Single crystal X-ray structure of lawsone anion: evidence for coordination of alkali metal ions and formation of naphthosemiquinone radical in basic media
| Title | Single crystal X-ray structure of lawsone anion: evidence for coordination of alkali metal ions and formation of naphthosemiquinone radical in basic media |
| Publication Type | Journal Article |
| Year of Publication | 2012 |
| Authors | Salunke-Gawali, S, Kathawate, L, Shinde, Y, Puranik, VG, Weyhermueller, T |
| Journal | Journal of Molecular Structure |
| Volume | 1010 |
| Pagination | 38-45 |
| Date Published | FEB |
| ISSN | 0022-2860 |
| Keywords | 2-Hydroxy-1, 4-naphthoquione, EPR, hydrogen bonding, Lawsone, Naphthosemiquinone radicals |
| Abstract | 2-hydroxy-1,4-naphthoquinone; Lawsone (Lw) is a natural compound found in henna leaves. The reaction of lawsone with `Na' metal (Lw-1), CH3COONa (Lw-2), NaOH (Lw-3), KOH (Lw-4), K2CO3 (Lw-5) and Tris(hydroxymethyl)aminomethane (Lw-6) were studied. Red orange solids obtained for Lw-1 to Lw-6 are characterized by Elemental Analysis, FTIR, (HNMR)-H-1 and EPR studies. The results reveal the coordination of alkali metals `Na' and `K' to lawsone anion. The single crystal X-ray structure of Lw-6 was solved and it crystallizes in triclinic space group P-1 with extensive hydrogen bonding network of C-H center dot center dot center dot O, N-H center dot center dot center dot O and O-H center dot center dot center dot O between cations and anions. Polycrystalline powder X-band EPR spectra of Lw-1 to Lw-5 shows signals similar to 2.004 at 133 K, while Lw-6 is EPR silent. The naphthosemiquinone (NSQ) radical formed in Lw-2 to Lw-5, is due to disproportion reaction of catechol and naphthoquinone. (C) 2011 Elsevier B.V. All rights reserved. |
| DOI | 10.1016/j.molstruc.2011.11.015 |
| Type of Journal (Indian or Foreign) | Foreign |
| Impact Factor (IF) | 1.404 |