Supramolecular spectroscopic properties

In a further step, Yam and coworkers constructed helical superstructures emplo5nng chiral alkynylplatiniun(II)-terpyridyl complexes, obtaining metallogels that show helical fibrous nanostructures. The chiral supramolecular structiue and the spectroscopic properties depend on the extent of aggregation through Pt- Pt and n-n interactions, which can be influenced by varying the nature of counteranions, as revealed by UV/vis, circular dichroism, and luminescence studies (221). 

In supramolecular systems, electronic interactions between metal-polypyridine and other redox-active or units are too small to perturb ground-state electrochemical and spectroscopic properties but are sufficient to enable very fast intramolecular electron-transfer reactions upon excitation. 

In this chapter we introduce compounds which have been successfully applied in the construction of supramolecular assemblies. Only the amphiphiles which have been prepared in sufficient quantities have been admitted milligram quantities being considered unacceptable as starting materials for the preparation, analysis and application of assemblies. Experience proves that complicated dyes, pore builders, receptors etc. never reappear in the literature after their syntheses and spectroscopic properties have been reported. On the other hand, such easily attainable synkinons and surfactants around the ten gram scale need not, of course, be too simple. On the contrary, they may contain all the components of the chiral pool, i.e. amino acids, carbohydrates, steroids etc., as well as all commercial dyes of interest such as protoporphyrin, phthalo-cyanines, carotenes, viologen and quinones. 

Complex supramolecular systems may also be studied by modem computational methods, which have become useful interpretative and predictive tools. Benedetta Menucci, Stefano Caprasecca and Giro Guido review environmental effects on properties and processes involving molecular probes in solution or in biomacromolecular systems. The capabilities of such techniques are demonstrated with a particular focus on simulations of spectroscopic properties, which allow for direct comparison between calculated and... 

Dufour, B., P. Rannou, P. Fedorko, D. Djurado, J.P Travers, and A. Pron. 2001. Effect of plasticizing dopants on spectroscopic properties, supramolecular structure, and electrical transport in metallic polyaniline. Chem Mat 13 4032. 

Acid-base and spectroscopic properties of a novel supramolecular porphyrin bonded to four pentacyanoferrate(lI) groups. Inorg. Chim. Acta 338, 27-35. 

Constable, E.C. (1994) Metallosupramolecular chemistry Chem. Ind., 56-59 Constable, E.C, Cargill Thompson, A.M.W. and D.A. Tocher (1992) Into the third dimension of coordination chemistry towards starburst arrays in Supramolecular Chemistry Eds Balzani, V. and De (Zola, L. Klewer Academic Press, Dordrecht 219-233 Constable, E.C, Cargill Thompson, A.M.W. and D.A. Tocher (1992) Synthesis, characterisation and spectroscopic properties of ruthenium(II)-2,2 6, 2"-terpyridine coordination triades. X-Ray structures of 4 -(A,A-dimethylamino)-2,2 6, 2"-terpyridine and w(4 -(A,A-dimethylamino)-2,2 6, 2"-terpyridine)ruthenium(II) hex uoro-phosphate acetonitrile solvate New J. Chem., 16, 855-867 Krohnke, F (1976) The specific synthesis of pyridines and oligopyridines Synthesis, 1-24... 

Solvation behavior can be effectively predicted using electronic structure methods coupled with solvation methods, for example, the combination of continuum solvation methods such as COSMO with DFT as implemented in DMoF of Accelrys Materials Studio. An attractive alternative is statistical-mechanical 3D-RISM-KH molecular theory of solvation that predicts, from the first principles, the solvation structure and thermodynamics of solvated macromolecules with full molecular detail at the level of molecular simulation. In particular, this is illustrated here on the adsorption of bitumen fragments on zeolite nanoparticles. Furthermore, we have shown that the self-consistent field combinations of the KS-DFT and the OFE method with 3D-RISM-KH can predict electronic and solvation structure, and properties of various macromolecules in solution in a wide range of solvent composition and thermodynamic conditions. This includes the electronic structure, geometry optimization, reaction modeling with transition states, spectroscopic properties, adsorption strength and arrangement, supramolecular self-assembly,"and other effects for macromolecular systems in pure solvents, solvent mixtures, electrolyte solutions, " ionic liquids, and simple and complex solvents confined in nanoporous materials. Currently, the self-consistent field KS-DFT/3D-RISM-KH multiscale method is available only in the ADF software. 

Abstract In this chapter, recent progress in the synthesis, crystal structures and physical properties of monomeric phthalocyanines (Pcs) is summarized and analysed. The strategies for synthesis and modification of Pcs include axial coordination of central metal ions, peripheral substitution of Pc rings and the ionization of Pcs. The crystal structures of various typical Pcs, especially the effects of different synthetic and modification strategies on the supramolecular assemblies of Pcs via %—% interactions between Pc rings, are discussed in detail. Finally, the UV-vis spectroscopic, conducting, magnetic and catalytic properties of some Pcs with crystal structures are presented briefly, and the correlations between various properties and the molecular structure discussed. 

It should also be recalled that a full electrochemical, as well as spectroscopic and photophysical, characterization of complex systems such as rotaxanes and catenanes requires the comparison with the behavior of the separated molecular components (ring and thread for rotaxanes and constituting rings in the case of catenanes), or suitable model compounds. As it will appear clearly from the examples reported in the following, this comparison is of fundamental importance to evidence how and to which extent the molecular and supramolecular architecture influences the electronic properties of the component units. An appropriate experimental and theoretical approach comprises the use of several techniques that, as far as electrochemistry is concerned, include cyclic voltammetry, steady-state voltammetry, chronoampero-metry, coulometry, impedance spectroscopy, and spectra- and photoelectrochemistry. 

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