@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 = {<p>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.</p>},
	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:000351969900008,
	title = {First naphthosemiquinone complex of K+ with vitamin K3 analog: experiment and density functional theory},
	journal = {Journal of Molecular Structure},
	volume = {1088},
	year = {2015},
	month = {MAY},
	pages = {56-63},
	publisher = {ELSEVIER SCIENCE BV},
	address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS},
	abstract = {<p>Synthesis and characterization of potassium complex of 2-hydroxy-3-methyl-1,4-naphthoquinone (phthiocol), the vitamin K3 analog, has been carried out using FT-IR, UV-Vis, H-1 and C-13 NMR, EPR, cyclic voltammetry and single crystal X-ray diffraction experiments combined with the density functional theory. It has been observed that naphthosemiquinone binds to two K+ ions extending the polymeric chain through bridging oxygens O(2) and O(3). The crystal network possesses hydrogen bonding interactions from coordinated water molecules showing water channels along the c-axis. C-13 NMR spectra revealed that the complexation of phthiocol with potassium ion engenders deshielding of C(2) signals, which appear at delta = similar to 14.6 ppm whereas those of C(3) exhibit up-field signals near delta similar to 6.9 ppm. These inferences are supported by the M06-2x based density functional theory. Electrochemical experiments further suggest that reduction of naphthosemiquinone results in only a cathodic peak from catechol. A triplet state arising from interactions between neighboring phthiocol anion lead to a half field signal at g = 4.1 in the polycrystalline X-band EPR spectra at 133 K. (C) 2015 Elsevier B.V. All rights reserved.</p>},
	keywords = {C-13 NMR, DFT, hydrogen bonding, Naphthosemiquinone, Phthiocol, Vitamin K3},
	issn = {0022-2860},
	doi = {10.1016/j.molstruc.2015.01.053},
	author = {Kathawate, Laxmi and Gejji, Shridhar P. and Yeole, Sachin D. and Verma, Prakash L. and Puranik, Vedavati G. and Salunke-Gawali, Sunita}
}
