@article {UGC-New Delhi},
	title = {Single crystal X-ray structure of lawsone anion: evidence for coordination of alkali metal ions and formation of naphthosemiquinone radical in basic media},
	journal = {Journal of Molecular Structure},
	volume = {1010},
	number = {3-4},
	year = {2012},
	month = {FEB},
	pages = {38-45},
	publisher = {ELSEVIER SCIENCE BV},
	address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS},
	abstract = {<p>2-hydroxy-1,4-naphthoquinone; Lawsone (Lw) is a natural compound found in henna leaves. The reaction of lawsone with {\textquoteleft}Na{\textquoteright} 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 {\textquoteleft}Na{\textquoteright} and {\textquoteleft}K{\textquoteright} 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.</p>},
	keywords = {2-Hydroxy-1, 4-naphthoquione, EPR, hydrogen bonding, Lawsone, Naphthosemiquinone radicals},
	issn = {0022-2860},
	doi = {10.1016/j.molstruc.2011.11.015},
	author = {Salunke-Gawali, Sunita and Kathawate, Laxmi and Shinde, Yogesh and Puranik, Vedavati G. and Weyhermueller, Thomas}
}
@article { ISI:000330147900013,
	title = {Synthesis, characterization and molecular structures of homologated analogs of 2-bromo-3-(n-alkylamino)-1,4-napthoquinone},
	journal = {Journal of Molecular Structure},
	volume = {1056},
	year = {2014},
	month = {JAN},
	pages = {97-103},
	publisher = {ELSEVIER SCIENCE BV},
	address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS},
	abstract = {<p>Four analogues of 2-bromo-3-(n-alkylamino)-1,4-napthoquinone (where n-alkyl is methyl in L-1Br, ethyl in L-2Br, propyl in L-3Br and butyl in L-4Br) are synthesized and characterized. A reaction mechanism is proposed for the formation of L-1 Br to L-4Br from the starting material 2,3-dibromo-1,4-naphthoquinone. The v(N-H) frequency in the FT-IR spectra is affected by the intramolecular hydrogen bonding in L-1Br to L-4Br and is observed similar to 3267 cm(-1) in L-2Br. A shift of similar to 25 cm(-1) is observed in the v(C-Br) frequency in all the compounds as compared to 2,3-dibromo-1,4-naphthoquinone (627 cm(-1)). A broad charge transfer band is observed between 400 and 600 nm in the UV-Vis spectra, which imparts red colour to all the compounds. Molecular structures of L-2Br and L-3Br were studied by single crystal X-ray diffraction studies. Molecules of L-2Br crystallize in Pca2(1), whereas the molecule L-3Br crystallizes in the P-1 space group. Molecules of L-2Br forms a polymeric chain through N-H...O interaction and forms beautiful butterfly like arrangement of molecules when viewed down the {\textquoteleft}a{\textquoteright} axis. Ladder like polymeric chain of molecules is observed in L-3Br via C-H...O and N-H...O interactions. Every alternating neighbouring chains of L-3Br, show pi-pi stacking interactions between the quinonoid rings of the molecules, however this interaction is not observed in L-2Br. (C) 2013 Elsevier B.V. All rights reserved.</p>},
	keywords = {2, 3-Dibromo-1, 4-naphthoquinone, Aminonaphthoquinone, hydrogen bonding, Michael addition, pi-pi stacking},
	issn = {0022-2860},
	doi = {10.1016/j.molstruc.2013.10.016},
	author = {Salunke-Gawali, Sunita and Pawar, Omkar and Nikalje, Milind and Patil, Rishikesh and Weyhermueller, Thomas and Puranik, Vedavati G. and Konkimalla, V. Badireenath}
}
