The Journal of Physical Chemistry B
Article
functional with a 6-31G** split-valence basis set. The same
level of calculation was also performed for geometry
optimization, as this functional is suitable for non-Coulomb
interactions and provides a faithful representation of charge
transfer excitation.59
was washed several times with cold diethyl ether and finally
dried in vacuo to obtain DASA-Mel as a pure pink compound.
1H NMR (400 MHz, CDCl3): δ 1.70 (s, 6H), 3.25, 3.41 (s,
3H), 3.79−3.86 (m, 2H), 4.49−4.59 (m, 2H), 5.86−5.92 (t,
1H), 6.25−6.34 (m, 1H), 6.94−6.99 (m, 2H), 7.77−7.83 (m,
2H), 8.22−8.30 (m, 2H), 8.55−8.62 (m, 2H), and 11.23 (s,
1H). 13C (100 MHz, CDCl3): δ 27.0, 37.4, 38.2, 44.4, 44.9,
57.1, 64.5, 83.3, 92.7, 102.3, 103.9, 121.9, 127.5, 128.4, 130.0,
132.2, 135.3, 142.0, 145.6, 147.5, 149.7, 156.9, 164.6 and
167.2. HRMS (m/z) found 477.1666, calculated for [M + H+]
Synthesis of DASA-Bar. Briefly, 10 mL of a THF solution
of Nap-N(Me) (0.254 g, 1.0 mmol) was added dropwise into a
suspension solution (15 mL of THF) of DBar (0.206 g, 1.0
mol) under stirring. The mixture was stirred for 10 min at
room temperature, followed by a reduction of the temperature
of the mixture to 0 °C for another 30 min. The reaction
mixture was then filtered to collect the precipitate. The solid
was washed several times with cold diethyl ether and finally
dried in vacuo to obtain DASA-Bar as a pure violet compound.
1H NMR (400 MHz, CDCl3): δ 3.03, 3.10 (s, 3H), 3.62−3.76
(m, 2H), 4.39−4.52 (m, 2H), 5.89−5.95 (t, 1H), 6.40−6.43
(d, 1H), 7.00−7.12 (m, 2H), 7.76−7.80 (m, 2H), 8.23−8.29
(m, 2H), and 8.57−8.64 (m, 2H). 13C (100 MHz, CDCl3): δ
37.0, 38.0, 46.7, 47.9, 58.1, 64.5, 82.7, 91.2, 105.1, 122.4, 126.9,
128.5, 130.7, 131.6, 134.5, 143.9, 148.9, 150.7, 152.9, 158.6,
159.9, 166.5, and 170.5. HRMS (m/z) found 461.1455,
calculated for [M + H+] 461.1461, where M was C26H25N2O7
Synthesis of Compound Nap-N(Me). An ethanolic (10
mL) solution of N′-methyl-ethane-1,2-diamine (96 μL, 1.1
mmol) was added dropwise to 30 mL of an ethanolic solution
of 1,8-naphthalic anhydride (0.198 g, 1.0 mmol) under stirring.
The solution mixture was stirred for 30 min and then allowed
to reflux for another 2 h. After completion of the reaction
(monitored by TLC), the solvent was evaporated using a
rotary evaporator. A white crystalline product was obtained
after washing several times with cold ethanol. The isolated
compound was dried in vacuum to give a pure crystalline
1
compound Nap-N(Me) (isolated yield, 91%). H NMR (400
MHz, CDCl3): δ 2.48 (s, 3H), 2.96−2.99 (t, 2H), 4.33−4.36
(t, 2H), 7.70−7.74 (t, 2H), 8.17−8.19 (d, 2H), and 8.56−8.58
(d, 2H). 13C (100 MHz, CDCl3): δ 36.2, 39.7, 49.8, 122.5,
126.8, 128.1, 131.2, 131.5, 133.9, and 164.4. HRMS (m/z)
found 255.1133, calculated for [M + H+] 255.1126, where M
was C15H14N2O2 (see the Supporting Information (SI) Figures
DMel and DBar (Scheme 2) were synthesized by the
reaction of Meldrum acid and barbituric acid with furfural,
respectively, according to reported procedures.3
Scheme 2. Synthetic Routes for DASA-Mel and DASA-Bar
aConditions
and the Isomeric Open Forms
Encapsulation of DASAs. Briefly, 0.005 mmol of BB was
dissolved in 2.0 mL of D2O, and the solution was added to
0.01 mmol of DASA (guest) molecules separately. This
suspension was stirred for 7 days at room temperature.
Then, the resulting solution was centrifuged to obtain a clear
solution. On the other hand, in the competitive encapsulation
experiment, we followed the same procedure as described
earlier, except that we used DASA-Mel (0.01 mmol) and
DASA-Bar (0.01 mmol) together as a mixture.
RESULTS AND DISCUSSION
■
The macrocycle BB was synthesized following the reported
procedure56 and characterized by H NMR spectroscopy to
1
confirm its purity (Figure S1, see the SI). DASA-Mel and
DASA-Bar were synthesized following a stepwise procedure
(Scheme 2). First, naphthalimide and N-methylethylenedi-
amine were mixed in a 1:1.1 molar ratio and refluxed for 2 h in
ethanol. The solvent was removed and washed several times
with ethanol to obtain the pure product as a white powder and
1
was characterized by H, 13C NMR, and high-resolution mass
The furan adducts of Meldrum acid and barbituric acid were
synthesized as yellow and green powders, respectively,
following a previously reported method.3 Finally, the furan
adducts were separately added dropwise to a THF solution of
2-(2-(methylamino)ethyl)-1H-benzo[de]isoquinoline-1,3(2H)
dione (1:1 molar ratio) under stirring at 0 °C to obtain pink
and purple precipitates of DASA-Mel and DASA-Bar,
respectively. The precipitates were filtered and washed thrice
with cold diethyl ether and dried in vacuum. The DASAs were
well characterized by 1H, 13C NMR, and HRMS spectroscopic
aConditions
used: (a) EtOH and reflux; (b) Meldrum acid, water, and
75 °C for 2 h; (c) barbituric acid, water, and room temperature for 3
h; and (d) Nap-N(Me), tetrahydrofuran (THF), and 0 °C.
Synthesis of DASA-Mel. Briefly, 10 mL of a THF solution
of Nap-N(Me) (0.254 g, 1.0 mmol) was added dropwise into a
suspension solution (10 mL of THF) of DMel (0.222 g, 1.0
mol) under stirring. The mixture was stirred for 10 min at
room temperature, followed by a reduction of the temperature
of the mixture to 0 °C for another 30 min. The reaction
mixture was then filtered to collect the precipitate. The solid
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J. Phys. Chem. B 2021, 125, 7222−7230