Morphing structures

Pandey, R.B., Anderson, K.L., and Farmer, B.L. (2007) Morphing structures and dynamics with particles, chains and sheets. SAMPE Fall Technical Conference, Cincinnati. 

The dehydration and interconversion reactions of the various forms of calcium sulphate [dihydrate, hemihydrate (a and 3 pseudo morphs) and anhydrous salt (hexagonal and orthorhombic structures)] have been studied by Ball et al. [281,590,591] who compared their observations with the available rate and microscopic data. The important features of the complicated behaviour found are summarized in the scheme [281]... 

The effect of relative humidity and temperature on the physical and structural properties of the 1 1 isopropanol solvatomorph of warfarin has been studied [58], Below the critical relative humidity of 60-68% the solid is not hygroscopic, but becomes deliquescent at higher values of relative humidity without exchange of water for isopropanol. Storage of the solvate-morph at elevated temperatures causes formation of an amorphous solid owing to loss of isopropanol, which may proceed through an intermediate crystalline phase. 

When several X-ray structures are known for the same target, it is possible to detect the parts of the molecular surface of the binding site that move when transferring from one protein conformation to the other. The morphing technique is a simple way to analyze the variability of the binding site. 

Defense Advanced Research Projects Agency (DARPA) begins a project, Morphing Aircraft Structures, to investigate the potential of such technology as shape-changing wings. 

Humbert, W. Localization, structure et gen se des concretions mindrales dans le m senteron des Collemboles Tomoceridae (Insecta, Collembola). Z. Morph. Okol. Tiere 78, 93 (1974)... 

Common hosts such as urea or p-f-butylcalix[4]arene can exist as various crystal phases, some if which do not contain cavities. The crystal form of the pure host without cavities is called the a-phase. The 30 (apohost) phase contains unfilled cavities while the p -phases have the same host structure but contain different guests. Such structures are sometimes referred to as pseudopoly morphs. Further pure phases (y-phase) or clathrates (y1. phases) may also exist in some cases, as in tri-o-thymotide. Apohosts are usually relatively unstable but allow the inclusion of interesting guests such as gases. 

There is abundant information to support the contention that the lower-melting monoisopropylidene-mannitol (m. p. 85°) is the 3,4-derivative. For example, its tetrabenzoate is identical with that obtained by acetonation of 1,2,5,6-tetrabenzoyl-mannitol,11498 the structure of which is based on independent evidence.114 The larger fragment resulting from the oxidative scission of the D-enantiomorph of the isopropylidene-man-nitol with lead tetraacetate is 2,3-isopropylidene-D-//treo-dihydroxy-succinic dialdehyde, characterized by its subsequent conversion into D-i/ireo-tartaric acid.126 When methylated and hydrolyzed, the L-enantio-morph of the monoketal affords a tetramethyl-mannitol, which, in turn, yields dimethyl-L-glyceraldehyde with lead tetraacetate.127 Each of these facts is in itself proof that the acetone residue occupies the 3,4-position in the mannitol molecule. 

The junction zones of CAQ organogel networks are lyotropic microdomains that vary from hexagonal in decane to more compact, lamellar-like ordering in 1-octanol 94. Schlieren optical textures confirm the inhomogeneity of the orientation of the threadlike structures (Fig. 16), and CD spectra resemble those of neat CAQ solid, cooled from its mesophase. However, the solid morph obtained from solvent crystallization is packed differently from the gel strands 114. ... 

Fabric evidence from the earlier site, as represented by pseudo-morphs after fabric found on two copper earspools and a copper plate, is one of the simplest types of twining observed, namely, spaced twining. It can be seen on the upper surface of the earspool and on both surfaces of the plate from Mound C. Because no evidence indicated that yarn pseudomorphs had been dislodged, the original fabric structure is assumed to have consisted of spaced twining. The very nature of spaced twining requires action of the weft yams rather than those of the warp ... 

In the description of crystals and crystal structures the two terms/om and habit have very specific and very different meanings. Form refers to the internal crystal structure and etymologically is the descendant of the Greek morph. Hence, polymorph refers to a number of different crystal modifications or different crystal structures, and the naming of different structures as Form F or a Form follows directly from this definition and usage. As we have seen above, the difference in crystal structure is very much, although not exclusively, a function of thermodynamics. Certainly, only the structures which are thermodynamically accessible can ever exist, but there often is a question of thermodynamic vs kinetic control over which particular structure may be obtained under any particular set of crystal growth conditions. 

Synthetic methods employed for the preparation of ligands of the type R SCH2C0NHCH2CH2NHC0CH2SRA H2ema(R )(R ), where R = alkyl, amino-alkyl and carboxyalkyl and R = H, benzoyl, acetamidomethyl and benzamidomethyl, as well as for the synthesis of the [TcO(emaR)] complexes, and for the quantitative synthesis of [AsPh4][TcO(ema)] have been described also . The m.p., I.R., H N.M.R. and analytical data were identical with earlier published data . The crystal data for structure determination of [TcO(ema(morph))], and for the characterization of the neutral complex [TcO(emaR)] (R = Me, undec, morph and benzyl) have also been presented . ... 

Sometimes different compounds give apparently identical crystals. Isomorphism is the similarity of crystal shape, unit cell dimensions, and structure between substances of nearly, but not completely, identical chemical composition. It is derived from the Greek words - isos meaning equal and morphe for form or shape. The arrangements of atoms in the isomorphous crystals are identical, but the identity of one or more atoms in this arrangement has been changed. For example, sulfur in a sulfate may often be replaced by selenium, to give an isomorphous selenate. Ideally, isomorphous compounds are so closely similar in composition that... 

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