Supramolecular arrays

N(C6H4-p-Me)Au[3 to aggregate through gold-gold intermolecular interactions forming these supramolecular arrays confers to its extraordinary luminescent properties which have been described by Balch as solvoluminescence [48]. 

Fernandez, F.J., Jones, P.G., Laguna, A., Lopez-de-Luzuriaga, J.M., Monge, M., Perez, J. and Olmos, M.E. (2002) Synthesis, Structure, and Photophysical Studies of Luminescent Two- and Three-Dimensional Gold-Thallium Supramolecular Arrays. Inorganic Chemistry, 41(5), 1056-1063. 

Other supramolecular structures such as dendrimers have also been synthesized with zinc-containing porphyrins. Sixteen free base and sixteen zinc porphyrin units were added at the fifth generation of dendritic poly(L-lysine) and intramolecular fluorescence energy transfer was observed.823 Assembly of supramolecular arrays in the solid state has been achieved with the incorporation of an amide group for hydrogen bonding. Zinc meso-tetra(4-amidophenyl)porphyrin... 

Fig. 2. A supramolecular array (9 a) obtained enclosing the eight ferrocene units of dendrimer 9 into (3-CD molecules... 

The structural chemistry of some metal dithiocarbamates, i.e. systematics, coordination modes, crystal packing, and supramolecular self-assembly patterns of nickel, zinc, cadmium, mercury,363 organotin,364 and tellurium,365 366 complexes has been thoroughly analyzed and discussed in detail. Supramolecular self-assembly frequently occurs in non-transition heavier soft metal dithiocarbamates. Thus, lead(II),367 bismuth(III)368 zinc,369 cadmium,370 and (organo)mercury371 dithiocarbamates are associated through M- S secondary bonds, to form either dimeric supermolecules or chain-like supramolecular arrays. The arsenic(III)372 and antimony(III)373 dithiocarbamates are... 

Such secondary bonds are formed by donation from the lone pair of a nucleophile into the a orbital of a covalent bond ( n —> a attack ). Weak covalent bonds (implying low-energy a levels) are easier attacked by n - a overlap, leading to unsymmetric or symmetric 3c le bonds, than strong bonds this is why supramolecular arrays, due to secondary interactions or 3c-4e bonds, play a particular role in the chemistry of the heavier main group elements. 

Over the last 20 years, supramolecular photochemistry has made considerable advances and photoinduced processes involving supramolecular arrays have been developed that may be exploited for practical purposes, such as ... 

Recently, tetracobalt(II) supramolecular arrays with the ligand 4,6-bis-(2, 2/-bipyrid-6/-yl)-2-R-pyrimidine have been presented, Scheme 16. 

These same general templating strategies are extended into the mesopore size regime with the use of self-assembled supramolecular arrays, a topic which has been extensively reviewed elsewhere. 

Finally, although much less frequent, there are also supramolecular gold materials formed as a result of the presence of different types of interactions in which n electron density is responsible for the formation of a supermolecule or a supramolecular array. Thus, Au- %, —H- % or % n interactions will also be considered in this chapter. 

On other occasions, the change in one of the ligands bonded to gold leads to different supramolecular arrays, such as in ] Au(SSNH2) 2( i-dpph)] and [ Au (SSCNH2) 2( i-dpph)] (SSCNH2 = 2-amino-5-mercapto-l,3,4-thiadiazolate SSNH2 =... 

These ligands exhibit interesting solid-state structures [34] but discussion of these is beyond the scope of this chapter. This and other similar ligands [35] have been used in the preparation of interesting supramolecular arrays combined with organic substrates that offer complementary donor-acceptor functions and lead to the formation of strong hydrogen bonds. 

Over the last years the utilisation of supramolecular arrays of surfactant molecules as structure-directing templates [1] has been applied to the synthesis of numerous mesostructured aluminophosphates [2-11]. In most cases the preparations were carried out in aqueous systems under hydrothermal conditions, but tetraethylene glycol and/or unbranched primary alcohols were also used [2,4]. Several discussions have been made on the reaction mechanisms that are involved in the syntheses of mesostructured materials [1,12-15] and recently a number of in-situ investigations on the formation processes of mesostructured silica phases in aqueous media have been reported these studies employed small angle X-ray diffraction [16-19] as well as 2H, 13C, 29Si, and 8lBr NMR spectroscopy and polarised light optical microscopy [17]. 

Supramolecular Arrays of Metal Ions. Racks, Ladders, Grids... 

V.R. Pedireddi, W. Jones, A.P. Chorlton, R. Docherty, Creation of crystalline supramolecular arrays a comparison of cocrystal formation from solution and by solid-state grinding, Chem. Commun. (1996) 987-988. 

The Fullerenes form particularly strong complexes with porphyrins as exemplified by the X-ray crystal structure of the covalent Fullerene-porphyrin conjugate 15.8 (Figure 15.29).48 This property allows fullerenes and porphyrins to form extended supramolecular arrays (even when not covalently linked) and has been used to engineer host-guest complexes in which a Fullerene is sandwiched in between a pair of porphyrins, and ordered arrays involving interleaved porphyrins and Fullerenes. Applications include the use of porphyrin solid phases in the chromatographic separation of Fullerenes and potential applications in porous frameworks and photovoltaic devices.49... 

There are two types of objects in supramolecular chemistry supermolecules (i.e., well-defined discrete oligomolecular species that result from the inter-molecular association of a few components), and supramolecular arrays (i.e., polymolecular entities that result from the spontaneous association of a large, undefined number of components) (4, 5). Both are observed in some metal-xanthate structures to be described herein. The most frequent intermolecular forces leading to self-assembly in metal xanthates are so-called secondary bonds . The secondary bond concept has been introduced by Nathaniel W. Alcock to describe interactions between molecules that result in interatomic distances longer than covalent bonds and shorter than the sum of van der Waals radii (6). Secondary bonds [sometimes called soft-soft interactions (7)] are typical for heavier p-block elements and play an important role as bonding motifs in supramolecular organometallic chemistry (8). Other types of intermolecular forces (e.g., Ji- -ji stacking) are also observed in the crystal structures of metal xanthates. 

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