DFT and FT-IR analyses of hydrogen bonding in 3-substistuted-3-oxo-arylhydrazonopropanenitriles.

Ab initio calculations, FT-IR and X-ray crystal analysis, indicated that the most stable configuration of 3-oxo-2-(phenylhydrazono)-3-(thien-2-yl)-propionitrile is the anti phenylhydrazone structure 1. Stability of such a conformation, over the possible E-form, 2, that would be stabilized by intramolecular hydrogen bonding, is due to interaction between electron-pair domains of the N, S and O atoms. However, the simulated and experimental IR frequency data indicated intermolecular hydrogen bonding between NH and CN, the latter being lowered to 2214 cm(-1).

Cetirizine dihydrochloride interaction with some diclofenac complexes.

IR, 1H NMR and mass spectrometric studies showed that cetirizine dihydrochloride interacted strongly with diclofenac sodium, even when the latter was metal bound, forming high molecular weight stable adducts. These new formations were unaffected by the possible steric constraints that may exist because of coordination yet did not have the power to break the formed coordinate bonds. The formed ionic bond took place between the carbonyl ion of diclofenac and the positively charged piperazine ring of cetirizine, forming a ternary compound in the case of the divalent metal clusters (Ca{(dic)2.

Drug-drug interaction between diclofenac, cetirizine and ranitidine.

The interactions between diclofenac (1), cetirizine (2) and ranitidine (3) were investigated by thermal analyses and UV, IR and (1)H NMR spectroscopic studies. In aqueous solution interaction occurred only between 1 and 2, yielding a high molecular weight (1:1), water insoluble ionic salt. Weak charge transfer (CT) interaction exists between the doubly charged piperazine moiety in 2, acting as an electron acceptor and (1).