Experiences with the Databases LiqCryst

A comment by Prof. Dr. Dietrich Demus,
International Scientific Consulting Office, Halle, Germany

Since 1995, when the electronic database LiqCryst became avalaible, I am a user of this valuable and convenient scientific tool. Databases of this kind are a must for all people, planning syntheses or designing novel liquid crystalline compounds, looking for materials suited for physical investigations or practical applications, checking the literature in order to find news items for patent applications or to avoid double applications.

Because databases are so useful, I decided with my coauthors H. Zaschke and H. Demus, to elaborate the book "Flüssige Kristalle in Tabellen" volumes 1 and 2. in 1972 and 1984 resp.. In this time only the uncomplete collection of liquid crystalline compounds, made by W. Kast in 1960 for the series of table books "Landoldt-Börnstein", had been available. It contained about 1100 compounds and soon after the beginning of the synthetic boom, caused by the development of applications of liquid crystals in displays and thermographic materials, became out-of-date. Until 1982 about 13000 liquid crystalline compounds became known and had been collected in the mentioned table books. The version LiqCryst 2.1 contains 68773 compounds. It seems unrealistic, to be able to publish such comprehensive information in a printed book on the actual stand. In fact, the Landolt-Börnstein series of "Liquid Crystals" founded in 1992 by Dr. V. Vill and planned for 19 subvolumes, actually is published until subvolumes 8. Of course, when the final subvolume will be published, the first one will be out-of-date. This disadvantage, quite serious for a database, does not exist in the electronic version, which is updated twice a year.

Using the database I learned, that Dr. V. Vill is doing his best, with great success, to hold unavoidable gaps on a minimum and to include liquid crystal compounds from all available sources in LiqCryst. Remembering my own experience in elaboration of databases, I only can admire this hard and troublesome work, which for the users makes time-consuming own literature searches in most cases superfluous. The updating of the database does not concern only the number of compounds included, but also improvements in the program. The DOS version of LiqCryst 1.0 has been still clumsy, compared with the WINDOWS versions 2.0 and 2.1. In the actual version the possibility to search compounds by many different options, specially by line notaion, is a remarkable advance.

In order to avoid search in the 10 different data files of the actual version, for the future I would like to have an unification of the data files. The speed of some functions like selection of rings and bridges as well as the search of compounds needs measurable time and is a little bit tiring, when a large number of compounds is to be treated. I trust that in future versions the functions will be more speedy. The database LiqCryst is a unique tool, undispensable for all people involved in liquid crystal chemistry. It is a quite selfish desire, to wish Dr. V. Vill enough patience for continuation of the database, and to wish Dr. V. Vill and the database a long life.

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