molecule of MeOH and after the second by three molecules of MeOH. The pyridine ring was not involved in coordination to Eu3+, which explained the measured lifetimes and derived coordination shells in methanol. The calculations on 3 · Eu3+ revealed that the conformation with the pendant arms in an anti configuration is unlikely to exist in solution, whereas the syn form calculated by MM rearranged to a structure with two molecules of MeOH in the first coordination sphere. This is consistent with experimental data, which show that the two dominant species in methanol solution have two molecules of MeOH coordinated to the Eu3+. All calculations were performed with the Quanta/CHARMm package.

Reactions of the four-membered cyclic nitrones 1 with acetyl chloride differ strongly from those of other (cyclic) nitrones. In the presence of water, the nitrones 1 yield the 2-[(acetyloxy)-amino]-N,N-diethylalkanamides 4. The structure of 4b was confirmed by X-ray analysis. In the absence of water, the N,N-diethyl-4-methylene-2-azetidinecarboxamides 5 or the N,N-diethyl-2,3-dihydro-2-azetecarboxamides 6 were obtained. X-ray analysis elucidated the structure of 5a. Under acidic conditions, compounds 5a yielded the 2-oxa-5-azabicyclo[2.1.1]hexan-3-one derivative 13. Acid hydrolysis of 6a gave the α-chloroketone derivative 18 and the 2-oxopropanamide derivative 19.

The 1-(benzyloxy)azetidines 7a-c and 16a,b were synthesized by reductive cyclization of the corresponding oximes 5a-c and 14a-d. Oxidation of the 1-hydroxyazetidines 8a-c and 17 with PbO2 afforded the corresponding four-membered cyclic nitrones 18a-c and the bicyclic four-membered nitrones 18d and 18e, which were characterized as the cycloadducts 19a-c and 20 by reaction with dimethyl acetylenedicarboxylate. Pb(OAc)4 oxidation of the monocyclic l-hydroxy-azetidine 8a gave 1,4-bis(acetyloxy) β-lactam 22a and 1,4,4-tris(acetyloxy) β-lactam 23a, while oxidation of the 1-hydroxyazetidines 8b,c gave exclusively the 1,4-bis(acetyloxy) β-lactams 22b and 22c. Oxidation of bicyclic l-hydroxyazetidine 17 with Pb(OAc)4 afforded the bicyclic bis(acetyloxy) β-lactam 21.

Crystals of 5,17‐bis(acetamido)‐25,26,27,28‐tetrapropoxycalix[4]arene · ethyl‐acetate (1: 1), C44H54N2O6 · C4H8O2 are triclinic, space group P‐1, a = 13.319(4), b = 15.519(4), c = 22.386(6) Å, α = 104.73(3), β = 99.02(3), γ = 95.30(3)°, T = 100(5) K, Z = 4. The asymmetric unit contains two calix[4]arene molecules and two ethyl acetate molecules. The two calix[4]arene molecules have different pinched cone conformations. The phenyl rings show small but consistent boat‐like deformations. The final R factor is 7.9%.

Macroheterocyclic molecules can be used to organize the binding sites required for selective molecular recognition and/or molecular catalysis. Although most work in the literature deals with recognition of ionic species, there is an increasing interest in the selective complexation of neutral molecules. Based on X-ray analysis of solid complexes and NMR in solution, hydrogen bonding of host to guest and/or vice versa determines the structure, and very likely also the stability of these complexes between neutral host and guests. This paper describes an NMR method to determine the (weak) association constants of such complexes. Subsequently, two strategies are described for the enhancement of the thermodynamic stability, viz. the introduction of (intraannular) acidic groups in the molecular cavity and the use of metallomacrocyclic hosts in which a ‘soft’ cavity is combined with a ‘hard’ macrocyclic moiety. For both approaches novel synthetic methodology has been designed and for the first approach, the pKa values of acidic groups present in molecular cavities have been studied. Finally we have used the novel metallomacrocycles to organize two (or more) different metal centres in molecular cavities.

Within the past years there has been much effort in developing and improving new techniques for the nanoscale patterning of functional materials used in promising applications like nano(opto)electronics. Here a high-resolution soft lithography technique—nanomolding in capillaries (NAMIC)—is demonstrated. Composite PDMS stamps with sub-100 nm features are fabricated by nanoimprint lithography to yield nanomolds for NAMIC. NAMIC is used to pattern different functional materials such as fluorescent dyes, proteins, nanoparticles, thermoplastic polymers, and conductive polymers at the nanometer scale over large areas. These results show that NAMIC is a simple, versatile, low-cost, and high-throughput nanopatterning tool.

FePt nanoparticles (NPs) were assembled on aluminum oxide substrates, and their ferromagnetic properties were studied before and after thermal annealing. For the first time, phosph(on)ates were used as an adsorbate to form self-assembled monolayers (SAMs) on alumina to direct the assembly of NPs onto the surface. The Al(2)O(3) substrates were functionalized with aminobutylphosphonic acid (ABP) or phosphonoundecanoic acid (PNDA) SAMs or with poly(ethyleneimine) (PEI) as a reference. FePt NPs assembled on all of these monolayers, but much less on unmodified Al(2)O(3), which shows that ligand exchange at the NPs is the most likely mechanism of attachment. Proper modification of the Al(2)O(3) surface and controlling the immersion time of the modified Al(2)O(3) substrates into the FePt NP solution resulted in FePt NPs assembly with controlled NP density. Alumina substrates were patterned by microcontact printing using aminobutylphosphonic acid as the ink, allowing local NP assembly. Thermal annealing under reducing conditions (96%N(2)/4%H(2)) led to a phase change of the FePt NPs from the disordered FCC phase to the ordered FCT phase. This resulted in ferromagnetic behavior at room temperature. Such a process can potentially be applied in the fabrication of spintronic devices.

In complete control: The magnitude of current rectification in well-defined supramolecular tunneling junctions can be controlled by changing the terminal functionality (red spheres) of dendrimers (gray spheres) immobilized on a supramolecular platform (see picture). Junctions containing biferrocene and ferrocene end groups showed larger rectification ratios than junctions containing adamantyl end groups.

Supramolecular microcontact printing was used to obtain controlled patterns consisting of quantum dots (QDs) functionalized at their periphery with beta-cyclodextrin (beta-CD) in combination with adamantyl terminated dendrimeric "glues". Functionalization of core--shell CdSe/ZnS QDs was achieved by surface ligation. Immobilization of the QDs from solution onto glass substrates printed with (a) adamantyl-terminated poly(propylene imine) dendrimers and (b) via direct microcontact printing of QDs onto the dendrimer layer both yielded stable and robust multilayer structures. The stability of the patterns was primarily due to multivalent supramolecular host--guest interactions between beta-CD located at the QD surface and adamantyl groups at the dendrimer periphery as the dendrimers acted as a "supramolecular glue". The surface-immobilized QDs were capable of forming host--guest complexes with other molecules of interest at binding cavities not occupied by adamantyl groups. Complex formation with ferrocene-functionalized molecules at these sites led to partial quenching of the luminescence emission of QDs demonstrating the principle for sensing using the QD multilayer structures.

Fabricating well-defined and stable nanoparticle crystals in a controlled fashion receives growing attention in nanotechnology. The order and packing symmetry within a nanoparticle crystal is of utmost importance for the development of materials with unique optical and electronic properties. To generate stable and ordered 3D nanoparticle structures, nanotechnology is combined with supramolecular chemistry to control the self-assembly of 2D and 3D receptor-functionalized nanoparticles. This review focuses on the use of molecular recognition chemistry to establish stable, ordered, and functional nanoparticle structures. The host–guest complexation of β-cyclodextrin (CD) and its guest molecules (e.g., adamantane and ferrocene) are applied to assist the nanoparticle assembly. Direct adsorption of supramolecular guest- and host-functionalized nanoparticles onto (patterned) CD self-assembled monolayers (SAMs) occurs via multivalent host–guest interactions and layer-by-layer (LbL) assembly. The reversibility and fine-tuning of the nanoparticle-surface binding strength in this supramolecular assembly scheme are the control parameters in the process. Furthermore, the supramolecular nanoparticle assembly has been integrated with top-down nanofabrication schemes to generate stable and ordered 3D nanoparticle structures, with controlled geometries and sizes, on surfaces, other interfaces, and as free-standing structures.

Magnetic nanoparticles are of great scientific and technological interest. The application of ferromagnetic nanoparticles for high-density data storage has great potential, but energy efficient synthesis of uniform, isolated, and patternable nanoparticles that remain ferromagnetic at room temperature is not trivial. Here, we present a low-temperature solution synthesis method for FePtAu nanoparticles that addresses all those issues and therefore can be regarded as an important step toward applications. We show that the onset of the chemically ordered face-centered tetragonal (L1(0)) phase is obtained for thermal annealing temperatures as low as 150 degrees C. Large uniaxial magnetic anisotropy (10(7) erg/cm(3)) and a high long-range order parameter have been obtained. Our low-temperature solution annealing leaves the organic ligands intact, so that the possibility for postanneal monolayer formation and chemically assisted patterning on a surface is maintained.

The treatment of a suspension of graphite oxide (GO) with sodium azide leads to a material that, after reduction, features amino groups at the top and bottom of the sheets. These groups react through microcontact printing with an isothiocyanate monolayer on a silicon oxide substrate to form covalent bonds that strongly attach to the particles on the surface. With ultrasonication it is possible to obtain exfoliation of the sheets that are not covalently bound to the surface leaving single-layer platelets attached to the substrate. The azido derivative can be also used to functionalize the graphene oxide with long alkylic chains through a click chemistry approach. This functionalization results in the exfoliation of this material in dimethylformamide. The novel materials were fully characterized by different techniques including IR spectroscopy, thermogravimetric analysis (TGA), scanning and transmission electron microscopy (SEM and TEM), X-Ray photoelectron spectroscopy (XPS), and solid state NMR spectroscopy. The material with amino groups, after the reduction step, is conductive with a resistivity only approximately seven times larger than that of unprocessed graphite. This implies that after reduction of the GO, the conjugated sp2 network is largely restored. We consider this to be an important step towards a chemical approach for forming conducting large-area platelet films of single-layer graphene.

This paper describes a method for the direct transfer of biomolecules encapsulated within a viscous fluid matrix by dip-pen nanolithography (DPN). The method relies on the use of agarose as a "universal" carrier that is compatible with many types of biomolecules including proteins and oligonucleotides. Agarose-assisted DPN allows one to generate nanoarrays of such materials on activated glass substrates with the same deposition rates for different biomolecules, which will greatly expand future capabilities for parallel, multiplexed biomolecule deposition. The fluidity of the matrix may be systematically varied to control the deposition process, resulting in an additional parameter affecting deposition rates besides tip-substrate contact-time and humidity. Agarose-assisted DPN results in extremely fast biomolecule patterning with typical contact times less than 1 s. Feature sizes as small as 50 nm are demonstrated. The biorecognition properties of both protein and oligonucleotide structures are characterized by studying their reactivity with fluorophore-labeled antibody and complementary oligonucleotide sequences, respectively.

Mechanically robust and crystalline supramolecular particle structures have been constructed by decoupling nanoparticle assembly and supramolecular glue infiltration into a sequential process. First, beta-cyclodextrin (CD)-functionalized polystyrene particles (d approximately 500 nm) were assembled on a CD-functionalized surface via convective assembly to form highly ordered, but mechanically unstable, particle crystals. Subsequently, the crystals were infiltrated by a solution of adamantyl-functionalized dendrimers, functioning as a supramolecular glue to bind neighboring particles together and to couple the entire particle crystal to the CD surface, both in a noncovalent manner. The supramolecular particle crystals are highly robust, as witnessed by their ability to withstand agitation by ultrasonication. When assembled on a poly(dimethylsiloxane) (PDMS) stamp, the dendrimer-infiltrated particle crystals could be transfer-printed onto a CD-functionalized target surface. By variation of the geometry and size of the PDMS stamps, single particle lines, interconnected particle rings, and V-shaped particle assemblies were obtained. The particle structures served as 3D receptors for the binding of (multiple) complementary guest molecules, indicating that the supramolecular host functionalities of the particle crystals were retained throughout the fabrication process.

Microcontact printing (µCP) offers a simple and low-cost surface patterning methodology with high versatility and sub-micrometer accuracy. The process has undergone a spectacular evolution since its invention, improving its capability to form sub-100 nm SAM patterns of various polar and apolar materials and biomolecules over macroscopic areas. Diverse development lines of µCP are discussed in this work detailing various printing strategies. New printing schemes with improved stamp materials render µCP a reproducible surface-patterning technique with an increased pattern resolution. New stamp materials and PDMS surface-treatment methods allow the use of polar molecules as inks. Flat elastomeric surfaces and low-diffusive inks push the feature sizes to the nanometer range. Chemical and supramolecular interactions between the ink and the substrate increase the applicability of the µCP process.

High pressure organic reactions both in closed and continuous flow systems are reviewed with special attention to the instrumentation and miniaturized systems.

We report here the results of the preliminary characterization of the monolayer obtained both by self-assembling and microcontact printing of a di-alkyl sulfide nitronyl nitroxide derivative, 11-decyl sulfanyl-undecanyl nitronyl nitroxide of which we describe the synthesis. The sulfide unit has been introduced in order to allow the grafting of the molecule to the gold surface as well as to improve the stability of the organic radical with respect to different grafting agents like thiols, whereas the two long alkyl chains have been introduced to enhance the packing order of the molecules in a self assembled monolayer structure. X-band ESR was used to demonstrate the persistence of the paramagnetic character of the radical in the self-assembled monolayers, and to study its relatively large mobility. The microcontact printed monolayer was characterized by AFM, suggesting a non-negligible mobility of the molecules on the surfaces and a strong tilting of the molecules on the surface.

The self-organisation of silver-containing hydrogen-bonded rosette assemblies on highly oriented pyrolytic graphite (HOPG) surfaces is described. The introduction of silver atoms into the double rosette architecture was achieved using the affinity of silver cations for cooperative -donors or cyano functionalities on the double rosettes. Highly ordered 2-D nanorod domains with an inter-row spacing of 4-5 nm oriented in different directions were revealed by tapping-mode atomic force microscopy (AFM). This new and simple strategy for the creation of metal-containing supramolecular nanorod arrays that can act as well-defined surface-immobilised self-assembled scaffolds, will contribute to the development of functionalised nanoarchitectures via bottom-up approaches.

Fluorescent self-assembled monolayers (SAMs) are used as dip-pen nanolithography (DPN) substrates for the fabrication of patterns of Ca(2+) and Cu(2+) ions. The driving force for the transfer of these ions from an atomic force microscopy (AFM) tip to the surface is their complexation to organic ligands on the monolayer. By means of fluorescent surfaces, the patterns can be visualized under a fluorescence microscope. We use a custom-built atomic force fluorescence microscope (AFFM), a combination of atomic force and confocal fluorescence microscopes, to deposit the metal ions onto the sensing SAMs by DPN and to subsequently visualize modulations of fluorescence intensity in a sequential write-read mode.

Regenerable surfaces and reversible attachment of nanostructures onto them is an important aim in nanotechnology. Reversible attachment of nanostructures at molecular printboards was illustrated by the adsorption and desorption of β-cyclodextrin (β-CD)-functionalized nanoparticles onto and from stimuli-responsive preadsorbed ferrocenyl-functionalized poly(propylene imine) dendrimers at a β-CD self-assembled monolayer (SAM). Electrochemical oxidation of the ferrocenyl endgroups was employed to induce desorption of nanostructures from the β-CD SAMs. A combined surface plasmon resonance spectroscopy and electrochemistry setup was used to monitor the in situ adsorption and desorption of ferrocenyl dendrimers and β-CD-functionalized Au nanoparticles (CD-Au, d 2.8 nm) onto and from the molecular printboard. In the case of the larger β-CD-functionalized silica nanoparticles (CD-SiO2, d 60 nm), ultrasonication was used to reduce the desorption time. By electrochemical oxidation applied to a specific area of a nanoparticle layer, local desorption of nanoparticles was observed. In the nonoxidized area, nanoparticles remained robustly attached to the surface, whereas nanoparticles on the electrochemically oxidized area were completely removed.

Novel tripodal CMPO ligands having either aryl groups at the N-atom or alkyl groups at the CMPO methylene bridge were prepared in good yields. In the latter case one alkyl group per CMPO moiety was selectively introduced. Extraction studies with Am3+ and Eu3+ show that there is an influence of the electronic character of the aryl groups on the extraction. Alkylation of the CMPO methylene group gives rise to a considerable decrease of the D-values (about 100–1000 times), dependent on the bulkiness of the alkyl substituent.

Different methods to create chemically patterned, flat PDMS stamps with two different chemical functionalities were compared. The best method for making such stamps, functionalized with 1H,1H,2H,2H-perfluorodecyltrichlorosilane (PFDTS) and 3-(aminopropyl)triethoxysilane (APTS), appeared to be full functionalization of a freshly oxidized flat PDMS stamp with either adsorbate, followed by renewed oxidation through a mask and attachment of the other adsorbate. These stamps were used to transfer polar inks (a thioether-functionalized dendrimer and a fluorescent dye) by microcontact printing. The PFDTS monolayer was used as a barrier against ink transfer, while the APTS SAM areas functioned as an ink reservoir for polar inks. The printing results confirmed the excellent transfer of hydrophilic inks with these stamps to gold and glass substrates, even from aqueous solutions. Attachment of a fluorescent dye on the amino-functionalized regions shows the possibility of the further modification of the chemically patterned stamps for tailoring of the stamps' properties.

This article reviews the recent developments in the assembly of nanoparticles into patterned arrays. An introduction is given on nanoparticles assembly and its applications. This is followed by a discussion on recent papers, seen from the perspective of the interaction between particle and substrate: (i) absence of interactions, (ii) presence of electrostatic interactions, and (iii) presence of supramolecular interactions. The techniques used to create the patterns and to assemble the nanoparticles are discussed as well.