Synthon identification in co-crystals and polymorphs with IR spectroscopy. Primary amides as a case study

Synthon identification in co-crystals and polymorphs with IR spectroscopy. Primary amides as a case study

CrystEngComm, 2013, Advance Article
DOI: 10.1039/C3CE40286J, Paper
Arijit Mukherjee, Srinu Tothadi, Shaunak Chakraborty, Somnath Ganguly, Gautam R. Desiraju
IR marker bands are used to identify multiple synthons in polymorphs and co-crystals

IR spectroscopy has been widely employed to distinguish between different crystal forms such as polymorphs, clathrates, hydrates and co-crystals. IR has been used to monitor co-crystal formation and single synthon detection. In this work, we have developed a strategy to identify multiple supramolecular synthons in polymorphs and co-crystals with this technique.

The identification of multiple synthons in co-crystals with IR is difficult for several reasons. In this paper, a four step method involving well assigned IR spectral markers that correspond to bonds in a synthon is used. IR spectra of three forms of the co-crystal system, 4-hydroxybenzoic acid:4,4′-bipyridine (2 : 1), show clear differences that may be attributed to differences in the synthon combinations existing in the forms (synthon polymorphism).

These differences were picked out from the three IR spectra and the bands analysed and assigned to synthons. Our method first identifies IR marker bands corresponding to (covalent) bonds in known/model crystals and then the markers are mapped in known co-crystals having single synthons. Thereafter, the IR markers are queried in known co-crystals with multiple synthons.

Finally they are queried in unknown co-crystals with multiple synthons. In the last part of the study, the N–H stretching absorptions of primary amides that crystallize with the amide dimers linked in a ladder like chain show two specific absorptions which are used as marker absorptions and all variations of this band structure have been used to provide details on the environment around the dimer. The extended dimer can accordingly be easily distinguished from the isolated dimer.

CrystEngComm, 2013, Advance Article

Arijit mukherjee et al
DOI: 10.1039/C3CE40286J
Received 14 Feb 2013, Accepted 28 Mar 2013
First published online 02 Apr 2013

link

http://pubs.rsc.org/en/Content/ArticleLanding/2013/CE/C3CE40286J?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+rss%2FCE+%28RSC+-+CrystEngComm+latest+articles%29

Advertisements

2 thoughts on “Synthon identification in co-crystals and polymorphs with IR spectroscopy. Primary amides as a case study

  1. I know this if off topic but I’m looking into starting my own blog and was curious what all is needed to get set up?
    I’m assuming having a blog like yours would cost
    a pretty penny? I’m not very web smart so I’m not 100% sure.

    Any recommendations or advice would be greatly appreciated.
    Thank you

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s