Chemistry Reference
In-Depth Information
N
N
NH
HN
N
N
(i) bipp
N
N
N
N
H
3
C
N
N
N
N
H
2
C
N
N
N
N
H
3
C
n
(j) tpphz
(k) bb
n
N
N
Figure 11.2
Continued
4+
S
N
N
S
O
(dpq)
2
Ru
Ru(dpq)
2
N
N
Figure 11.3
Representation of [{Ru(dpq)
2
}
2
(
m
-phen-5-SOS-5-phen)]
4+
.
53
The introduction of some greater degree of fl exibility between the two bridging
dppz moieties was found to result in more expedient threading. The complex [m -
C4(cpdppz)
2
(phen)
4
Ru
2
]
4+
(C4(cpdppz)
2
=
N,N
′
- bis(12 - cyano - 12,13 - dihydro - 11H - 8 -
cyclopenta[
b
]dipyrido[3,2 -
h
:2
-
j
]phenazine - 12 - carbonyl) - 1,4 - diaminobutane;
Figure 11.2h) threaded through the DNA helix such that the ancillary phen ligands
sat in the minor groove while the fl exible linker occupied the major groove.
60,61
Due
to the bis-intercalative nature of the bridging ligand, the complex bound with an
affi nity several orders of magnitude greater than the analogous mononuclear species
[Ru(phen)
2
(dppz)]
2+
(
′
,3
′
10
10
M
− 1
versus 10
6
M
− 1
).
61
The threading process is believed
to require extensive conformational changes to the DNA helix, including the break-
ing and re-forming of base pairs. This is supported by the observation that, as with
∼
