Prototype structures

Na+/H+ Exchangers. Figure 1 Prototypical structure and transmembrane disposition of NHE. The amino (N) and carboxy termini of the molecule are indicated. 

The phenylalkylamine hallucinogens show a close structural resemblance to the catecholamines, noradrenahne and dopamine. The prototype structure is found in mescaline, a naturally occurring substance. Modification of the mescaline molecule has led to synthetic amphetamine derivatives with hallucinogenic action. 

RY Tsien. (1980). New calcium indicators and buffers with high selectivity against magnesium and protons Design, synthesis, and properties of prototype structures. Biochemistry 19 2396-2404. 

In another chapter concerning the intermetallic crystallochemistry (Chapter 7), a number of selected structural prototypes are described presenting some of their typical features and commenting on their distribution among different types of alloys. Attention is especially given to relationships between different prototype structures, and examples of their possible grouping in structural families are underlined. This chapter, therefore, could possibly be used as a first draft of a gazetteer of intermetallic structure types and could be considered as an introduction (partial and provisional indeed ) to the descriptive systematics of intermetallic crystal chemistry. 

References to the so-defined AET and the corresponding coordination number, indicated as CNE, are reported for various prototype structures listed in Chapter 7. 

Scheme 3.32 Prototypical structures for the synthesis of natural product-like libraries.

SOLID STATE AND MOLECULAR STRUCTURES 13.4.4.1 Prototypal Structures for Homoleptic Amides 13.4.4.1.1. Mononuclear complexes... 

Figure 1 Prototypal structures for small oligomeric metal alkoxides (a) the cubane-M404 unit in [TKOMe) , and [Na(OBu )]4 (b) die planar [CufOBu1) , structure (c) and (d) fused trigonal and fused trigonal-tetrahedral units as seen in [Be(OR)2) compounds, where n = 3 and 2 (e) fused tetrahedral-octahedral units seen in [Al(OPri)3]4 (f) edge-shared tetrahedra as in [Al(OBu )3]2 (g) fused octahedra as in [MfOEt), , where M = Ti, V, W and (h) edge-shared octahedra as...

The prototypical structural class of nonselective PDE inhibitors is represented by the methylxanthines (Figure 9.4), a family of plant-derived alkaloids that includes theophylline (1), caffeine (2), and theobromine (3) [9], Although limited in potency, these simple naturally occurring xanthines were the parents in the later discoveries of more potent synthetic derivatives such as pentoxyfylline (4) and isobutylmethyl-xanthine (IBMX, 5). In particular, the latter compound has been widely used and has been regarded for decades as the gold standard nonselective inhibitor of all PDEs. Only recently has it become clear that some of the newer PDEs (8 and 9) are not inhibited by IBMX. Derivatives of IBMX carrying substituents at the 8 position confer increased potency [10], An example is compound 6, which retains most of... 

Figure 16-20 Prototypical structures for octahedral cluster species (a) the MsXg type (b) the MoX12 type.

Among the variety of compounds emerging from prototype structures 10-28 mentioned in the Introduction (Table I), X-ray structural determinations have been performed on six representative examples the mesomeric betaines 55, 116, 117, and 120 the higher homologue 119 and the novel aza analogue of sesquifulvalene with a betaine character 118 (Scheme 9 and Table VIII). As mentioned earlier, the experimental dipole moments for molecules 55,116-119 were found to be in the range 9 to 13 D (III,B, Scheme 8 and Table Vll). Comparison of the experimental molecular geometries and dipole moment values with those obtained from semiempir-ical molecular orbital calculations is discussed below (III,D). 

In the early design stages where a prototype is available, the optimum solution for data acquisition is to use experimental analysis on the prototype structure to refine an analytical model which can then be used for damping design(4). 

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