Controlled solid state structures

The solid-state polymerization of diacetylenes is an example of a lattice-controlled solid-state reaction. Polydiacetylenes are synthesized via a 1,4-addition reaction of monomer crystals of the form R-C=C-CeC-R. The polymer backbone has a planar, fully conjugated structure. The electronic structure is essentially one dimensional with a lowest-energy optical transition of typically 16 000 cm-l. The polydiacetylenes are unique among organic polymers in that they may be obtained as large-dimension single crystals. 

Studying further the 1,5-interactions in peri-substituted naphthalenes (which culminated in the complete formation of a single bond in zwitterion 63 (Section 8.11.3.1.1) the corresponding methylthio derivative 242 was investigated <2006CEJ7724> also in this case the MeS sp -C attractive interaction controls the solid state structure of compound 242. 

Exposure of the crystalline palladium(O) complex 10 to air at room temperature caused a color change from deep red to pale yellow. The formation of the palladium(II)peroxocarbonate complex 12 was confirmed by spectroscopic analysis as well as a solid-state structure. Control reactions revealed that the first intermediate is a palladium(II)peroxo complex 11. 

The polymer-dispersed liquid crystal was used as a modulating medium in optically controlled modulators instead of the liquid crystal [261-264], The sandwiched structure from polyimide photosensitive film and the polymer dispersed liquid crystal film - i.e. the optically controlled solid state modulator -had the characteristics presented in Fig. 36 [261]. Contrast ratio 35 1, response time > 400 ps, decay time 80 ms and sensitivity 5 x 10 sJcm 2 were obtained. 

In the last decade, progress has also been made with using superlattices as templates, or structure-directing agents, to kinetically control solid-state reactions. This is accomplished by allowing interdiffusion to reach completion before the occurrence of heterogeneous nucleation, thus trapping the system in the... 

Another control experiment was run to further confirm the significance of the cation-pi interaction in these bibracchial lariat ether model complexes. In this case, a diaza-18-crown-6 derivative was prepared in which a 2-phenylethyl pi-donor sidearm was attached to one nitrogen and a 2-methoxyethyl sigma donor was attached to the other <2002CC1808>. The structure is illustrated as 14, above. The solid-state structure of the 14 KI complex showed the typical apical solvation of the ring bound cation. In this case, however, one apex was solvated in the pi-fashion (benzene) and the other by the oxygen sigma donor. 

The goal of this article is to describe ways in which crystal structure, morphology, and crystallization kinetics can be utilized to reproducibly maintain metastable states and control solid-state outcomes. Experimental methods that can be employed to investigate the factors that regulate crystallization from solution will be presented. 

Fig. 39 Template-controlled solid-state reactivity, X-ray crystal structures of (a) four-component assembly 2(4-bn-res) 2(l,4-bpeb) (b) targeted cyclophane (c) four-component assembly 2(5-OMe-res) 2(l,6-bpht) and (d) targeted [5]-ladderane.

The solution and solid state structural features of the optically pure [Rh(TpMenth)(CO)2] have been reported, TpMenth being found in both k2- and k3-coordination modes. The optically active TpMenth and XpMementh are able to control the stereoselectivity of the C-H bond activation by their coordinated rhodium center. Irradiation of [Rh(TpMenth)(CO)2] under N2 resulted in the generation of an 85 15 mixture of diastereomeric alkyl hydrides due to intramolecular cyclometalation reaction involving the methyl substituents on the ligand isopropyl group (Fig. 3.51).240... 

A. Muller, D. Fenske, and P. Kogerler, From giant molecular clusters and precursors to solid-state structures, Curr. Op. SolidState Mat. Sci. 3 141 (1999) L. Cronin, P. Kogerler, and A. Muller, Controlling growth ofnovel solid-state materials via discrete molybdenum-oxide-based building blocks as synthons, /. Solid State Chem. 152 57 (2000). 

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