ISSN:
1572-8854
Keywords:
4-iminecinnoline analogs of quinolones
;
X-ray structure
;
intramolecular hydrogen bond
;
packing
Source:
Springer Online Journal Archives 1860-2000
Topics:
Geosciences
,
Physics
Notes:
Abstract Crystal structures of hydrochlorides of 7-chloro- and 7-methyl-4-iminecinnoline analogs of antibacterial quinolones have been determined by X-ray diffraction methods. The cell parameters for the 7-chloro (1) analog in the space group P21/c are a = 9.061(1), b = 19.062(1), c = 7.310(1)Å, β = 104.92(1)°, Z = 4, and D calc = 1.569 g/cm3 and for the 7-methyl (2) analog in the space group P $${\bar 1}$$ are a = 7.277(5), b = 9.080(5), c = 10.058(5) Å, α = 106.10(1), β = 102.38(1), γ = 90.18(1)°, Z = 2, and D calc = 1.429 g/cm3. Despite geometrical equivalency of methyl and chlorine and some resemblance of their packings, the crystal structures are not isostructural. Each compound forms a strong intramolecular hydrogen bond between protonated 4-imine (a donor) and 3-carboxylic (an acceptor) groups. Compounds with a similar bond, but with reversed functionality and orientation of the 3-carboxylic group, form common quinolones, being mostly 4-oxoquinoline-3-carboxylic acids. The difference should exclude chemical affinity of 4-imine analogs to the guanine base of a bacterial DNA in DNA-gyrase complex, as proposed by Shen et al. 2 for 4-oxoquinoline-3-carboxylic acids showing antibacterial activity. Also the free acidic function of a carboxyl group may significantly lower permeability of 4-imine-3-carboxylic analogs of quinolones. Surprisingly, they have demonstrated antibacterial activity comparable with that of nalidixic acid.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1009575821102
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