Infrared spectral databases

In this work an infrared spectral database of comparative materials was initiated. Spectra of plant fibers from the Comparative Plant Fiber Collection (CPFC) and of rabbit hair and wool were studied to evaluate whether they could... 

C. Klawun and C. L. Wilkins, Anal. Chem., 67, 374 (1995). Neural Network Assisted Rapid Screening of Large Infrared Spectral Databases. 

B. Debska, B. Guzowska-Swider, and D. Carbol-Bass, J. Chem. Inf. Comput. Set., 40, 330-338 (2000). Automatic Generation of Knowledge Base from Infrared Spectral Database for Substructure Recognition. 

Various infrared spectral databases or libraries are available, which contain collections of the infrared spectra of a number of specific chemical species. Spectral search or data retrieval is a technique enabling one to identify a material of unknown origin by comparing its spectrum with library spectra, or to make a guess at the chemical structure of the unknown material from the similarity of its spectmm to some library spectra. 

Infrared spectral databases consisting of spectra of a great number of chemical compounds are commercially available. When the purpose of spectral search is clearly defined. 

Raman, and nmr spectra. An extensive bibliography of older hard-copy ir spectra is given in The Coblent Sodety Desk Book of Infrared Spectra (62). Since the mid-1980s, comprehensive databases have been available in computerized form where the spectra themselves, not merely the bibliographic references, are searchable and displayable. The search algorithms vary considerably among the available systems no algorithm standard exists (ca 1994), but several are under development (63,64). Expert systems, which assist in the automatic interpretation and identification of spectra, have existed for many years but are not commonly used (65). Computerized spectral databases are either local, PC-based, or public. 

Figure 5.9. Spectral search at Spectral Database Systems (SDBS). The infrared (IR), nuclear magnetic resonance H-NMR and 13C-NMR), electron spin resonance (ESR), and mass (MS) spectra of organic compounds and common biochemical compounds can be viewed/retrieved from SDBS.

Figure 5.10. Sample spectra retrieval from SDBS. (a) 13C-NMR spectrum in DMSO-d6. (b) -NMR (400 MHz) spectrum in DMSO-d6. (c) Mass spectrum, (d) Infrared spectrum in KBr. Sample spectra (including spectral analysis) of uracil are retrieved from Spectral Database Systems. The structure of uracil (molecular weight = 112) is represented with the number corresponding to the position of carbons and the alphabet denoting the position of protons to facilitate NMR assignments ...

RDF descriptors exhibit a series of unique properties that correlate well with the similarity of structure models. Thus, it would be possible to retrieve a similar molecular model from a descriptor database by selecting the most similar descriptor. It sounds strange to use again a database retrieval method to elucidate the structure, and the question lies at hand Why not directly use an infrared spectra database The answer is simple. Spectral library identification is extremely limited with respect to about 28 million chemical compounds reported in the literature and only about 150,000 spectra available in the largest commercial database. However, in most cases scientists work in a well-defined area of structural chemistry. Structure identification can then be restricted to special databases that already exist. The advantage of the prediction of a descriptor and a subsequent search in a descriptor database is that we can enhance the descriptor database easily with any arbitrary compound, whether or not a corresponding spectrum exists. Thus, the structure space can be enhanced arbitrarily, or extrapolated, whereas the spectrum space is limited. 

Integrated Spectral DataBase System for Organic Compounds, National Institute of Materials and Chemical Research, Tsukuba, Ibaraki 305-8565, Japan. This database includes infrared, mass spectra, and NMR data (proton and carbon-13) for a number of compounds. 

Peter Lundberg, University of Umea, Sweden, has compiled a very complete list of educational NMR software. It is available from a number of sites, including http //atlas.chemistry.uakron.edu 8080/cdept.docs/ MAGNET/sware.html and the Bruker Web sites. http //www.aist.go.jp/RIODB/SDBS/menu-e.html Integrated Spectral DataBase System for Organic Compounds, National Institute of Materials and Chemical Research, Tsukuba, Ibaraki 305-8565, Japan. This database includes infrared, mass spectra, and NMR data (proton and carbon-13) for a number of compounds. http //www. chem. ucla. edu/ webnmr/... 

Spectral Database for Organic Compounds (SDBS) is an integrated spectral database system for organic compounds, which includes six different types of spectra, an electron-impact mass spectrum (EI-MS), a Fourier transform infrared spectrum (FT-IR), a H NMR spectrum, a NMR spectrum, a laser Raman spectrum, and an electron spin resonance (ESR) spectrum [72], SDBS is maintained by the National Metrology Institute of Japan (NMU) under the National Instimte of Advanced Industrial Science and technology (AIST). Currently, EI-MS spectrum, H NMR spectrum, C NMR spectrum, FT-IR spectrum, and the compound dictionary are... 

During the first half of the twentieth century many workers extended the spectral database of organic compounds and assigned spectral features to functional groups. While infrared spectroscopy had moved away from being a scientific curiosity it was used very little suitable spectrometers did not exist and few chemists had access to what instruments there were. Over half a century was to pass between Coblentz s original work and the routine use of spectroscopy as a tool indeed, two-thirds of a century would pass before routine NIR measurement made its debut. 

The National Institute of Standards and Technology (NIST) has developed the WehBook. This site includes gas-phase infrared spectra and mass spectral data for compounds. This site is not as useful as the SDBS website for infrared spectra, since most of the listed infrared spectra were determined in the gas phase rather than as a liquid phase. The mass spectral database is more useful. 

Spectral data banks There are several which offer real spectra of several tens of thousands of compormds in infrared, proton and carbon-13 NMR, and mass spectrometry. For example The Aldridi/ACD Library of FT-NMR Spectra (12 000 spectra) Nicolet/Aldridi FT-IR Condensed Phase Library (18500 spectra) NIST/EPA/NIH Mass Spectral Database (130000 spectra). 

A computer file of about 19,000 peak wavenumbers and intensities, along with search software, is distributed by the Infrared Data Committee of Japan (IRDC). Donated spectra, which are evaluated by the Coblentz Society in coUaboration with the Joint Committee on Atomic and Molecular Physical Data (JCAMP), are digitized and made avaUable (64). Almost 25,000 ir spectra are avaUable on the SDBS system developed by the NCLl as described. A project was initiated at the University of California, Riverside, in 1986 for the constmction of a database of digitized ftir spectra. The team involved also developed algorithms for spectra evaluation (75). Other sources of spectral Hbraries include Sprouse Scientific, Aston Scientific, and the American Society for Testing and Materials (ASTM). 

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