Ligand search system

Besides structure and substructure searches, Gmclin provides a special search strategy for coordiuation compouuds which is found in no other database the ligand search system, This superior search method gives access to coordination compounds from a completely different point of view it is possible to retrieve all coordination compounds with the same ligand environment, independently of the central atom or the empirical formula of the compound. 

To facilitate searches for organometallic compounds, a special Ligand search system was developed enabling the user to access distinct types of compounds characterized by the types of central atom, of ligand, and further characterized by the kind of interaction between central atom and ligand. The ligand search system is defined by several rules. 

One speciality of the Gmelin database is its ligand search system for coordination compounds. It is a sophisticated easy, and low-cost substructure search. Ligand atoms are arranged in classes (Table 21). In addition, special ligands are included ... 

Because rigid pharmacophoric searching is based on the positions of explicit atoms or points, it is often difficult to pose queries based on directed vectors in space. A specialized search system, CAVEAT, has been developed that permits the specification of queries based on the relative orientation and position of bond vectors in space. If the query bond vectors have been derived from a docked flexible ligand, then when a database of rigid ring-systems (CAST-3D or CSD) is searched, CAVEAT will identify potential substructural skeletons which could act as a rigid mimic of the core substructure of the ligand. 

Dmg receptors represent another type of receptor family. The central nervous system (CNS) effects of the anxiolytic, diazepam, and the psychotropic actions of the caimabiaoids and phencycUdine have resulted ia the identification of specific receptors for these molecules. This has resulted ia the search for an endogenous ligand for these receptors. Thus, ia these situations, the pharmacological action has preceded the discovery of the receptor which, ia turn, has provided clues ia several iastances to the endogenous ligand. 

In this chapter, we briefly review various aspects of the chemical information systems used by the chemist for literature and patent searches the field of computer-aided drug design technologies, cheminformatics, as well as other applications. We place special emphases on the ligand-based techniques and only briefly mention the structure-based design technologies. 

In view of the low Nin/Niin redox potential of [NiFe] hydrogenase, the search for low-potential Nin/Niin complexes not only with pure S-donor but also with mixed N/S environment has been of major interest, and significant advances in this field have been reported.298,299 Various mononuclear systems are listed in Figure 1 according to their redox potentials (usually in DMF). Homodinuclear Ni2 and heterodinuclear NiM complexes with N/S donor ligands, in particular... 

Using the results of an earlier study concerning enantioselective copper-catalyzed intramolecular C—H insertion of metal carbenoids,109 an interesting system for optimizing the proper combination of ligand, transition metal, and solvent for the reaction of the diazo compound (75) was devised (see Scheme 19).110 The reaction parameters were varied systematically on a standard 96-well microtiter/filtration plate. A total of five different ligands, seven metal precursors, and four solvents were tested in an iterative optimization mode. Standard HPLC was used to monitor stereoselectivity following DDQ-induced oxidation. This type of catalyst search led to the... 

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