@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 = {

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.

}, 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:000323468500032, title = {Synthesis and molecular structure of a zinc complex of the vitamin K-3 analogue phthiocol}, journal = {Journal of Molecular Structure}, volume = {1048}, year = {2013}, month = {SEP}, pages = {223-229}, publisher = {ELSEVIER SCIENCE BV}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

The complex [Zn(phthiocol)(2)(H2O)(2)]; 1, where phthiocol is 2-hydroxy-3-methyl-1,4-naphthoquinone, has been synthesized and characterized by elemental analysis, FT-IR, H-1 NMR, UV-vis spectroscopy, thermogravimetric (TG) analysis, electrochemical and single crystal X-ray diffraction studies. The v(C=O) stretch shifts to lower frequencies upon complexation of phthiocol to Zn2+. H-1 NMR spectra show an upfield shift of the benzenoid ring protons in 1. There is a bathochromic shift of the LMCT band in the UV-vis spectra of 1. Single crystal X-ray structure of 1 show distorted octahedral geometry around Zn2+. Two phthiocol ligands are in plane with the metal, while water molecules are trans to this plane. Coordination of deprotonated phthiocol ligands is {\textquoteleft}trans, trans{\textquoteright} to Zn2+. Intra as well as intermolecular interactions are observed in 1. Molecules of 1 show three dimensional network through C-H center dot center dot center dot O and O-H center dot center dot center dot O interactions. Additional anodic peaks are observed in cyclic voltammogram of phthiocol ligand due to oxidation of reduced species formed during reduction. One-electron reduction of 1 is shown to be reversible and DFT studies define this redox event as ligand-centered. (c) 2013 Elsevier B.V. All rights reserved.

}, keywords = {hydrogen bonding, Naphthoquinone, Phthiocol, Trans coordination, Vitamin K-3, Zinc complex}, issn = {0022-2860}, doi = {10.1016/j.molstruc.2013.05.057}, author = {Kathawate, Laxmi and Sproules, Stephen and Pawar, Omkar and Markad, Ganesh and Haram, Santosh K. and Puranik, Vedavati G. and Salunke-Gawali, Sunita} } @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 = {

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.

}, 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} } @article {46864, title = {Synthesis and biological activity of imidazole based 1,4-naphthoquinones}, journal = {New Journal of Chemistry}, volume = {44}, year = {2020}, month = {MAY }, pages = {6889-6901}, type = {Article}, abstract = {

Design and development of drugs in multi-drug resistant (MDR) infections have been of growing interest. We report the syntheses, and antibacterial and antifungal activities of imidazole-based 1,4-naphthoquinones (I-1 to I-4; 1-alkyl-2-methyl-1H-naphtho[2,3-d]imidazole-4,9-dione (alkyl = methyl to butyl)) and their precursors (B-3; N-(3-chloro-1,-dioxo-1,4-dihydronaphthalen-2-yl)acetamide) and A-1 to A-4; N-(3-(alkylamino)-1,4-dioxo-1,4-dihydronaphthalen-2-yl)acetamide (alkyl = methyl to butyl). Crystal structures of B-3, A-1 to A-3 and I-2 to I-4 were obtained through single crystal X-ray diffraction experiments. Electronic structure and charge distribution have further been characterized with the use of Density Functional Theory. Seven of these derivatives display a broad spectrum of antibacterial activity against few selected bacterial strains (Gram-positive and Gram-negative). As demonstrated MIC values with B-2 and B-3 against bacterial isolates were 8-64 mu g ml(-1) and those against pathogenic yeast, C. albicans, were observed in the range of 128-256 mu g ml(-1). MIC data of these derivatives suggest them to be promising against pathogens.

}, issn = {1144-0546}, doi = {10.1039/c9nj04339j}, author = {Choudhari, Dinkar and Salunke-Gawali, Sunita and Chakravarty, Debamitra and Shaikh, Samir R. and Lande, Dipali N. and Gejji, Shridhar P. and Rao, Pradeep Kumar and Satpute, Surekha and Puranik, Vedavati G. and Gonnade, Rajesh} }