ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • self-assembly  (5)
  • Self-assembly  (4)
  • Polymer and Materials Science  (3)
  • molecular devices  (3)
Collection
Publisher
Years
  • 1
    ISSN: 0570-0833
    Keywords: Self-assembly ; Information processing ; Molecular information processing ; Molecular recognition ; Supramolecular chemistry ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The selective binding of a substrate by a molecular receptor to form a supramolecular species involves molecular recognition which rests on the molecular information stored in the interacting species. The functions of supermolecules cover recognition, as well as catalysis and transport. In combination with polymolecular organization, they open ways towards molecular and supramolecular devices for information processing and signal generation. The development of such devices requires the design of molecular components performing a given function (e.g., photoactive, electroactive, ionoactive, thermoactive, or chemoactive) and suitable for assembly into an organized array. Light-conversion devices and charge-separation centers have been realized with photoactive cryptates formed by receptors containing photosensitive groups. Eleclroactive and ionoactive devices are required for carrying information via electronic and ionic signals. Redox-active polyolefinic chains, like the “caroviologens”, represent molecular wires for electron transfer through membranes. Push-pull polyolefins possess marked nonlinear optical properties. Tubular mesophases, formed by organized stacking of suitable macro-cyclic components, as well as “chundle”-type structures, based on bundles of chains grafted onto a macrocyclic support, represent approaches to ion channels. Lipophilic macrocyclic units form Langmuir-Blodgett films that may display molecular recognition at the air-water interface. Supramolecular chemistry has relied on more or less preorganized molecular receptors for effecting molecular recognition, catalysis, and transport processes. A step beyond preorganization consists in the design of systems undergoing self-organization, that is, systems capable of spontaneously generating a well-defined supramolecular architecture by self-assembling from their components under a given set of conditions. Several approaches to self-assembling systems have been pursued: the formation of helical metal complexes, the double-stranded helicates, which result from the spontaneous organization of two linear polybipyridine ligands into a double helix by binding of specific metal ions; the generation of mesophases and liquid crystalline polymers of supramolecular nature from complementary components, amounting to macroscopic expression of molecular recognition; the molecular-recognition-directed formation of ordered solid-state structures. Endowing photo-, electro-, and ionoactive components with recognition elements opens perspectives towards the design of programmed molecular and supramolecular systems capable of self-assembly into organized and functional supramolecular devices. Such systems may be able to perform highly selective operations of recognition, reaction, transfer, and structure generation for signal and information processing at the molecular and supramolecular levels.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    ISSN: 0570-0833
    Keywords: complexes with nitrogen ligands ; ruthenium compounds ; self-assembly ; supramolecular chemistry ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    ISSN: 0935-9648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 4
    ISSN: 0570-0833
    Keywords: copper ; pseudorotaxanes ; self-assembly ; supramolecular chemistry ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 5
    ISSN: 0570-0833
    Keywords: coordination modes ; multinuclear complexes ; N ligands ; self-assembly ; silver ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 6
    ISSN: 0947-6539
    Keywords: complexes with nitrogen ligands ; ruthenium complexes ; self-assembly ; supramolecular chemistry ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A series of mono- and dimetallic complexes of rack type containing a dinucleating bis-tridentate ligand and RuII-2,2′:6′,2′-terpyridyl (tpy) sites were synthesised and characterised. The 1H NMR spectra of the dimetallic complexes were correlated to structural features, and the crystal structures of the dimetallic complexes were determined. They provide information about the way in which the central substitutent affects the overall shape of the racks and the relative disposition of the metal centres, measured by the pinching angle of the bis-tridentate ligand and the convergence angle of the ancillary tpy units. The latter demonstrates that a CH3 group yields the least bent complex and indicates how parallel the tpy units are. The dimetallic racks exhibit metal-metal interactions mediated by the bis-tridentate ligands as indicated by electrochemical and spectroscopic methods. The bridging-ligand π* orbital and the dπ metal orbital are stabilised by complexation of a second metal. The results obtained provide guidelines for the design of extended racks bearing several metal centres in a linear arrangement, which also represent potential components of molecular electronic devices.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 7
    ISSN: 0947-6539
    Keywords: bipyridine ligands ; helicates ; kinetics ; mass spectrometry ; self-assembly ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The self-assembly of the pentanuclear double helicates Hh, Ha and He from the corresponding oligobipyridine strands Lh, La and Le and Cu1 ions has been investigated by NMR and electrospray mass spectrometry (ESMS). Where as Hh is assembled rapidly (in less than 20 min), He (about 20 h) and especially Ha (about 60 h) form much more slowly. The rate decreases strongly with increasing steric bulk of the substituents in the 4,4′-positions on the bipyridine units; this indicates that the search processes (wrapping, unwrapping) that lead to the final helicate are strongly hindered by the size of the substituents. The ESMS data give information about the species present in solution under different conditions and allow the formulation of possible formation pathways, which may involve, in particular, helicates of hairpin type.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 8
    ISSN: 0947-6539
    Keywords: electrochromes ; fluorescence ; molecular devices ; oligothiophenes ; photochromes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The extended dithienylethene compounds 1-3 have been synthesized. They undergo photochromic and electrochemical changes by photoinduced interconversion between open and closed forms of type A and B. In addition, both forms of the N-methylated derivatives 1b and 2b have absorption bands in which excitation results in very large differences in fluorescence between the two forms with very little effect on the opening/closing state, a feature of interest for optical memory data systems. The compounds 2 and 3 contain six and eight conjugated thiophene units in the closed forms, respectively, and thus represent oligothiophenes endowed with a photoactivated switch; they are of special interest in this respect in view of the potential use of switched oligothiophenes in molecular electronic devices.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 9
    ISSN: 1434-1948
    Keywords: Grid complexes ; Self-assembly ; Co ; Zn ; Coordination chemistry ; Bis(tridentate) ligands ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The tretrametallic [2 × 2] grid-type complexes 1-4 are formed by self-assembly of the bis(tridentate) ligands 5 and 6 with ZnII and CoII cations. They have been characterized by spectroscopic studies in solution as well as by crystal structure determination. The substituents in the central pyrimidine ring play an important role in terms of geometry and physical properties of the complexes. They induce an orthogonal orientation of the ligand in the complexes which is critical for the formation of ordered monolayers and extended self-organized arrays of grids. The physical properties of the complexes such as metal-metal interaction and π-π* stacking between the ligands may be modulated by changing these substituents.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 10
    ISSN: 0947-6539
    Keywords: diarylethenes ; molecular devices ; nonlinear optics ; photochromes ; redox switches ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Organic photochromic systems represent a starting point for the elaboration of light-triggered molecular switching devices. The novel bispyridinium and bispyridine compounds 12+ and 6 were synthesized as their uncyclized isomers from 3,5-dibromo-2-methylthiophene in overall yields of 43 and 44%, respectively. The diarylethene photochromes 2 and 10-13, substituted with electron donors and acceptors, were prepared from 5-methylthiophene-2-carboxaldehyde in 21-32% overall yield. All of the compounds were found to exhibit pronounced photochromic properties. Irradiation with UV light resulted in essentially complete photocyclization of the open forms to the intensely coloured closed isomers which could, in turn, be reconverted back to the open state with visible light of γ〉600 nm. The absorption maxima of the described compounds in their closed forms are shifted far towards, and even into, the near-IR region. Whereas no thermochromic properties were observed for the open isomers, the rates of thermal decolouration of the cyclized forms was found to be highly dependent on the nature of the substituents on the thiophene rings. It was demonstrated that reversible photochemical interconversion between the two photochromic states could be used to effectively switch a number of physical properties. Thus, the molecules 12+ and 12 represent two kinds of redox switches, the former in reduction and the latter in oxidation, in which electron conduction is switched on in the closed state and off in the open state. Compound 12 may also be considered to be a photoswitchable analogue of tetrathiafulvalene type substances. On the other hand, compound 2 displays a marked increase in nonlinear optical activity on conversion from the open to the closed form. Such systems are prototypes of photoswitchable molecular wires where electron conduction and push-pull interaction can be reversibly modulated by an external stimulus, namely, irradiation by light.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...