@article {162,
	title = {A red zwitterionic co-crystal of acetaminophen and 2,4-pyridinedicarboxylic acid.},
	journal = {Journal of Pharmaceutical Sciences},
	volume = {99},
	year = {2010},
	note = {CAPLUS AN 2010:933031(Journal)},
	month = {2010///},
	pages = {3676 - 3683},
	publisher = {Wiley-Liss, Inc.},
	abstract = {We report on a co-crystal of acetaminophen (APAP) and 2,4-pyridinedicarboxylic acid (PDA).  The co-crystal was discovered by screening using the soln.-mediated phase transformation (SMPT) technique.  Despite the bulk solids of each component being white in color, the new co-crystal phase exhibited a red color.  The new phase was analyzed using single-crystal X-ray diffraction and identified as (APAP){\textperiodcentered}(PDA){\textperiodcentered}(1).  Structural anal. revealed PDA to exist in a hitherto unreported zwitterionic form in the co-crystal.  A structural anal. of pure PDA revealed the presence of the zwitterion form in (PDA){\textperiodcentered}(H2O) (2), as well.  The components of 1 self-assemble as a three-dimensional (3D) hydrogen-bonded network with a pronounced 2D structure.  The origin of the red color was investigated using d. functional theory calcns., which demonstrate a decreasing π-π* sepn. involving the components of the solid. {\textcopyright} 2010 Wiley-Liss, Inc. and the American Pharmacists Assocn. J Pharm Sci 99:3676-3683, 2010. [on SciFinder(R)]},
	keywords = {zwitterion cocrystal acetaminophen pyridinedicarboxylate crystn crystal engineering solid state},
	isbn = {0022-3549},
	author = {Sander, John R. G. and Bucar, Dejan-Kresimir and Henry, Rodger F. and Baltrusaitis, Jonas and Zhang, Geoff G. Z. and MacGillivray, Leonard R.}
}
