1. Two polymorphs and the diethylammonium salt of the barbiturate eldoral
Thomas Gelbrich, Denise Rossi, Ulrich J Griesser Acta Crystallogr C. 2012 Feb;68(Pt 2):o65-70. doi: 10.1107/S0108270111055120. Epub 2012 Jan 6.
Polymorph (Ia) of eldoral [5-ethyl-5-(piperidin-1-yl)barbituric acid or 5-ethyl-5-(piperidin-1-yl)-1,3-diazinane-2,4,6-trione], C(11)H(17)N(3)O(3), displays a hydrogen-bonded layer structure parallel to (100). The piperidine N atom and the barbiturate carbonyl group in the 2-position are utilized in N-H···N and N-H···O=C hydrogen bonds, respectively. The structure of polymorph (Ib) contains pseudosymmetry elements. The two independent molecules of (Ib) are connected via N-H···O=C(4/6-position) and N-H···N(piperidine) hydrogen bonds to give a chain structure in the [100] direction. The hydrogen-bonded layers, parallel to (010), formed in the salt diethylammonium 5-ethyl-5-(piperidin-1-yl)barbiturate [or diethylammonium 5-ethyl-2,4,6-trioxo-5-(piperidin-1-yl)-1,3-diazinan-1-ide], C(4)H(12)N(+)·C(11)H(16)N(3)O(3)(-), (II), closely resemble the corresponding hydrogen-bonded structure in polymorph (Ia). Like many other 5,5-disubstituted derivatives of barbituric acid, polymorphs (Ia) and (Ib) contain the R(2)(2)(8) N-H···O=C hydrogen-bond motif. However, the overall hydrogen-bonded chain and layer structures of (Ia) and (Ib) are unique because of the involvement of the hydrogen-bond acceptor function in the piperidine group.
2. Charge-reversal nanoparticles: novel targeted drug delivery carriers
Xinli Chen, Lisha Liu, Chen Jiang Acta Pharm Sin B. 2016 Jul;6(4):261-7. doi: 10.1016/j.apsb.2016.05.011. Epub 2016 Jun 8.
Spurred by significant progress in materials chemistry and drug delivery, charge-reversal nanocarriers are being developed to deliver anticancer formulations in spatial-, temporal- and dosage-controlled approaches. Charge-reversal nanoparticles can release their drug payload in response to specific stimuli that alter the charge on their surface. They can elude clearance from the circulation and be activated by protonation, enzymatic cleavage, or a molecular conformational change. In this review, we discuss the physiological basis for, and recent advances in the design of charge-reversal nanoparticles that are able to control drug biodistribution in response to specific stimuli, endogenous factors (changes in pH, redox gradients, or enzyme concentration) or exogenous factors (light or thermos-stimulation).
3. Diethyl-ammonium anilino(meth-oxy)-phosphinate
Zhiyong Fu, Xiaoling Liu Acta Crystallogr Sect E Struct Rep Online. 2008 Oct 22;64(Pt 11):o2171. doi: 10.1107/S1600536808033023.
The title compound, [Et(2)NH(2)][(EtO)PO(2)(C(6)H(5)NH)] or C(4)H(12)N(+)·C(8)H(11)NO(3)P(-), is a molecular salt with two anions containing PO(3)N groupings and two cations in the asymmetric unit. A network of N-H⋯O hydrogen bonds link the cations and anions into a two-dimensional network.
