. Author manuscript; available in PMC: 2009 Feb 6.

Published in final edited form as: J Med Chem. 2008 Jun 26;51(12):3466–3479. doi: 10.1021/jm701478a

Table 2.

Calculated and Measured pKa for representative compounds

	SPARC Approx.^a			Experimental^c

Compound	pK_a1^b	pK_a2^b	pK_a3^b	pK_a1^b	pK_a2^b
CQ	6.3	9.3	-	8.6	9.8
8	6.6	9.3	-	8.5	9.8
13	3.7	9.4	-	4.5	9.8
18	5.0	9.3	-	4.1	9.5
22	5.0	9.9	9.9	nd	nd

. SPARC is an online pK_a approximation program developed at the University of Georgia (S.W. Karickhoff, L.A.Carreira and S.H. Hilal)

. pK_a1 or pK_a3 represent the pK_a of side chain tertiary N and pK_a2 represents the pK_a of quinolyl N

. The pKa measurements represent an average of three determinations performed by acid/base titrations at room temperature. See also ref 61 for previous determination of CQ pKa.

nd = not determined.