Connection Table Format description

Most computer systems have their own connection table formats for disk storage, and such connection tables can only be written or read by one particular system. Some manufacturers who produce a range of programs for handling chemical structures use a single connection table format which can be written or read by all programs in their range. Such formats do, however, remain proprietary products of individual companies, and their exact descriptions are not always pubUcly available. 

A connection table format can be considered a special-purpose external database format which is used to store a limited amount of chemical information. Our goal is to produce a method which allows accurate description and interpretation of connection tables in the general case. 

A CONNECTION TABLE FORMAT (CTF) DESCRIPTION LANGUAGE General... 

DESCRIPTION "TriPos MOL-1 connection table format (used by SYBYL)" FILETYPES .SYB. MOL. MOLl"... 

The CTF description language appears to be flexible enough to describe the vast majority of connection table formats in use today, and extensible enough to be adapted to those likely to arise in the future. A practical limitation of the language as described here is the inability to handle binary data conveniently. If interpretation of binary connection table formats becomes important, binary-oriented translation operators could be added to the language. 

All these formats are based on a connection table (CT from this comes the name CTFile formats) for description of a molecular structure and differ in their capabilities and purpose. Table 5.2 gives an overview of the most commonly found CTFile formats. 

The GEMINI approach to connection table interpretation provides a useful front-end for programs which process chemical information. CTF descriptions are compact enough that they can be included along with conection tables when transmitting data between sites with incompatible formats. 

The atom connection table has been used for many years, mainly for storage and retrieval of chemical structures and substructures. CAS became the first major user of connection tables when the Chemical Registry System was established. It was then followed by Telesystemes-DARC (Description, Acquisition, Retrieval, and Correlation) devised at the University of Paris. In comparison with the CAS format, that used in DARC was definitely more compact and easier to process on minicomputers. 

These model compormds provide reasonable estimates of the ligands electronic characteristics, as required for an energetic description of the glass-transition process. At the present time, any connection between the density functional calculations smn-marized above and experimental Tg-enhancement data is empirical. It is necessary to establish a quantitative link between the formation of mobility-restricting nanoclusters in the coordination sphere of the metal center and the efficiency of Tg enhancement, where the latter is summarized in Table 15 for several polymer/metal-complex combinations. 

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