Molecular ladder

Figure 4.2 (a) Representation of Gd(HCOO)3 n and (b) representation of a molecular ladder of GdjtfumJjtHjO -BHjOJn. Supramolec-ular arrangement of these ladders gives... 

Very recently, MacGillivray et al. succeeded in the supramolecular construction of molecular ladders in the solid state using a linear template approach [48]. They designed the cocrystals 1,3-benzenediol (resorcinol) or a derivative with an all-trans-bis(4-pyridyl)butadiene or hexatriene, in which two resorcinol molecules preorganize two polyene molecules through two hydrogen bond interactions, for [2-1-2] photoaddition (Scheme 5). In this design, two polyenes would... 

Figure 7. By increasing the number of rungs and the size of a molecular ladder, the probability of further twisting of the strip before cyclization also increases [40],...

A directed knot synthesis relying upon the Mobius strip principle was conceived by Schill and coworkers [41-50] who synthesized the doubly bridged tetraamino-p-benzoquinone 9. Connection of three such molecules by long chains should give the molecular ladder 10, precursor of the three half-twist-containing Mobius strip 11 (Figure 8). 

Figure 8. A way of introducing three half twists in a molecular ladder, as envisaged by Schill and his group [41, 42].

Fig. 18. The topologically-relevant step in the synthesis of the chiral three-rung Mobius ladder 63, starting from the linear molecular ladder 69...

Flexibility in ligands can lead to subtle or dramatic changes in architecture. For example, l,2-bis(pyridyl)ethane, dipy-Et, can readily adapt gauche or anti conformations. In the case of [Co(dipy-Et), 5(N03)2]n, which contains a T-shape node, infinite molecular ladders which contain six molecules of chloroform per cavity exist as the most commonly encountered architecture (Figure 3A).45b In such a situation all spacer ligands are necessarily anti. However, under certain crystal-... 

The construction of molecular ladders from two conjugated polyenes employs UV-induced [2 + 2] photodimerizations. The task is complicated by a requirement to position the sidepieces, in the form of polyenes, in the orientation for the reaction. Such control of positioning may be accomplished using two distinct approaches. The first one is intramolecular, involving a [2 + 2] cycloaddition of... 

Figure 2.22 Asymmetric unit of complex Eu(L )3(DPEPO). Thermal ellipsoids are shown at the 30% probability level and all hydrogen atoms have been omitted for clarity [51c]. (Reprinted with permission from S. Biju, M.L.P. Reddy, A.H. Cowley and K.V. Vasudevan, Molecular ladders of lanthanide-3-phenyl-4-benzoyl-5-isoxazolonate and bis(2-(diphenylphosphino)phenyl) ether oxide complexes the role of the ancillary ligand in the sensitization of Eu + and Tb + luminescence, Crystal Growth and Design, 9, 3562-3569, 2009. 2009 American Chemical Society.)...

Remya, P.N., Biju, S., Reddy, M.L.R, et al. (2008) ID Molecular ladder of the ionic complex of terbium-4-sebacoylbis(l-phenyl-3-methyl-5-pyrazolonate) and sodium dibenzo-18-crown-6 synthesis, crystal structure, and photophysical properties. Inorganic Chemistry, 47, 7396-7404. 

Different types of ID motifs can give polycatenation, including chains of alternating rings and rods, ribbons of rings, molecular ladders and more complex species. Some examples are illustrated in Fig. 1.3.13. Almost all the known real cases are, at present, based on infinite molecular ladders interlocked to give 2D or... 

Schroder and co-workers have successfully isolated a unique poly-catenated undulating molecular ladder that forms interwoven two-dimensional sheets (252). The reaction of [Cu(MeCN)4]PF6 with 1,4-bis(4-pyridyl)butadiyne (L93) in MeCN-CH2Cl2 yielded the complex [Cu2(MeCN)2(L93)3](PF6)2. The compound exists as a network of molecular ladders in which the two independent Cu1 centers are each coordinated in a tetrahedral geometry to three L93 groups and one MeCN molecule. The lattices are polycatenated to give a remarkable two-dimensional layer structure (Fig. 77). The sheets of interwoven molecules are separated by PF3 counteranions and solvent molecules. The structure is further stabilized by the tt—tt interactions between adjacent, symmetry-related ladders. 

Carbon is the basis of organic chemistry there are more compounds of carbon than of any other element except hydrogen and possibly fluorine. However, most of the chemistry of carbon is the province of organic chemistry and thus not covered in this encyclopedia. The inorganic chemistry of carbon discussed in this article, which is an update of an excellent article written previously by professor R. Bruce King (University of Georgia, Athens), includes the allotropic forms of elemental carbon, simple molecular carbon halides and oxides, carbon oxyacids and oxyanions, carbon-sulfur derivatives, simple cyano derivatives, and carbon-based molecular ladders. 

Mixing a solution of Co(N03)2-6H20 with 4,4 -bipyridine (molar ratio 1 1.5) yields after few hours red crystals of 33 [98]. In air the crystals are stable for only a few hours. X-ray analysis shows that 33 consists of a molecular ladder structure (Fig. 7-4). The 4,4 -bipyridine ligands coordinate to Co and form the side part and the rung of a ladder in the direction of the a-axis by selforganization. 

Blake, A.J. Champness, N.R. Khlobystov, A. Lemenovs-kii. D.A. Li. W.-S. Schroder, M. Polycatenated copper(I) molecular ladders A new structural motif in inorganic coordination polymers. Chem. Commun. 1997, 2027-2028. 

Molecular ladders with finite dimensions are still scarce. Much more numerous are the one-dimensional, infinite... 

Losier. P. Zaworotko, M.J. A noninterpenetrated molecular ladder with hydrophobic cavities. Angew. Chem., Int. Ed. Engl. 1996.35 (23 24), 2779-2782. 

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