Table 2. Absorption and emission properties of 2 and 4b–d in the presence of ct DNA and 22AG .

Derivative	λ abs a /nm	lg ε b	Δλ abs,ct-DNA c /nm	Δλ abs, 22AG c /nm	λ fl d /nm	Δλ fl,ct-DNA e /nm	Δλ fl, 22AG e /nm	K ct-DNA f /105 M–1	K 22AG f /105 M–1
2	421 g	4.16 g	— h	3 g	472 g	— h	— h	7.0 i	50 g
4b	482	4.03	28	0	480	215	215	2.3	0.33
4c	435	4.08	11	14	492	15	9	— h	— h
4d	435	4.07	11	14	486	13	13	— h	— h

^aLong-wavelength absorption maximum; c = 20 μM in phosphate buffer (c _Na⁺ = 16 mM, pH 7.0; with 10% v/v DMSO).

^bMolar extinction coefficient.

^cShift of the long-wavelength absorption maximum between free and bound ligand.

^dLong-wavelength emission maximum; c = 20 μM in phosphate buffer (c _Na⁺ = 16 mM, pH 7.0; with 10% v/v DMSO); λ _ex = 400 nm.

^eShift of the long-wavelength emission maximum between free and bound ligand.

^fBinding constant K determined from fluorimetric titrations.

^g Ref. 26.

^hNot determined.

ⁱ Ref. 18.