英语翻译It should be noted that although shifts in the 1H NMRspe

英语翻译
It should be noted that although shifts in the 1H NMR
spectrum of 3 in CD3CN provide evidence of p-stacking at
high concentrations (1 to 11 mM,Fig.S3,ESIw),similar to
related systems,12 these interactions are negligible at concentrations
r0.5 mM in this solvent.The absorption and luminescence
spectra of 3 were collected at concentrations well below
this value (5–70 mM),such that the photophysical data are
expected to correspond to monomeric 3 in solution.
The transient absorption spectra of 3 collected in the ns to
ms timescale are similar to that previously reported for the
complex and to that of the free dppn ligand,featuring a strong
absorption band at 540 nm with t = 33 \3 5 ms in CH3CN
(Fig.S4,ESIw).9b A lifetime of 18 \3 2 ms was measured
for free dppn in CHCl3,typical of 3pp* excited states of
polycyclic aromatic heterocycles.13 As previously discussed,9b
the lowest-energy excited state of 3 is therefore assignedas dppn-localized 3pp*.In contrast,2 is well known to exhibit
3MLCT as the lowest excited state (t = 750 ns) in CH3CN.14
Ultrafast transient absorption spectra were collected to
ascertain the presence of an emissive 3MLCT state and nonemissive
3pp* in the same complex.Although not
unprecedented,8,9 such behavior is unusual.The signal at
370 nm is known to be associated with the 3MLCT state,
and its intensity remains relatively constant from 1 to 20 ps
(Fig.2a).The 3pp* absorption at 536 nm grows at early times
with a risetime of 2.1(4) ps,then remains unchanged from
20 ps to 2 ns (Fig.2).Some contribution from the broad
3MLCT absorption in the 500–650 nm range is also expected,
similar to that of 2 (Fig.S5,ESIw).Since the 3MLCT signal
does not decrease while that of the 3pp* state increases at early
times (Fig.2a),it may be concluded that the latter is not
populated from the former.Therefore,it is believed that
intersystem crossing (isc) results in population of both the
3MLCT and 3pp*,as previously described for related
systems.15,16 A slight decrease in the 3MLCT signal is observed
from 20 ps to 1 ns,which can be associated with the decay of
that state and is also observed for 2 (Fig.S5,ESIw).

应该指出,虽然3在CD3CN中的1H 核磁共振谱的漂移提供了在高浓度（1到11mM,图S3,ESI）下π堆积的证据,与有关的系统相似12,这些互作用在这种溶剂中浓度≤0.5mM时可忽略不计.3的的吸收和发光谱是在在明显低于此值（5－70μM）的浓度下采集的,这样,光物理数据预计相应于溶液中的单体3.
在ns到μs时间量度中采集的3的瞬态吸收谱类似于以前对该络合物报道的瞬态吸收谱,并类似于游离dppn配体的瞬态吸收谱,体现了在CH3CN中τ＝33±5μs时于540nm处强吸收带的特点（图S4,ESI）9b.对于CHCl3中的游离dppn,测得了18±2μs的寿命时间,这是多环芳香杂环的3ππ*激发态典型的13.如以前讨论的那样9b,3的最低能级激发态因此被指定为dppn局限的3ππ*.与此相反,众所周知2在CH3CN中显示3MLCT作为最低激发态（τ＝750ns）14.
我们采集了超快瞬态吸收谱,以确定同一络合物中发射3MLCT态和非发射3ππ*态的存在.虽然不是没有先例的8,9,但这一性状是不寻常的.在370nm处的信号已知与3MLCT态相关,其强度从1到20ps保持相对恒定（图2a）.在536nm处的3ππ*吸收在早期随着2.1（4）ps的上升时间增长,然后从20ps到2ns保持不变（图2）.来自500－650nm范围宽的3MLCT吸收的某些贡献也是预料之中的,这与2的情况类似（图S5,ESI）.由于3MLCT信号不下降,而3ππ*态的吸收在早期增加（图2a）,所以可以得出结论,后者没有被前者充满（populated）.因此,人们相信,系统间的交叉（isc)导致了3MLCT和3ππ*两种态的群体,就像前面对有关系统描述的那样15,16.从20ps到1ns观察到了3MLCT信号的少许下降,这可以与该态的衰落相关联,而且对2也观察到了（图S5,ESI）.