Molecular complexes, representation

Fig. 17 (a) Molecular arrangement of 2,5-DSP and l OEt in the molecular complex (2,5-DSP l OEt). (b) Schematic representation of the photoproduct of the molecular complex (2,5-DSP l OEt). Black and white rods represent single polymer chain of poly-2,5-DSP and poly-1 OEt, respectively. Three arrows represent the direction of the a-, b-, and c-axes of the original complex before irradiation. 

Nonlinear coupling, multidegenerate conditions higher order coupling, complex representations, 243-244 molecular systems, 233-249 adiabatic-to-diabatic transformation, 241— 242... 

The CoA binding tunnel provides access to the internal cavity. B. Molecular surface representation of the CHS-CoA complex oriented as shown in (A). In the -bottom panel, the two CHS monomers are separated and rotated slightly to highlight the flat dimerization interface along with the methionine side chain and dyad related hole in the backside of the CHS active site. 

Figure 2.12. Diagrammatic representation of the GABA-benzodiazepine supra-molecular complex. Compounds that increase inhibitory transmission may do so either by directly activating the GABA receptor site (e.g. muscimol) or by acting directly on the chloride ionophore (e.g. barbiturates). Benzodiazepines (e.g. diazepam) enhance the sensitivity of the GABA-A receptor to GABA. Compounds that decrease inhibitory transmission may do so by activating the picrotoxin site, which closes the chloride ionophore, or by blocking the GABA-A receptor.

Discussion of the subject matter centers primarily on such physicochemical properties as are deemed indicative of -electron mobility and the attendant development of aromatic or antiaromatic character. Although it is not entirely neglected, the description of synthetic procedure is limited for the most part to the crucial final step. It may also be well to note that, while a serious attempt has been made to provide as complete as possible coverage of the area, the main emphasis in this review is on proper representation rather than on exhaustive enumeration. Also, in order to achieve maximum effectiveness in the coverage of the literature, compounds belonging to a given size-class are described in terms of increasing molecular complexity rather than historical sequence. 

Fig. 20. Saturation of secondary affinity. Two-dimensional representation of an electron-domain model of the formation of a molecular complex the reaction of a Lewis base (NH3) with a relatively weak Lewis acid (Bt2)...

Fig. 21. Saturation of residual affinity. Schematic, tangent-circle representations o( electron-domain models of the molecular complexes Me N 1 L> and MesN -111...

Figure 2 Schematic representations of formation of discrete molecular complexes by an endo receptor and a exo substrate (a), by an exo receptor and two exo substrate acting as stoppers (b) and of a linear molecular network by an exo receptor and a connector (c).

General Theory. In addition to the work already quoted, a few papers considering various aspects of the general theory of polarizabilities are also included. We mention the efforts to consider the effects of the polarizability of relatively crude models (such as metallic spheres) [101, 103]. The tensor representations of molecular polarizabilities have been carefully discussed [84, 141, 362]. More general procedures applicable to a variety of systems (including big molecules and molecular complexes) that are often based on classical electrostatics have been proposed [4, 21, 118, 119, 127, 135, 136]. Various books and articles are concerned with the definition of the terms in common use [12, 13, 20, 91, 109]. Other articles deal with relevant general properties of matter [22, 113] and molecules in electric and magnetic fields [31,239], triplet polarizabilities [10,61, 102,126,208], and the calculations of polarizabilities of molecules in the liquid. 

Figure 1. Molecular graphics representation of Co(II)-complex of N,N -bis(salicylidene) -1,2-phenylenediamine (Co-salophen).

As noted in [4] and [5], and in the discussion above, the electronic structure of Ti " " has been addressed for both Ti20s [14], and the hydrated ion Ti(H20)6 complex [11]. However it is important understand these two applications are different. The d description applies exactly to each hydrated Ti ion. In contrast, the d designation for the Ti-atoms in Ti203 is based on a SALC molecular orbital representation of the Ti203 electronic structure, in particular on overall and local charge neutrality. 

Molecular structures may be considered at different levels, each containing certain types of information. The simplest representation is the empirical chemical formula, while a highly complex representation is a molecular electrostatic potential (MEP) representation on the van der Waals surface which includes both steric and electronic information. 

Physically, it is most reasonable to assume that a wide spectrum of aggregates, ranging from 1 1 to something best described as a solvent cage, may occur. Thus, for example, chloroform and toluene definitely form a 1 1 molecular complex (cryoscopic evidence ) and, by inference, probably associate in a 1 1 ratio in solution. However, at the other end of the spectrum, some systems are perhaps best described without reference to specific stoicheiometries and geometries in such instances, pictorial representations of the collision complexes do not have any physical significance. 

Fig. 4. Molecular graphics representation of a FePc complex into the supercage of zeolite Y (after ref. 23).

Figure 57 Schematic representation of the electronic structure of bulk semiconductors (left), nanometer-sized clusters and colloids (middle), and molecular complexes (right).

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